Battery light on; rev counter not working!

Hi All,

Had an interesting scenario this morning. I got into my car to drive to work, having not started it for 4 days, and whilst it started 1st time, it sounded a little lethargic. However, I noticed (a) the battery light was on and (b) when I pulled away, the rev counter needle didn't move. All other electricals seemed to work, the lights worked, the radio was good. I switched off everything electrical, thinking that the car would conk out, but about 15 minutes later as I pulled up to some traffic lights, the rev counter needle started working and the battery light switched off!

I've looked at a few other searches on this, and the only similar post I found was one that detailed the link between the rev counter and the alternator. Is this the start of an alternator failure? Should I check the security of the fittings on the back of the alternator? I can understand that a loose connection there could cause the rev counter not to work, but how would that drain the battery? Is it something else? Can I expect this to get worse?

It has been left for a week before with no problems are similar occurences. I had the head gasket replaced 3 weeks ago, could something have been moved or unseated during that, and if so, would it take 3 weeks for a battery drain to occur?

You are correct in saying it is to do with the alternator, I had the same problem, except miner went flat to staart with. Then on restarting the rev counter did not work and the battery light stayed on. This was the case for a short while and then the rev counter came back but if ir remeb=mber the light stayed on. I ran it like this for a number of weeks before I changed the altornator.

It would be well worth the money changing it jujst for peace of mind that it is charging properly especial in the winter. For the time being check the connections for tightness and moisture as this could have caused it to loose connection.

Hope all this helps

Sounds like the alternator is not switching, the light will only go out when the alternator makes more leccy than the battery. The rev counter comes from similar electrics on the alternator, so I would be looking at a rebuild, or new alternator. I would think is is just the alternator, as if the belt was slipping that badly it would give you some other tell tale signs.

As said above, check connections, a loose conection could be all it is. Take the wee wires off and scrape the terminals with a knife, incase its copper oxide.

discomania said:

Sounds like the alternator is not switching, the light will only go out when the alternator makes more leccy than the battery. The rev counter comes from similar electrics on the alternator, so I would be looking at a rebuild, or new alternator. I would think is is just the alternator, as if the belt was slipping that badly it would give you some other tell tale signs.
As said above, check connections, a loose conection could be all it is. Take the wee wires off and scrape the terminals with a knife, incase its copper oxide.

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Thanks James, Discomania. If the alternator was on its way out, would the light just 'blink off' when it was making more leccy than the battery? Would this not be indicative of a loose connection suddenly finding its way again, in the blink of an eye? Or, am I clutching at straws, in a futile attempt to hold off the ridiculously expensive cost in replacing an alternator?

If its a loose connection, would I be OK in putting electrical jelly sparingly on the connectors? I guess I have to remove the heatshield to get at the connections, yes? And more importantly, once the negative battery connection is loosened, does the alternator hold any charge?

Are they easy to change, BTW? Should I get an OEM unit, reconditioned or new after market (if available)? Any idea of a budget way to replace?

Many questions, I know, and I apologise for that, but me and electrics don't mix well.

Try the contact first, take the heat sheild off, take all the push fit contacts off, clean em up, plug them in, and when you do, push and pull them a few times to scratch a nice contact into each other. Then give it a go.

If you have a voltmeter/multimeter, meter the battery, start the car, and see that the meter reading goes up substantialy, if not... get a new one.

See if you can find one of these guys that will rebuild it in a morning sort a job... usualy little shacks at the back of industrail estates, but they are damn good.

Not a biggy to change, I would expect you can do it for £45 - rebuild to £100 MAX if you fit it yourself.

Easy enough to change your self, the hardest part is getting the tension while tightning it back up again, you may just need another pair of hands to hold the tension. should only take half an hour to do or an hour with a tea break!

Well, thanks again for the info. It didn't happen at all today, so I'll not do anything yet, apart from check the connections, clean them and lube them as necessary.

I might try a few load tests (satnav, coolbox, dvd player) whilst driving to and from work, as I plan to drive across to the Czech Republic at Xmas with the wife, little daughter and baby boy, so don't want anything to happen en route!

Lights, lots and lots of lights you want on, sat nav and dvd player won't be that power consuming to be honest. Full beams, fogs, hazards, heater on full...

if yer want to load yer charge system, the best things to switch on are headlights and rear heated screen