Dual battery system not working

[Timcyn7]

So when i purchased my nav a few months ago i was happy it had a dual battery setup already installed. But since i Havant used it yet i wasn't sure if it was working. When i pushed the "link" & "auto" buttons, i could hear it clicking on and off, but the 2nd battery would never go above 10v. Now after a few months i have noticed when i push the buttons, nothing clicks etc, no noises.
I dont know whats buggered? With the engine running the 2nd battery still shows 10v.
Any ideas?

 

[happy john]

It sounds like it's never been charged to show such a low voltage. I would start by disconnecting the positive from the aux battery and check if the charge is making it to the battery whilst at idle It should be around 14.4, failing that is there a circuit breaker tripped?, only other thing I can think is to charge the battery manually with a normal charger and take it to a specialist for a load test. It could have a collapsed cell

 

[nuckin futs]

if the second battery is stuffed the system could be shuting down to protect the main battery (starting battery) from going flat as well

 

[nuckin futs]

also, like happy john said, check fuses and check all electrical connections

 

[Old.Tony]

^ All good advice.

As suggested by nuckin futs, it sounds to me like the isolator is protecting the main battery. It's basically a voltage sensitive switch - when the voltage rises above 13.2V (usually) it switches on and passes power to the auxiliary battery. When the voltage falls below a certain level - and I think that's 11.5V or so, depends on the manufacturer - the isolator turns things off.

Also as suggested, remove the second battery and charge it with a mains charger. It may or may not work. Do NOT use jumper leads to connect it to your main battery, which will dump power quickly with that much voltage difference. If it doesn't start showing 12V or more across its terminals within 8 hours of attaching a charger, it may have a dead cell as John suggests, and given the amount of time it's spent this flat, that's entirely possible.

Be careful when charging it. If it's a gel battery, it needs to be charged at no higher than its rated capacity divided by 10 and at no higher than 14.1V. For example, an 80Ah gel battery can suffer damage if charged higher than 8A.

 

[Navmania]

I'm not sure of the engine your running and Old Tony will be able to confirm if what I'm saying is a possibility. Some alternators have a thermal resistor (I think that's what it's called) and doesn't allow the alternator to reach the correct voltage for charging using the system you are. If your system is suffering from that problem then you normally use a charger instead of a separator like you are running. Something like a Redarc BCDC 1220 will charge at the voltage required.

I could be completely wrong and the system you are using May be fine, hopefully someone knows what I'm getting at and can shed more light on it.

Cheers

 

[Timcyn7]

Thanks for the advice guys, ill have a crack in the morning after work. It use to click but never seen any increase in the 2nd battery. The main battery was reaching 18.8v while the engine was running though! but that has stopped now. Im not sure if i should take it to someone and just redo the whole lot?

 

[happy john]

Tim 18.8 volts has to be incorrect. The alternator is not capable of producing such voltage and if it did it would boil the battery dry. How did you obtain this reading?.

 

[Timcyn7]

reading straight off the battery, could have been the multimeter lol, i havnt got that ready with the new meter lol

 

[happy john]

Yep thought so the multimeter is giving a false reading. Also have you done a search to see if there is any spec's available on the isolator that can shed any light.

 

[Old.Tony]

I suspect your car's a D22 that's at least 2011 or older. Engine bay looks like it's had a change of air filter and while it's fairly clean it does have some signs of age. I doubt it's got one of the smart alternators.

It's obviously important that the voltages are read correctly, if that multimeter is showing 18.8V (which would boil the battery quickly, as already said) then either the regulator on the alternator is shot or the multimeter needs replacing. I'd say it's the multimeter!

Can you let us know what year and model Navara, and what approximate location you're in (eg Central Tablelands, mid-north coast etc)?

 

[Timcyn7]

Yeah its an 02 d22, zd30, 130km. Located Mudgee NSW. I tried googling some info on it but couldn't find anything. I might call tjm and see what they say.

 

[Timcyn7]

ok, i took the 2nd battery out and put it on charge. I then grab the multimeter and started poking wires. I also checked fuses. This might be pretty obvious, but either the controller is working fine and telling the relay to kick in and the relay is stuffed, or the controller is stuffed and not telling the relay to kick in? Can i manually switch the relay to see if its kicking in and out?

 

[happy john]

Tim the "link" button more commonly known as a manual bypass activates the solenoid and links the batteries in parallel for winching ect. Not knowing your model makes it hard to diagnose the issue. I have seen a couple fail before, if you activate the link you should be able to hear it click on and off. Have you had any water crossings that were deep enough to ingress the unit?

 

[Timcyn7]

Tim the "link" button more commonly known as a manual bypass activates the solenoid and links the batteries in parallel for winching ect. Not knowing your model makes it hard to diagnose the issue. I have seen a couple fail before, if you activate the link you should be able to hear it click on and off. Have you had any water crossings that were deep enough to ingress the unit?

Well no water crossings but ........
I washed the engine bay, and without thinking.......so thats probably what caused it? lol

edit: So having said that, what new isolator should i go with?

 

[ozstickman]

I got to pull mine out of the xtrail to go in the Nav on Thursday. I'm going to pull it out this arvo, I'll take a pic of it for you. Never had a problem with it. From memory it was about $140 from positive batteries in Rockhampton.

 

[happy john]

A basic Redarc is reliable for around the price Ozstickman paid, if everything is in place it should be a simple install. Check your earths as well for any corrosion, very often that can be the culprit.

 

[ozstickman]

Here is what I've got.

 

[Timcyn7]

Rhito thanks fellas, very much appreciated. The TJM one was 200amp, i was looking at a 150amp one. Any dramas anyone can see with that?

 

[Old.Tony]

The current rating of either is more than sufficient. In normal operation you don't want to charge your batteries too fast anyway. Deep cycle batteries usually like to do things more slowly - both charge and discharge. Spiral-wound AGMs are an exception - my Optima D31A can happily be charged at 35A for a full charge (from dead) in 2 hours. If it's rated at 200A you won't want to be starting through it, your starter is capable of pulling 500A.

The reason for the link option - when starting the car, the battery voltage will fall below 11V easily, which will switch off the isolator. Manually engaging the link will allow some power to flow through to the starter - but it's not something I'd want to do with one of our diesels.

However, that link button gives me an idea.

If you have the aux battery disconnected, with the engine OFF, press the link button then take two measurements: voltage at the cranker battery, and voltage at the terminals for the aux battery. This will tell us two things: whether or not the isolator is working, and what the voltage drop across the length of your cable is.