Path: eternal-september.org!news.eternal-september.org!feeder3.eternal-september.org!panix!.POSTED.2602:f977:0:1::2!not-for-mail From: Ted Heise Newsgroups: rec.outdoors.rv-travel Subject: Re: battery change questions Date: Sun, 4 Aug 2024 20:10:57 -0000 (UTC) Organization: My own, such as it is Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Date: Sun, 4 Aug 2024 20:10:57 -0000 (UTC) Injection-Info: reader1.panix.com; posting-host="2602:f977:0:1::2"; logging-data="24981"; mail-complaints-to="abuse@panix.com" User-Agent: slrn/1.0.3 (NetBSD) On Sat, 3 Aug 2024 15:38:30 -0500, George Anthony wrote: > On 8/3/2024 1:00 PM, bfh wrote: > > Ted Heise wrote: > >> On Fri, 2 Aug 2024 23:13:42 -0400, > >>    bfh wrote: > >>>   Ted Heise wrote: > >>>> 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? Yes, I've checked the 1 and 4 pins on the 7-pin receptacle with a multimeter, and there is 12 V there--even when the car is shut off. I'm also able to run 12 V equipment (e.g., tongue jack, lights, exhaust fans) when the trailer (without any battery) is connected to the 7-pin on the tow vehicle. The thing that doesn't make sense to me is that when the battery and 7-pin are both connected, the battery still reports it's discharging. I could get that it doesn't charge much, but to be discharging just seems unexpected--like something in the trailer (e.g., the PD4000 power control enter) is not supplying anything to the battery. FWIW, it does charge when the trailer is hooked to shore power. -- Ted Heise West Lafayette, IN, USA