6 replies to this topic

[mini-mad-mark]

Hi All,

Took the mini out yesterday and noted that the Voltmeter was only showing 12v when typically it had been a solid 14v+ when the engine was running

 

When the engine isn't running I only have 11.5v now - unfortunately before this issue I didn't really notice what the voltage was, without the engine running but would have expected 12v or maybe a shade more?

 

I changed the alternator  (as I happened to have a spare one) but made no difference - the IGN warning light is NOT illuminated (with engine running) so kind of suggests the alternator(s) is/are OK?

 

Battery is more than 3 years old - I have religiously disconnected it after use as not able to trickle charge it where the car is situated (and also as a (limited) anti theft measure)  - of course the car wasn't used hardly at all during the lockdown but since the middle of last year been used at least once a week for at least half an hour I would say

 

It needed a jump start on the first start up after lockdown but been fine, started first time every time since then  - and did earlier on this evening

 

Unfortunately my other mini is at the body shop for some rust-oration of the boot floor so I don't have a spare battery to hand to try at the moment although that battery has a similar history.....

 

So as per the title do we think Alternator, Battery or some other Charging issue I may not have considered (or am too dumb to know!)

 

PS I have an Ammeter fitted also and that is not showing any discharge (until things are switched on of course)

 

Thanks for your comments/suggestions

[nicklouse]

All dash lights are original?

[timmy850]

Is the ignition lamp turning on with the key on and engine off? Is the bulb still the usual incandescent bulb (not an LED)

If you take the battery to a decent auto parts shop they should be able to use the analyser to test it to see if it’s functioning properly

It could also be something simple like a slipping fan belt

[Earwax]

Add another C to check as well

 

Connections - especially battery earth , Starter motor power and engine earth strap - check for heat also.

 

have engine revving above two-three thous rpm and check voltage at battery across the posts-  should go up to 14.2 ish( this just double checks if your voltmeter is indeed reading correctly ) -   if not trigger wire/bulb etc as above 

[mini13]

Sounds like an iffy battery to me,

 

Car batterys are pretty fickle when it comes to maintainence, 2 things they really dont like is being left to discharge ( if they go below a certain percentage charge ( somthing like 10v iirc) they will loose a large proportion of their capacity, and being cold.

 

as it needed a jump that puts it firmly in the having lost a load of capacity catogory.

[sonscar]

Turn on the head lamps and operate the starter.Do they almost go out?Battery dead failing under load,I find measuring the voltage across the battery to be misleading unless it is loaded.That said the alternator should be showing charging above 13 volts.Steve..

[mini-mad-mark]

Thanks for all the responses.

 

I probably should have waited to post the question yesterday as I thought I'd have another go this evening being less cheesed off -  my original thought was correct - Alternator 

 

Fetched the battery from the other mini at the body shop earlier to try that but made no difference

 

I had another spare alternator in the garage so thought I might as well try that this evening for the sake of 15 minutes and "bingo" it worked - back to 14v+

 

Just my luck that the first spare alternator was duff ??      I was sure it came from a running driving car - lucky I had a third one which is working.

 

Cheers again