5 replies to this topic

[M0U5EY]

Hi guys,

I was recently driving my 1898 mini cooper and decided it needed a wash. This went as expected with a nice clean car as the end result. However, when going to start the car there was no power to anything, lights, immobilizer, the lot. Once jump-started, the car is fine and running well and seems to not be losing charge. The one thing I did notice when turning on after jumping was that I did happen to leave the headlights on while washing, is it possible that some water got in there and shorted out the battery, completely draining it or is there something else that could have caused it?

Thanks!

[nicklouse]

or your battery is on the way out and leaving the lights on drained your battery to a level that it did not have enough charge to start.

 

when was the last time it had a real good 240V charge?

[M0U5EY]

Not too long ago, but I have left the lights on for a few hours at a time recently (again by accident), come back and it starts fine, this is the first time it has completely died.

[Cooperman]

An 1898 Mini - it must be steam powered. You don't need the battery, just put some more coal in the firebox  .

 

It is surprising how quickly the headlights being left on will drain the battery. Remember, if you have, say, a 50 amp-hour battery and 50 amp alternator, it will take an hour to fully charge up at normal running speeds and more if any electrical accessories are switched on. The headlights with sidelights, rear lights, number plate lights, panel lights, etc, will drain a lot of amps so the battery goes down very quickly. An old battery may not have as much power as a new one.

 

Best thing is to borrow or buy a simple 12-volt battery charger and leave it to charge over-night. Check the battery connections as well and clean them up, then give them a coating of Vaseline or non-conductive grease. 

[M0U5EY]

It's a new battery with new terminals + leads and as I say, I've left the light on for a couple hours at a time and not had an issue at all, just seems rather weird for me to leave them on for 30 mins and have absolutely no sign of life...

[tiger99]

It depends on teh state of charge of the battery when you left the lights on. Two 48 watt headlights, four 6 watt side/tail lights totals up to 10 amps, so a 40 amp hour battery is gone in 4 hours. It goes down fairly quickly towards the end, if it has not quite reached that point the car will start normally and you will never know how close it was to being flat.

 

Washing the car had nothing to do with it. In case you were, quite reasonably, thinking that the water caused a short, filthy, polluted or salty water is moderately conductive electrically, but average to clean water is only slightly conductive, at low voltage. High voltage is another matter, although a laser that I once, way back in about 1975, had to repair and modify had the high voltage side immersed in de-ionised water which did not break down during an applied 10kv pulse. Don't take risks with mains in wet conditions, or any other time, it is quite easy to have a fatal accident, but I am just explaining that water does not cause an immense battery drain, even if it gets onto the wiring.

 

If you flooded the battery box, which would get into the vents, dilute the acid, and spread conductive electrolyte all over the place, bridging cells, the battery would go down rather quickly, and probably permanently, but I doubt that you would have done that to your valuable car.

 

So it is all just timing, luck, previous charging history, and possibly an ageing battery that will soon need replacement.