Rock Ape replied:

When you say failing, do you mean it has carked it or is it just flat.

If it is flat then being a motor start battery I am not surprised.

please add more info.

The Ape

kinnean replied:

Appears to be carking in. Drove for 3 hours after failing and still showing only 11volts. I have tested to check isolation solenoid is ok by removing battery and it is all good.

Member - Phil G (SA) replied:

Sounds like its not getting any charge. When the motor is running, what is the voltage of the aux battery??? If its still only 11v, your isolator is not working.

barney rubble replied:

Gday mate i had the same fault with cf80 in the gq patrol which ive since replaced with gu when swapping dual battery system elecy upgraded solenoid type and wiring in/out plus shortened lead from t plug to fridge
only using same n70 battery fridge works a treat in fact enjoying icy cold one from it now hope this helps cheers

Member - Doug T (W.A) replied:

You need to get one of these for the second battery, They are not cheap, but they will do the job you ask of it,just place the cursor on the Yellow section, read it then click it
www.optimabatteries.com.au/

My Yellow runs Car Audio , HF Codan , 31ltr Waeco fridge , 2x55 watt beacons, 2x100w roof mount driving lights, Invertor , 2 GPS units, 27mhz CB , UHF CB , sometimes it runs all that at once , and has been for 18 months '

The other problem you just could have is the Alternator might be one the way or just can't cope, get a bigger one,

Doug

Gerhardp1 replied:

If you are using a standard start battery for a fridge, you will ruin the battery in no time at all if you flatten it. It only takes once to ruin it - it then won't ever accept a charge again.

You need a deep cycle battery, preferably an AGM.

Derek from Affordable Batteries & Radiators replied:

Hi Kinnean

How good is the earth connection ?

With the engine running and solenoid engaged you should have 13 to 14 volts on the terminals of the battery even if the battery is dead.

You may have a simple earth or wiring problem.

Test each joint and find where you loose either earth or the power from the isolator.

I have heard of people forgetting to earth the auxilliary battery to the body.

Regards

Derek.

obee replied:

when the motor is running and the isolater is switched to connect, you should be getting 13.8 volts at the ausillary battery regardless of condition. If not then check all the connections and wonder if there is a fault in the isolater. The points therein may not be contacting sufficiently or if the isolater is non mechanical the mosfets or capacitors may have blown.

Disconnect the battery (auxillary) and see if you get same voltages both sides of the isolater.

Like the man says, if the battery has been run down to flat then likely it will only hold 30% of its nominal charge.

Mate of mine let his boat batteries go flat and blamed the people who fitted the motor. He never looked at them for a year. I still cant convince him to keep the voltage up in those seldom used batteries.

Owen