Join Date: Aug 2006
Location: Arlington, VA
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Good...seems like you're on the right track. I'd strongly suggest that you look at the Iota chargers. IMHO, these are the best on the market in terms of both value for the dollar and in terms of their ability to keep your batteries happy over the long term. They come in a variety of sizes from 10A to 90A, and are surprisingly economical. Look on eBay. Be sure to get one with the IQ-4 smart charge option.
AGMs are very much like flooded cells, with a couple of differences which you've noted. You don't have to add water, they can be charged much faster, they have a lower self-discharge rate, and they may not require equalization as often as flooded cells. Charging voltages are very similar to those of flooded batteries.
AGMs can sulfate like other lead-acid types, and can therefore benefit from occasional equalization. Lifeline AGMs call for 15.5 volts for 8 hours, I believe; others suggest slightly different treatment, while some manufacturers say don't equalize at all.
One thing not mentioned above is the effect of temperature, especially on charging regimes. Unless you use a PWM charger like the Iotas, it's a good idea to have a battery temperature sensing charger which can compensate for wide fluctuations in ambient temperature. Problem is, recently we've seen lots of variation in the accuracy of temperature sensors...to the point where one doesn't know what to trust.
If the sensor reads higher than actual, your charging may be cut back to the point where the battery is chronically undercharged. Conversely, if it reads lower than actual, you risk overcharging and, in extreme conditions, worse.
For me, that makes an even stronger case for the Iota's and similar PWM chargers which don't require any special setting for battery type or temperature sensor, and which by design are highly unlikely to cause your battery to overheat.
Michael isn't the only one who has scary "insomnia moments". The more you think you know about battery chemistry, construction and behavior under varying conditions, the more you're prone to such occurences :-)
Last edited by btrayfors; 11-13-2008 at 04:27 PM.