Problem (I think) with Redarc Isolator

[maulbeagle]

My 2011 D22 had two batteries for cranking from the factory.

I disconnected the positive feed from the drivers side battery, then ran this feed through a manual reset switch/breaker, to the Redarc Isolator.
The Redarc isolates the batteries when the voltage of the cranking (passenger side) battery drops too low, however what it doesn't do (and I'd assume it should) is isolate the batteries if the feed from the main (cranking) battery disappears. This could be because the manual reset switch/breaker has been tripped.
In this case, the Redarc stays engaged, so both batteries are connected.

Is this normal ?

Thanks,
Paul

 

[Old.Tony]

I might be reading it wrong, or I'm a little confused.

Normally the battery on the right-hand side of the vehicle is the cranker. The left-hand battery is not needed and that's the battery usually changed into the aux. Primarily the path to the starter motor - which draws 500 to 550 amps - is shorter from the right-hand-side battery.

Assuming that is the way you've got it and I'm just not reading right, the isolator should be sitting on the right hand battery with its output heading to the left hand battery and there should be no other lead heading from the car to the left hand battery. You then run a lead from that left hand battery through a fuse to the devices you want to operate while the car is stopped.

Wired like that, it shouldn't cause any problems unless the isolator has a fault.

If you've got the left-hand wired as a cranker and the right hand is also capable of cranking and you're drawing cranking power back through the isolator, it's possible to destroy the isolator, I think they're only rated for 100A or a little more. Cranking amps will kill them fast.

I think a diagram is needed so we can see how it's been done. It is possible that the unit is faulty - that's what warranties are for.

 

[sparra04]

Tony is right you also need to terminate the active on the pass side battery so they are no longer linked

 

[bods]

To add to that, the isolator won't disconnect until the battery you have connected to the "main" terminal on the isolator drops below a certain voltage

 

[maulbeagle]

Hi guys, yep I understand what you're saying.
Tony, when you say "right" or "left" hand side I don't know whether you mean looking at the car from the front or from inside the car, so I use drivers and passenger terminology.
Sparra, the batteries are no longer linked, as I removed the positive terminal, with all it's connections, from the driver's side battery and hooked it up through a breaker to the "main" terminal on the isolator.
Bods, the isolator does do that, as described in the original post.
However, if I trip the breaker between the passenger side battery and the "main" terminal on the isolator, the isolator doesn't disengage, even though the breaker is no longer engaged (verified with continuity test on breaker).

 

[mitch92]

Sounds like you need it the other way then.

Is your driver battery (going to main terminal) the now "dual", and passenger side is main cranker?

 

[maulbeagle]

yes the driver's side battery is the auxiliary battery.
why would it matter which is which ?

 

[baitfish]

because it depends on which one has the feed going to it from the alternator and also which one is linked to the starter.

 

[maulbeagle]

the batteries were connected in parallel from factory, so both batteries would've been connected to both alternator and starter.
I merely disconnected driver's side battery, leaving all other connections to the passenger side battery.
sorry if i'm missing something obvious here.

 

[sparra04]

I disconnected the passenger side and kept the drivers side as cranker
Most people do it this way
Why?
Don't really know but all the car aux power is fed from drivers side battery and the whole idea is to isolate the 2 batteries using 1 as starter and 1 as aux for fridge ect
Once you terminate the active from aux battery the car circuit doesn't need the 2nd battery,the isolator is there to simply charge 2nd battery when it sees ignition source at isolator therefor charging 2nd battery for extra aux use,
In my opinion you have removed the wrong battery from cranker circuit

 

[maulbeagle]

Hi Sparra,
I agree with what you're saying, I've done exactly what you say except the other way around.
I removed the positive terminal (fully intact with all connections still on it) from the drivers side battery, and taped it up securely. So the drivers's side battery is now completely removed from the car's electrical circuits.
Then, I ran a wire from this positive terminal, to the "main" terminal on the Redarc isolator. the "Aux" output from the isolator, then connects to the positive terminal on the driver's side battery.

Any reason this shouldn't work ?

 

[sparra04]

I really can't awnser that?
When you now put your key to aux can you run radio ect as from what ime understanding is you won't have any aux power till you have alt running
Is it too big a job to reverse what you have done and try with drivers side as cranker and see how you go?

 

[maulbeagle]

yep everything works as it should in the car.
i'm drawing some diagrams to clarify the situation.

 

[maulbeagle]

Original wiring

OK here's how the wiring was originally.

 

[maulbeagle]

And Modified

and here's how it is now

 

[Old.Tony]

I use "Right hand side" to denote the side of the vehicle that is on the right hand side if you were sitting in the vehicle facing forward. If I use "driver's side" then anyone from the USA (remember, this is an international forum) would become confused.

The right-hand side battery (driver's side in Australia) is the closest to the starter and it's the one connected to the starter (or should be). That's the battery that's usually considered the "main" battery - your diagrams have cleared up my confusion there!

I think the negative lead from the right-hand side battery should run straight to the engine block, too - that's to allow the current to get to the starter more efficiently. If you're going to keep the left-hand side battery as the main, you might want to run an extra cable across and onto the engine block.

It's probably easier to just rewire the isolator so the input comes from the right-hand side battery, output goes to the left-hand side battery - but if you like it the other way, it's your car and you do it the way you're comfortable with.

 

[maulbeagle]

OK so apart from the fact I've done it the opposite way to everyone else (!), is there anything wrong (i'll add the extra cable to the engine block) with having is this way around ?
would anyone mind doing a test (back to my original question), by tripping the breaker between their "main" battery and the "main" terminal of the isolator ? does your isolator then disengage (assuming it was engaged to begin with) ?

thanks

 

[Old.Tony]

If the input for the isolator is coming from the left-hand side battery and the output for the isolator is connected to the right-hand-side battery, I'd make sure that the positive terminal on the right-hand side battery is NOT connected to ANYTHING else except auxiliary items, I would make sure it's not connected back to the car's circuitry for anything (even accessories). That should ensure that it behaves itself!

 

[maulbeagle]

ok there are a couple of things, but I think nothing internal to the car.
i'll map it out and double check.
by the way, good point about being an international forum.
So, to remove any confusion, sitting in the car, looking forward, the "main" battery is the left-hand (and passenger) side.

 

[sparra04]

Can't help you with the test
I went to a dcdc setup 12 mths ago