Re: More Battery Recharging Questions

On Fri, 23 Dec 2005 01:05:24 GMT, "BF Lake" <nomail@xxxxxxxxxx> wrote:

>
><altar> wrote in message news:07gmq1dstk6ncbgfkrspoce0ubj89vmvug@xxxxxxxxxx
>
>> No way am I going to live on 25% percent of capacity.
>Isn't that what you really do? The boondocking advice I've seen says it is
>impractical to charge your batteries to more than ~75% (until you get shore
>power again) because beyond that the amps are so low and the time taken is
>so long. So when you discharge to 50% and then re-charge, your effective
>cycle is between 75 and 50%, which is 25% .

That depends on the batteries. My pair of Group 29s in parallel
(about 210ah nameplate, about 180ah real) Will charge to about 70% in
the bulk phase. An hour in the absorption phase will bring them to
80-80%.

When I foolishly changed to a pair of 6 volt cart batteries, I found
that the bulk phase ended before 50%. Another hour on absorption
would only get to maybe 60-65%. Completely unacceptable for my way of
camping.

Now that I'm back to Group 29s, I can do the whole cycle to about 85%
charge in about 2 hours with my CBC.

The first cycle off of shore power I get around 130-140 ah from my
pack to 80% DOD. After that it drops back to oh, 110-120ah until I do
the next full charge cycle on shore power.

Between the bright reading lights I use because of my declining
vision, the electric blanket, the inverter-operated microwave and the
furnace, I can easily use that much in a 24 hour period. Even if I
don't, I try to charge each day "just in case."

>
>AFAIK (I would like to know if this is correct) that means on a 200 amphr
>battery bank you are operating with a 50 amphrs a day allowance at 77F (or
>~35 amps a day when it is near freezing--mostly furnace at that). The
>average RVer uses at least 50 amps a day so that is why some people have a
>400 amphr bank.

The only way to know this for YOUR setup is with an E-meter. Batteries
vary fairly widely by brand and model. I know, for example, that the
Stowaway Sam's Club batteries are not as good as the Trojans but
they're not bad enough to get me to pay double for the Trojans. I
simply use my E-meter, keep a log and rely on the trend (aka, my
experience.)

The next time I change out my pack, I'm going to move them indoors
under the dinette couch so they'll stay warm in the winter and not
lose so much capacity. I've already moved mom's pack to under the
dinette and the results are most satisfying. She has a smaller pack
in her rig and sometimes we couldn't make it through the night in the
winter. Now we can.

John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
A foolish consistency is the hobgoblin of little minds.-Ralph Waldo Emerson
.

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