Mini Mad
Posted 15 July 2013 - 12:51 PM
you won't find the current drain with the engine running
test for the drain with the engine switched off just like it will be over night
Wouldn't that just be the difference between these two? :
- Battery out the car - 13.34v
- Battery in the car, car off - 13.31v
Crazy About Mini's
Posted 15 July 2013 - 12:57 PM
No to check battery drain you have to put the voltemeter set to amp and put the terminals in series with the negative battery lead, as per bungles post.
Such a test have to be carried with engine switched off obviousely.
Anyway 12.6V at idle is too low, is your red ignition light coming on?
Mini Mad
Posted 15 July 2013 - 12:59 PM
No to check battery drain you have to put the voltemeter set to amp and put the terminals in series with the negative battery lead, as per bungles post.
Such a test have to be carried with engine switched off obviousely.
Anyway 12.6V at idle is too low, is your red ignition light coming on?
Ok, I get you.
Yes it does seem too low - and no the red ignition light isn't coming on when idling (it is working though as it flashes up when you first turn key in ignition).
Have ordered a new alternator just to eliminate that...
Camshaft & Stage Two Head
Posted 15 July 2013 - 01:01 PM
Looks to me like no charge from alternator, but before rushing out to spend ££££££'s on a new one, i think you should tell us about your red dash light and what it is doing. I may be old and a bit blind, but i am sure, apart from Kernow coopers article that nobody has mentioned it. Do you have a red light glowing on the dash when you turn the key to the run position? you should have one orange and one red. If so they should both be glowing but it is the red one we are interested in. If it glows with ignition on, does it then go out when you start the engine? If you have no red light on at all, then you have either a blown bulb, a broken connection between it and the alternator or lastly the alternator has failed and needs testing or replacing.
Blown bulb = replace it.
bad connection= repair it.
alternator busted=fix or replace it.
Go read Kernow Coopers article again and do ALL of the tests if you have not already done so. Hopefully it will be the bulb blown and you wont have to go any further with the tests.
An easy way to test the alternator is busted or not, is to use a smart probe and inject 12V to the back of the plug (small wire, usually brown with yellow trace) and you will hear the engine slow down ever so slightly. Its an old school quick test that was done before any of this modern gear like Moulting meters, nipple clamp meters and the like were available.
I am just old and freely admit it.
Old school all the way guys! Yay.
Edited by Yoda, 16 July 2013 - 05:29 AM.
Camshaft & Stage Two Head
Posted 15 July 2013 - 01:03 PM
Oops, last post i missed. back to sleep I shall go.
Edited by Yoda, 16 July 2013 - 10:47 AM.
Mini Mad
Posted 15 July 2013 - 01:04 PM
Looks to me like no charge from alternator, but before rushing out to spend ££££££'s on a new one, i think you should tell us about your red dash light and what it is doing. I may be old and a bit blind, but i am sure, apart from Kernow coopers article that nobody has mentioned it. Do you have a red light glowing on the dash when you turn the key to the run position? you should have one orange and one red. If so they should both be glowing but it is the red one we are interested in. If it glows with ignition on, does it then go out when you start the engine? If you have no red light on at all, then you have either a blown bulb, a broken connection between it and the alternator or lastly the alternator has failed and needs testing or replacing.
Blown bulb = replace it.
bad connection= repair it.
alternator busted=fix or replace it.
Go read Kernow Coopers article again and do ALL of the tests if you have not already done so. Hopefully it will be the bulb blown and you wont have to go any further with the tests.
Yepp, I've gone through the list.. and checked the bulb. It does turn on when I turn the key, and goes out when I start the engine. So the bulb is not blown.
I really reckon it's the alternator, it hasn't been re-charging well over past 6 months and has got progressively worse. It's a new battery too.
Already spent the money on an alternator from Mini Spares so we shall see..!!
Camshaft & Stage Two Head
Posted 15 July 2013 - 11:59 PM
as above check the car is charging and also switch you multi meter to amps and check for a current drain
ammeters must be fitter in series , so remove a lead and fit the meter between the lead and the battery
Yes, but please be careful doing that - to be honest a multimeter in series on car electrics isn't a good idea - the alternator alone is more than capable of taking out the 10A fuse on the current range. Amps go both ways and while the car is running, the battery will be being charged under most circumstances.
You really can't add a current loop to a car that's running, it means disconnecting the battery while the car is running and inserting the meter in series You'd need to ensure the alternator had a bit of load on it first before attempting this - for someone not completely confident with electrical systems and in particular, low voltage high current systems, better not to do this.
you won't find the current drain with the engine running
test for the drain with the engine switched off just like it will be over night
I know that and you know that, but my post was meant to warn the OP about the possible dangers of sticking an ammeter in series with a car battery.
Camshaft & Stage Two Head
Posted 16 July 2013 - 12:12 AM
An easy way to test the alternator is busted or not, is to use a smart probe and inject 12V to the back of the plug (small wire, usually brown with yellow trace) and you will hear the engine slow down ever so slightly. Its an old school quick test that was done before any of this modern gear like Moulting meters, nipple clamp meters and the like were available.
Old shool all the way guys! Yay.
Interested to hear the science behind this one. Brown with a yellow trace is the "IND" terminal and it will have 12V on it at all times unless the bulb has failed - it only provides the indicator feedback and the initial excitation voltage once the alternator is up and running it won't do anything as these alternators are machine sensing not battery sensing.
The only way putting a 12V feed on to that wire will cause anything to happen is if the IND wire has no voltage on it - bulb has filed or fuse has blown etc - even then the chances of hearing the revs drop are slim - you'd need a big current draw - flat battery etc to cause that.
Yes, some of the "old school" tricks have a lot of merit - but something like this could have someone on a wild goose chase for ages thinking they have found a problem that they haven't.
Camshaft & Stage Two Head
Posted 16 July 2013 - 06:36 AM
No need for science, The force is within me. Just remove the bulb from your dash and you can expect the alternator not to charge due to no excitement. inject 12v to the small terminal and excitement will happen and the alternator will load the engine slightly.
I am not going to enter into an argument here, but you supplied enough science in your own comment.
Brown with a yellow trace is the "IND" terminal and it will have 12V on it at all times unless the bulb has failed - it only provides the indicator feedback and the initial excitation voltage
Mini Mad
Posted 16 July 2013 - 08:56 AM
Ok, so it seems on closer inspection, this may be something to do with the issue...!
Connector plug and connections pretty much disintegrated. With a bit of jiggling around the voltage jumped back up to around 13.8 - 14.2 when car running at idle.
New plug and alternator ordered. Thank you all for help so far!! I hate electrics, so I wasn't going to start sticking meters in series lol.
Camshaft & Stage Two Head
Posted 16 July 2013 - 09:09 AM
So, you did not run through Kernow Coopers article then. One of the first things you were asked to do was remove the plug from the alternator. Had you done this, i suspect you may have found the problem sooner 
Never mind, at least you have justified a new alternator, even though yours is repairable. 
Good luck, and make sure you keep the contacts nice and clean and add some battery terminal paste to them to prevent this happening again.
Mini Mad
Posted 16 July 2013 - 10:01 AM
Yes sir, sorry sir!
I guess I missed the obvious first thing, but last night was the first time I had time to properly check everything over! I'd just whipped the battery out to charge it, and run a quick voltage test in the morning before I headed out to work.
A couple of the contacts in the alternator look a little broken, so would rather replace now and do it properly.
Thanks!!
Sparkie
Posted 16 July 2013 - 10:09 AM
The contacts burnt away are part of the Rectifier which is available so if you get one of those and replace it you could have a working spare, there not expensive either.
Mini Mad
Posted 16 July 2013 - 10:24 AM
Ah I see what you mean.. hmm well I've got a new alternator on the way, one it's all replaced maybe I'll see about replacing the rectifier in the old one :)
Easy job to do?
Camshaft & Stage Two Head
Posted 16 July 2013 - 11:12 AM
Hey look! I found a really interesting description of how an alternator works, NOT. Prepare to be bored for 15 minutes.
This guy is a real gem, i must find more of his explanations.
Hope this is scientific enough for you Captain mainwaring!
Edited by Yoda, 16 July 2013 - 11:12 AM.
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