Battery Thoughts

[Dale M.]

Here is a site with some pretty good technical information about batteries.

http://www.uuhome.de/william.darden/

Dale

[dahoon]

I have been selling batteries and other auto parts for over 25 years. Here are some pearls of wisdom I have gained.

The difference between automotive and deep cycle batteries is the make up of the cells. Deep-cycles have thicker plates in their cells and the grids on the plates are different.

An automotive battery is designed to have its charged maintained, they really like to keep themselves fully charged all the time. The main job of an auto battery is to start the vehicle once the car is started then its work is done unless the alternator quits. The alternator is supposed to replace the amperage in the battery that was expended when starting the vehicle. That is if the regulator is doing its job. So they need to have lots of amps availible quickly, but die out sooner.

The deep-cycle battery has thicker plates in the cells and their grids are heavier, so its reserve capacity is longer and its charge can be taken down deeper. They are designed to have their amperage drawn down and then recharged. An important note when recharging a deep-cycle battery is: LOW AND SLOW.

I have taken a lot of WAL-MART batteries in as cores. There is a reason why they are so cheap, they don't use as much lead in their batteries so they don't hold up as well. Trojan is a decent battery. But, my preference is Interstate and East Penn and AC Delco put out the best deep-cycle bateries on the market.

Amp hour rating is and ambigous number that a manufacturer can place on a battery. The tests they use are that accurate. The reserve capacity of a battery is a more accurate gauge of the strength of a battery. It more realibly tells what the charge life of a battery is at the amperage draw.

Remeber when charging a deep-cycle battery do it LOW AND SLOW. A 6 amp or maybe a 10 amp charger can be used, but I wouldn't go larger.

I had even contemplated using two 6-volt batteries in series. That would give the biggest bang for the buck and the best reserve capacity. But didn't think we would be camping for that long at a time.

Mike

[GeorgeTelford]

Most batteries sold as deep cycle are no more than rebadged standard batteries.

Check the weight of many so called deep cycle batteries and you will find it very similar to that of a standard auto battery of same Ah.

Reserve capacity is an industry measure for rating auto starting batteries and is not really relevent to Deep cycle batteries. RC is the number of minutes a fully charged battery at 80° F (26.7° C) can be discharged at a constant 25 amps until the voltage falls below 10.5 volts its a different way of measuring AH but to guage starting capacity

A normal deep cycle battery is a lead acid battery and most manufacturers reccomend a 20% charge ampage ie for a 100 Ah battery a 20 Amp charger is the ideal.

This low and slow thing is a myth (an harmless myth, all it does is take longer than needed to charge)

[Dave Bob]

I'm no battery expert, but know just enough to be dangerous. I have a small solar electric system at my hunting camp and I use Trojan T-105 6v golf cart batteries. I have 6 batteries in a 12v system wired series parallel for 660 amp hrs. This setup with two 75 watt solar panels has ran my cabin for the last 5 years.

AGM batteries have one other advantage that has not been mentioned, a lot lower self discharge rate. this would help if for instance the battery was fully charged then left off the charger, an AGM would last a lot longer without damage than a flooded lead acid battery. However most deep cycle batteries damage is caused because of not being recharged immediately (or as soon as you can) after discharge - flooded lead acid or AGM.

Dave