Battery isolators... required?

[JoeK 10+ year member]

If running additional batteries off of my main battery, should i buy a battery isolator? I just have my trunk battery in parallel with my main battery

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[NT_Hardcore 10+ year member]

you wont need them unless you plan to play with the car off for long periods of time

 

[mclerico83 5,000+ posts]

yea if you are going to run the system with the car off you should get one, depends on how strong the system is etc. I have a really good one stinger 240 amp. i will send it to you for 45 bucks

Stinger S2402 240 Amp 3 Post Battery Isolator - S2402

this one

 

[JoeK 10+ year member]

I dont run the system hard with the car off, maybe low volume for 5-10 minutes at most. If im pounding then the car is on.

 

[goingdef 10+ year member]

I would use an isolator if the battery's are different in either brand or size or type just to prevent one from draining the other just in case they have different resting voltages.

 

[naughtyca 10+ year member]

I dont run the system hard with the car off, maybe low volume for 5-10 minutes at most. If im pounding then the car is on.

you dont need one, i have 2 batt with no isolator and have no problem

 

[Fi-brations 10+ year member]

they prevent the larger battery from drawing from the smaller one, if you are running one for strictly audio purposes and the other for the rest of your car, then you should get one. The reason you want one when playing music and not running the car is so that only your audio battery is drained

 

[Villeza1 10+ year member]

I would use an isolator if the batteries are different types just to prevent one from draining the other just in case they have different resting voltages.

Fixed

 

[mclerico83 5,000+ posts]

Fixed

x2 i bought the isolator because i was running a general front battery from autozone with huge cd batteries in the rear and they never charged correctly due to being different sizes and i used this to fix the issue. I now run 2 xs s3400's so i no longer needed it.

 

[Kangaroux 5,000+ posts]

I don't like battery isolators. @keep_hope_alive; gave some good reasons, one of which is if you drain your audio battery way down, then come to start your car, your now connecting a battery with a very low charge to one with a high charge. This can hurt the batteries since they aren't equally charged

 

[Villeza1 10+ year member]

[quote name='Kangaroux']I don't like battery isolators. @keep_hope_alive; gave some good reasons, one of which is if you drain your audio battery way down, then come to start your car, your now connecting a battery with a very low charge to one with a high charge. This can hurt the batteries since they aren't equally charged[/QUOTE]

I've heard about that as well. Never seen it happen in person. The shop I go to stopped selling iso's b/c a customer had that exact issue. Apparently the shop owner never liked iso's to begin with.

 

[Fi-brations 10+ year member]

[quote name='Kangaroux']I don't like battery isolators. @keep_hope_alive; gave some good reasons, one of which is if you drain your audio battery way down, then come to start your car, your now connecting a battery with a very low charge to one with a high charge. This can hurt the batteries since they aren't equally charged[/QUOTE]
Doesn't the isolator stop the batteries from connecting? Isn't that its purpose? When you start the car, shouldn't the only thing being connected is the alternator to each battery individually?

 

[Kangaroux 5,000+ posts]

Doesn't the isolator stop the batteries from connecting? Isn't that its purpose? When you start the car, shouldn't the only thing being connected is the alternator to each battery individually?

Think about it. No matter how you change the wires, both batteries will still be connected to the alternator. As long as there is a common point, current will flow between the two batteries

 

[Fi-brations 10+ year member]

Think about it. No matter how you change the wires, both batteries will still be connected to the alternator. As long as there is a common point, current will flow between the two batteries

I hear ya. So what is the purpose of them then? I thought there purpose was to separate the current between the two and allow the use of certain batteries for audio and others for other things. Do they only have the current exchange when turning the car on?

 

[Kangaroux 5,000+ posts]

I hear ya. So what is the purpose of them then? I thought there purpose was to separate the current between the two and allow the use of certain batteries for audio and others for other things. Do they only have the current exchange when turning the car on?

There is always current exchange going on between them but when you have an isolator that current exchange begins immediately when you turn the key. Their purpose is so if your rear batt is drained completely you can still start your car. However the side effect of this is that now you shorten both of your battery's lifespans by connecting a dead battery and a charged battery. Not to mention the alternator already has to charge up the front batt from the ignition as it is.