Battery Care

We destroyed our first batteries even though many people warned us that we WOULD destroy our first set of batteries. I'm hoping to save you the same trouble.

A conservative life-span for lead-acid batteries in an electric car is 3 years. But there are folks running alternative vehicles like our tractor that have been using the same batteries for over 10 years. A car is generally run more often and regularly and to a much greater extent of discharge. Altough we use our tractors often, we are generally only going a mile or so at a time then re-charging them, so they don't get permanently exhausted as fast.

The most important statistic for you to know is that 85% of dead/old batteries in Electric Vehicles are only dead because of excessive sulfation NOT because they really "need" to be dead.

I am copying below information from www.uuhome.de/willima.darden/carfaq16.html on desulfating batteries, but the most important thing for you to know is that you should keepsulfation from happening rather than trying to fix it and "Recover" your batteries. We let ours go too long and were NOT able to recover them that first time. Since then, we have had no problems.

How do I prevent permanent sulfation?
(From http://www.uuhome.de/william.darden/carfaq16.htm)

The best way to prevent sulfation is to keep a lead-acid battery fully charged because lead sulfate does not form. This can be accomplished three ways. The best solution is to use a charger that is capable of delivering a continuous "float" charge at the battery manufacturer's recommended float or maintenance voltage for a fully charged battery. 12-volt batteries, depending on the battery type, usually have fixed float voltages between 13.2 VDC and 13.8 VDC, measured at 80 F (26.7 C) with an accurate (.5% or better) digital voltmeter. Based on the battery type you are using, charging can best be accomplished with a microprocessor controlled, three stage (for AGM or Gel Cell batteries) or four stage (for wet batteries) "smart" charger or by voltage-regulated float charger to "float" or maintain fully a charged battery. A cheap, unregulated "trickle" charger or manual two stage charger can overcharge a battery and destroy it.

A second and less desirable method is to periodically recharge the battery when the State-of-Charge drops to 80% or below. Maintaining a high State-of-Charge (SoC) tends to prevent irreversible sulfation. The recharge frequency is dependent on the parasitic load, temperature, the battery's condition, and plate formulation (battery type). Temperature matters! Lower temperatures slow down electro chemical reactions and higher temperatures speed them up. A battery stored at 95 F (35 C) will self-discharge twice as fast than one stored at 75 F (23.9 C).

A third technique is to use a regulated solar panel or wind or water generator designed to float charge the battery. This is a popular solution when AC power is unavailable for charging.

How do I recover sulfated batteries?
(From http://www.uuhome.de/william.darden/carfaq16.htm)

Here are three methods to try to recover permanently sulfated batteries:

Light Sulfation
Check the electrolyte levels and apply a constant current at 2% of the battery's RC or 1% of the AH capacity rating for 48 to 120 hours at 14.4 VDC or more, depending on the electrolyte temperature and capacity of the battery. Cycle (discharge to 50% and recharge) the battery a couple of times and test its capacity. You might have to increase the voltage in order to break down the hard lead sulfate crystals. If the battery gets above 125 F (51.7 C) then stop charging and allow the battery to cool down before continuing.

Heavy Sulfation
Replace the old electrolyte with distilled, deionized or demineralized water, let stand for one hour, apply a constant current at four amps at 13.8 VDC until there is no additional rise in specific gravity, remove the electrolyte, wash the sediment out, replace with fresh electrolyte (battery acid), and recharge. If the specific gravity exceeds 1.300, then remove the new electrolyte, wash the sediment out, and start over from the beginning with distilled water. You might have to increase the voltage in order to break down the hard lead sulfate crystals. If the battery gets above 125 F (51.7 C) then stop charging and allow the battery to cool down before continuing. Cycle (discharge to 50% and recharge) the battery a couple of times and test capacity. The sulfate crystals are more soluble in water than in electrolyte. As these crystals are dissolved, the sulfate is converted back into sulfuric acid and the specific gravity rises. This procedure will only work with some batteries.

Desulfators
Use a desulfator also known as a pulse charger. A list of some of the desulfator or pulse charger manufacturers is available on the Battery References Links List at http://www.batteryfaq.org.

Despite manufacturer's claims, some battery experts feel that desulfators and pulse chargers do not work any better at removing permanent sulfation than do constant voltage chargers.