Battery Isolator...Does it protect the car?

[bigmack2007 10+ year member]

i have had several car electrical problems (computer, etc.) and was wondering about adding an isolator to the batteries. i have 1 up front that will power the car and will have 4 in the back for my stereo. Will an isolator protect my cars main functions? My understanding is that the front battery would keep acceptable voltage and all the cars stock electronics would not be stressed or put in tough electrical conditions. It seems to me like it would work but i was just looking for some insight on it from someone who knows.

Thanks

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[helotaxi 5,000+ posts]

What are the exact problems that you're having?

 

[bigmack2007 10+ year member]

well ive just had some problems with the ecu and i recently had an engine replacement. ive had 2 or three ecu replacements since i have had a large stereo. i have also gone through several alternators but i havent had trouble except for once with that since i got a high output one, plus i can install an alternator myself. the car has been in the shop for about three months for engine/computer repairs and im just now getting it back. i have a 200 amp alternator and will be running 4 extra batteries in the back. im just trying to keep the electrical system running the car as safe as i can so that where my idea about the isolator came in. im just thinking if it keeps the voltage at 12.8+ for the cars stock functions it will protect my ecu and other electrical components. I'm gonna be running a massive stereo (7 kw+) at times but i dont play it too hard very often. I just want to protect the car when i do.

 

[king ranch 5,000+ posts]

run seperate alt for stereo and dont run the upfront battery with the stereo

 

[bubbagumper6 5,000+ posts]

isolators don't isolate while the car is on because the alternator has to charge the batteries...

 

[Horsemanwill 10+ year member]

ya wat king ranch said if you have the room put in a dual alt setup

 

[bigmack2007 10+ year member]

there is no way to fit another alternator in a 4.7 liter grand cherokee. wouldnt a diode isolator work while the car is on?

 

[bubbagumper6 5,000+ posts]

if you isolate the batteries while the car is on...how would the ones in the back get charged?

 

[bigmack2007 10+ year member]

it is my understanding that it would charge strait from the alternator. both sets of batteries would be charged from the alternator and would not charge eachother.

 

[bubbagumper6 5,000+ posts]

but if they're both connected to the alternator then they will still be connected...with only 1 charge source theres no way to keep them separated while the car is running.

I guess I should add all of this is to my knowledge...I could be wrong, I'm going to school to be an electrical engineer but I'm only in my second year //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[bigmack2007 10+ year member]

naw but see they are both connected to the isolator(diode). the diode is separately connected to the alternator. thats why i think they would remain isolated with the car on.

 

[bubbagumper6 5,000+ posts]

hook it up then whip out the DMM?

 

[bigmack2007 10+ year member]

hhaha yea man but i don't have an isolator yet. thats why im trying to find out about the potential uses of one for protecting a cars electrical system.

 

[wevie 10+ year member]

I understand your logic, but it is flawed.

The alternator will be connected to both your cars battery and your stereo's battery bank. The current will leave the alternator, pass through the diodes and into each storage unit. The diode in an isolator will keep the current from the rear batteries from reaching the front battery.

However. . . when the rear bank calls for massive current draw from the alternator, the voltage out of the alternator will be pulled down. The car's battery will also see this drop in voltage. Lets say the alternator output starts at 14.0 volts and is pulled down to 12.7 volts. Both of these are higher than either battery, so both systems will see the voltage swings. If the alternator output is pulled down to 11.9 volts, then the car's battery will be isolated during that time and maintain its own inherent voltage (12.0??)

The only way to completely isolate the batteries is with totally seperate systems sharing ONLY a ground. Dual alternators wired independently.

 

[bigmack2007 10+ year member]

YES!!! You know what im talking about. that is my goal, to keep the cars stock components separated from my stereos massive draw. As long as they stay at 12 volts or higher i am happy (my yellowtop up front sits at 12.7). I would indeed still get voltage drop but it would only be down to the 12's up front as opposed to the 11's or 10's in the back. also, would it work to only have the battery up front on an isolator while leaving the one in the back hooked up to the alternator?

THANKS!!!