Battery not charging

Voltages are a tad low, especially for a new battery. Sounds like a cell has gone u/s to me. I'd try another battery as it clearly is receiving a charging voltage. Might be interesting to connect a mains charger and see what current you get. A flat battery will draw quite a few amps, 3-5, a fully charged one will only draw less than one.

If it is your alternator it can only be because it can deliver the volts but maybe not enough current.

TonyB

In my experience it's more likely to be a poor engine earth strap. With the engine running at a good fast idle check the voltage between the battery earth terminal and the engine block. It should be less than 0.1 volts. If it isn't then remove the engine earth strap and clean all the connections on the strap, the engine and the chassis/body. If it is less than 0.1 volts then check the terminals on the back of the alternator for corrosion. If these checks are all in order then it is likely to be a dodgy diode pack in the alternator. Depending on the cost of a recon alternator for your vehicle then it is often cheaper to buy just the diode pack, although in some cases it isn't a simple remove a few screws and connectors job so have a look first.

Phil

T>>Battery not charging, charge light extinguishes as soon as engine starts.

Those voltages do sound low - my Disco puts out about 13.9 volts when running.

Fully charged battery should produce just under 2.1V per cell, so if you charge the battery OUT of the car, you should end up with somewhere between

By charging out of the car, you will eliminate alternator problems and earthing problems, so it will be a true test of the battery. If after that, the battery is fine, I'd agree with other posters and look at earthing and the alternator - as I said, 13.2 at teh alternator does seem very low.

Cheers! Graham Carter

Thanks for all the info'. I should have stated that the battery voltage of 11.9 was with it flat. Have since recharged it and am running about on battery current and it is starting well so I think the battery is OK. I'll go through the cleaning of contacts and connections next. Thanks again.

Alternator should be regulating to somewhere between 13.8 and 14.4 volts with engine running at idle. A good check for output current is to confirm the voltage and monitor it whilst adding more electrical loads. Start with the headlights on full beam, then add the heated rear window, then the blower motor etc etc until you reach a loading where the voltage drops just below 13.8. Now increase the rpm to around 1500ish and the volts ought to rise back to somewhere over the lower figure of 13.8, unless you are applying more load than the rated output. Badger.

Thanks Badger, I thought the voltage figures should be somewhere around yours. At present the best I can do is 13.2 volts, not enough to overcome counter voltage.

On or around Mon, 23 Jan 2006 18:53:19 +0000 (UTC), "Badger" enlightened us thusly:

with minimal electrical load, mind.

I trust you have got an "ignition" light when the engine's stopped. The wire through the ignition light supplies the reference voltage to start it charging. Disconnect it and no chargee. I suspect that on some systems you get no chargee with a blown bulb...