Battery Light - 90 300tdi

On start-up my battery light stays illuminated, but if I give it some revs the light goes out??? Any ideas??? I haven't checked anything yet.

Alternator? Belt (loose or worn?) Poor earth connection? Battery?

Could be any of those, someone more knowledgeable may be able to help more.

Ok, got the same and heard this is not a prob. For clarity, turn on ignition, fires up ok and engine runs fine. Battery light stays on, but on touching accelerator, the light goes out (assume this is same as original post). Is this just not normal practice but perhaps with an alternator that has seen some work but still doing its job? Views appreciated

the light is on because the battery is reading low. when you dab the Acc pedal it kicks the alternator into working "charge" mode, the volts rise from 12.whatever to 14.4v thus the light goes out.

If its one during tick over then I suggest an overnight charge with a good mains charger. This should hopefully bring your battery up to scratch and the light should not come on again.

G

Griffdowg, I'll give that a go, it has been standing a bit recently whilst being worked on so it may well have discharged a bit. Kwhajh, yeah starts and fires fine, i expected after 1st noticing it for it to struggle to fire the next morning but no probs, I'll see what an overnight charge does!

Your alternator has gone lazy, will not self energise it's self to charge until revs are higher, ok providing the engine does not idle for long, ie if sat at traffic lights with lights on it will not be charging. 100% fix is a new alternator..

Steve-c ur right just checked the batt and its fine, so anyone reccomend a alternator at a good price, I'm going to install a split charge system at the same time so does this make any diff to the alternator I should be thinking of getting?

depends hows much electrickery your running? why the split charge?

if you want the most charge, get a 100amp unit.

G

Well I was going to run all the standard car needs on one and then run a leisure batt for spots, winch, and other bits and bobs?

The Badger said:

Well I was going to run all the standard car needs on one and then run a leisure batt for spots, winch, and other bits and bobs?

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sounds about right. either the standard 65a or a 100a will do it then. obviously the 100a will charge quicker, depends what you want to pay.

Im still not convinced there is much wrong with your alternator. they take a few seconds after starting for the alt to kick in. You can see it clearly on my national luna twin volt meter! everytime.

G

mine does exacly the same as the badgers has been like it since i took the battery of it a year ago never failed to start even in the freezing winter we just had, and reads 14 odd volts on tick over so no issue with my alternator guess iv got a dodgey earth problem

This is it it starts fine and there is no apparent loss of power from the batt, my mate checked it up at the garage and said the batts fine, so need to just monitor it for the next week. Ive noticed that the warning light isn't fully illuminated like the handbrake light for example, its just a dull red buld which is 50% on, but then fades in and out, all a bit odd

The Badger said:

This is it it starts fine and there is no apparent loss of power from the batt, my mate checked it up at the garage and said the batts fine, so need to just monitor it for the next week. Ive noticed that the warning light isn't fully illuminated like the handbrake light for example, its just a dull red buld which is 50% on, but then fades in and out, all a bit odd

Click to expand...

you have described the problem i also have to a tee
well its not really a problem

Badger, do you have a multimeter?

you need to take a reading of the batt with engine off (after 24hrs say). then, warm the plugs, start it, take a reading immediately, then blip the throttle (to get a response from the Alt) and take another reading. It should read over 14v. monitor it to see if it dips. dont turn on the stereo, lights or anytihng else, turn off the interior light etc so its just running with no electrical draw. If it idles at over 14v for a few minutes you dont a problem with the Alt, its most likely an earth or a short causing the light to iluminate. try tracing all the wireing that goes to/from that warning light to check for chaffing, split contacts, un-insulated contacts etc.

G