Thread: Batteries

12/01 7:29 PM <Jon> the reason the optima is so much better is because it's not just a lead acid battery, they're absorbent glass mat. Much better charge/discharge characteristics. Your lead acid battery is probably just sulphated though... sometimes just putting it on a 2 amp trickle charge for what seems like forever will cause the sulphation to fall off the lead plates and reabsorb into the acid
12/01 7:29 PM <Jon> there's also a chemical mix you can put in the battery to remove sulfate from the plates... I forget what it's called though

I cannot find the name of this product, but...

12/01 7:40 PM <username182> i see
12/01 7:41 PM <username182> thats not something a regular dude can do tho
12/01 7:41 PM <username182> don't you need to empty the acid shit then clean it out?

No, you simply add the powder into the acid, and when you charge, it reacts with the sulfate on the lead plates, and reabsorbs it into the acid.

12/01 9:14 PM <BenGSX> The lead in a lead acid battery undergoes an oxidation process.. Once it is deep cycled too many times the lead is actually gone... It's become ionzed and is in solution... Its not coming back. The optima battery is a deep cycle battery that is designed to handle deep cycling.. A lead acid battery has big giant lead plates designed for huge current and not much capacity... They become physically damaged when deep cycled...........

Ben, While this is all true, what I am referring to is the result of a battery being left dead/low/unmaintained for periods of time, rather than being constantly deep cycled. In a car with a working alternator, the battery is almost never deep cycled, rather, it drains all the energy that it can dump at once (the surface charge), and it acts as if it is dead, but if you let it sit for a period of time (sometimes 10-15 minutes), it will regain that surface charge, and be able to crank again. The starter takes a lot of amps at once, and leeches the surface charge, but doesn't deep cycle the battery. Do this a lot, and you get sulfation. Once your plates are sulfated, they a) can't accept as much of a charge and b) cannot discharge as fast as before (due to decreased surface area) In order to deep cycle a battery you need to draw all the energy out of it - if you keep doing the cranking til it's dead/waiting for it to recover cycle enough times, you can deep cycle it, but leaving a light on is more likely to do this.

On the EV mailing list, the consensus is a good battery charger with a 1 or 2 amp constant trickle setting hooked up to your battery for a long period of time (days or more) will result in the sulfate slowly being reabsorbed into the acid, but you have to monitor the water level and add distilled water from time to time, as you are technically overcharging the battery, and some of the water will evaporate (but not the sulfur)

For a basic starting battery, you should be fine going to Kragen and getting an Exide. They make good batteries, and you should be able to get one for under $100. I think the one in my Chevy K1500 cost me $85 plus a core. It's also way less of a pain that the afforementioned desulfation process, which requires a charger that won't turn off when the battery reaches 14.5 volts.

A regular car battery is deep cycled any time you run accessories without the alternator turning.. If you sit in your car and listen to your radio untill the battery is dead you have just deep cycled it..

I just glanced at the chat board and saw a question about a deep cycle battery as compared to a lead acid.. Had to throw that out there as that is the largest difference..

Its kinda funny that this comes up now..

I have an exam on electrochemistry and thermodynamics tomorrow.. I am literally studying commercial battery systems right this very second.. LOL..

For the last 2 weeks I have been building voltaic cells in the lab..

Yea, I just was remembering a string of conversations from las spring or something discussing how battery recyclers recycle batteries... Often times, they simply charge them until the sulfate is all gone. This is true of both regular starting batteries, but especially of deep cycle batteries, such as from golf carts and forklifts. As long as the lead plates are intact, often times the only problem is that they won't take a charge because of the sulfate.

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