What Should a Fully Charged 12 Volt Battery Read?

THE Nuts ON BATTERIES
*Important Items Highlighted/ Colored

Kickoff things outset. A 12-volt battery is not a 12-volt battery. Twelve volts is just a nominal, user-friendly term used to distinguish one bombardment from another. A fully-charged 12-volt battery, allowed to "residuum" for a few hours (or days) with no load beingness drawn from it (or charge going to it), will balance out its accuse and measure out about 12.6 volts between terminals.

When a bombardment reads only 12 volts nether the above weather condition, information technology's nearly fully depleted. Actually, if a battery'southward resting voltage is only 12.0 to 12.ane it means simply 20 to 25% of its useful energy remains. It'southward either a goner or it has been deep cycled, and a battery can only be deep-cycled a express number of times before it is indeed dead.

12-volt batteries supply useful energy but through a limited range — from over 14 volts (when fully charged and unrested) down to 10.5 volts in use/nether load (when lights dim, pumps groan and TV pictures get minor). No 12-volt battery will remain at over 14 volts for more than seconds unless it's being charged. The lowest limit is 10.five volts (used in testing) and plainly unsatisfactory in practical use. Experienced RVers try to apply no more than than xx% to 50% of the energy bachelor in a battery before recharging. That means they never let resting voltage get below 12.5. They never use more than 50% before recharging (resting volts of 12.3) except in an emergency. They know that, if resting voltage e'er reaches 12.i, they have deep-discharged i bike and that a battery is good for just so many cycles (from as low as 20 in an automotive bombardment to 180 in a golf game cart bombardment, with the typical RV/marine battery good for no more than xxx).

Watts = Volts x Amps example: 60W = 12V x A and lx ÷ 12 = v amps

Battery CHARGING VOLTAGE
Charging voltage is different. Some more basics: If y'all read articles on how electricity flows, you run into comparisons as to how water flows. This is okay upwardly to a point, but water besides flows by gravity. Electricity doesn't, it has to exist "pushed" (merely equally h2o has to sometimes exist pumped).

Y'all have to have more "juice" at one finish of a wire than you need at the output or electricity won't flow. The wire you pump electricity through and the connections in the lines resist the menstruation. You take to overpower it. Similarly, batteries accept an inherent resistance to take a accuse because of their chemical makeup. You have to force more electricity into a battery than information technology would similar to accept or it won't be fully charged. To charge a standard 12-volt bombardment, yous accept to bring it up to above 14 volts (amount varies with the type of battery).

When checking the batteries, (at residue) utilize these "Voltage Landmarks".

12.6 volts = 100%
12.5 volts = 70%
12.iii volts = 50%
11.4 volts = 20%

The typical wet-cell battery (atomic number 82 plates in a mixture of sulfuric acid and water) needs to exist charged up to virtually 14.+ volts in order to adequately distribute those funny piddling things called electrons through the plates. Once that's done, the battery tin can balance. As it does, the electrons distribute themselves and eventually balance out at 12.half dozen volts (more or less, depending on the blazon battery and its status). This is your starting signal.

More AMPS AND VOLTS
As mentioned earlier, you should but draw a battery down to about 12.3 volts before recharging . Apparently, there's more to it than that. Amperes are the measure of actual power available. They're usually converted to amp(ere) hours (AH). Think of information technology as the amount of (nominal) 12-volt power you can draw out of a battery for a certain amount of time. It's not just three-tenths of a volt. It's 12 (nominal) volts for a certain amount of time. The three-tenths stuff is nothing more than a difference in measurement — like the difference between iii-fourths of a tank of gas and a one-half tank.

Look at voltage as 2 things: First, a force that pushes electrons — 2d, equally a handy measurement.

Expect at amperes as 2 things: Starting time, a quantity of energy (like you lot would a gallon of gas) — Second, equally a handy measurement. From a (nominal again, don't forget) 12-volt tub of energy, y'all can extract just so many amperes of power.

Keep in heed that the laws of physics prevent you lot from getting more out of something than you put into it! Keep in listen that waste (those wires, battery contents and such) prevents you from taking out every bit much as yous put in. Proceed in mind that y'all're going to have to put in most 10% more electrical ability than yous utilize (high school physics). A battery banking company is like a "money" bank or checking account — if you lot repeatedly have more out than y'all put in, you'll eventually be in trouble.

More than ON Bombardment CHARGING
Not all batteries are the same. Standard wet-prison cell batteries can exist charged to 14.+ volts (usually xiv.3 merely depends on the manufacturer). Gel-cell batteries and other sealed batteries should never be charged to more than nigh 14.1 volts (over again, may vary depending on manufacturer). And these figures just pertain when the charger will be disconnected as those levels are reached (as with a generator, solar organisation, portable charger, or engine alternator). Every bit the volts drop (ordinarily down to about 12.6 to 13.3), charging begins again, either manually or through an automatic regulator. Annotation also: The maximum charging voltage quoted for gels by the manufacturer is equally a sustained voltage, not an intermittent i. That means cursory over-voltages earlier a regulator shuts off are OK.

Sustained charging, where the batteries are "floated" at a abiding charge (as in the RV converter or with an automatic portable charger) should not exist washed at more thirteen.8 volts (and 13.65 makes batteries final longer). It's supposed to keep the batteries "up" to a reasonable level without undercharging or overcharging them (the assumption being you'll "summit them off" past driving). Unfortunately, many cheap chargers and RV converters don't regulate very well. Overcharging destroys batteries quickly. Undercharging destroys batteries too, just more subtly equally the battery stratifies and volition no longer maintain a charge. In effect, the 100 amp/hr RV battery becomes a 10 amp/hour bombardment afterward consequent undercharge. Information technology will read total voltage, merely as soon as a pocket-sized load is placed on it, it drops to nothing. RVers who remain plugged into commercial power for long periods ofttimes never know this has happened until they unplug, because the converter's transformer also supplies power direct to the RV circuits while it'southward charging the battery — or trying to.

Battery EQUALIZING
Sometimes an equalizing charge can correct the above state of affairs. BUT, don't ever try to equalize a really sealed moisture battery or gel-celled or AGM battery! Yous've got to be really careful when doing this! The battery is going to "gas" (bubbles in the cells, hydrogen gas escaping). It shouldn't be violent, spewing acrid an over the place, merely gentle to rapid bubbling but it requires caution. It'southward ordinarily done by hooking up a manual charger, and then bringing the voltage upwards to xiv.1 or xiv.three and, instead of stopping as usual, keeping it there, at nigh a 5-amp charge, for iii to half dozen hours (until voltage reaches 14.v to 15). Exercise this with the caps off of a standard battery then you can see what's going on. About three hours is usually normal for one of these equalizing charges.

Follow condom precautions, apply safety goggles, plenty of ventilation, etc.

Some battery people recommend equalizing in this manner every 3 months (or after 5 deep cycles). I think the wear and tear on a 12V battery from equalizing this often does more damage than information technology's worth.

Batteries held at 13.8 or so for long periods go lazy and like it there. They need some "equalizing" also. Non every bit drastic as above, fortunately. If you bulldoze occasionally, your engine alternator should practice it (assuming the regulator is ready properly). So will a solar electric organization or a good, well-regulated contained battery charger. If nothing else, use the transmission charger one time in a while when parked and plugged in, simply just bring volts up to 14.+ (whatever's appropriate) and stop at that place.

Golf Cart Battery
Half-dozen volt heavy-duty batteries (similar golf carts, etc.) differ. Their heavy plates and other construction features allow periodic equalizing. I recommend the same 5 amp charge rate, for three to six hours (until voltage reaches a maximum of xvi.5) every six months or then. It varies, with some people doing it monthly (which might mean another problem).

BATTERY Charge/DISCHARGE RATE
You lot'll see references in battery books to the proper charge rate. C/10, C/20, etc. Sometimes it can exist disruptive. What you need to know is that information technology means the "fourth dimension" information technology takes to fully accuse a "dead" battery at a certain amp rate. For instance: A 105AH bombardment will fully recharge (from expressionless) in virtually 10 hours at about 10 amps of charge (C/ten) or about 20 hours at five amps of accuse (C/twenty). Faster accuse rates, like C/5 or C/8 shouldn't exist used with most batteries because the loftier amperage required for such a fast charge amercement the bombardment. C/five on a dead 105 AH battery requires pounding in over twenty amps. (This is sufficient reason to stay away from fast-chargers in service stations where a gigantic amount of amps are pummeling your battery when they "accuse" (destroy) it in twenty minutes. And when you buy a bombardment off the shelf, don't let the guy "put it on a charger for just a few minutes" or it will be damaged before you ever use it.

Bombardment TROUBLESHOOTING AND Bombardment TESTING
Don't but replace batteries and keep on trucking! Find out what went wrong kickoff. Is the converter working? Voltage too high? Likewise low? Is it connected to the bombardment? Fuse blown? Wire broken? Contacts cruddy? Kill switch on motor dwelling on or off (whichever is appropriate — and the wrong position a common fault among motor homers)? How many times have yous deep-cycled? Short in the system? Been hooked up a long time? Automotive regulator/alternator OK? (More later.)

Measuring, metering, testing and troubleshooting require but a few tools and bones knowledge. Much of it is common sense, requiring no tools. Do non ever depend on the red/yellow/green idiot meter installed in near RV's. Become a digital meter. You demand a digital meter to accurately read bombardment voltage to tenths of a volt. You should have an Analog (needle face) meter likewise. Yous tin can't tell the difference between battery voltages with an analog with great accurateness, but they are better in some ways (because it's easier to come across rapid changes) than digital meters for reading fluctuations. (Much more subsequently.)

Get a 12-volt troubleshooting light/test lamp from whatever motorcar shop cheap or brand your own. (Meters will indicate voltage even if there's but i strand left in a wire. Test lamps won't light if in that location's not enough wire to acquit the load.)

Get a decent hydrometer if you lot have moisture-cell batteries and can remove the caps. Don't get a cheapie with colored, floating balls. Learn how to read a hydrometer.

Battery Testing
Can exist washed in more than than one way: The most accurate method of measurement is using a hydrometer to measure specific gravity and using a D.C. voltmeter to get the battery voltage.
A quality load tester may exist a practiced purchase if you need to test sealed12 volt batteries.
For any of these methods, you must starting time fully charge the battery so remove the surface accuse. If the battery has been sitting at least several hours (I prefer at to the lowest degree 12 hours) you may begin testing. To remove surface charge the battery must be discharged for several minutes. Using a headlight (high beam) volition do the trick. After turning off the light y'all are prepare to exam the battery.

Country of Charge	Specific Gravity	Voltage
		12V	6V
100%	1.265	12.vii	6.3
75%	1.225	12.4	6.two
50%	1.190	12.2	6.1
25%	one.155	12.0	6.0
Discharged	1.120	xi.9	six.0

Specific Gravity: Full charge SG will run from about 1.260 in an auto battery to about 1.275 in a golf cart. Loftier SG (more acid) allows more juice (electric current) to exist drawn–but only upwards to a point; then the battery deteriorates–fast. Golf cart plates are made to handle this, RV/Marine somewhat, automotive not at all. Don't try to get more AH past calculation acid (or vinegar instead of distilled water), the bombardment will but dice sooner.

More than ON SPECIFIC GRAVITY–and checking resting voltage
If you accept standard batteries, become a good hydrometer (not one with colored floating balls in it). It must accept a tube inside with SG increments conspicuously marked and a built in thermometer with a temperature correction chart. It's unlikely that a new battery, even freshly charged, will requite more than than 80% of its rated output. Y'all'll become more after it'southward been used and recharged a few times–unless it's faulty. Bank check SG anyway to establish a "baseline" reading.

Look especially for differences between cells. A variation of .050 between any means a possible problem. This is after information technology's charged and bubbled a bit to mix chemicals thoroughly. If it's a new bombardment and this happens, have it back. If old, programme on replacing it soon. Information technology probably has a stratified/shorted cell. Initially, there's no need in checking SG until a battery reaches most 70% of full charge and is bubbles/gassing slightly (not humid like a java pot). Then, take readings once each hour and write them downward. When three successive readings are akin, the battery is equally charged as information technology volition get. Tape readings for each cell and battery. Disconnect bombardment from any accuse or load and get out information technology overnight (24 hours is better). Check SG again. Readings may be a flake lower, but should be consistent. Tape these as your new baseline: your normal, full charge, resting values.

Practise this again after two weeks or a month of apply. Readings may be slightly higher, but once again, should be consistent. If the batteries have been constantly overcharged or undercharged, it will show up here. Yous should take checked that your bombardment charger was set up properly earlier starting all this, but if yous get abnormal readings check that your charger is regulating properly (run across later). If you have to add water this presently, you are almost definitely overcharging. Once you've done the to a higher place tests, y'all shouldn't take to do it more than twice a year unless you detect a problem. You should check water level nearly once a month. Ideally, yous shouldn't have to add water more than two to iv times a year. More than that probably indicates overcharging.

Using a Hydrometer Without Making a Mess

Stick information technology in a prison cell until it only rests on meridian of the plates. Eject in and out a few times–gently, don't splatter. So fill until the inner tube floats. Too lilliputian and information technology will rest on bottom of hydrometer. Too much and it will hitting the top. In either case, you'll get imitation readings. Don't remove the thing from the cell to read information technology, you'll just drip acid all over. Take your reading and write it down. Read at the fluid level, non at the slight curvature where the fluid touches the inner tube. (Earlier moving to the side by side prison cell, don't forget to squirt the acrid back in.) Annotation temperature on thermometer and correct reading as indicated. Note, again, that all readings for a battery should exist within .050 of each other. Keep in heed you might have a cheap or faulty hydrometer. El cheapos take a paper SG scale in the tube that slips up and downwardly.

Load testing is notwithstanding another way of testing a battery. Load test removes amps from a bombardment much similar starting an engine would. A load tester can be purchased at most auto parts stores. Some bombardment companies label their bombardment with the amp load for testing. This number is commonly 1/2 of the CCA rating. For case, a 500CCA battery would load test at 250 amps for 15 seconds. A load exam tin only be performed if the battery is well-nigh or at full charge.

Hydrometer readings should not vary more .05 differences betwixt cells.

Digital Voltmeters should read as the voltage is shown in this document. The sealed AGM and Gel-Cell battery voltage (full charged) will be slightly college in the 12.eight to 12.9 ranges. If you lot accept voltage readings in the 10.5 volts range on a charged bombardment, that typically indicates a shorted cell.

If you lot take a maintenance free wet cell, the only ways to test are voltmeter and load examination. Whatsoever of the maintenance gratis type batteries that have a built in hydrometer(black/light-green window) will tell you the condition of 1 cell of 6. You may get a good reading from 1 cell but have a problem with other cells in the battery.

MAINTENANCE

Maintenance is all-important. Crud on top of a bombardment provides a path between poles. It's a "short." 1 almost people never notice, only it uses free energy constantly.You don't demand to slop baking soda all over. Frequently just a spray 'n wipe with household cleaner is all that'due south needed.

• Corrosion will build up. Some-times you can't even meet it. Accept contacts autonomously and clean them. (At present is when you might use baking soda, just don't let it arrive the cells.) Done one time or twice a year, it's fast and easy.
• Before putting things dorsum together, coat all surfaces (thinly) with silicone dielectric grease. That's earlier, not after. You won't achieve a affair by smearing grease on top of corrosion.
• Never employ crimson bombardment spray. It just makes things worse. The red/dark-green felt, noncorrosive washers are okay.
• Label or color-code cable and wire ends. Make a diagram. If you don't, you'll just claw things upwards incorrect.

More than DETAILS ON BATTERIES (MOSTLY GEL CELLS and AGM)
Much of the aforementioned material applies: All batteries need to be maintained. All batteries demand to be kept charged — simply not overcharged or undercharged. All demand clean connections and practiced, stout cable and wire of the proper size. No battery should be routinely deep-cycled. Of most importance, charging needs to be well regulated.

And here's where the divergence between gels, AGMs and regular, moisture-cell batteries starts to show up seriously.

• Wet prison cell (flooded) batteries: Suspended plates, unremarkably with some form of separators (so plates don't bear on each other) are immersed in liquid electrolyte. These may be charged, just as a starter battery, which makes things a lot simpler.
• Gel batteries: Plates are suspended in a thick gelled electrolyte that insures stability and eliminates voids or "air pockets" at the plates. The best gels are those past "East Penn Mfg." (under "SeaGel," Prevailer" and other labels — but the E Penn proper noun will appear somewhere). Competitors are lite weights. Gels are seldom charged to more fourteen.one volts initial (majority) charge and thirteen.8 (thirteen.65 is better) as a "float" charge (see later).
• AGM (Absorbed Glass Mat) batteries: A dense fiber matting between the plates and a liquid electrolyte provide
  similar features to gel batteries only are much more rugged since they were designed for use in shipping and rough terrain vehicles. The best AGMs are those made by "Concorde" (usually nether the "Lifeline" label but Concorde will appear somewhere). AGMs (like gels) are very sensitive to overcharge. 14.38 volts is recommended for the initial (bulk) accuse and xiii.38 as a "float" charge.

Pros and Cons:

Standard, old-timey flooded batteries are cheap (initially). They'll do the job (golf carts or similar better than RV/Marine stuff). Run across remarks elsewhere. They will vent gas and fluid, simply information technology tin can be replenished with distilled water. They crave a lot of care.

Gells and AGMs can practice a meliorate job and last longer, BUT besides require special care. They're rather expensive initially (but my half dozen gels are in their tenth year, every bit good as new, and the cost nets out to less than standard batteries). Withal, they are very carefully charged and that requires an expensive charger/regulator. Gels and AGMs don't need a lot of maintenance and cleaning (other than a quick spray and wipe from a household cleaner) UNLESS you do something stupid and overcharge them. They won't spill acid, are very daze resistant, don't pass gas (pun intended) unless seriously overcharged, have a VERY low self-discharge rate (squeamish when the RV is in storage) and have a very long bicycle life.

I've used golf cart batteries, regular batteries and gels. Every bit I'll repeat with more detail elsewhere, golf carts and like batteries are, all things considered, the best solution. Were I to accept to replace my batteries today (they're in the living compartment in a small RV), I'd get with AGM. In a bigger RV, I'd go with golf cart or fork elevator batteries.

You should never charge a gel battery to more than than 14.1 volts (or to more the voltage specified by the manufacturer) before the regulator shuts off the charger except for very brief periods. And then, as a battery is "floated" (kept on the charger with a charge applied to keep it up to a reasonable level), information technology should never exceed thirteen.8 volts (better, for long life is a maximum of 13.65 volts). Once again, though, you don't float the bombardment permanently. Y'all occasionally bring it up to xiv.+ (this is EZ with a solar regulator or better quality battery charger that will perform regulating tasks ofttimes and automatically. (more after.)AGMs are charged similarly, but with different voltages.

Actually, you'd exist foolish to go along (float) any battery at a sustained charge of over 14 volts. You'd simply wear it out prematurely and it would exist spewing acrid all the time, making a mess. But with a regular, wet-cell battery with removable caps, y'all can add h2o and clean up the corrosion. With a gel, or any other (really) sealed bombardment, you can't add h2o. All you can practise is watch the battery deteriorate.

Gel batteries and AGMs practice have caps, just don't ever try to remove them. Outset, yous'll violate the warranty. Second, you'll contaminate the inside. When information technology dies early, the dealer/mill will know you lot did this and will void the warranty. Also, if yous overcharge a gel or AGM bombardment, the factory can notice that, too. Over again, no more warranty.

TEMPERATURE
Temperature is important when charging whatsoever kind of batteries. A really hot battery (EZ to achieve if they're sitting out in a cheap, plastic box) will overcharge well earlier the voltages listed earlier. Keeping batteries "indoors" helps proceed them at about an ideal temperature (of about 68 to 77ºF). Actually, high temperature but becomes a real problem when the battery is being "floated." A 13.eight volt float can hands become a 14+ a-whole-bunch float at 90º. Temp can also exist a winter problem as batteries endeavour to freeze and their amp hour chapters is reduced by over 30%.

More ON REGULATING CHARGE
There are only a few RV converter/combination battery chargers that are worth having. Near practice an absolutely lousy job and you oasis't the faintest thought what wild voltage (or lack of) is going to your batteries. Some converter/chargers do work. Check yours no matter what kind of battery you use. With the thing operating, and the battery reasonably-well charged, and not much more than load on the battery than the TV antenna amplifier and reefer brain (RV reefers with a circuit board use 12 volts all the fourth dimension, just to operate the board), put a digital volt meter across the "house" bombardment terminals. Go out it in that location awhile and meet if information technology's belongings the batteries to around thirteen.eight volts. (Or is it charging them upward to something ridiculous?) (Or is it charging at all?) Some, even fewer, RVs employ a split up battery charger (non as part of a converter). By and large, these are pretty good (and expensive). But check them the same manner. It's not at all uncommon to observe stock RV battery chargers floating batteries at fourteen.3 volts or higher. The best chargers regulate in two, three or 4 stages. Outset, anytime there's sufficient need, they full charge to fourteen.+ volts (adjustable past you). Second, they revert to a "bladder" charge of about 13.8 (which in skilful chargers is adjustable again). Some have a third, "equalizing" stage, automated or transmission, that should also be adaptable. (There are some four-phase chargers as well.)

If you want to use gel or AGM batteries, you lot must have a good, reliable, user-adjustable regulator and charger. The best manner to charge batteries is with a solar electrical organization. (Again, cheque first and last with "RV Solar Electric" higher up.) A solar organization (if it has a user-adjustable regulator) will allow yous set the charge cut-off at desired volts. Unremarkably, someday the solar system achieves that, it volition cut off and drop to nearly xiii.1 volts before resuming (some solar regs will back off to a float voltage). This gives the batteries a "residual" and keeps them from overcharging. (And, of course, at dark, solar systems don't do anything, and so in that location'south a skillful balance, too.) For a backup, you can use a generator or commercial power. Make sure your generator (if it has a direct DC 12 volt charging outlet) is fix to regulate at proper volts! If it just charges through your converter, you'll have checked that above, just recheck it with the generator running. Do the same with an independent charger. Many others are available.

Deep Cycling
Let's consider something here: 1 does not deep wheel a battery daily as a thing of form. If one did, then the maximum life of whatever battery would equal the available number of cycles and no battery would last more than 6 to 9 months. Ideally, what you need is a battery (batteries) that will provide the power you lot require without existence cycled (depleted from resting full accuse) by more than 20 to 50% before being recharged. (If you have a 100AH bombardment and take no more than than 20AH from information technology before recharging, it might last longer than you will.) Unfortunately, this isn't realistic, but you lot can take up to fifty% from a battery before recharging and still get long life. Simple arithmetics–how many AH used versus how many AH available volition tell y'all how many batteries are needed. Proceed in mind that you shouldn't wait only 80% of the manufacturer's rating. And then a 105AH battery is really about 84AH. MAX! No bombardment volition give you its rated output in real life! They're rated down to an cease point of ten.five volts. By then, lights get dim and TV movie small. A Specific Gravity of about i.200 or a voltage of 12.25 to 12.3 means the bombardment is about 50% discharged. By the fourth dimension it's down to xi.eight or 12 volts, it'southward virtually dead.

AMP Hours and Battery Chapters
What are "Amp Hours"? Amp hours is the amount of current in "Amps" times the number of hours it can deliver that current.
Example: A 100 amp-hour battery can evangelize 10 amps for 10 hours or twenty amps for 5 hours.
1 amp for 100 hours, or any combination, should allow you to rate batteries, but it doesn't work like that. (It's a logarithmic, not a linear, progression.) Further, capacity, in AH, depends on several things: size, corporeality/type electrolyte, plate thickness, etc. You lot don't desire to investigate all that crap. Of key interest to united states of america are:

Rate of Belch: Generally 20 hours for automotive, vi for golf cart and 8 for RV/Marine. A 180AH golf cart will, technically, requite you 30 amps for its rated 6 hours, but information technology volition non give 60 amps for three hours. (Has to exercise with things like heat at this college rate due to farthermost chemical action demanded–stuff you lot don't want to fool with.) It will give i amp for nearly 105 hours, though, which is prissy to know. Don't just read AH. Read the charts when comparing batteries.

Specific Gravity: Full charge SG will run from about ane.260 in an auto battery to about 1.275 in a golf cart. Loftier SG (more than acid) allows more juice (electric current) to be drawn–but only up to a point; then the battery deteriorates–fast. Golf game cart plates are made to handle this, RV/Marine somewhat, automotive not at all. Don't try to get more than AH by adding acid (or vinegar instead of distilled water), the bombardment will only die sooner.

Temperature: Batteries are made to perform best at 77°F. At higher temps, they put out more, but die sooner. At lower temps, they put out less, but concluding longer (unless you let them freeze).

CABLES AND CONNECTIONS

Tying the system together is of import. No point spending a lot of money on batteries and chargers and wiring information technology upwardly with skimpy junk. Large battery cables tin be purchased from San Diego Battery Wholesale. Custom-made cable to your lengths with terminals that match your vehicle is also available.

METERING BATTERIES
If you lot have maintenance free (maintenance prohibitive) batteries, you can't have fun with a hydrometer. Fifty-fifty if y'all can use a hydrometer, you don't demand to (or want to) exercise it more than a couple of times a year. Use the chart (see later) to go on an accurate check on country of charge. When taking SG readings, measure voltage at the aforementioned time. Proceed in mind that if a battery is charging, voltage will read about ½ to 1 volt higher than bodily. Note that chart voltages (later) are as footling as .05 apart. You can't read that accurately on an analog (dial/needle-faced) meter. You need a digital meter. You don't need to spend over $200 for a professional model. Run into ads in electronics magazines for reasonably priced meters. Y'all need a 3½ digit" meter (reads to two decimal places) and get one with at least a ten amp current mensurate (20 is meliorate). At present, the all-time deal is a Metex make #M3800 3½ digit at 20 amp capacity for $40 from: JAMECO. (See Sources.) All RVers need ane of these anyway.

When checking the batteries, (at residue) use these "Voltage Landmarks".

12.vi volts = 100%
12.five volts = 70%
12.3 volts = l%
11.iv volts = 20%

MORE ON UNDERCHARGE AND OVERCHARGE
"Under" results in stratification. "Over" but eats the plates. Use a regulator to prevent overcharge. When y'all think a battery is charged, too high a SG means over. Too low means under. Compare with an accurate voltage bank check. You should only need to add water a few times a year. More than ways battery's gassing besides much. You can't tell by feeling the heat of the battery example whatever more than (better plastics). Yous must put almost 10% more energy into a battery than you lot take out (more high school physics–someday free energy is transformed, at that place must be some loss). An "old" battery can crave more. Compare how much you're putting in versus what you take out and size your organisation appropriately.

CONNECTING BATTERIES IN PARALLEL, SERIES and SERIES-PARALLEL

This is really simple, merely it's amazing how many RVers screw information technology all upwardly!

In serial, volts increment; amps remain the same.
In parallel, amps increase; volts remain the same.

In Parallel: you connect the (+) of one 12vbat to the (+) of the other. Connect (-) of 1 to the (-) of the other. You lot will so take all the same have a 12volt bat, but with greater amp 60 minutes chapters. This is now an ordinary 12V bat, except that instead of being in one "box," it is in two boxes.

In Series: If yous were to hook 2 12 volt batteries in serial, yous'd have 24 volts. Clearly non the thing to do unless you have a jitney conversion or custom rig that uses 24Volts. Withal, many RVers use 6 volt (commonly golf cart) batteries. E.G., Two 105AH 6v in series would nonetheless = about 105AH but @ a nominal 12V.

Wiring in Serial:
To visualize information technology easier. Kickoff with a simple block diagram. Two 6V batteries.
On left bat, place (-) at left end, place (+) on correct end.
On correct bat, place (-) on left end, place (+) on right finish.
Draw a line from (+) on left bat to next (-) on right bat.

This is at present an ordinary 12V bat, except that instead of being in one "box" with cells all connected in series on the interior, it is in two boxes joined with a cable. Information technology's still a single 12 volt bat, electrically, so Starting time THINKING OF IT THIS Way and don't misfile yourself by thinking of it as bat one and bat 2.

At this point, you've got two unused bat posts — just similar an ordinary 12 volt bat; i neg that goes to chassis footing and one pos that goes to normal 12V isolator/supply/etc.

Series/Parallel:
Just echo the serial step above with two more than 6 volt bats and you terminate up with two 12V bats. Think of information technology this way instead of every bit 4 6V bats! You now have ii (-) unused posts. Connect them together (simply as y'all would when connecting two ordinary 12V bats in parallel). Repeat for the two unused (+) posts.

It's really quite uncomplicated. The trouble many people have is in thinking that this is very complicated. Information technology's not.

The only fourth dimension you think of the bats as iv 6V bats is when you disconnect them for maintenance and cleaning. And so, just to brand absolutely sure that you don't screw upwards when putting them back together.
Toward this finish, it'due south essential that you clearly label posts and cable ends!

% Of Accuse	Standard Bombardment Typical Specific Gravity (Afterwards Temperature Correction)	Standard Battery Equivalent Resting Volts	Gel-Cell Bombardment Equivalent Resting Volts
100%	1.260 (car) to one.280 (industrial)	12.sixty-12.75	12.90-thirteen.00
95%	i.255	12.threescore-12.lxx	12.80
90%	ane.250 (Resting Southward.Chiliad. for standard RV battery.)	12.60-12.65	12.lxx
85%	1.245 (Aforementioned as to a higher place. No point being too picky.)	12.60
80%	1.235-1.240 (We try not to discharge below this point.)	12.50-12.55	12.60
75%	1.225-ane.230 (1.230=minimum SG for a charged battery.)	12.50
70%	1.220 (Anything below 1.220 is "poorly" charged.)	12.45	12.50
65%	1.215	12.40
60%	1.205	12.35	12.40
55%	1.200	12.thirty
fifty%	1.190-1.195 (Endeavor to never discharge beneath this point.)	12.25	12.35
45%	1.185	12.twenty
xl%	one.180	12.15-12.20	12.25
25%	ane.160-1.170 (Dangerously depression; battery being damaged.)	12.x-12.fifteen
20%	1.150 (Cells die soon at this betoken. Cheerio-bye battery.)	11.80-12.00	12.15

TROUBLESHOOTING

House Battery: The intent here is to determine if the battery itself is good, and, in its role as a "firm" battery, how yous tin test information technology, the business firm wiring and charging excursion.

Situation: You lot're charging the bombardment from any i of several sources. Everything has been working fine; but for no apparent reason and all all of a sudden, there'south no electricity. Don't just offset taking everything autonomously! Look effectually for the obvious. Is the battery notwithstanding there? Is everything in one piece? (A nearby lightning strike tin blow the top off.) Are the cables connected? I once spent an hour roaming effectually with a volt meter only to notice I'd just left the negative cable off.

Steps:
Connect a volt meter across the bombardment. Information technology should read some, reasonable voltage even if well discharged (unless it's dead). If voltage is adequate, and assuming things are normal, effort moving/twisting the principal cablevision clamps at the battery. Often, even on a clean-appearing battery, a thin moving-picture show of corrosion builds up between post and connector (that you can't see). While the corrosion builds up very gradually, its consequence can happen of a sudden.

• Next, especially if the connections are unsightly, place the tip of an upright, apartment-bladed screwdriver on pinnacle at the circular junction of postal service and clench and give information technology a good sock with your fist (non a hammer).
• Do the aforementioned with the other mail service. If bad connections are the problem, the higher up should allow at least some electricity to flow–plenty to indicate the problem. If the above helps at all, take things autonomously and clean them.
• If the above doesn't assistance, beginning disconnect the charging source then disconnect the battery (you lot might besides go ahead and remove information technology). Before you start phiddling with the battery, attach a pair of jumper cables from a known, good battery to the RV cables.
• Adhere the (+) cable outset. If you lot don't let the loose end touch something, there should exist no sparks because in that location's no place for electricity to go (yet).
• Then attach the (-) cable to the "good" battery. (Once more, there should be no sparks if yous don't spiral upwardly.)
• Finally, attach the last (-) finish to the RV cable (If the bad battery was removed, sparks at this final connection shouldn't hurt anything. This seems like a roundabout mode to exercise all this only in that location'due south a reason for it.
• If there's now electricity in your house, y'all know y'all had a discharged battery. Perhaps a bad battery, but not necessarily. Once again, before yous offset phiddling with the "bad" battery, yous need to check the charging system. The thought here is find out why the battery discharged.
• Run a load (lamp or any) to remove the surface charge from your "good" temporary bombardment. Depending on what kind of battery charger you have, y'all may need to run the battery down to virtually 13V or less to get the regulator to allow charging to resume. Keep measuring voltage. When charging resumes, it volition increase.
• If the voltage doesn't increment, information technology'south possible that your charging source (converter, generator, solar organisation) isn't working or the period is interrupted.

Make the dumb checks showtime:

• Is the converter working? Is the "kill" switch on or off on some motor homes? It'south unlikely, because and so you should have had a gradual loss, non a sudden one. It is possible though.
• And information technology'southward possible you lot take a bad battery AND a bad charging system. RV converters with built-in bombardment chargers tin actually confuse you. In that location are ii outputs to these things: 1 furnishes 12V straight from the transformer to most firm circuits. The other goes from battery charger portion to battery. If you've been plugged into commercial ability, the primary transformer may have been running everything while the battery charger was not working. As well, the "kill" switch may have been off or fuse from charger blown. (Check the dumb things first.)
• Put a volt meter at the battery end while you're doing it. Quite often, a little manipulating will clear things right up. If not, go back to the source of the charging system with your volt meter. Is there ability at the charger output? At the output to battery concluding at solar panels or solar regulator?
• Again, check fuses advisedly. You can't tell if a fuse is bad by looking at information technology, you demand to measure it with a test lamp. Think that a meter can indicate "adept" if there'due south only a slight contact simply a test lamp won't piece of work if there'due south not enough to carry the load.
• If this also fails, you may have to bank check at the charging source with no bombardment attached. It'south like shooting fish in a barrel with an RV converter, just if yous utilize a solar arrangement or current of air generator you may not be able to (some can exist severely damaged if run without a load). RTFM (Read The F****** Manual)! Our purpose in checking at the source (with or without battery connected) is to see if there'south annihilation there.

If there's still no voltage, now starts the onerous process of checking the whole system.

• Do information technology logically. Go all the mode to the source first. Disconnect generator, solar panels, whatever, from the arrangement. You can now measure them in performance without damaging annihilation (except some wind chargers). If the charger works, you know that you have two long pieces of wire (+) and (-) with a problem somewhere. Don't ignore the (-) wire. It is every bit as necessary equally the (+). Reconnect charger and bombardment if necessary.
• Go to some logical halfway point with your volt meter. One fashion or the other, y'all'll get voltage (unless you missed something at the source). Proceed in this manner, roughly going halfway (each time on the dead side). Unless you spiral up, you lot'll soon isolate the trouble to just a few anxiety of wire. If something hasn't been left unconnected or the wire been cut, you'll commonly isolate the problem to a connexion or fuse.
• Look at things, pull on wires to make certain they're actually fastened. This is where bad crimped connections show upwardly. (I spent an hr helping someone runway down a solar arrangement this way. Every crimped terminal fell apart in my hands. He'd crimped them with normal pliers.) Look for corrosion at terminals, simply as at bombardment cables. Call up that simply because a converter is buzzing, information technology doesn't mean the battery charger is working. If working with a solar organization, never try to put a jumper across the solar (+) and battery (+) to bypass the regulator–you'll fry it. However, if you disconnect those wires from the regulator, and so you lot tin can put them together.

All the in a higher place can be done with a volt meter or examination lamp. In fact, a test lamp works better at continuity checks, because a volt meter might point power if just one strand of wire is nonetheless connected while a test lamp won't lite if information technology doesn't take a excursion heavy plenty for the load.

TO CHECK THE Bombardment ITSELF–MORE ON RESTING VOLTAGE

It can exist checked with a hydrometer, but a battery tin read OK and still be faulty. Here's a practiced way to check a bombardment. Information technology takes fourth dimension, but it's worth it:

• Accuse it fully, preferably with a skillful battery charger or an contained, manual, automotive charger (y'all demand 1 anyway for emergencies). This tin can take awhile if it's been deep discharged (dead).
• Measure out voltage. Information technology should exist quite high–over 13 volts and 14.+ is improve. Disconnect the charger. Exit the battery (with nada connected to it) at to the lowest degree 6 hours. Overnight or 24 hours is better.
• Mensurate voltage again. It should be 12.6 volts. If not, even if it'southward 12.5, it's a goner or it'due south going. If it reads 12.6, it all the same might be bad.
• A commercial battery shop tin can check this with a variable load tester. And then can yous. If the battery is at least a then-called l00AH RV/Marine type, it should first about engines in decent weather. Connect a volt meter across it. If it doesn't commencement, jump beginning it. Run the engine at a nice, fast idle (1,500 to 2,000 rpm).
• If the voltage rises to over xiv volts in simply 4 or five minutes, yous accept a bad battery. Due to things nosotros won't dwell on hither, the AH capacity has been severely reduced (stratification, deep discharges, etc.). What y'all have is a battery that has about a l0AH capacity instead of l00AH. It tests OK because it has some chapters (might run a lamp a few hours), merely non enough. This mutual problem often drives people basics. It tests OK, it but won't last long.
• The same examination works on auto batteries. They examination OK but won't outset an engine.

Battery ISOLATORS

Almost everybody has one. Most people never pay attending to them. I do. And I've got mine remoted to a switch on the nuance to avoid the [many] problems they can cause. Most isolators send a charge to the batteries automatically. I don't want to do that. Normally, my solar organisation keeps the "firm" batteries charged just fine. In that location are times, in bad weather, when I need to boost the batteries, so when on the road I hit the switch that goes to the accuse line to business firm batteries and the engine alternator charges them in the normal way. A cheap, voltmeter on the dash keeps me informed when to shut charging off.

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Source: https://deepcyclebatterystore.com/how-to-maintain-batteries/

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