samcooke Posted July 22, 2002 Posted July 22, 2002 Whilst driving along the other day (1700xflow SE) I noticed the voltmeter reading dropping from its usually 13+ down slowly past 12 to settle at just less than 11. Left for a few days the battery doesn't have the power to turn the starter. If I charge the battery it lasts a couple of days, then dies. New battery then, obviously. But... if I put a multimeter on the battery it reads 12.7 odd when the car's voltmeter points at less than 11, which makes me think it might be more complicated. The rest of the gauges read all funny when driving too, I got 80mph in top at 2500 revs and 85psi oil pressure... I can't take the battery out of my other car and try it as I don't know the radio code. But when I hook up jump leads the car gauge whips back up to 13V. It's only the multimeter reading that is stopping me just getting a new battery. Any ideas? Sam. PS - Assuming you all tell me just to swap the battery, is it worth getting anything special or just any old one from my motor factors. Quote
ACW Posted July 22, 2002 Posted July 22, 2002 Measure the battery voltage under a load. Turn on all the lights, heater (if fitted) etc. A knackered battery will still show good voltage with no load. once loaded a bad cell or battery will show a much lower output voltage. Quote
chrisbin Posted July 22, 2002 Posted July 22, 2002 I've actually noticed a similar issue with mine. Starting is no problem - battery seems to have plenty of life. Voltmeter stays stable. However, after using the car for, say, 30mins, the speedo and rev counter can get a bit erratic.... same effect when switching on lights, and this can be straight away, not after 30mins use....... Its in my "to do" list to query with someone, but seeing this, I thought I'd raise it......... Quote
ACW Posted July 22, 2002 Posted July 22, 2002 As Jim says check you main loom eath, your engine to chassis eath strap and also that the alternator is earthed properly to the engine... Quote
samcooke Posted July 23, 2002 Author Posted July 23, 2002 Battery still gives 11.7v under as much load as I can give it (lights, heater, wiper, winkers, foglight). I'll check the earths, then. Main one is obvious, I'm sure but where should I be looking on the alternator? From memory... it's a Lucas unit with a push connector on the back with three (I think) wires. Where's my main loom earth? Guide for the mechanically fuckwitted please. Quote
Blatman Posted July 23, 2002 Posted July 23, 2002 11.7 volts under load means a knackered alternator.........It shouldn't ever drop below 12 volts, and ideally always be above 12.5 volts. Quote
Nick M Posted July 23, 2002 Posted July 23, 2002 What Blatman said. I replaced the battery on mine, thinking it was that which was knackered as it wouldn't hold a charge, then drove all the way from Essex to within spitting distance of the Eurotunnel before the car died on me. Alternator was fooked but lights, heater, etc. were all being run off the battery and the little misfire that had been there before was gone. They're only about £35 so definitely worth changing if it's doubtful. Quote
samcooke Posted July 23, 2002 Author Posted July 23, 2002 11.7v was with the engine not running, should've said that. Quote
Blatman Posted July 23, 2002 Posted July 23, 2002 Check it with the engine running.........Under 13.5 volts means knackered alternator. 13.5 volts or more, but flat battery symptoms when starting, suggests knackered battery or possibly a knackered starter motor. I've just re-read your first posting. You have a knackered alternator........... Nick. Afternoon...... Did your catch tank arrive, and did you fit it? If you did, and you're happy with it, I have plan 'B' for mine.......... Quote
samcooke Posted July 23, 2002 Author Posted July 23, 2002 I've just re-read your first posting. You have a knackered alternator........... Lovely. That's what I like. A no nonsense answer. I'll get me a new one. Quote
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