Alternator or dual battery problem

[biggles]

Symptoms:

Charged both batteries on the intelligent trick charger to full. Early morning take a drive and the Madman is beeping at me and showing 15V+ at 3000rpm. Anyway I had pull a keelboat out of the dam and only the Patrol had the oomph and teh towbar to get it done. So off I went and kept the revs low and everything seemed OK. Even I was happy as usually voltage is less than 13.1V. But wondering what is going on.

Next day I am doing alot of stop start shopping and short hops and after a day of that the Patrol finally refuses to start (I had linked the two batteries to get it started the last two starts). So on the charger again and a long trip to namibia and the battery is slowly draining with the main beams and brights are killing it.

The low charge is nothing new (pieter du toit had the same issue with low voltage).

But the Nat Luna charger only draws current when it reaches 10 minutes at +13.1volts. So how can that have an effect when the alternator never puts out more than 13V?
The voltage on the Madman increases with revs so alternator is working.
Voltage seems to be all over the place and depends on the charge in the batteries.

Any ideas?

[Tinus lotz]

Just replace the voltage regulator on the alternator I am sure thats your problem

[Russ Kellermann]

This is a great post,...it just reminded me of how little i know about Auto Electrics.... I really wish i was more knowledgable. Im interested to hear what the end outcome was.

[bogeyman]

Steven,
Many voltage and charging issues are caused by bad connection in the wiring.
Battery terminals corrode and make bad contact and it is not always visible. The bonding strap between engine and chassis could also be the culprit.

If you are sure about the wiring conductivity , you can check the charging rate with a DC amp meter. When the battery voltage is low , the alternator should deliver close to maximum output (45 to 60 amps). this should gradually decrease as the battery voltage rises and should be about 5 amps when the voltage reaches 13.5 volts. If this does not happen , the voltage regulator or the diodes and stator or the brushes in the alternator are faulty. Also check the fan belt tension.

If a disconnected battery loses charge overnight , there is usually a dead cell in the battery. This will also mess with the charging rate. There could also be a cell connector inside the battery making bad contact. A good battery supplier can test for that.

Hope this helps,
Chris.

[biggles]

Problem is what I know about electrics is fatal. And usually ends up with a qualified electrician taking over and me blaming "that idiot mate of mine who did that".

The checks seem easy enough. Both batteries are new. And it seems now there was no need to replace the original battery as I thought that was the culprit.

[biggles]

So to close the thread off: I eventually got it to an autosparky. Who rebuilt the alternator and the starter, which had also just given up the ghost. He also tracked down several voltage drains and now a bunch of electrical niggles have gone away

[Herrie]

Nice Steve!

[biggles]

I swear it goes better after the alternator fix. Possibly the fuel pump was not getting enough volts to push all the diesel up front!!

[Tinus lotz]

Trap hom ... must have fun in namib sand....put some pics

[biggles]

Sand was cut short by whine from passenger seat area. But it went very well. Definitly power is up since I was last in sand at Atlantis Dunes.


This awning is amazing.