Dual battery system.. help!!

Need advice for a dual battery system. I’ve been told optima yellow top is the best, but what group? I’d like to run a fridge, 8k diesal heater and a winch eventually. Any tips?

 

if you’re planning on mounting in the engine bay a good deep cycle should do the trick. But if you’re gonna mount it inside the vehicle I would go lithium. But make sure it has a low temp charging cut off protector.

 

Any opion on the optima yellow top? When I check the local auto parts store it’s telling me a group 35.. but I’m not sure.

I’ll be mounting under the hood. I gotta guy that knows how to set it up. He told me to check around on forums to see what everyone else is running.

 

Never personally ran optima yellow top. I personally run NorthStar and it’s been going for 7 years strong, I have heard a lot of good things about Diehard lately as well.

Edit : Just some food for thought, you’ll only get about 50% of the batteries capacity if you choose to run a deep cycle. Running lithium you’ll almost be able to use 100% of its capacity.
Whenever I decide to add a secondary battery I will be mounting lithium under the back seat or behind it, and it will make connecting those accessories a really short run to the battery.

 

Spent a lot of time (a year or so) deciding what battery to use in mine and after a lot of research Optima's were off the list. Used to run an IBS dual battery system with group 35 deep cycle batteries and just upgraded to a Genesis Offroad dual battery system using group 35 deep cycle batteries. Dark and rainy outside right now, will get you the brand I'm using tomorrow. Lithium is not a good choice at all to run in tandem with an AGM battery but it is a good choice if used as seperate power supply but lithiums have different charging parameters that need to be met to use them safely (lithium battery fires are bad news). PM me to remind me and will send you some pictures tomorrow.

 

Agreed on not running in tandem. Dc to Dc charger and/or a Battery Isolation Manager and you’re good.

 

I went the easy route and got a kit from sdhq, with two odyssey batteries, group 34. Truck has been tuned and the alternator was increased for the agm batteries. And later, added a 80 watt good solar panel from cascadia 4x4. No complaints, it’s been like 3.5 years on the battery and 3 with the solar panel.

 

Group really just determines the physical size of the battery. For a second battery in a dual setup you want to pay attention to the amp hours of the battery. Typically the smaller the group size the fewer the amp hours.

Things you need to determine;

1) How long do you plan to go between charges?

2) What type of charging system do you want? Solar? Charge from the vehicle? Both?

3) Is a fridge and heater all you plan to run? What about lights, electronics chargers, will you have on board water and run a pump, etc.?


Just for reference, I have a Duracell 110ah AGM in my trailer that charges off a single 100W solar panel. If we have good sun it will last a couple weeks before it even hits 50% running my fridge, all lights on the trailer, vent fan, and charge two phones each night. I usually see a roughly 20% drop overnight if we charge both phones, and a day of good sunlight will get that close to 100% most of the time, but it usually works out to a 5% loss per day. Start day 1 with 100%, by day 5 we are at 75%, and so forth.

In my truck I've been running that same battery for my "house" battery off a 10 amp DC to DC charger, but I'm going to downsize and run a 80ah AGM. I'll never use more than 20% per night, and it only takes a couple hour drive to be back to 100%.

The winch can run off the vehicle battery. You need to have the vehicle running when using the winch anyways since they draw too many amps.

 

Dang, those batteries mentioned above are expensive! I just put my original battery on as number 2 and purchased a larger group battery for the starter. It runs all my stuff with enough left over. I also put in my own mount behind the air filter using angle iron brackets from True Value and a blue seas charging relay to keep it topped off from the alternator. Total cost was less than $250. I added a few extra solar panels and a controller later on that were more expensive than the two batteries and relay, but now it keeps a charge even after running the refrigerator all week.

 

I had the yellow in my 93 pathfinder and honestly IMO it was a total waste of money. It lasted less than the interstate it replaced and cost a lot more. If you're looking to power a bunch of overlanding accessories you're better off doing what was suggested with lithium and a solar setup

 

FYI. Warn states "do not use a lithium battery with a winch" I would stick with an AGM. Mount at least one inside or in the bed. The inner fenders and core support do not like a lot of additional weight where it was not designed to be.

 

Useful knowledge in this thread that I'll keep in mind when I too go dual battery.

Interesting note regarding the additional weight. I haven't considered this

 

Which tune do you have? I have the OTT and an AGM but didn't ask the tuner to change the charging output of the alternator. Is your alternator stock?

 

How long are you hoping to run the fridge, heater, and other small loads (not including the winch) between running the truck / charging the battery?

Reason I ask is you may very well be able to get away with a single battery, and one of those Noco jump starter packs for emergencies. Dual batteries = a lot of weight up front. These trucks dont like that in the long term. I did dual batteries a long time ago. Looking back I would only do a single now. Either that or run a small starter battery and a larger Aux battery in the bed or behind the rear seats just for the sake of weight.

 

Optima’s aren’t what they used to be. Been kinda crappy for a while
Odyssey for a starting/winch battery, lifepo4 not under the hood for everything else. Can always push the easy button and grab an Ecoflow; ~$700 you can get 1000 watt hours, alternator charger and cables and charge it in 1.5hrs off the truck, run anything 120v that you would want, ready for solar and 12v hook up for the fridge
Recommend solar if it’s gonna sit a while and you want to keep the fridge going, I put 400 watts of solar on my cap rack

 

Yes , stock alternator.

 

Good to know. And I’ve considered solar also. With all the advice now I’m thinking mounting the aux in the bed with a good solar panel just for charging.

using a roof top tent I’m usually land locked for the trip , 2-3 nights. Using a heater at night and the fridge of course for the entire trip. Now I’m thinking the winch can be used off the main.

 

Kdmax… stock alternator.