mixing battery groups

[jdawg 5,000+ posts]

they have a 34 stock right? a 31 is alot bigger. Wish i could fit one.

 

[audiolife 5,000+ posts]

can you elaborate more on this?

want a matrix or a book?

 

[hrtbrk1 5,000+ posts]

i modified the tray...

 

[hrtbrk1 5,000+ posts]

want a matrix or a book?

lol im just not familiar with multi batt set ups thats why

 

[Annnarbor84 5,000+ posts]

I wouldnt, stick to the same type, even if its a reg batt up front and a deep cycle in the back, people run into problems with the deep cycle draining the front battery

How does that work, when you hook batteries up together in parallel, they have a parasitic effect anyways. Batteries in parallel act as one battery anyway.

 

[hrtbrk1 5,000+ posts]

parallel is + to + and - to - right?

 

[jco1385 5,000+ posts]

parallel is + to + and - to - right?

yes

 

[hrtbrk1 5,000+ posts]

thanks

 

[audiolife 5,000+ posts]

Age, size, charge rates,discharge rates all play a role in a batteries lifespan when you are connecting them together. You can hook up regular wet flooded cells to agm batteries and it would work BUT it will come at the cost of the batteries lifespan. The closer you get to the SAME the longer BOTH batteries will last. Take two of the same brand but different size they will not charge and discharge the exact same, do it with 2 batteries close to new of the same brand, condition, size and model they should in effect last the longest. A bad mix of batteries might last 6 months or 3 years plus under good conditions, mix two of the same brand it might last a little longer before one goes. If you have the same kind same age same model they should and could last 5+ years under good conditions.

Lets say you have an old Napa flooded cell under the hood and then you add a group 31 agm in back. Eventually the mix will cause one or the other to fail faster than it normally would. Relays and or isolators help but are not perfect. They help prolong life spans but can have a negitive effect on the overall performance. Even if relays or isolators are used it is still a very good idea to monitor the conditions of both batteries regularly.

 

[hrtbrk1 5,000+ posts]

whoa ok thanks audiolife

 

[hoss 5,000+ posts]

I wouldnt, stick to the same type, even if its a reg batt up front and a deep cycle in the back, people run into problems with the deep cycle draining the front battery

This could happen with any batteries, not just when you pair a deep cycle with a regular battery.

It is called parisitic drain, the batteries will see ANY voltage difference between each other and will constantly try to equalize the voltage between them. They will keep doing their dance of giving and taking until one, or both, is drained completely. This can be greatly reduced by adding a battery isolator into the system to keep them from draining each other.

Personally, in my old truck, I had a stock battery under the hood, and a G31 under the box. I drove the truck every day, constantly put both batts under EXTREME stress (could easily take the whole system to under 10 volts), and never once had any issues with batteries draining.

 

[jdawg 5,000+ posts]

haha i was looking for technical terms but couldnt find any. I just know it does, especially if one of the batteries is old. Seen it happen.

 

[jdawg 5,000+ posts]

I know when i had hydros (8 batteries) and one would die (or break) and i had to replace it the others would fall off pretty quickly. Of course i didnt really understand this 10 years ago and if i was going from say 48v then added another to go 60 to a pump the oldest ones would die. I was like man, pos batteries lol.

 

[audiolife 5,000+ posts]

haha i was looking for technical terms but couldnt find any. I just know it does, especially if one of the batteries is old. Seen it happen.

Will 2 different sized/types batteries discharge the same on a 200 amp load? That 200 amp load can be more of the stored energy to the smaller battery or the larger one and vice versa. The closer you get to the same battery the closer they will act as one when connected together.

 

[hrtbrk1 5,000+ posts]

lol