

| Subject: | Re: charging aux battery: too much of a good thing? |
| From: | David Beierl |
| Date: | Tue, 20 Apr 2010 19:12:25 -0400 |
At 06:11 PM 4/20/2010, mark drillock wrote: >Today I was able to fire up my 3 battery system for the first time. A >dedicated 125 amp hour deep cycle was added for the Vitrifrigo fridge <snip> >run the engine to get another night of camping. I was surprised to see >the meter reading over 60 amps going into the battery when I first Mark, that's a bit high -- the rule of thumb is 1/4 the amp-hour capacity for flooded cells, 1/3 for gel cells. However since it's only for a few minutes I doubt you'll come to much harm. If you're getting 14.5 volts at the batteries, that's probably good for charging itself, but will likely put the batteries in the gassing range which will boil the water out of flooded batteries fairly quickly and may harm gel batteries -- I forget. Normal float voltage at room temperature should be around 13.6, but the batteries won't charge either fast or fully at that voltage. I might suggest going to a 14.2v regulator, but that will slow down the charge rate noticeably. You can regularly check and add water to the batteries; but the real solution is a three-stage "smart regulator" which isn't free. You can manually simulate one for very little money; pmail me about that if you want. YOurs, David
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