Monday, Feb 18, 2008 at 23:03
It sounded fair enough to me as well. Some of it no doubt is true, such as the issues of inadequate cable sizes and that deep discharging reduces battery life.
Can the "electrical gurus" give us a technical rebuttal of what they believe are the key porkpies? That's what forums are about. It's a bit like the Sci-Fi movies or the X-files where the line went "The truth is out there". It's out there somewhere but zeroing in on it can be a problem!
Some of the key points this fellow has made (and which should be corrected if wrong) include:
* AGM batteries don't vent (i.e. are spillproof) and can be laid on their side etc
* Car alternators (or ordinary battery chargers) only recharge the car batteries or wet deep cycle (WDC) batteries to 70% to 80% of actual full charge
* A car alternator will take 8 to 12 hours to recharge a deeply discharged deep-cycle battery
* Deep cycle batteries are only designed to be discharged to 50%, i.e. the "useful" amp-hours is only about 50% of the nameplate values. "Deep discharges" (i.e. below 50%) reduce the life of the battery dramatically
* AGM batteries will handle "deep discharges" better than WDC batteries
* For maximum (indefinite) life out of any deep cycle battery (AGM or WDC), there should be sufficient batteries that the "daily discharge depth is only about 20% to 25% [This implies a trade-off to me; more batteries means less discharge so a much longer life, but at the expense of higher up-front cost and lugging more batteries around all the time]
* A standard Honday generator does a poor job of charging batteries, but the "specific purpose" Honda petrol battery charger does a good job, achieving 100% charge of the batteries (the same as a well-designed solar panel/regulator system or a 240 volt "smart 3 stage" charger)
* If using a standard Honda generator, it is better to charge batteries using a smart-charger on the 240 volt output then to the batteries
* AGM batteries can be charged in 2.5 to 3 hours
* AGM batteries (unlike WDC batteries) can be left idle for 12 months and then be fully charged, without ill effect
I do know some other specialists in this area, so I'll put these questions to them myself also.
Rick
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