43 replies to this topic

[blackbelt1990]

Remember that the battery type supplied with the car new should be sufficient to run it, if it isn't, don't use a bigger battery to mask a potential problem with the alternator. Do the checks as suggested.

Just saying. I've got a bigger battery anyway lol

[Mrstars11]

Also the difference is, it didn't have a heated rear window new, or so many speakers and a stereo to run, i also have angel eye headlights. I don't know how these are in comparison to regular lights but either way a few things are using more power than would have when the car was new.....I'm guessing this is why people upgrade to bigger batteries.

I know my alternator works, because the AA man checked it and told me it was fine when I broke down after collecting the car. And a friend of mine checked it out for me when we fitted the new battery.

[Italianjob]

Could be an intermittent alternator problem? ive had one of these! pain in the arse! took six garages to work it out. Everytime it came back as 'Working perfectly' or 'its your battery' by that stage we had 4 new batteries. Worked eveytime they were testing it until one garage had it on test for most of the day. The AA like every road side company will test for a few minutes and i wouldnt always go with what they say.

[dsgoody]

Halfords also list the HB053 battery for MPi Minis. It's not the battery that's the problem, it's the alternator. KenrowCoooers guide says the ideal charging voltage is between 14.2 V to 14.5 V. As you aren't hitting that in any of your tests I'd say it's the alternator.

Dave.

[Mrstars11]

im not too sure what im hitting exactly. i know my pal tested it when i fitted the new battery and he said it was fine. 

 

ive been on my own since so its hard to see what its showing at the battery when the revs are on, as i cant be in both places at once. 

next time i have it out the garage ill try it with a brick on the gas pedal. so i can see exactly whats coming out the battery with the alternator powering it. 

 

the reason ive started asking and started to debate upgrading the battery is because the other day i had to run a quick errand, took the mini, id been driving for maybe 5 mins, i switched my stereo on, that was all, no lights, heater, heated window etc. and i got to my destination all ok, pulled up, switched the engine off, went and did my errands was maybe 5 mins. 

got back to the car, and it struggled to fire up, it was doing the click click click noise, the same as when i broke down from picking it up when the battery was no good. 

after a couple of clicks and a bit of revs it did fire up and start. but i didnt have the radio on. thats the only time ive used anything electrical while driving. 

 

i havent been out in the dark, listened to my radio, or used the heater. all for fear of it not starting up properly. I was unsure even if the alternator is working, if the stereo in the car is using up more power than the battery even when charged, can give. 

its only a sony head unit and there are 2 speakers in the dash, and 2 speakers in the back. so nothing massive. no big ice with subs and amps and that. 

 

i will do a check on the alternator to see what that charging level is at, if it is hitting between 14.2 and 14.5 i will replace the battery, if nothing but for a little peace of mind to be honest. 

[Yoda]

Make sure if it has not already been said, that your battery connections are clean and tight. you may see full alternator voltage on the battery terminal clamp, but a bad connection between the battery post and clamp will not allow it to actually charge the battery fully. So, do the Kernowcooper alternator testing AFTER making sure all battery connections and earths are confirmed to be good.

[blackbelt1990]

You don't need to keep the revs on to test the alternator. Once the car has reved up once or the red light is out, the alternator should be charging it.

[blackbelt1990]

So don't use a brick!

[Alex_B]

You can also position the multimeter somewhere that is visible, I either put it on the lip of the boot seal facing in the car connected to the battery or if it wont stay there then on the scuttle panel resting on a wiper blade connected to the starter solenoid, that way I can see revs and dash lights whilst seeing voltage readouts 

[Mrstars11]

right, 

 

plenty more info here to look into. thanks guys. 

[Mrstars11]

actually blackbelt,

 

if what your saying is true, i dont think my alternator is working, because once ive started the car and drove for a little while that would mean the alternator is charging the battery,so if i drove round the block a few times then i parked it up on the drive.  which if im not using any battery power so no lights on, no stereo etc, the battery level should hold steady or increase. (am i understanding this correctly?)

 

because now if i do this, the voltage on the battery drops and the engine cuts out, unless i keep revs on it. like when im sat at traffic lights even, if im waiting a couple minutes, the voltmeter needle drops fom like 13.5/14 down to about 12/11.5. now even if the volt meter is reading wrong, its still dropping.

and i have to rev the engine to get that needle to start climbing again.

 

so if the alternator should charge after a few revs then the needle should hold steady at traffic lights right??? unless im using power. which at the moment im not.

[blackbelt1990]

Yepp, you're right. Have you checked that your fan belt is tight enough?

I'd never discourage anyone from upgrading their battery, but find your problem aswell :)

[Yoda]

Right. lets start at the begining.

 

When you turn on the ignition, do you have the red light on the dash which goes out when the engine is started? you should see one red lamp and one orange lamp. The important one right now is the red lamp. If this is not on when ignition is switched on, then it may be either the bulb has blown, the connection for it at the alternator is badly connected or corroded or the wiring is open circuit that feeds the bulb. any of these and the alternator will not work. The easiest part of this to check is the plug on the back of the alternator. make sure that the terminals in the plug are nice and clean and that the small brown/yellow wire is connected. Next thing to check is that the bulb has not blown. If it has, just replace it If after these checks you still have no red lamp working, then we can look further into the wiring.

 

If the lamp is working correcly, ie, comes on when you turn the key to "on" and goes out when you start the engine, then the problem is elsewhere.

 

If the red light comes on and does not go out when you start the engine, then it is most likely that the alternator is faulty.

 

If the red light does what it is supposed to, then it may just be either a very bad earth somewhere, poor battery connections. or loose fan belt

 

This should give you something to do for the rest of today and then come back with your results.

[Badboytunes]

I fitted a Pug 306 diesel battery. I think its an 086, but not 100%. its been perfect since, including using heater, 4 extra lamps and wipers.....

[Yoda]

As has been stated, the battery recommended for the car should more than cope with any standard fitted electrical item on the mini. this includes rear screen heater, spotlamps etc as all have been fitted to various standard models at some time. The electrical supply for the car electrical system is provided mainly by the alternator once the engine is running. the alternator supplies power to all circuits and also charges the battery to top it up once used for starting. This is over simplified to explain to you that the battery should be more than capable of powering all circuits on the car. so if the battery is draining while driving, then it usually means you are drawing most of the required power only from the battery and the alternator is not taking over and also topping the battery back up to full charge.

 

I hope this helps take away the confusion and helps you understand what should be happening so that you can find out which part of the system is faulty

Edited by Yoda, 26 June 2014 - 04:53 PM.