LiPo4 battery in bed, AGM battery in front, Help

I have an agm battery under the hood i run vehicle systems and camper lights, fridge, and water pump off of. It is charged only the alternator and i have a GM resistor plugged into the ALT fuse location to boost the charge voltage to 14.3 or so for the agm battery.
I just got a deal on a LiPo4 50ah battery i would like to use for the systems in the bed.
i understand that they cannot be connected inline with one another. Can i get something like a RedArc battery management controller to correct the charge so the alt can still charge it? Does it need to be an independent system completely? I camp for a week at a time at most typically and usually just for a weekend. Tell me what i need???!

 

Yea a dc to dc charger like the redarc will work but you’ll have to separate those other systems to work on that separate circuit. But the alternator will still charge it. A benefit of using a dc to dc charger like that is you could add in solar later relatively easily

 

It sounds like the red arc is exactly what i need as those are all the outcomes I wanted.

 

I have the same thing. An AGM battery in front and a lipo battery in the bed. I used the Redarc 1225 ( I talked with them at overland expo and they said for just fridge and accessories the 1225 would be best. I also have it hooked up to solar. It works great and have had no problems.

 

I've got a Redarc BCDC charger and it works great. It can be configured to charge your second battery at the correct voltage.

You could connect your lights and fridge via a 5 pin relay where the BLUE wire is connected to the main battery, YELLOW to the secondary battery, WHITE to your ignition trigger, and RED to your equipment. If the ignition is NOT on, then the equipment will be powered by the secondary battery. If the ignition is on, then it will be powered by the main battery/alternator.

 

If the alternator is on and feeding the redarc it will technically power his lights from the alternator anyway right? Why a relay

 

You could use it without the relay but with the relay in place the alternator and Redarc can charge the secondary battery, without any load, so that you're secondary battery is fully topped off when you get to camp.

 

Don't know if I want the alternator charging my lipo without going through a charge controller, I don't have a redarc so I may be missing something here

 

Either redarc or renogy mppt dc-to-dc. Nice feature of renogy is that it will charge your starting battery once the house battery is full. Redarc doesn’t do that but redarc is a much higher quality product

 

The Redarc is a charge controller - it's connected to the primary battery, which is connected to the alternator. So if you bought one it would properly charge your Lipo.

 

And is 1 50ah enough to keep a dometic 65 running for a weekend ?

 

What's your amp hour draw on your fridge? How many hours per day will your fridge be drawing from the Lipo? Other things to consider is if you'll be driving around (on trails), or if you'll have solar, which will recharge your Lipo, and extend your battery life.

 

If you search the forum for dometic there may be some people who’ve posted how long their fridge lasts on x hour battery

 

i dont know. I understand it depends on load, temp and a multitude of diff factors. Just trying to gauge rule of thumb if i am sitting still with no solar.

 

you can connect them together just fine with the proper combiner. Boat guys do it for trolling motor setups with an agm cranking battery. You just need the combiner voltage set a little higher than a typical combiner. Look at Yandina lithium combiners.

 

I have the Redarc BCDC1225 with solar and a Lifepo4 100ah for my National Luna Fridge and it is the best combination after trying a couple different things. I used to have a Dometic fridge before, the Dometic in my experience consumes more current than the National Luna fridge. The 50 Ah lifepo4 battery is too small to run the fridge and accessories IMHO. You might me able to get 20-30 hours of run time for the fridge without having to turn on your vehicle, not including accessories. The redarc dcdc charger is top notch. 100% recommended.

 

Good info. Thank you. I may end up getting an additional 50ah battery eventually but i think the 1 will cover me for now. Excited to get a red arc.

Ryan

 

Just ordered an additional 100ah battery so that will be 150ah. Hopefully that will keep me powered up.

 

Should keep you powered up just fine. From what I’ve found, solar panel size and the efficiency of those panels is more important than battery size. I’m in SoCal and during spring, summer, fall can run my fridge 24/7/365 just off a 100w renogy solar panel and 50ah battery. Winter is hit or miss depending on the weather. Adding on another 100w in the next couple weeks so should have zero problems going forward running the fridge year round