Battery isolation redarc, Help

[Milkman]

I have a redarc sbi12 never had any issues over the last 3 years until I installed the 115amp alternator, now the redarc sbi12 is flashing 3 times, so I checked everything and seems ok, I put a volt test on it and showing 14.1, after having the volt test light on the unit it started working!!!!, turned car off for a few min, back on and still working, sweet, morning time, checked unit again.....not working, put a wire between the terminals on the redarc and started working.......the unit is the 100amp redarc should I change this to the 200amp ? as the alternator is now 115amp

 

[sparra04]

good question about the alt amps, not sure on that one
is the aux battery full? and the redarc isolator staying open deliberately?

 

[Old.Tony]

Don't worry about the alternator size. It can only deliver that sort of power at near 5,000rpm and you've got other bits and pieces on your car that need power too, so you'll never bother the isolator with the amount of power generated (and especially so at idle!). That doesn't mean that your main battery can't produce that sort of power!

I downloaded the SBI12 manual and it says that 3 flashes means too much current flowing through the isolator. At idle, that can only mean either a fault, or the battery on the other end is sucking like a demon from your main battery. Technically, it's looking at a voltage drop of 1V across it, which is usually associated with large amounts of current (and possibly a short).

I'd take a look at the aux battery and make sure it was okay, and check the cables heading to the aux battery too.

 

[Milkman]

sweet , thanks guys, just seems strange was working fine before swapping out alternator, anyway I'll spend some time checking wiring and fuse's, second battery is now at 11.5v, main still fully charged

 

[Old.Tony]

11.5V is rather drained (full is around 13.2V). I'd whack it on a mains charger and juice it up with that first. There's a good chance the entire issue is the aux just drawing too much too quickly.

 

[Milkman]

Have no idea what happened, checked all fuses wiring and everything seems fine, ordered a new 200amp redarc smart isolator, fitted today...and well bugger me the old 100amp one starts working, fitted the new 200amp all sweet, light comes on a few seconds after starting car, second battery getting charge
Thanks everyone for your help and advice, very much appreciated