last trip out in van today just before I pulled onto the drive the van cut out...I had head lights and radio on...turned those off and it sparked up but the battery light stayed on...run the engine again later on...fired up fine but battery light stayed on...then went off after few minutes....but when I turned engine off it stayed on for a few seconds...tested battery with volt meter with engine off reading 12.64 volts...turned engine on battery reading was 14.2 volts....any ideas if it's it's battery the alternator or something else any help appreciated
14 odd volts implies the alternators making the effort. May be the battery's not holding charge? How old is it?
It has to be 3 or 4 years old now I would say..i have a little volt meter via the cigarette lighter...and it seems to drop down from around 12.5 when the van stops after a run to about 12.2 ish when left sitting for a few days....I suppose the 1st thing is to change the battery then thanks for the reply
thanks buddy so if the power drains away over the next few days workout switching anything on...I suppose it confirms the battery is not holding its charge
It could be the brushes are worn on the alternator, and its just about charging the battery - 14.2 volts is OK. But its not giving enough current to run the headlamps as well because it has become weaker, because it cannot get enough current through the brushes and field winding to magnetise the rotor enough to deliver the current. The battery shouldnt be discharging that fast when the engine is stopped. A LED voltmeter wont help if its lit up all the time.. but should take a max of say 0.05 A.. which will flatten a 65AH battery by 50% in about a month. Good for the kind of drop you are seeing.. also any unswitched USB chargers off the starter battery. Having the fascia of my Sony stereo in place causes the radio to drain 0.25A from the battery through the backup power connection - its less than 0.005A with the fascia removed...
It’s only 3 or 4 years old. I’d expect 5 years minimum. I’d also thought most batteries come with a 5 year warranty. Leisure batteries on the other hand…
It all depends on a lot of factors but if a lead acid battery is in its last legs once the temperature drops it finishes them off. The modern digital battery testers don’t cost a lot and are a worthwhile investment if you want to know the true health of your battery
You can total an AGM battery leaving it flat for 3 days, and a normal wet cell lead acid in a week or so. It doesnt take much abuse to get the battery sulphated up. With a wet cell you can blast the sulphate off the plates and "recover" it at the expense of losing plate material every time. If your ignition failed with the engine running and the lights on that is not so much the battery as the charging that is the problem. (Or was it just a blocked idle jet in the carburettor ?) About 2 amps is needed to run the engine, maybe 8 amps for the headlamps. From a 30 or 38 amp dynamo or a 50 or 55 amp alternator. If the engine still cranks the battery isnt totally dead yet. But it seems like you have a low output charging system which causes the engine to die when you idle for a while. And a parasitic drain when its standing. Yes the battery is being damaged but from the description its a symptom of a deeper pair of problems not the cause.
