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Discussion Starter · #1 ·
Last December I bought and installed a second battery and a dual battery charging system. The second battery was for running the lights on our small van when free camping. This seemed to be working OK during a trip in January but on a second trip around Easter I began having difficulty starting the car which is when I noticed that the new battery tell tale viewer showed it as requiring charging. I used a battery charger to bring it back to life only to have it gradually lose charge over the next few weeks. I have since disconnected this battery from the starting battery and have not had a problem since. When I reconnected the second battery and left the car unused for 3 days the main battery would not start the car.
It seems that the (newer) second battery is draining the (older) starting battery. I thought they should be isolated from each other when the ignition is off?
Can anyone recommend a set of steps to take to check that the system is working properly and the battery is capable of holding a charge. (please bear in mind that I am somewhat auto electrically challenged) :(
Thanks in advance
 

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builder not a buyer!
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What brand of solenoid did you buy? Simple reason, you get what you pay for

You might get a better response if this is was in the auto electrical threa

good luck
 

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Chev 6.5 litre V8: no substitute for cubic inches
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Last December I bought and installed a second battery and a dual battery charging system. The second battery was for running the lights on our small van when free camping. This seemed to be working OK during a trip in January but on a second trip around Easter I began having difficulty starting the car which is when I noticed that the new battery tell tale viewer showed it as requiring charging. I used a battery charger to bring it back to life only to have it gradually lose charge over the next few weeks. I have since disconnected this battery from the starting battery and have not had a problem since. When I reconnected the second battery and left the car unused for 3 days the main battery would not start the car.
It seems that the (newer) second battery is draining the (older) starting battery. I thought they should be isolated from each other when the ignition is off?
Can anyone recommend a set of steps to take to check that the system is working properly and the battery is capable of holding a charge. (please bear in mind that I am somewhat auto electrically challenged) :(
Thanks in advance
G'day Robo,
I would remove the 2nd battery from the vehicle, place it on a decent 240v charger and get it up to spec. Then, once you're satisfied it is fully charged, remove the charger and let it sit idle for 24 hours. Check the voltage after 24 hours and if it isn't holding at least 12.65v I would say it is kaput.

Now, back to the vehicle...you have some issues to sort out!! Even if the 2nd battery is a dud, it shouldn't affect the capability of the main battery to start the engine. What sort of isolation system do you have? I would say it is faulty and is allowing the 2 batteries to remain connected when the engine is off.

Personally i don't like the "smart" systems and prefer to use a manual solenoid isolator, controlled by a switch that I can turn on and off.

That will do to start with, but you will have other questions and we can answer them as they come up.

Roachie
 

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Is the Aux battery discharging also or only the Cranker ?

What brand is the Dual Battery Charging System?
 

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Discussion Starter · #5 ·
Bought my Patrol early December last year. I needed a dual battery setup for our unpowered camping between Xmas and New Year. I bought and installed a Calibre Dual Battery charging system and 2nd battery. I know you will say you get what you pay for but it was Xmas and I had just bought a car (I wish I had joined this forum before all this!).
The point is, I paid for something that should work - maybe not as well as a more expensive one but it still should work.
Sorry Chuckles, still fairly new to this. i will post in correct area next time.
Evil Twin, both batteries discharge when all is connected. Could this happen if it is not wired correctly?
Thanks for the instructions Roachie. That is the sort of info I was after so that I can try to resolve this issue step by step. I will try charging the battery on the weekend.
Yes, my vehicle does have some issues (since I bought it it has had more issues than Readers Digest) but I like it. This is a smaller issue but I need to resolve it before warranties run out.
Thanks
 

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OK, first thing's first. I would check the Isolater is wired correctly and working.

Also, remember that MANY (not all) of these Dual Battery Isolaters WILL NOT ALWAYS ensure that the Cranker is fully charged.

Anyway, here is a series of simple tests you can try... there are other ways, this is just one option

Disconnect the Aux Battery Positive... DON"T LET IT SHORT OUT TO METAL
Check the Voltage on the Cranker Battery terminal side of the Isolator... should be 12.6 ish Volts or so
Check the Voltage on the Aux Battery Terminal side of the Isolater... should be Zero ish
That confirms the Isolator isn't short circuit.

Start the engine and make sure the Alternator is putting out at least 13.5 Volts or more to the Cranker Battery.
Check the Voltage on the Cranker side of the Isolator... should be 13.3 Volts or more and within .2 volts of the cranker
Check the Voltage on the Aux side of the Isolator... should be 13.2 Volts or more and within .1 volts of the other terminal
That confirms the Isolator will actuate when it should (most need min of 13.2 and some have a timer so that even above 13.2 Volts it will still take a minute or two to actuate)

At idle turn on high beam, spotties and anything else like A/C fan to drop the Alt Voltage below 12.5 and you should get the same results in the first steps as the Isolator should disconnect. If the Voltage isn't below 12.5 on the Cranker side the Isolater will stay energised and you may need to stop the engine and the Isolator should de-energise immediately.
That confirms the Isolator cutoff voltage is around 12 Volts.
 

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Discussion Starter · #7 ·
Thanks evil twin. I appreciate the help. I think I follow what you are saying (sorry I think I am pretty good with most things but as soon as anything involves volts my brain just turns to mush).
I will give that a go on Saturday.
 
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