Adding 3rd Battery on Duramax...

[Elite130]

I am wanting to add a 3rd battery to on my 2022 Duramax. This battery would be mounted in the bed of my pickup inside my truck box. The purpose of this battery would be to power auxiliary items while camping without worrying about discharging the two starting batteries. The items would include:

- Inverter (800watts max) - Running/charging a laptop or TV, 120v air inflator for lake toys (i.e. tubes, stand-up paddleboards, etc) and/or running Traeger Tailgater Smoker (400watts for first 5 minutes, 50 watts to run). 

- Air compressor - Viair 300P portable air compressor or future air-on-board air compressor 

 

I'm thinking I'd run a positive cable from the alternator back to the battery. I'd have a breaker with an isolator inline within the engine bay. The battery will be mounted in a battery box that is vented out of the truck box. The inverter and compressor will be connected to the battery and mounted within the truck box. 

 

Has anyone done this? Does anyone have comments, tips or tricks? Again, the purpose of this is to run items off the auxiliary battery instead of the main starting/running batteries. 

[Another JR]

Based on the loads you described I think you will be much happier if you go with a lithium (LiFePO4) battery and a DC to DC converter charger instead of a lead-acid battery. 

 

To size the battery you’d want to estimate your daily energy usage and how many days you’d like to be able to go without running the truck to recharge.  One of the nicest accessories to have camping if you have the space and the power is a 12 volt compressor fridge, so consider adding that to your sizing calculations.
 

The DC to DC charger I’d recommend is the Victron Orion XS 50 amp charger. 

[bruceb58]

5 hours ago, Another JR said:

Based on the loads you described I think you will be much happier if you go with a lithium (LiFePO4) battery and a DC to DC converter charger instead of a lead-acid battery. 

 

To size the battery you’d want to estimate your daily energy usage and how many days you’d like to be able to go without running the truck to recharge.  One of the nicest accessories to have camping if you have the space and the power is a 12 volt compressor fridge, so consider adding that to your sizing calculations.
 

The DC to DC charger I’d recommend is the Victron Orion XS 50 amp charger. 

Exactly what I would do. I have lithium batteries and the that same Victron XS DC to DC converter on my trailer.

[Elite130]

Thank you guys for the input! I'm look into the Victron DC-DC chargers, and DC-DC chargers in general. I'm assuming these DC-DC chargers eliminate the need for an isolator and they manage charging rates to the battery dependent upon which battery I go with. If I decide to stay with a lead-acid battery, is the DC-DC charger necessary?

 

I'm just getting into this and don't fully understand all of the different options. There is so much more to adding a battery than I ever thought. Thanks for the help!

[redwngr]

They have both smaller and larger ones available. 

 

 

[Elite130]

3 hours ago, redwngr said:

They have both smaller and larger ones available. 

 

 

 

Haha... not what I want or need. I already have one of those if need be. Not looking to carry additional fuel (propane or gas) and my 3000 watt generator (Firman dual-fuel) in the bed of my pickup. 

[bruceb58]

6 hours ago, Elite130 said:

Thank you guys for the input! I'm look into the Victron DC-DC chargers, and DC-DC chargers in general. I'm assuming these DC-DC chargers eliminate the need for an isolator and they manage charging rates to the battery dependent upon which battery I go with. If I decide to stay with a lead-acid battery, is the DC-DC charger necessary?

 

I'm just getting into this and don't fully understand all of the different options. There is so much more to adding a battery than I ever thought. Thanks for the help!

Even with a lead acid battery, I would get a DC to DC charger since you need to isolate it anyway.

 

There is NO way I would go lead acid for that battery. Lithiums are too inexpensive to not do.

[redwngr]

44 minutes ago, Elite130 said:

 

Haha... not what I want or need. I already have one of those if need be. Not looking to carry additional fuel (propane or gas) and my 3000 watt generator (Firman dual-fuel) in the bed of my pickup. 

I was thinking it would be better to run a little generator to recharge the battery instead of the dmax. 

Quiet running and the idle down feature are nice.

 

I wouldn't haul my full size one around for that job either. 

 

[Elite130]

1 hour ago, bruceb58 said:

Even with a lead acid battery, I would get a DC to DC charger since you need to isolate it anyway.

 

There is NO way I would go lead acid for that battery. Lithiums are too inexpensive to not do.

 Ok. I'm thinking the same thing. I'll go with a lithium.