Never add new electrolyte (battery acid), use distilled water.
- Don’t use unregulated high output battery charges to charge batteries, especially AGM and Gel batteries.
- Don’t put your equipment or toys (jet skis, vintage cars etc) into storage without some form of maintenance charger.
- Don’t disconnect battery cables while the engine is running (your battery acts as a filter).
- Don’t put off recharging your batteries.
- Don’t add tap water, as it may contain minerals that may contaminate the electrolyte.
- Don’t discharge the battery any deeper than you possibly have to.
- Don’t let a battery get hot to the touch and boil violently when charging.
- Don’t mix size and type of batteries in battery banks.
- Think safety first; wear safety goggles and gloves when charging batteries.
- Do regular inspection and maintenance or water levels on connections, especially in hot weather.
- Recharge batteries immediately after discharge or at least the same day.
- Fully charge a battery before it goes into storage.
- Always use batteries of identical make, model and manufacturing code.
- Make sure the battery cable is not undersized for the battery system.
A lead acid battery when overcharged will produce hydrogen gas. If the ventilation is inadequate a flammable concentration of hydrogen gas may remain in the cell or in the battery enclosure. Any spark can cause the hydrogen explosion, which will damage the battery and its surroundings.
Without the right testing equipment it can be very difficult to test a battery. The easiest method is to measure the specific gravity by using a hydrometer and to measure the voltage using a digital multimeter, if you test a lot of batteries you may need to buy a good load tester.
First you must fully charge the battery, see chart above. Check the battery voltage after removing any surface charge, it should read above 12.65 volts for a fully charged battery, if your battery is measuring 10.5 volts after charging it typically indicates a shorted or faulty cell. If you can check every cell in the battery with a hydrometer, the cell readings should all be the same, a fully charged cell reads 1.265 – 1.280, if there is more than 0.05 points different it indicates a faulty battery. Readings below 1.225 indicate the battery needs to be charged before load testing.
If the battery is sealed it should have a built in hydrometer telling the charge of one cell, you may get a good reading in that cell but the problem may be in one of the other cells.
A problem can arise when you battery is extremely discharged, for example; a light is left on in the vehicle and the battery voltage drops below 7 volts. Some chargers will not charge a battery when the voltage is that low and you will have to take it to a professional to charge it for you. Chargers are getting better and there are some on the market that will start at 3 or even 0 volts. The problem is that the battery has developed an extremely high internal resistance (caused by sulfation) and the charger is not strong enough to push current through the battery.