Battery Or Alternator Or Both?

[Scorpion]

First off, sorry, once again this isn't Surf related but you guys are always the quickest and best source of information. I was off roading on Sunday at Pea Farm, lots of mud and water, the Vitara went around the course no problem (apart from when I tried to be clever and got stuck)!

I drove home from the site with no problems but when I took it out last night the lights started to go dim and the heater motor and wipers started to slow down, the rev counter also stopped working. I assume it's either the alternator or the battery, so I tested the battery today with a meter. The meter only shows 10.3 volts across the battery with the engine running but 17.5 volts with the engine off.

Although the battery shows 17.5 volts (way too high, I know) it will still not turn the engine over. The Vitara starts no problem with jump leads and ticks over fine, however if I remove the jump leads the engine starts to miss and finally cuts out after about 5 minutes.

As always any advice would be greatfully appreciated.

[IanB2]

I've always measured volts when dealing with the battery and charging system, is that what you meant? If yes, then those numbers are backwards (and out of range) from what I'd expect, how do you get higher volts when the alternator isn't charging?!?

[Scorpion]

I've always measured volts when dealing with the battery and charging system, is that what you meant? If yes, then those numbers are backwards (and out of range) from what I'd expect, how do you get higher volts when the alternator isn't charging?!?

Yeah, sorry about that. I'll alter my post now. Cheers.

[spacast]

Sounds like something is wrong with the alternator, possibly the voltage regulator.

Be careful with the battery - if it's gassing don't make sparks close by or it could explode.

[Ploddit]

Lots of WD40 and disconnect and reconnect alternator connection's and make sure it's dry.

[Ambobeer]

Sounds to me like the battery is not well too. There ought to be 12v across it.
There's 6 cells in the battery at 2volts each. 2+2+2+2+2+2=12, if you're only getting 10 then it would suggest that one of the cells has gone short circuit.

17 volts is way too high and may have contributed to battery failure. Whats the voltage across the battery with jump leads connected while it's running?

[Scorpion]

Sorted, got a little tip from a guy on the Pea Farm site. Power washed the alternator to get all the crap out of it then soaked it, and all the electrical bits, with Solvol.

Battery isn't in the best nick but it now gets a charge from the alternator!

Thanks to everyone who offered advice.

[Scorpion]

Just read my post again and I would like to correct one little point. I didn't soak the alternator in Solvol (all it would have done was make it very shiny), I soaked it in Powersolv!