Dual Battery Isolator, How big do you need?

[ianafloat Junior Member Find all posts View Profile Close ianafloat]

Hi All,
I am fitting a dual battery system to my 98RV 2.7 with a new winch that I bought. I am trying to do all the work myself, on a budget and I don't know what the size (Amp) ratings mean ? I am looking at a 100 amp isolator, should that be enough? Thanks in advance for any advice
Ian

[Tazdevil Moderated member Find all posts View Profile Close Tazdevil]

Ian

A 100 amp isolator will be good enough for most people.

I am looking at putting a Redarc SBI212 200 AMP isolator in as this will allow me to join both batterys together if i want to for extra winching power or incase I need to jump start myself (these can be found on eBay for around the $220)

[Derb Senior Member Find all posts View Profile Close Derb]

Hi Tazdevil. 200 amps won't handle cranking amps. Look for 400 amps upward. Cheers.

[Tazdevil Moderated member Find all posts View Profile Close Tazdevil]

Derb

The 200amp Redarc is designed for providing the Cranking Battery with a boost not to be the sole link to the starter.

[Derb Senior Member Find all posts View Profile Close Derb]

Hi Boss. So if your starting/main battery is totally discharged, and the Redark closes in the 2nd battery, it will not allow the closed relay to carry the total cranking load? Because if the main battery is flat and the relay is closed, that cranking current will be climbing across that relay unless the Redark is pretty clever and trips it out. Just my basic understanding of electrickery. cheers.

[Tazdevil Moderated member Find all posts View Profile Close Tazdevil]

Derb

The Redarc SBI212 has a rating of 200amp continuous and a peak of 600amp, here is the spec sheet for the redarc controller http://redarc.com.au/static/files/SBI_1_Page_Spec.pdf

let me know what you think.

Thanks

[Derb Senior Member Find all posts View Profile Close Derb]

Hi Boss. Looks like it will start the engine with the 600 amp peak ability. Prolonged cranking of a hard starting diesel will probably duff it though. Looks like the biz. cheers.