Anyone know whats causing my electrical problem?

Sadam_Husain · Post by **Sadam_Husain** » Sun Jan 07, 2007 2:00 pm

I jumped into my truck yesterday after it had been sitting for a week while I was out in the scrub and found other than it starting and running fine all the other electrics seemed to have a big voltage drop accross them?

I've had a quick assessment today and dont know whether to tackle it myself or drop it into an auto sparky?

The trucks a 70 series cruiser with a twin battery setup, the batteries were proffesionaly installed 4 years ago by the previous owner and have a relay between them, the winch battery is dead flat (ie: 0 volts) and the other battery is fine (I used the winch 4 weeks ago and it functioned ok). I've removed the winch battery and the other battery has about 12.5 volts idle and 14.5v with the engine running so it looks like its charging.

When I put the meter accross the fuse box I only get 10v and when I turn on the lights/wipers etc it drops down to around 2.5v, when I do this and measure accross the battery the voltage remains at around the 12v mark. I thought the problem may be the feed to the fuse box but the solinoid on the starter/ignition must run through and works fine while the wipers come to a stop, air horn wont work and headlight relay chatters?

anyone out there got any ideas :idea:

4wdnuts · Post by **4wdnuts** » Sun Jan 07, 2007 3:36 pm

maybe try cleaning all the earths?

wjw · Post by **wjw** » Sun Jan 07, 2007 3:41 pm

Could be something to do with the way the 2nd battery is hooked up, I would borrow a battery to see what happens when you put the secondary back.

If it was me, I'd run all the electrics off one battery and the motor off the other... with a switch to change it over should the secondary battery die.

Jerry · Post by **Jerry** » Sun Jan 07, 2007 10:34 pm

Andrew Farmer may be able to help....and he comes to you 027 444 6803....give him a call

dctecho · Post by **dctecho** » Sun Jan 07, 2007 11:12 pm

I would check the fusable links, Either at the positive battery terminal or off the starter main terminal.The low voltage may not be effecting the starter because it is energised off another relay.I'll have a look at work tomorrow for a wiring diagram and see if I can find anything else.In the meantime you could just try running a new wire from battery positive to fusebox temporarily and see what happens.Do you know what is operating the solenoid for your dual battery setup??

cheers Scotty

Sadam_Husain · Post by **Sadam_Husain** » Mon Jan 08, 2007 6:16 pm

Well I've found part of the problem and 4wdnuts

was right about the earths. My mate rang me last night and I told him about it and he reckoned I had a good earth bond to the engine (hence starting and charging ok) and a crook bond onto the chassis/body. I measured the voltage accross the battery and engne and came up wth 12.4v and then accross the battery and chassis and came up with 12.3v. When I turned the lights on the voltage accross the battery and chassis dropped to around 3v when under load so I put a temp earth bond from the battery to the chassis and everything came up and worked ok :lol:

. I'll buy a new earth strap and put it on in the next copuple of days.

It dosent explain why the winch battery when dead flat but maybe it has somehow backfed itself and discharged because of the crook earth? I'll charge it up and see what happens when I replace the faulty earth strap.