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From: George Anthony <ganthony@gmail.org>
Newsgroups: rec.outdoors.rv-travel
Subject: Re: battery change questions
Date: Sat, 3 Aug 2024 15:38:30 -0500
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On 8/3/2024 1:00 PM, bfh wrote:
> Ted Heise wrote:
>> On Fri, 2 Aug 2024 23:13:42 -0400,
>>    bfh <redydog@rye.net> wrote:
>>>   Ted Heise wrote:
>>>> On Fri, 2 Aug 2024 14:07:23 -0400,
>>>>     bfh <redydog@rye.net> wrote:
>>
>>>>>    Back in a previous life, we did a lot of flatspotting and got
>>>>>    along fine without a generator, but we didn't have a microwave,
>>>>>    electric coffee pot, or a toaster.
>>>>
>>>> The wife and I are spoiled, what can I say.    :)
>>>>
>>>> But how did you charge the trailer battery?
>>>
>>>   It charged through the 7-pin when driving, and with the
>>>   built-in charger when we had shore power. I don't remember
>>>   having any battery problems when flatspotting, but we rarely
>>>   stayed in one place longer than 2 days/nights. Plus, we weren't
>>>   spoiled back then, and all we used when parked were 1 - maybe 2
>>>   - lights and the water pump.
>>
>> Okay, charging from the 7-pin is what I'd expect, but I haven't
>> seen any evidence of that happening since I put in the new LiFEPO4
>> battery.  Admittedly, it's just been one trip of ~5 days.
>>
>> I do wonder if the battery has to reach some lower SOC than I've
>> seen (85%?) for charging from the 7-pin to kick in.  Operation of
>> the Dometic battery monitor is still largely a mystery to me...
>>
>> https://www.amazon.com/Go-Power-GP-BMK-25-Battery-Monitor/dp/B09NRXD9G8
>>
>> Is it possible the 7-pin will actually charge the battery if it
>> gets to a lower SOC?  If yes, do the GP-BMK-25 settings make a
>> difference in this level?  I can't tell from the "manual" and mre
>> broadly havn't been able to get a good unserstanding of how it
>> works.
>>

I really don't think it will charge from the 7-pin connection if the 
battery is low. At least not with the standard size wire you now have. 
By the way, I may have missed it but did you ever verify if you have 
voltage coming through the 7-pin connection at the positive battery 
cable on the trailer battery?

>> Maybe another relevant point is that the new battery shows its
>> state in good detail via a nifty bluetooth linked app; the info
>> from the battery makes sense, but diverges at times from what the
>> Dometic monitor shows (especially as it relates to SOC).
>>
> 
> I don't know. I didn't have a battery monitor, and the battery was a 
> standard old deep-cycle battery. It just charged when I drove or was 
> plugged into shore power.
> 

LiFePo batteries are a different breed. My opinion, FWIW, is to go with 
a small generator.
-- 
“The Party told you to reject the evidence of your eyes and ears..." 
George Orwell