Is Circuit Breaker Needed When Wiring Deka Battery Isolator # DW08771

Updated 09/03/2020 | Published 08/30/2018

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Deka Battery Isolator - 120 Amp

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$107.74

Redarc Smart Start Battery Isolator - Dual Sensing - 12 Volt - 200 Amp

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$385.00

Question:

Can I use 70A isolator and 40A circuit breaker for Dodge Ram van with 127A alternator to charge 2nd battery? or I shoud get 120A isolator and higher Amp circuit breaker like 80A? Thanks.

asked by: Toddy

Expert Reply:

When wiring up the Deka Battery Isolator # DW08771 the main/first battery will connect directly to position one on the isolator without the need for a circuit breaker. The second battery though should be attached to the second position on the isolator via a circuit breaker that is rated appropriately for the battery. The alternator will go to the A post on the isolator.

I have attached a diagram that you might find helpful as well.

You should not have to worry about the second battery being overcharged. The alternator simply won't be strong enough to provide enough charge for this to be an issue.

expert reply by: Chris R

click to enlarge

Toddy

8/30/2018

Can I use 70A isolator and 40A circuit breaker for Dodge Ram van with 127A alternator to charge 2nd battery? or I shoud get 120A isolator and higher Amp circuit breaker like 80A? Thanks.

Chris R.

8/30/2018

When choosing an isolator like this you will want to find one that has an amperage rating above that of your alternator. This prevents any damage to the isolator itself when it's wired up. With that in mind, you will definitely want to go with a higher rated isolator and circuit breaker for your particular application. We do have higher rated isolators like the Redarc Smart Start Battery Isolator # 331-SBI212D that is rated for 200 amps. I have attached the written manual for this isolator that you can also take a look at.

Jose L.

5/22/2020

I have an RV that has a main battery to start and two auxiliaries the auxiliaries are deep cycle marine which isolator should I use? and I would like to send me the connection diagram

Chris R.

5/25/2020

Are the two auxiliary batteries wired together? If so, you can use an isolator like the Deka # DW08771 mentioned above by connecting to the positive terminal of the first battery and grounding the negative terminal of the second battery.