Alternator / battery / bulbs issues

Hi,

Haven't posted here for a while, but recently had a battery situation and just wanted to check my diagnosis (1997 Honda Accord).

Had about six bulbs go in the space of about two weeks, and hadn't changed any for a while before that so didn't think too much of it. Then got up one morning to find the battery completely dead - not turning over and so dead that the dash lights glimmered briefly and then died. Got a mate to jump start the engine, drove around for about forty minutes and parked up by the tyre/battery place I ususally use. Engine off, then tried it to see if it would start - still as dead as it had been before.

First thought at this point was the alternator having failed, possibly overcharging for a while before it went (to blow the bulbs). Nice people at the battery centre replaced the battery and said it had boiled dry. Battery was three years old, which didn't seem like a lot. Anyway, they put a new battery on, and said alternator seemed fine, but maybe I should get an electrical specialist to do a full diagnostic on it.

Got home and read about how an overcharging alternator can boil a battery dry so decided to do the diagnostics in the service manual myself. Everything was fine, including the alternator putting out 14.3v to 14.5v with and without full electrical load.

It was at this point I realised I had made one stupid assumption - that the previous battery had been a 'zero maintenance' one. Turns out it was 'low maintenance' and it looked like neither myself nor any of the previous service staff had topped up the distilled water at any point, which might explain why it had boiled dry after 3 years!

I think the last straw for the battery was the night before it died when we sat in a car park with the engine off but with the interior lights on for about 40 minutes. Assuming it had just boiled dry through my own poor maintenance, that only leaves the question of why the bulbs all went. It could have been coincidence, but I was wondering if a failing battery might have some side effects including short power surges strong enough to blow bulbs?

Anyone any idea if this seems possible?

Thanks, Al Reynolds

Reply to
Al Reynolds
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If it's dry then you can overvolt everything. 14.5 is at the high end to start with.

Reply to
Duncan Wood

Agreed, a properly functioning battery is often an important element of the voltage regulation system.

Reply to
Vim Fuego

"Duncan Wood" wrote in news:op.tlutiigbyuobwl@lucy:

Yeah, the alternator relies on the resistance of the battery to maintain regulation. If your old battery was running dry then it was most likely responsible for your problem.

Stu

Reply to
Stu

I see. Honda manual says 13.6 to 14.8 is fine for 2000rpm and full load, so I won't worry too much about the 14.5. Thanks for the input people!

Al

Reply to
Al Reynolds

I'm not so sure. If the battery went so high impedance as to effect the alternator regulator it wouldn't be able to supply enough current to start the car.

Reply to
Dave Plowman (News)

Yes, I think you are right. As everyone knows, one of the DON'Ts in car maintenance is never to disconnect the battery when the engine is running. The reason is that the power line from the alternator is 'dirty', and the battery eliminates completely the odd surges and spites on the power line (naturally, considering its construction is like that of the electrolytic condenser of bygone years); it is a very effective surge suppresser. Without a battery, the delicate electronics are vulnerable. In this case in question (a dry battery is equivalent to a non-existent battery), the suppression is nil.

I bet now that you have the new battery, there is no more erratic popping off of bulbs. In this context too, I don't think the 40 min use of interior light with the engine *not* running was the coup de grace.

By the way, three years of no or little addition of distilled water to the battery is not that surprising. I service my own car, and in 5½ years I don't remember I have ever put anything in my car's battery, and the electrolyte still remains high at its optimal level.

Reply to
Lin Chung

On Tue, 09 Jan 2007 08:46:38 GMT, I waved a wand and this message magically appears in front of Lin Chung:

Most batteries sold today are sealed for life, thus they don't require any maintenance. One thing less to worry about.

Reply to
Alex Buell

Yes - most modern designs are low maintenance types which sort of catch any 'vapour' and 'condense' it back to electrolyte. They are often incorrectly called sealed, but a true SLA battery uses a gel instead of a liquid and requires different charging characteristics. Some of these low maintenance types have no easy way of checking the electrolyte level anyway.

Reply to
Dave Plowman (News)

"Dave Plowman (News)" wrote in news: snipped-for-privacy@davenoise.co.uk:

Not high, low. Some articles on the web say that if they are allowed to run dry, the internal resistance can lower, because a low resistance bridge forms across the top of the plates. The low resistance makes the battery appear good from it's voltage, yet because the acid level is dropped the performance suffers in terms of CCA.

Stu

Reply to
Stu

New one on me.

Reply to
Dave Plowman (News)

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