Dual Battery Setups! Let's see them! Multiple Batteries Thread!

To carry the analogy further along, if a simple relay is considered 'dumb' and an ml-acr is 'smart', then a DC to DC charger is a 'genious' because it has the ability to maintain optimal battery health with dissimilar types of batteries.

If you must run a traditional, wet-cell starting battery and want to run a big, deep cycle AGM type as an auxiliary, then the DC to DC charger is the optimal choice because it takes the power from the alternator and manipulates it so that the AGM can be fully charged without damaging the wet-cell starting battery. Another plus is that most of them can easily manage the addition of a solar panel.

The only real downside I see to a DC to DC system is you can't self-jump or link the batteries together for winching which are big reasons for going the ml-acr route. That and its 500 amp continuous load capacity.

 

thank you!! thats frustrating that you cant self-jump and winch with DC-DC but on the other hand i DO want to do a solar panel in the future...just wanna have my cake and eat it too...decisions decisions

 

You can do the dc-dc charger and run a heavy gauge wire through a continuous duty or a starting relay (both Shound be good around 200A) that way the battery’s charge off the dc-dc but you can have a switch in the cab to link them when needed

 

If your batteries are relatively close you can always use jumper cables. I'm not sure the ability to parallel your batteries from the cab is really all that important TBH. It's more important to have a system that works to keep batteries charged and protects the starting one from ever going dead in the first place.

 

This is my plan as well. Using only the ML-ACR to charge the auxiliary battery tends to leave the aux battery not fully charged.

My question is, do you need to disconnect the DC-DC charger when the batteries are tied together through the relay?

 

Most practical? Probably not...But:

I have two 6v Trojan T105s in series in my bed (cost about $90 ea. from local golf cart place). These are hooked up to an A/B switch in cubby, with truck main battery on other pole. The two trojans (225ah) will run my edgestar 43qt fridge for 3-4 days by themselves. I keep two flexible plastic 100w solar panels in the back and put them on the roof rack whenever Im parked. 3-4 hrs of sun a day is enough to charge to batteries and run the fridge pretty much indefinitely.

 

Apparently, I'll keep reading.

 

Thanks, I'll add it to the list of possibilities, I would like to have one battery on the passenger side (2017 Off Road) where there is a lot of room already. Looking at mounting options is my first step I guess?

 

Good idea

Figuring out how much power do you need is probably the best place to start. What do you want to run and for how long... Meaning how many watts for how long? I would suggest going at least 10% or more over your minimum power needs.

Once you know your power needs then you can figure out what battery and charging combinations will meet your needs. Find locations for things to fit.

Personally I prefer to run a DC to DC charger for the Aux/House batteries.

Good luck and if you have more questions let us know.

 

Right now I just want to be able to run my electric cooler overnight and while stoped for a few days. Eventually I will upgrade to a refrigerator but for now that’s all I need. I defiantly want to have a battery under the hood on the passenger side and to run an outlet for the cooler to the bed.

 

Where to you guys get your welding cable?

Remy Battery is out of stock on 1 awg.
Lowes does not carry 1 AWG.
Fastenal wants $5/ft for a 1wg welding.

Thinking about sizing down to 2 awg from Lowes. It's not specified as welding wire so I don't know if it will be as flexible as I need it to be.

I've never heard of Temco, but I could get 80 ft of 1 awg for $150

$242 TEMCo WC0460-80' (40' Blk, 40' Red) 1 Gauge AWG Welding Lead & Car Battery Cable Copper Wire Black + RED | Made in USA

https://smile.amazon.com/dp/B01JMNKT7O/ref=twister_B01JMNKHVC?_encoding=UTF8&psc=1

edit: Screw it. I'm going to go with Temco off Amazon. Hopefully it won't burn the truck down.

 

I bought all more wire/ terminal ends from temco on eBay. Was cheeper Than Amazon

 

Crimp supply...

$175 Crimp Supply Ultra-Flexible Car Battery/Welding Cable - 1/0 Gauge, (15 Feet Red/15 Feet Black) - and 5 Copper Lugs

https://www.amazon.com/dp/B0161NX786

 

I checked a few places and got conflicting answers so I just went with 0 awg ofc amplifier power wire from a buddy who owns an audio shop. I hope this doesn't become a mistake down the line. The main thing catching my attention was how low of a temp rating the other wires insulation had. The wire I ended up going with had almost double the temperature rating and since I ran along the frame rail and up the firewall under the bonnet I figured the higher rating the better. I dont have a fridge or winch yet but between my audio and lighting I guesstimated the wattage use and added 15% for good measure. When I do go fridge and winch add on I dont know what the hell Im going to do.

 

I have just by happenstance two yellowtop dual purpose agms. Same size and age but heard if it isnt a "dual purpose" agm that some people have had problems using a deep cycle as thier starting battery. I could be wrong but I believe the dark grey case yellow top optimas are not for starting while the light grey case yellow top is dual purpose.

 

Most fridges are 4 - 5 amps. 0 awg should suffice for that. ( ;^)

 

First off ofc is a joke. Sounds good and can charge more for no benefits.
0awg for a second battery in the bed is fine. 2awg wound work well but the larger the better so Your good. Factory winch wire are ~4awg... but not meant to run long distances

 

What you are comparing against and double of what? The best source of large gauge cable locally is welding supply houses and generally speaking it's the cheapest way to get very high quality cable if you're buying online.

It's high strand count so it's very flexible. It'll be high quality copper if you buy known brands from reputable places. And the insulation is usually at least 125°C and sometimes 150°C and mechanically very durable, being EPDM rubber.

Welding cable is pretty the only thing I use for cable larger than 4 gauge. But I only ran a 8 gauge to the bed of my truck and welding cable doesn't go that small so I just used UL1426 marine cable that was rated 105°C. But nothing wrong with J1128 automotive wire, which you can get that up to 125°C.

If you're using hardware store wire designed for households, then yeah, it's going to be 60°C or whatever since that's all you need for a house. Those types of insulation aren't designed to be as resistant to chemicals and oil, either.

 

Good to know about the chemical resistance I didnt think about that but yeah the stuff at home depot definitely didn't look like a good idea. Like you said it isnt supposed to be used in automotive right? Welding cable probably is the best choice, I went with amp wire mainly since I lucked out and got it cheap through a friend.

 

Maybe. There aren't really any codes that you must use or have inspected the wiring like in homes, although the rules for marine and RV are probably the best general guideline. So what you have available at Home Depot is often not really intended for automotive use but it may work fine. They sell spools of 90°C THHW PVC hook up wire, which has alright chemical resistance to gasoline and oil (since you might find that in a garage or shop). But being a building wire it's not designed to flex or be in wet condition and stiffens up in cold temperatures, so there are better choices for vehicles. But standard SAE-J1128 automotive wire is also PVC and IMO not really that much better. It's pretty stiff, too, so I prefer using the cross linked polyethylene insulations (SXL, TXL, GXL), which will have better temperature range (and this is what is suggested in the J1128 for use in engine bays over PVC).