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[mrjimbo]

Went out yesterday to go and get some milk and the car wont start again, 3rd time in as many months. There doesn't seem to be any sort of pattern to it other than if it's left for more than 48hrs battery can't cope.
Anyway, i jump started it and went merrily about my business, drove to Oxford and back to charge the battery, approximately 30miles altogether. After taking the shopping in i went out and checked the voltage across the battery - 12.4volts at 17.00hrs. Got up this morning and went out to check the voltage again - 12.0volts at 10.00hrs.
Now the thing is, last time this happened i did all the checks in Kevins "how to" and all was as it should be, no apparent drain and altenator charging OK but again the battery goes flat after 48hrs or so. It can do it after a long run or a short run, it doesn't seem to make any differance.
I suspect the battery is the culprit, any ideas what else could be causing it ?

[freecall666]

could be a bad cell in battery, or a bad pole on the battery.

[mrjimbo]

Battery terminals all clean and coated with Vaseline and the crimping all nice and tight and the clamp isn't getting warm either.

[Evo]

I guess you could disconnect the terminals & clean them to remove any oxidation to ensure proper metal to metal contact & also check that the negative lead has a very sound connection to the engine/chassis.

[millwall]

sounds like a duff battery

[Auto Addict]

A fully charged battery should be reading 12.7 v plus.

[mrjimbo]

I thought it may be the battery but the local parts factor tested it last time and they said the battery was fine.

[mrjimbo]

I used the mains charger at dinner time and after letting the battery rest for 15min or so afterwards the meter said 12.7volts. i checked again an hour later and reading had gone down to 12.3volts. I've just checked again and getting a reading of 12.2volts.
The battery charger charges at a constant 14.2volts and the altenator is charging at 14.6volts @ 1800rpm.

[Kevin Wood]

Sounds like you've got something draining the battery when parked. Try disconnecting the power sounder as a starter for ten.

Also, have a look here: http://www.omegaowners.com/forum/YaBB.pl?num=1225724099

Kevin

[Richard A]

Change the the battery !!!
Suggest it has a 'cell' down.
Regards
Richarda

[Welung666]

Right back to basics! Over time the charge level drops, is this with the battery still connected to the car? If so disconnect it, charge it again and monitor it for a few hours. If the voltage drops when it is disconnected then it's a dead cell as suggested. If not then it's something on the car draining it.

[mrjimbo]

Right back to basics! Over time the charge level drops, is this with the battery still connected to the car? If so disconnect it, charge it again and monitor it for a few hours. If the voltage drops when it is disconnected then it's a dead cell as suggested. If not then it's something on the car draining it.

Cheers Welung, I'm going to charge it again in the morning and leave it disconnected and check the voltage drop if any and see what shows up, all readings have been taken with battery on car up to now.

[mrjimbo]

Sounds like you've got something draining the battery when parked. Try disconnecting the power sounder as a starter for ten.

Also, have a look here: http://www.omegaowners.com/forum/YaBB.pl?num=1225724099

Kevin

I'm pretty sure it's the battery to be honest. It's an estate so any interior light staying on will be visible and it doesn't have a Power sounder fitted but i'll have a bit more time tomorrow and i'll charge the battery off the car and see if the voltage drops at all before refitting and then do all the checks in the link and see whats what 

[Kevin Wood]

Work through the checks in my HOWTO posted above.

If worried about the battery, charge it and check it, as said, but then put it on the car and turn the headlights on as you watch the voltage. It will drop a little but if it takes a dive down below 12 volts within a few minutes the battery is dead.

Generally if a cell is dead it will drop straight down to 10 volts ish as soon as it's under any load, and it will really struggle to start a car even if fully charged. This battery is evidently starting the car when fully charged, so I suspect the battery is OK.

But the HOWTO will guide you through checking the battery condition, charging system and looking for any current drain.

Kevin

[mrjimbo]

It's annoying because if the car is used every day then there's no problem but as soon as it's parked for 48/60hrs then it won't start, it was only parked this long due to the New Year festivities, parked it when i got home from work Thursday morning at 03.30 all OK but come 16.00 on Sunday not enough power to turn engine over.