BATTERY CHARGING TIPS
Bill Darden
People kill more deep cycle batteries with bad charging and maintenance practices, than die of old age! Lead-acid batteries are perishable.
1. Always wear glasses when working around a battery in the unlikely event that it might explode.
2. Use the battery manufacturer's charging recommendations and voltages whenever possible for optimum capacity, maintenance and service life.
3. Never disconnect a battery cable from a car with the engine running, because the battery acts like a filter for the electrical system. Unfiltered (pulsating DC) electricity sometimes exceeding 40 volts and can damage expensive electronic and electrical components such as emmissions computer, audio system, charging system, alarm system, etc.
4. Before recharging check the electrolyte level and insure it covers the plates at all times and that it is not frozen. After recharging, recheck the electrolyte levels after the battery has cooled and top off with distilled water as required, but do not over fill.
5. Reinstall the vent caps before recharging and recharge ONLY in well-ventilated areas. Do not smoke or cause sparks or flames while the battery is being recharged because it produces explosive gasses.
6. If your battery is sealed, avoid recharging with current above 20% of the RC (or 50% of the ampere hour) rating. For example, 24 amps maximum for a 120 minute RC (48 ampere hour) rated battery.
7. Follow the battery and charger manufacturers' procedures for connecting and disconnecting cables. Operate in a manner to minimize the possibility of an explosion or incorrectly charging the battery. You should turn the charger OFF before connecting or disconnecting cables to a battery. Do not wiggle the cable clamps while the battery is recharging, because a spark could occur and this might cause an explosion. Good ventilation or a fan is recommended to disperse the gasses created by the recharging process.
8. If a battery becomes hot, over 110° F (43.3° C), or violent gassing or spewing of electrolyte occurs, turn the charger off temporarily or reduce the charging rate. This will also prevent "thermal runaway" that can occur with sealed Valve Regulated Lead-Acid (AGM or Gel Cell) batteries.
9. Insure that charging the battery with an external manual charger will not damage the vehicles's electrical system with high voltages. If this is even a remote possibility, then disconnect both battery cables from the battery before connecting the charger.
10. If you are recharging Gel Cell batteries, the battery manufacturer's charging voltages are very critical. You might need special recharging equipment. In most cases, standard deep cycle chargers used to recharge wet batteries cannot be used to recharge Gel Cell and some AGM batteries because of their charging profiles or voltages; using them will shorten battery life or cause "thermal runaway". MATCH the charger (or charger's setting) for the battery type you are recharging (or maintaining) and insure the charging voltages are compatible.
11. Usually when a car is jump started, it is not driven long enough to fully recharge the battery. The length of time to fully recharge the battery depends on the amount of discharge, the amount of surplus current that is diverted to the battery, how long the engine is run, engine speed, and ambient temperature. An alternator is sized by the car manufacturer to carry the maximum accessory load and to maintain a battery and NOT to recharge a dead battery. Recharge with an external battery charger and test the battery.
12. If left unattended, cheap, unregulated trickle or manual two stage battery chargers can overcharge your battery because they can "decompose" the water out of the electrolyte by electrolysis. Avoid using fast, high rate, or boost chargers on any battery that is sulfated or deeply discharged. The electrolyte should never bubble violently while recharging because high currents only create heat and excess explosive gasses.
13. Battery charging requires patience. When a battery is discharged, the same amount of power has to be replaced. However, some of the power is converted to heat and lost due to the resistance in the cables, connectors and elements within the battery. For most batteries that are discharged less than 10% of their full capacity, an estimate of time is amp hours to be replaced divided by 90% the current output of the charger. For batteries that are deeply discharged, an estimate of time is two times the number of amp hours to be replaced divided by the current output of the charger.
14. If a battery is overcharged and all the electrolyte is "boiled" out, some batteries can produce deadly CO (Carbon Monoxide) gas or cause a fire.