Re: Battery charging/discharging

On 6/13/2025 7:20 AM, Ted Heise wrote:

On Thu, 12 Jun 2025 19:48:51 -0500,
   sticks <wolverine01@charter.net> wrote:

  On 6/12/2025 12:44 PM, Ted Heise wrote:

 

FWIW, here are the details from each of the three test
cases...
>
7-pin        Power     Current   Voltage
Connected    -220.1 W  -16.7 A   13.2 V
Dis-connect  -242.2 W  -18.5 A   13.1 V
Connected    -215.7 W  -16.4 A   13.1 V
>
And this was all with the battery SOC being about 98%.

>
  I can't recall from the earlier discussions, but where does the
  hot prong on the 7-pin on the trailer go to?  Does it have a
  wire going to the battery?

 I think you may have asked this question before, but am pretty
sure I would not have answered it because I'm not sure how to
tell.  Is the idea to see what role the trailer's power center may
play?

First off, I don't see how the the towing vehicle would lower the battery on the trailer, but I'm not positive on this. The power to the 7-prong comes from the battery and when running the alternator will keep the voltage over 12 volt.  Usually something like 14.4 volts.  This is one of the reasons DC to DC chargers are used to protect the alternator, but IIRC you have a heavy duty alternator.  I can see when you turn off the tow vehicle and if you don't have it isolated, the Acadia could be backcharging from the lithiums.  If the Acadia is running, it might not give enough power to charge, but I can't see how it would pull power from the trailer.
That said, I'm not sure what the power center you mention is, but I would want to know where the power wire from the 7-prong on the trailer goes.  Your signal and brake lights do not use power from the trailer batteries.  They use the towing vehicles power.  Often, the power prong is used for trailer braking I believe.
On my TOAD setup on our Bronco, I installed a wire from the 7-prong and put a fuse in the route, and took it directly to the battery.  It kept the TOAD battery fully charged with an electric Patriot Brake that I use.
If it were me, I would follow the wire on the trailers umbilical from the power prong and find out where it goes to start with.  Now I don't have lithium batteries, but I recall when we were discussing this before there is a little difficulty getting them to start charging, and we agreed on 3/7 you could not get enough power from your tow vehicle to charge them.  We also kind of agreed there is a wire going to the battery per manufacturer literature.
Message-ID: <vqfbhe$3ict3$1@dont-email.me>
This is one of the reasons people install those DC to DC converters.  I think they will charge at a steady 20 amps with a good size wire, and higher if you go down to say a gauge 4 wire.
--
Darwinism Is Junk Science!!