12 replies to this topic

[stitch-86]

Model: Cooper
Year: 1991
Description of problem (please be as in depth as possible): If I drive with the light on the battery is flat when I stop (just drove 65mile round trip and battery is still flat)



Any non-standard parts that might be involved with the problem?

Hi, Battery was flat this morning, had barely enough juice to start (and i mean barely!) and after a 60 mile round trip the battery is still flat

Problem started when I left the lights on the other night and run the battery dead and since then the battery has been hit or miss wether it has any charge.

Today for instance: Went down to the car and the battery was almost completely dead

I drove to the Stevenage car show (about 20 - 30 Miles), parked up looked arounf for a couple of hours, came back and the battery was practically dead again.

Drove back home with the lights on (dont quite know why I had them on but someone somewhere told me the battery charged quicker) parked up and tried to restart the car, but it didnt even have enough power to start.

So push started the car, drove around without the lights on for a while and then went home. The car started straight away, but i have a feeling it won't in the morning!

Possible problems:

Alternator - The lights do not flicker, go dim or anything whilst they are on car idle drops to 900rpm from 1100rpm when started with a flat battery, and back up to 1100 rpm after about 15-20 mins of driving. (Idle is fast i know, but this to me says this is working.

Battery - When i ran the battery flat the other night may have killed it? the battery doesnt look that old, but prob a good few years old and on a car that was not used that often (Masin suspect)

Lighting / other electrical - Could the car have developed an electrical problem or short somewhere else?

Any tests, checks or alike i can do to find the culprit? and what settings should I have things on and what reading should I get?

Thanks

[danie garry]

with everything off put the multi meter over the battery, should be around the 12v mark if the battery is ok
when the car is running put a multi meter across the battery, it should be reading over 13.5 if the alternator is doing its job

Edited by danie garry, 30 May 2011 - 04:24 PM.

[Scallywag630]

With a multimeter, check the output of the alternator at the alternator and at the battery. If the reading drops, it would suggest an engine earth problem. If this is the case, use a jumper cable from the engine to a good earth on the body and check the values again.

[tommy13]

First, charge the battery with a battery charger for at least 12 hours. allow it to stand for a day if possible and then refit. If the car will not turn over on the starter then this is your problem. If it is sluggish connect a voltmeter to the battery and note the voltage while someone cranks the engine over ( remove a coil lead so it does not start) crank for 10 seconds and note the voltage, if it falls below 9 volts the battery is tired, if OK check the charge rate as described by danie above and expect a reading between 13.6 and 14.4 volts at around 1500 rpm and should not drop too much with the lights and wipers on. Any problems here and you should start by checking the belt tension on the alternator. Just try to push the alternator pulley round with your thumb on the cooling fins and if it slips round easily without turning the crank pulley a little then the belt is worn and or too loose.
With the exception of a drain which is uncommon, the above tests should determine your problem. You should of course check that all battery/ solenoid and earthing connections are clean and tight.

[stitch-86]

Ok Thanks guys,

Just checked the voltage of the battery (immediately after driving to get a multimeter) and it was at 11.28V, Turned the engine back on and it went up to 13.28V at idle

I cant really take the battery out of the car as i need it for work; so my test is:

I've disconnected the battery at 11.28V, and I will reconnect in the morning and see what the new multimeter reading is. Surely the battery shouldnt lose much charge overnight?

I'm glad that these cars are easy to push start lol, its a good wakeup call at 6:30am! Push, run and jump in before I hit something!

[danie garry]

the battery will loose the charge if its shorting out somewhere

[Darkscamp]

Your battery is dead matey i'm afraid. Should be reading higher than than when the engine is off.

[Shifty]

Your battery is dead matey i'm afraid. Should be reading higher than than when the engine is off.

Yup, its the battery.

All the other readings check out.

If you can stretch to it, fit a battery off a pug 306 diesel, its much better than the standard mini one and will fit in the battery box ok.

[tommy13]

Ok Thanks guys,

Just checked the voltage of the battery (immediately after driving to get a multimeter) and it was at 11.28V, Turned the engine back on and it went up to 13.28V at idle

I cant really take the battery out of the car as i need it for work; so my test is:

I've disconnected the battery at 11.28V, and I will reconnect in the morning and see what the new multimeter reading is. Surely the battery shouldnt lose much charge overnight?

I'm glad that these cars are easy to push start lol, its a good wakeup call at 6:30am! Push, run and jump in before I hit something!

You should really perform the charging voltage test at a fast idle to get a proper reading. 13.2 is a little low although this may improve with increase in revs.
I would urge you to check the alternator belt as described,
The battery voltage reading really tells you very little about the condition of the battery. I assume it is starting on the starter tonight, leave it disconnected until morning as you have planned. this will rule out any drain or short. If the car will not start in the morning then the battery is shot. ( worn out batteries can lose charge overnight).

[stitch-86]

My thinking was that this will eliminate a short on the car, and also check if the battery is holding charge. I will check the alternator when it's not raining - although it does appear to be working, if maybe a little weak (another problem for another day!)

Must confess I was expecting to get a new battery after letting it run flat.

I did check the Alernator belt, and thats nice and tight, (had a new belt fitted just before L2B)

Is it definately the Pug 306 battery that fits? someone else said to get that one aswell, roughly what should a battery cost? Halfords are looking at £55 for the standard and £94 for the Pug. They reasonable (considering it is Halfords)

[thehelstonian]

halfords are always a little more expensive but usually more convenient...yep ive got a PUG battery in mine....try ebay if you dont want a brand new one, or you may even get a new one for a lower price

[DeanP]

It wouldn't do any harm to clean and vaseline all your electrical connections. Do the earth in the boot, clean the alternator connections and the ones to the fuse box. I had a similar problem recently, except mine was a new battery. Giving everything a good clean with emery paper solved my problem.

[oliver122]

it might be a long shot , but make sure the belt is tight , i had that problem , tightened the belt up and it charged up again , even though it was tightish before it still didn't charge properly , now that ive tighten it up even more works a treat

Is it definately the Pug 306 battery that fits? someone else said to get that one aswell, roughly what should a battery cost? Halfords are looking at £55 for the standard and £94 for the Pug. They reasonable (considering it is Halfords)

i give 60 pound for my from my local parts place and that was for a pug battery with 5 year warranty

Edited by oliver122, 31 May 2011 - 08:48 AM.