When adding another battery?

[302yota 10+ year member]

when you are adding another battery in the trunk of your car, i know you are supposed to fuse the wire 18" from the front battery, and within 18" from the rear battery....but my question is if battery regulator's, or isolators (also what are there purposes?) are neccessary when adding another battery?

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[BushJ311 5,000+ posts]

They are not necessary. I have seen a 2nd battery added without them.

 

[302yota 10+ year member]

now what if i added two batteries in the rear...then would they be necessary?...btw what do they do?

 

[BushJ311 5,000+ posts]

still not necessary. what does what do? regulators and isolaters?

 

[audiolife 5,000+ posts]

now what if i added two batteries in the rear...then would they be necessary?...btw what do they do?

Totally isolate the front from the back batteries or to at least isolate them when the key is off. Depends on the units in question

 

[BushJ311 5,000+ posts]

Isolaters

http://www.bcae1.com/battiso.htm

Regulators

http://en.wikipedia.org/wiki/Battery_regulator

 

[gotparts90 10+ year member]

They are not necessary. I have seen a 2nd battery added without them.

he is right they are not necessary for it to work but unsafe without. The fusing will protect it if you get a short and prevent fire. If your car is worthless to you then I would not fuse it.

Isolators or relays will allow you to run the radio with the car off or are a good thing to have if you have 2 different types of batteries. If you have matching batteries and never plan on playing a big radio with the car off then no isolator is recommended by most battery makers according to what I have read or been told by them. Matching means type lot number and manufacture date along with usage.

It would be easy to use the search feature of the forum as there are at least 100 threads like this

 

[dr_peeb 10+ year member]

when you are adding another battery in the trunk of your car, i know you are supposed to fuse the wire 18" from the front battery, and within 18" from the rear battery....but my question is if battery regulator's, or isolators (also what are there purposes?) are neccessary when adding another battery?

You only need 1 fuse in your power wire; More than 1 is completely unnecessary, i.e does nothing. And, the 18" distance really means "as close to the battery's positive terminal as you can get it." The closer the better. If you get a cut in your power wire and it contacts other metal on your car (aka "shorts") the fuse will pop and kill the circuit, instead of your car possibly catching on fire. That same cut power wire shorting scenaro can happen by the bare wire touching other metal under your hood, like the inner fender, so again the closer you fuse the wire to the battery's positive terminal, the safer it is.

A fuse is really an automatic disconnect switch that automatically halts power delivery immediately when something goes wrong, thus disconnecting the power from contacting anything else past the fuse location, thus eliminating the possibility of damage, and you want that switch located as close to the auto power source as possible.

 

[302yota 10+ year member]

ok, well i guess i'll run an isolator just to be safe....eventually i plan on running two batt's in the back on 2 aq2200's

 

[smoka 10+ year member]

You only need 1 fuse in your power wire; More than 1 is completely unnecessary, i.e does nothing.

2 batterys need 2 fuses, especially when one is in the front and another in the back.

 

[dr_peeb 10+ year member]

2 batterys need 2 fuses, especially when one is in the front and another in the back.

Oops sorry, that is true, brain fart: I missed the whole two battery thing. You need a fuse as close as possible to every positive battery terminal in your car.

 

[snb778 5,000+ posts]

You only need 1 fuse in your power wire; More than 1 is completely unnecessary, i.e does nothing. .

doesnt electricity flow in both directions... I believe so.. in that case... if you have a rear battery,and IT causes a short.. what is closer... your amp, or that fuse, 15-20ft. away up front under your hood........now what's going to burn up first...

 

[22mountaineer 10+ year member]

If it has a short between your third batt and your amp wouldnt it blow the fuse between your main and second batt?

So your saying I need a fuse right outside my front batt, and a fuse between the 8 inches of wire between my second and third batt, and then a fuse between my third batt and amp?

 

[22mountaineer 10+ year member]

doesnt electricity flow in both directions... I believe so.. in that case... if you have a rear battery,and IT causes a short.. what is closer... your amp, or that fuse, 15-20ft. away up front under your hood........now what's going to burn up first...

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