Electric Vehicle Conversion Help -

Lead Acid Batteries - Love'em and Hate'em!

You can both love and hate lead acid batteries all at the same time. How's that?

I love deep-cycle lead-acid batteries because they have an energy storage capacity that is useable in electric vehicles. They provide a reasonable range that is sufficient for many everyday commuters. Most of all, I love them because they are relatively inexpensive compared to today's alternatives which are tens times and more the cost. In fact, flooded lead-acid batteries are down right cheap at the current $67 per battery at Sam's Clubs, slightly higher at Costco.

I wish that were the end of the story. No, there's more. It's the 'hate' part. I hate lead-acid batteries because of the following unfortunate list:

Their capacity varies greatly with temperature - in the neighborhood of a 30% reduction at freezing.
They can freeze in cold weather if left uncharged or even partially drained.
They can fail because of severe bumps and vibration.
They require much more energy to recharge than what was used - as much as 25% more.
They must be charged relatively slowly at a maximum rate that is equal to the 20 hr. Capacity divided by 8. Most manufacturers recommend at least a 6-hour charge period.
The lead plates sulfate during discharge and may not totally desulfated during recharge, which reduces capacity and increases the internal resistance of the battery, which causes the equivalent of a brownout as you drive..
They have much fewer charge cycles than more costly battery types.
Their plates can erode because of severe over-charging.
They are very heavy.
Flooded lead-acid batteries can be dangerous because of hydrogen production during over-charge. Usually the hydrogen does not escape because it is reabsorbed into the sulfuric acid. The amount of hydrogen that actually escapes the battery depends on the amount being produced and the quality of the cell caps.
Batteries in the same string age differently, making equalization a priority and difficult unless distributed charging is used.
Flooded lead-acid batteries have to be watered. However, this should not have to be done more frequently than once per month or so. More frequently may be a sign of excessive over-charging.

So, love'em and hate'em. There is no other alternative at reasonable cost at this time. Take care of them as best you can.

- Mark