HELP ME PLZ!! Dual battery system

[Keithie88]

Hi there I have installed a dual battery system using a SCA battery isolater... I know there not the best but it's the only one that's in my budget... Question: why won't my isolator kick in?? It's meant to kick in to charge the 2nd battery once my main reaches 13.5v then cut out once the main drops to 11.5v.. My voltage meter on my dash says it's getting to 14v but isolator still isn't kicking in??? Plz help me

[lucus30]

Check the voltage with a multimeter

[Winnie]

Don't pay any attention to the dash gauge. Measure it with a multimeter. The dash gauge is good to see if it is going up or down but is not accurate. Mine says about 16V all the time but when measured is about 14.2-14.4V

[Yendor]

Have you connected the isolator correctly?

[Keithie88]

Yes double checked everything... Go for a 2 hour drive running non stop and still won't kick in :-( sending me nuts

[Cuppa]

Not your issue at the moment, but 11.5v is really too low as a cut out voltage. The idea is that it cuts out leaving you plenty of 'juice' in your starter battery to be able to start the vehicle. 11.5v is simply too low a voltage to rely on for this. Defeats the purpose of having an isolator. The Redarc SBI12 cuts in at 13.2v & cuts out at 12.7v.
As for not cutting in ...... as others have said, check the voltages with a multimeter & if you find it is not cutting in (or out) at the specified voltages return it, get your money back & save for a better one.

Cuppa

[the evil twin]

What Cuppa said X 2.

If the Isolator doesn't drop out before 12.5 (12.7 is obviously a tad better) then there is pretty much no point in having it other than rare circumstances.

I use quite a few different VSR style battery Isolators for work and recreation.
If yours isn't pulling in when the Alternator Voltage is genuinely above 13.5 then it is either knackered or incorrectly wired.

Contrary to popular opinion the Isolator WILL NOT do priority charging IE it WILL NOT charge the cranker first.
What they will do is stop an Aux load flattening the Cranker when there is no charging source
When the engine is running as soon as the Alternator voltage rises above the set point the Isolator pulls in no matter what the SOC of the cranker so you can drive for 5 minutes or 5 hours it won't make any difference.

[Yendor]

If you have battery 1 and battery 2 cables connected correctly at the isolator, a good earth connection and your alternator is charging above 13.5v (checked with a good multimeter) then your isolator is faulty.

Guys I think you will find the 11.5v is a typing error it should be 12.5v

[Cuppa]

Yes, I just enlarged a pic of the sca isolator & it did indeed look like it said 12.something Rodney.

ET, I also think that provided the batteries are starting a motor in good condition & tune, that 12.5v might actually be a bit better than 12.7v as it allows a little more capacity for aux use. If there is any chance the motor might be reluctant to start for any reason, the higher 12.7v would be preferable & is 'safer' in practice for this reason.
The 'priority charging' is a myth which just keeps on rolling along eh.

[kevin07]

off subject a bit but I would suggest take it back get your money as while your saving for a new dual battery charger your doing damage to your battery as it will not be getting the correct charge, so you will have to buy a new battery. ebay you can get ctek 250s for 200. how much was your isolator

[the evil twin]

If you have battery 1 and battery 2 cables connected correctly at the isolator, a good earth connection and your alternator is charging above 13.5v (checked with a good multimeter) then your isolator is faulty.

Guys I think you will find the 11.5v is a typing error it should be 12.5v

Hiya cobber,

Yep...

and... didn't think of a typo mainly because I use a lot of programmable Isolators so down 11.5 is not unusual for my gear but agree that is very unusual for a vehicle app.

[Kelvinator]

I bought a quality baintek(if I remember correctly) intelligent isolator for mine and to date out of 5 cars and multiple wiring setups it has never ever clicked over. Doesn't matter how good your gear is if its stuffed its stuffed. Take you SCA one back if you cannot get it working. Get a Redarc intelligent isolator, it wont cost that much more, and it will be far more reliable. Redarc has multiple easy to understand wiring diagrams on their sight so you cant stuff it up.

You have already stated that you can't afford an expensive dual battery charger so stick to your guns and get another isolator, I have run mine for years now and it works well. In the future when you can afford it you can replace it with a dc-dc charger or whatever you want.

[Cuppa]

So did you get it sorted Keithie?