Can two batteries of the same model be used together?

[amartin_72]

I have two of these, different lots im pretty sure, but the same exact model and "age", near brand new.

I got them from my brother for nothing will it work to just run them in parallell with a battery isolator or will they eventually kill themsleves somehow by not being the same exact lot. I would think this would work dont SPL vehicles often use many many batteries I cant see them all being from the same lot. Are they even worth messing around with? Specs say

680 cranking amps for 5 seconds

595 cranking amps for 10 seconds

525 cranking amps for 20 seconds

17 amp hours

Click to read more...

 

[photocrazy8 10+ year member]

they can be in parallel but one bigger battery would be better.

 

[BassAce 10+ year member]

Yes, if they are identical connect them in parallel for an increased amperage, and the voltage will remain the same.

 

[amartin_72]

And what exactly would these do to help my system do you guys think? I have some light dimming but is it not even worth the effort/wires/terminals/isolator?

 

[photocrazy8 10+ year member]

would these be in the back or under the hood?

 

[qtipextra 5,000+ posts]

You dont need an isolator, plain an simple. I wish people would get over this myth.

It would help when your bumpin with dimming lights, but also provide longer reserve battery power when your car is not running.

 

[ngsm13 5,000+ posts]

Parallel them...

nG

 

[jujumantb 10+ year member]

You dont need an isolator, plain an simple. I wish people would get over this myth. It would help when your bumpin with dimming lights, but also provide longer reserve battery power when your car is not running.

ok... its pretty basic knowledge that if batteries are not identical and hooked together in parallel, some current will flow and be lost. The extent of this loss (battery drainage) depends on many things. If you drive your car every day, then perhaps you dont *need* to isolate them, but if you sometimes go for a few days without driving it, you might. In this case, being that they are the same model battery and age, he doesnt need one.

 

[amartin_72]

Yes you do need a battery isolator if you have two different types or batteries. I have tried it without on my last truck/setup and the batteries would be dead if the truck sat for a while.

 

[chubby 10+ year member]

gkj

 

[ngsm13 5,000+ posts]

Yes you do need a battery isolator if you have two different types or batteries. I have tried it without on my last truck/setup and the batteries would be dead if the truck sat for a while.

Incorrect.

About 2 years ago... I drove around for about 6months with a red top under the hood, and a yellow top in the rear...

No problems what so ever...

nG

 

[amartin_72]

I understand you may be far more knowledgable than me about all of this, but i know for a fact that i had a prefectly fine working electrical system and i added another battery in the open spot in the other side of my engine bay and wired it to the other in paralell and it was workin for about a week and gradually I noticed sometimes the truck would be hard to start and then sometimes it would just not even have enough to start, had to have ppl push me and sometimes even do it myself lol pop start w/the clutch. Neither of these batteries I had were nice like your optimas, and you probably just had enough reserve between them that it would take weeks without running your vehicle for you to notice what is happening.

 

[ngsm13 5,000+ posts]

I understand you may be far more knowledgable than me about all of this, but i know for a fact that i had a prefectly fine working electrical system and i added another battery in the open spot in the iother side of my engine bay and wired it to the other in paralell and it was workin for about a week and gradually i noticed sometimes the truck would be hard to start and then sometimes it would just not even have enough to start, had to have ppl push me and sometimes even do it myself lol pop start w/the clutch.

That sucks.

I've never had any problems. Neither have any other of about a dozen friends who have installed a Yellow top in parallel with their factory battery...

//content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

nG

 

[OldOneEye 10+ year member]

I would argue you need to isolate the batteries, doesn't mean you need a RV type of isolator. If you want to listen to music with the car off, you want to make sure that battery in the back (or Aux battery in the front if you have room) is isolated so that if that goes dead you can still start your car.

You can do this with a number of things that won't give you a 1 volt loss like an RV isolator would. A big solonoid will do it, or you can use a part that PAC makes that turns off the battery at a certain voltage. If you want to use both batteries set it up so the PAC thing triggers the relay to close as soon as you get below a certain voltage (so it lets you use both batteries if they are both above a certain voltage, but drop that voltage and it protects the main battery so you can start the car).

Juan

 

[maylar 10+ year member]

I understand you may be far more knowledgable than me about all of this, but i know for a fact that i had a prefectly fine working electrical system and i added another battery in the open spot in the other side of my engine bay and wired it to the other in paralell and it was workin for about a week and gradually I noticed sometimes the truck would be hard to start....

One of them was defective, or of a very different design than the other. Two identical batteries in good condition should not drag each other down. An isolator is only needed when you intend to use battery power and don't want to risk not being able to start the car.

I see little to be gained from two batteries otherwise.