Battery not charging!

P

prospect8816

Member
Last September, I bought a new battery for my car but have driven it only a few times since then, as it's been away for, amongst other things, Power steering fitted. Last Weds, 2nd Dec, I drove it out & about, only for the Ignition light to come on & stay on. When I got home, I opened the caps on top of the battery, only to find to my horror, no water!! :shock: My question is therefore, should a fully topped up battery, lose all it's water in just over two months?? Another question, could the answer lie with the Alternator, worn bushes etc, or what!! Answers on a postcard please...! But joking aside, this is a serious problem, is it not??
Your replies would be most gratefully received. My car details: Series 2 1975 3.5 v8 auto.

Paul

PS. A reply to "harveyp6", I will (with a friend who also owns a P6) be looking into the inhibitor switch problem, this coming Sunday. I'll keep you posted.
 
Batteries do not loose water by themselves they need to over charged or be internally shorted to do that either that or your battery was supplied minus the electrolyte.

First thing I would do is top up the battery with distilled or deionized water (or very clean tap water if you must) then start the engine and then put a digital voltmeter on the appropriate voltage range and check the charging voltage. If the voltage does not increase to above 12.5/ 12.8 you have a problem, it should read about 14.2 to 14.5V if it reads higher than say 15.0V after a few minutes then you also have a problem.

Either way this still does not solve the cause of your problem as it could be the alternator that has done this to your battery or it could be the battery that has killed your alternator or the battery may have a single cell shorted causing boiling by overcharging.

If your battery with the engine running reads in the normal range 14.2 to 14.5 then your alternator is fine, switch off the motor and wait a few minutes (maybe 10 minutes) if the voltage across the battery now reads below about 12.8 to 13.0 volts you may have a problem as the battery is self discharging too fast ( though the clock will provide an unwanted drain on the battery during this time).

Just a few simple tips before you start throwing the battery and alternator out.

Cheers Graeme
 
I think there's 2 issues here .The charging light coming on is not because the battery is low on water. Are there any signs of the battery leaking or venting electrolyte ?
 
To: ghce. Graeme, Many thanks for your most interesting & informative reply. I forgot to mention in my 1st letter, that I did top up my battery after finding it empty, and put it on charge. I kept it on charge till the meter showed the battery fully charged. I then drove it around the block a few times, by which time the amp-meter on the dashboard was showing a reading "dead centre". In other words, neither plus nor minus, telling me that my battery is fully charged! I'll have to wait till Sunday before I can do what you suggest, as I don't have a "digital voltmeter", but I have a mechanic friend coming over then, so i'll ask him to bring it with him.

Paul
 
To: DaveHerns. Dave, Many thanks for your reply. In answer to your questions, "Not to my knowledge"!! When I topped up my battery (after finding it empty), I did at first over fill each of the six compartments, but I did syphon out quite a lot, leaving the water just over the plates, then placed it on charge! The car is now starting first time and there doesn't appear to be any water leaking or (as you say) "venting electrolyte". By that I take it you mean "acid"??? Tomorrow I shall check the battery again before I start the engine, and if the water levels are ok, then............??

Paul
 
prospect8816 said:
if the water levels are ok, then............??
Click to expand...

I'd suggest if the water levels are down again after just filling them - you're probably going to need a new battery anyway - it's seen stress & as the temps go down - may be on it's last legs - sorry. I'd definitely invest in a meter if you can & follow the guidance already suggested - basic digital ones are fairly cheap these days & when you have one - you'll never know how you ever got by without it!

Failing that, you may be able to lug the battery to a garage/auto store & have them test it prior to shelling out for a new one - they don't last forever. Similarly some places may test the alternator/charging circuit for you but that's a bigger deal as it's shop/labour time.

Years ago I had a discharging battery, charge light came on - in the end an auto-electrician ,diagnosed it as a short in the bulb in the charging system - was not a P6. Another vehicle many years later - was the computer so at least you don't have to worry about that. Just keep an eye out if your light goes on & what you ammeter and/or dash voltmeter read if you have them. Also think about a good set of jumper leads - don't get caught stranded.

Good luck,

Paul
 
To ghce.
Graeme, I have carried out your suggestions with the aid of a mechanic friend, and he found with the aid of a Digital Voltmeter, a reading of 14.5 initially, then after switching of the engine & waiting for about 5 minutes, he re-tested the battery & had a reading of 13.8, so we think that the battery & alternator are working just fine. Took it out for a good long run today and everything seems to be working ok.

Many thanks
Paul
 
Certainly sounds good, would pay to keep an eye on it though, possibly an intermittant in the alternator causing over charge??? one visible sign of overcharge on a battery is blackening on the underside of the battery filler cap, though overtime this will happen to most batteries it should no be apparent on a new Batttery. Another possibility may be an intermitant short on 1 cell however as now all appears ok there is not much you can do unless the symptoms reappear.


Graeme
 
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