Do I NEED a DC-DC Charger?

[JKellerJr]

Given that the solar panels produce more power than the alternator and can take the Li ion batters to full charge it seems to me a better work around would be to pull the fuse to disable the charging circuit in the 7 pin connector. Would this prevent the truck from seeing the over voltage condition you warned against or would the higher voltage still make it to the truck via the brake controller wires? I definitely don't want to damage the truck so if I have to disconnect the solar and let the truck charge the batteries to ~80% and charge the rest of the way up at my destination.

[MENTION=55441]BoredWeasel[/MENTION] has a point. I don't have solar and don't know much about it so I can't say one way or the other. The GM problem is not necessarily a solar problem. Many have it without solar. I have never had an issue but my dad did. He doesn't have solar either.

The simplest and cheapest fix if it pops up is to add a one way diode on the trailer. It will only allow current to flow one way effectively isolating the truck from the trailer. Some claim lithium alone with its higher voltage can have an effect on the truck batteries if you stay plugged in while the truck is off. I've been running lithium since 2017 on 2 different trailers and trucks and haven't had any problems. But I can't 100% rule it out either.

Want to be sure, add one of these in the charge line of the trailer. I don't have one but I may add it someday just for insurance.

https://www.etrailer.com/Accessories-and-Parts/Roadmaster/RM-690.html

 

[BillandLisa]

That's not a quirk but a designed in feature with the GMs....

When a trailer is connected and the vehicle is off, the Trailering App System will
periodically pulse the lighting circuits of the trailer to verify it is still connected. The trailer lights may periodically flash as a result of this trailer connection detection. These flashes may be more visible in dark ambient light environments. The flashing or flickering lights are a normal condition and the Trailering App System has built-in
protections to prevent the battery from draining.

Thank you for that information!

 

[BoredWeasel]

My TV is a 2020 GMC 2500 Denali Duramax. One issue/feature/quirk I have noticed is when the rv is parked but still connected to the TV (i.e. loading up for a trip in front of the house), I will get a periodic "Flash" of the trailer break lights, the duration of which is so short it does not illuminate the LED bulbs fully before it disappears. I "address" the issue by unplugging the 7 pin cord but I honestly do not know what causes the flash or if it represents an issue or can be left alone
.

I never noticed this, but my hitching routine is only a couple of minutes long and generally the truck is never off once the trailer is on the ball

 

[traveldawg]

That's not a quirk but a designed in feature with the GMs....

When a trailer is connected and the vehicle is off, the Trailering App System will
periodically pulse the lighting circuits of the trailer to verify it is still connected. The trailer lights may periodically flash as a result of this trailer connection detection. These flashes may be more visible in dark ambient light environments. The flashing or flickering lights are a normal condition and the Trailering App System has built-in
protections to prevent the battery from draining.

What ^^^^ [MENTION=51252]COGrandDes[/MENTION] said ^^^^^^. Same thing for Fords.

 

[Pepinross]

A DC-DC charger is highly recommended to protect your truck.

Totally agree with Soundsailor. I have 560 aH of LiP04 batteries that I trickle charge with my new truck's alternator through the 7-pin camper pigtail and I have solar as well. Solar does all the work really. I just don't see the need for myself to ever have a DC-DC charger...at least here in CO where the sun shines most of the time. I've run this camper and my last camper this way for year without issue.

ghly


A DC-DC charger is highly recommended to protect your truck from the high charging current demand of the LiFePO4 battery.

 

[JKellerJr]

ghly


A DC-DC charger is highly recommended to protect your truck from the high charging current demand of the LiFePO4 battery.

Please explain this "high charging current demand"

 

[JKJavelin]

I asked about a DC to DC charger when getting the quote for my solar installation.
This is how it was explained to me:
If you have a heavy cable running from your truck alternator to your lithium trailer batteries, and those batteries were discharged, they would suck a lot of electricity from your alternator, and might damage the alternator from it overheating.
But, because of the puny wire that comes with the truck and trailer, the current dissipates. I only get 6 to 9 amps from the truck when towing.
They could've sold me a DC to DC charger, but they said it wasn't necessary.
JK

 

[JKellerJr]

I asked about a DC to DC charger when getting the quote for my solar installation.
This is how it was explained to me:
If you have a heavy cable running from your truck alternator to your lithium trailer batteries, and those batteries were discharged, they would suck a lot of electricity from your alternator, and might damage the alternator from it overheating.
But, because of the puny wire that comes with the truck and trailer, the current dissipates. I only get 6 to 9 amps from the truck when towing.
They could've sold me a DC to DC charger, but they said it wasn't necessary.
JK

Exactly. There is a difference when using the truck as a true charging system and the trickle charging from the OEM system.

This the the video that Victron has that freaks everyone out.

https://www.youtube.com/watch?v=jgoIocPgOug&ab_channel=VictronEnergy

That battery is hooked up directly to the alternator. It does not apply when using the OEM truck system

 

[JKJavelin]

I neglected to mention that it's the combination of the light gauge wire and the long distance between the alternator and the batteries that dissipates the current.