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Car Forum / MINI / December 2003Battery Charging Problem on 2000 Cooper Sport
OK here's the problem... The battery started to go flat after a week or so of daily use. I replaced the battery but it continued to happen. I then took the car to my local garage and they checked the obvious earth straps, etc and had the alternator tested. The alternator was fine i.e. it was kicking out enough to charge the battery. The garage suggested trying an auto electrician. The autoelectrician checked over the car and came to the conclusion that it was to do with the brushes in the starter motor (this is because the car seemed harder to start if the enginge was still warm). The car would not start at all a few days after this and the AA man said it would unlikely be to do with the sarter motor but sounded more like a bad earth which was preventing the charge from the alternator from reaching the battery in the boot. A bad earth seems likely as the volt meter on the dashboard tends to fluctuate whilst driving. I have tried myself to locate the earth points and have cleaned up the contacts on the back of the starter solenoid (connected to the starter on newer models such as this) as these seemed fairly dirty. Unfortunately this has not made much if any difference. Has anyone any ideas?? Al. > OK here's the problem... > [quoted text clipped - 18 lines] > > Al. There will be an earth strap from the engine to the body. It is either along the top steady bar or from the clutch housing near the front down to the subframe. In this case, there will need to be another strap to the body from the subframe. Also, clean up the contacts of the earth strap from the battery. If you leave the car for a few days, is it turning over slower? i.e. is the battery draining or just not charging in the first place? If it is draining, check the main battery cable from the positive side of the battery, under the car to the solenoid. This can wear through causing a dead short.  SignatureRgds Steve steve@dsnclassics.co.uk www.dsnclassics.co.uk hiya might be silly question but how far do you drive each day ? because a battery takes quite a hammering when you start up. It can take 20 - 30 mins to return the battery to full charge, and in the winter when you have all the electrics running (lights radio heater rear demist etc) it can take longer . So if you only do 5 - 10 min trips the battery can become drained after a week, fragged > OK here's the problem... > [quoted text clipped - 18 lines] > > Al. > The battery started to go flat after a week or so of daily use. I replaced > the battery but it continued to happen. Batteries go flat for a reason. Another battery will go flat for exactly the same reason if you don't fix the underlying fault. The usual reasons are either that you're not charging the battery when you're driving, or that you're discharging it whilst your not driving. > I then took the car to my local garage and they checked the obvious earth straps, > etc and had the alternator tested. The alternator was fine i.e. it was kicking > out enough to charge the battery. Did they measure the charge voltage at the battery or at the alternator? If the battery voltage rises to 13.8V within a few minutes of running then the alternator *and associated wiring* are working. Which leaves parasitic loads when the car is off. > The garage suggested trying an auto electrician. The autoelectrician checked over > the car and came to the conclusion that it was to do with the brushes in the > starter motor (this is because the car seemed harder to start if the enginge was > still warm). Unless the starter motor issue is causing you to crank and crank and crank and crank until the battery is flat, it's not the cause of your flat battery problem. > The car would not start at all a few days after this and the AA man said it would > unlikely be to do with the sarter motor but sounded more like a bad earth which > was preventing the charge from the alternator from reaching the battery in the > boot. Which is why you measure the charge voltage at the battery..... 8-) > A bad earth seems likely as the volt meter on the dashboard tends to fluctuate > whilst driving. Ahhhh..... What values does it fluctuate between? Does it wander between about 12V and 13.8, rising with the revs? Thats normal. Does it drop when the revs rise? Thats often caused by a sick diode in the alternator. Does it drop dramatically sometimes with no rhyme or reason? Thats caused by a loose wheel brace... You know, it slides around in the boot on every corner, and sometimes it lands across the battery terminals.... > I have tried myself to locate the earth points and have cleaned up the contacts > on the back of the starter solenoid (connected to the starter on newer models > such as this) as these seemed fairly dirty. > Unfortunately this has not made much if any difference. Is your only symptom difficult starting? Have you checked that the battery is in fact going flat? > Has anyone any ideas?? A) Establish that the problem is a flat battery, not a sick starter motor. B) Establish whether the alternator is delivering a healthy 13.8V at the battery. It will take a few minutes to each this voltage on a cold start. C) Check the current draw at the battery terminals with everything turned off. Hi Guys I have the same probelm in my Cooper Sport. The reason is because I use it maybe once or twice a month. Sitting in the garage there is still a discharge from the battery. The immobiliser and alarm all draw a slight charge which over time is enough to drain the battery. I have just bought a solar powerd trikle charger device which is designed for just such a situation. The solar panel sits on the garage roof and connect to the battery via a converter unit. It keeps the battery "conditioned". Since fitting it I've had no problems and the car starts fresh and strong everytime. Alway avoid short trips in the car as well, as someone has already said in the thread it takes a minimum of time to re-coupe the loss of charge just from starting the engine. Not to mention the horrendous damage done to the engine from short runs. The engine was designed at a time when the only time you used the car was for a good run. Modern cars are a little more forgiving. UUse good oil such as Castrol Magnatec which has improved cold starting properties and operates from the moment you turn the key. It also makes the cold engine crank easier, so again saves hammering both the engine and the battery. Tim New Zealand > OK here's the problem... > [quoted text clipped - 18 lines] > > Al. Hi Tim, That sounds like a great piece of kit, but don't think it will have much effect here in UK, as you know we are entering our winter months, so there is hardly any sunlight,,, come to think of it,, there is hardly any daylight,, starts getting light here in the north west at 8-00am and starts going dark around 3-30pm,, I'm sure you remember these dark mornings and afternoons from your time here, Fitzy > Hi Guys > [quoted text clipped - 48 lines] > > > > Al. Tim Just out of interest, where have you & Liz moved to, Fitzy > Hi Tim, > That sounds like a great piece of kit, but don't think it will have much [quoted text clipped - 62 lines] > > > > > > Al. we are still in NZ, just moved out of the city and bought a small farm, about 15 acres. We are located in the lower central north island in a small rural township of Feilding. Closest big town is Palmerston North 19km to the north. best part is the 220sqm of shed space, so for the first time in my life i have all 6 Mini's, my landrover and the farm tractor all under cover...and even got room for the car trailor as well! The other great thing is that my northern boundary is shared by the Makino River, which is great brown torut fishing, and just across it, by way of a foot bridge, is Manfield Race Circuit. So i can walk to the motor racing in about 5 minutes these days. a lot of people think the noise would be an issue, but because of the raised banking and the double row of Poplar and Pinee trees between us and them the only time we hear anything is when the wind is blowing from the south...and the prevailing wind is north westerly... SO the life of semi retirement and being a gentleman farmer suits me very well indeed. I'm starting a job in the new year working for a parts supply company in town, selling the usual motorfactors type of stuff...and generous staff discounts to ! > Tim > Just out of interest, [quoted text clipped - 83 lines] > > > > > > > > Al. trout fishing a true gentlemans sport :) makka > we are still in NZ, just moved out of the city and bought a small farm, > about 15 acres. We are located in the lower central north island in a small [quoted text clipped - 112 lines] > > > > > > > > > > Al. Very nice Tim, All you need now is a couple of Metros and a Maestro for donor bits and a hydraulic engine lift, (big smile and raised eyebrows) But seriously ,, congratulations ,, it sounds fantastic,, Regards Fitzy > we are still in NZ, just moved out of the city and bought a small farm, > about 15 acres. We are located in the lower central north island in a small [quoted text clipped - 112 lines] > > > > > > > > > > Al. If you're lucky enough to have your Mini in a garage with power then look at battery conditioners. They are designed to be connected to the battery while it is still on the car and monitor the state of the battery, if it starts getting a bit low then it applies a small charge until it's OK again. Some of them come with a cigarette lighter plug so you don't even have to open the bonnet/boot to connect it up. Excellent for a car/bike that only gets occasional use especially those with a permanent current drain like an alarm. Shaun. > Hi Tim, > That sounds like a great piece of kit, but don't think it will have [quoted text clipped - 54 lines] >>> >>> Al. Hey Tim, Try parking it up without the alarm, and see how long the battery lasts, as the fault could be the voltage regulator on the back of the alternator, Fitzy > If you're lucky enough to have your Mini in a garage with power then look at > battery conditioners. They are designed to be connected to the battery [quoted text clipped - 66 lines] > >>> > >>> Al. Guys, Thanks for your detailed replies. In response to your suggestions: 1) I have already attached an additional earth strap between the engine and chassis although this has had no effect. 2) The earth strap connecting the battery to the boot floor has been sanded clean, as has the boot floor where it joins. 3) When the battery was near flat, the reading at the battery (with the engine running) was below 12v, i.e. not enough to charge the battery; yet it was nearer 14v at the alternator end. On this occasion it was a summers day and the car had been running for a good period of time some 15 mins earlier. More recently, in late autumn, the battery had been recently charged and the reading at the battery end better, although not quite as good as it should be. 4) The mini is my only car, so it drives me to and from work (approx 30 mins each way) everyday and longer distances at the weekends so the battery should get ample charge. 5) The starter usually starts the engine first time, unless the battery is getting flat and it takes a few attempts to crank the engine over. 6) The battery has to be charged once a week. I rotate the two batteries I now own but I like the suggestion for solar panels - this is the UK though; land of darkness and rain!!! 7) The AA man checked the positive cable running under the car. I assume he checked it for chafing which may cause a short. He spiked his multimeter (!) into the cable in order to test the charging of the battery in autumn (see 3 above). 8) The volt meter on the dash used to fluctuate 'normally' between about 12V and 13.8, but nowadays it tends to behave in a sporadic fashion, maxing at 14V and going down to as low as 8V. It is not fluctuating all the time though. Applying the brakes tends to reduce the voltage. The headlights do not appear to be any dimmer, nor does the heater tone change when the wipers are going (like in my old 1275 GT ;-) ). 9) When the alternator was checked, it was physicaly removed from the car and found to be in working order. Are the diodes associated with the alternator part of it or are they elsewhere in the loom?? If they are not attached I don't know if they may be faulty.. 10) The battery is firmly braced and is covered by the proper battery cover and its associated elastic band! 11) I haven't tried checking the current draw at the battery terminals with everything turned off as I assumed this was done when I first took the car to the garage. I will check this. Presumably the rover alarm / immobiliser will draw some current when the car is parked. There must be something else to try Please help! Al. > OK here's the problem... > [quoted text clipped - 18 lines] > > Al. I had a similar problem. I got the alternator and the entire ignition system checked out by an auto-electrician - all were reading perfectly and yet I was still having the same problems even after getting a new battery (always try the cheaper options first). In the end I replaced the alternator with a re-manufactured one and hey presto all was working fine - must have been an intermittent fault with the alternator. Anyway, just a suggestion. Regards, Stu. Guys, Thanks for your detailed replies. In response to your suggestions: 1) I have already attached an additional earth strap between the engine and chassis although this has had no effect. 2) The earth strap connecting the battery to the boot floor has been sanded clean, as has the boot floor where it joins. 3) When the battery was near flat, the reading at the battery (with the engine running) was below 12v, i.e. not enough to charge the battery; yet it was nearer 14v at the alternator end. On this occasion it was a summers day and the car had been running for a good period of time some 15 mins earlier. More recently, in late autumn, the battery had been recently charged and the reading at the battery end better, although not quite as good as it should be. 4) The mini is my only car, so it drives me to and from work (approx 30 mins each way) everyday and longer distances at the weekends so the battery should get ample charge. 5) The starter usually starts the engine first time, unless the battery is getting flat and it takes a few attempts to crank the engine over. 6) The battery has to be charged once a week. I rotate the two batteries I now own but I like the suggestion for solar panels - this is the UK though; land of darkness and rain!!! 7) The AA man checked the positive cable running under the car. I assume he checked it for chafing which may cause a short. He spiked his multimeter (!) into the cable in order to test the charging of the battery in autumn (see 3 above). 8) The volt meter on the dash used to fluctuate 'normally' between about 12V and 13.8, but nowadays it tends to behave in a sporadic fashion, maxing at 14V and going down to as low as 8V. It is not fluctuating all the time though. Applying the brakes tends to reduce the voltage. The headlights do not appear to be any dimmer, nor does the heater tone change when the wipers are going (like in my old 1275 GT ;-) ). 9) When the alternator was checked, it was physicaly removed from the car and found to be in working order. Are the diodes associated with the alternator part of it or are they elsewhere in the loom?? If they are not attached I don't know if they may be faulty.. 10) The battery is firmly braced and is covered by the proper battery cover and its associated elastic band! 11) I haven't tried checking the current draw at the battery terminals with everything turned off as I assumed this was done when I first took the car to the garage. I will check this. Presumably the rover alarm / immobiliser will draw some current when the car is parked. There must be something else to try Please help! Al. "Alistair Goldthorpe" <alistair@coppins.karoo.co.uk> wrote in message news:EhKdncnev_peRkmiXTWcmA@karoo.co.uk... > OK here's the problem... > > The battery started to go flat after a week or so of daily use. I replaced > the battery but it continued to happen. I then took the car to my local > garage and they checked the obvious earth straps, etc and had the alternator > tested. The alternator was fine i.e. it was kicking out enough to charge > the battery. The garage suggested trying an auto electrician. The > autoelectrician checked over the car and came to the conclusion that it was > to do with the brushes in the starter motor (this is because the car seemed > harder to start if the enginge was still warm). The car would not start at > all a few days after this and the AA man said it would unlikely be to do > with the sarter motor but sounded more like a bad earth which was preventing > the charge from the alternator from reaching the battery in the boot. A bad > earth seems likely as the volt meter on the dashboard tends to fluctuate > whilst driving. I have tried myself to locate the earth points and have [quoted text clipped - 5 lines] > > Al. > Thanks for your detailed replies. In response to your suggestions: ... > 3) When the battery was near flat, the reading at the battery (with the > engine running) was below 12v, i.e. not enough to charge the battery; yet it > was nearer 14v at the alternator end. There's your problem. > On this occasion it was a summers day > and the car had been running for a good period of time some 15 mins earlier. > More recently, in late autumn, the battery had been recently charged and the > reading at the battery end better, although not quite as good as it should > be. Nonetheless, you've got far too much voltage drop between the battery and the alternator. You need to find out why... The alternator itself is fine, which you already knew. > 8) The volt meter on the dash used to fluctuate 'normally' between about 12V > and 13.8, but nowadays it tends to behave in a sporadic fashion, maxing at > 14V and going down to as low as 8V. You should only ever see as low as 8V when the starter is engaged! > It is not fluctuating all the time though. I reckon you've got a damaged wire or a corroded connection somewhere between the alternator, the ignition switch and the battery. > Applying the brakes tends to reduce the voltage. Thats just the load for the brake lights coming on. Normally it drops momentarily then returns to normal. It may require a little rev of the motor to supply enough current to get back to 13.8V. > The headlights do not appear to be any dimmer, nor does the heater tone change > when the wipers are going (like in my old 1275 GT ;-) ). I reckon the front end is getting the full benefit of the 13.8V from the alternator but for some reason the battery is not. One obvious possibility is corroded battery terminals, either at the battery or where the lead enters the terminal itself. Another is that the battery is just ancient and worn out, but if I recall correctly, you've already tried a new battery and flattened it too? > 9) When the alternator was checked, it was physicaly removed from the car > and found to be in working order. No surprise there. > Are the diodes associated with the alternator part of it or are they elsewhere in > the loom?? They're internal. Your alternator is fine. > 10) The battery is firmly braced and is covered by the proper battery cover > and its associated elastic band! 8-) > 11) I haven't tried checking the current draw at the battery terminals with > everything turned off as I assumed this was done when I first took the car > to the garage. I will check this. Presumably the rover alarm / immobiliser > will draw some current when the car is parked. Do check this. > There must be something else to try Please help! The main battery positive lead is a heavy starter cable which runs from the battery to the battery to the starter solenoid in the engine bay. Any corrosion of either end, particularly at the battery, will slow cranking (looks like a flat battery) as well as reducing proper charging. Thats where my money says the problem is. From the starter solenoid, a lighter wire, brown in colour should go to the alternator. If either end of that is corroded that will also cause charging problems. Check the charge voltage at the solenoid + terminal to determine which side of it the problem is. Thanks - I'm gonna try out the suggestions! Al. > > Thanks for your detailed replies. In response to your suggestions: > ... [quoted text clipped - 79 lines] > Check the charge voltage at the solenoid + terminal to determine which > side of it the problem is. |
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