Anyone install a DC to DC Charge Controller on 2021 2500HD Duramax?

tortiseshell · October 26, 2021

Looking to hear from others who have done this. I have a slide in camper for my truck and want to improve the ability to charge the camper house battery while driving.

I know it depends on the battery in the camper, LA/AGM/Lithium... but what product did you use, why and what was the install like?

Several products out there are attractive, but I'm no mechanic or electrician. Looking to upgrade my current electrical capacity in the camper and need to start with a good charging system.

What did you use and can a rookie like me do this? Thanks!

Another JR · October 26, 2021

I have a dc to dc converter in my slide in camper that is powered from the main battery of my gas 3500hd. (I also have an OEM auxiliary battery. )

It’s a relatively simple installation. You should install the dc to dc charger very close to the camper battery, typically in the camper battery compartment. This allows the charger to compensate for voltage loss in the wires to the camper. You want to have a fuse or circuit breaker in the positive wire at the truck battery to protect against short to ground along that wire.

I have a Victron Orion Smart 12/12-30 charger which delivers 30 amps. I used 6awg wire end to end. I used the existing unused 80 amp fuse in the main battery fuse block.

nutdriver · October 30, 2021

On 10/26/2021 at 2:09 PM, Another JR said:

I have a dc to dc converter in my slide in camper that is powered from the main battery of my gas 3500hd. (I also have an OEM auxiliary battery. )

It’s a relatively simple installation. You should install the dc to dc charger very close to the camper battery, typically in the camper battery compartment. This allows the charger to compensate for voltage loss in the wires to the camper. You want to have a fuse or circuit breaker in the positive wire at the truck battery to protect against short to ground along that wire.

I have a Victron Orion Smart 12/12-30 charger which delivers 30 amps. I used 6awg wire end to end. I used the existing unused 80 amp fuse in the main battery fuse block.

Curious where this 80 amp fuse is located. I would be somewhat concerned that 80 amps is more than would ever be needed and could pose a fire risk. Can this fuse location be used but with a lower rated fuse?

Another JR · October 30, 2021

The fuse was an unused fuse on the battery mounted fuse block. It has a big fuse for the wire coming from the alternator, another going to the aux battery, one to the main fuse box, and this 80 amp unused one. I believe it is intended for this type of use powering a trailer or camper charging system.

An 80 amp fuse is just fine to protect Ancor Marine type 3 6awg wire. The charger pulls about 34 amps when in bulk charge. It doesn’t need an 80 amp fuse but the fuse is adequate to protect the wire run. The wire is upsized to reduce voltage drop. The fuse is permanently attached to the fuse block bus bar. If you blow a fuse GM intends you replace the whole thing is my understanding.

Edited November 1, 2021 by Another JR

Another JR · October 30, 2021

Here is a picture of the fuse block in case that helps. The 80 amp fuse was unused.

Edited October 31, 2021 by Another JR
Added picture

nutdriver · November 1, 2021

On 10/30/2021 at 12:13 PM, Another JR said:

The fuse was an unused fuse on the battery mounted fuse block. It has a big fuse for the wire coming from the alternator, another going to the aux battery, one to the main fuse box, and this 80 amp unused one. I believe it is intended for this type of use powering a trailer or camper charging system.

An 80 amp fuse is just fine to protect Ancor Marine type 3 6awg wire. The charger pulls about 34 amps when in bulk charge. It doesn’t need an 80 amp fuse but the fuse is adequate to protect the wire run. The wire is upsized to reduce voltage drop. The fuse is permanently attached to the fuse block bus bar. If you blow a fuse GM intends you replace the whole thing is my understanding.

Thanks for the additional information!

tortiseshell · November 1, 2021

Hey this is all super helpful! Thank you. Still mysterious for me and feel like I want to find a mentor (besides youtube) to help me tackle this. Would prefer to keep cost down and the more I do myself, the better I will understand what I have. Ultimately I want to increase my battery capacity. Big decision is lithium or agm... its a cost issue for me. Then a dc to dc charger that can handle different battery types should i change at some point. Would want the charger to isolate as well handle a portable solar panel. redarc makes some intriguing products. victron does as well. I don't see changing out what came with my camper, but I do see adding onto it. My battery space is pretty meager. Room for two 12 volt group 24, but will be tight. Currently i have one Group 21 agm in there. Also want to think about adding a 12v portable refer that would be kept in the back seat of the truck. Wondering how power and battery mgt will be taken care of for that. Open to all ideas. Thank you everyone!

Edited November 1, 2021 by tortiseshell

BigAlBuilds · November 20, 2021

I have the 50 A DC-DC with MPPT solar charger installed on my camper I love it but it was a pain to install. I had to run a 4 gauge all the way back to the tail gate...it was a pain. I am using it to charge a renogy 170 aH lithium battery in the camper when I drive and it work fantastic. If I could do it again, I would get the 30 A DC-DC charger and just wire a 7-pin trailer plug to the DC-DC and use the Silverado's built in 30A trailer charging circuit.

Another JR · November 20, 2021

The wire supplying the power pin of the 7 pin connector is inadequate to supply a 30 amp dc to dc charger. I don’t remember the exact gage, but it’s 10 awg or smaller. While ampacity charts will show 10 awg can handle 30 amps without overheating, the voltage drop will be excessive for a charger located in a camper and the engine running detection of the charger won’t function properly. Multiple people on a truck camper forum I frequent had problems trying to use a 30 amp dc to dc charger with 10 awg wire due to constant cycling if the charger on and off from low voltage. 6awg definitely works well with a 30 amp dc to dc charger from my direct experience. 8awg might work, but I haven’t tried it.

January 28, 2022

I built this for enclosed trailer setups to work out of at night. Two 12v golf cart batteries, 2AWG wire- only Positive from the battery, short negative to a close frame bolt, 200 Amp relay switched by one of the ignition activated fuses, resettable Circuit breaker (your choice on Amps 30 to 300), Amp winch connector from truck to trailer.

Truck Charges the trailer batteries only when it’s running. Golf cart batteries have been abused for a year trouble free 5-7 days a week. Battery bank charges all tool batteries, indoor and outdoor led lights, and when needed a giant Inverter.

DC charging like this to batteries seem to transfer power with the least amount of loss.
You can also look into a Low Voltage Cutoff switch for extra protection on the vehicle. I had a boat trolling motor battery go to complete crap on me this week. It was 9v after 7 months on a nice charger/maintainer.

Edited January 28, 2022 by Phobby