Dreaded Red Battery Light.......

Hi Everyone,

Today I noticed the battery dashboard light flickering whilst driving my Peugeot Boxer Auto sleeper 2004.
After parking up and leaving it for a few hours I tested the battery with a multimeter and it was 12.58 with engine off and 12.20 with engine on.
The red battery light stays on now when the engine is started.
To complicate things I had a problem with the large earth lead connected to the gearbox around 2 years ago which resulted in sparks flying when trying to start.  I replaced that and have had no starting problems since. I'm hoping this lead isn't the problem with 'charging'?
There is approx 45,000 miles on the clock so I would have thought it wouldn't be the alternator?
I also replaced the battery approx 2 years ago.
I'm not great with motors etc but will have a go, providing I feel it's within my capabilities!
If it is the alternator......what is the definite way of telling?........... how much would I expect to pay to have one fitted?
Also, I'm guessing it's not advisable to use the van or would I get a few local trips out of it before the battery goes flat?
This is my only vehicle so I need to get this sorted a.a.s.p so any help / advice is greatly received!!

You have already proved the battery is not being charged effectively, 12.58v off, 12.20 on.

Is the alternator belt tight enough? If your earth strap was faulty it would probably not start anyway.

Thanks for that,

The belt seems tight and there is no 'squealing' noises etc.

If it is the alternator which I'm presuming it is, then to go at 45,000 miles.......!!

With  the engine running you should be getting around 14.2 volts from the alternator. There is usually a regulator built on to the alternator and you might get away with replacing that.

go to a reputable battery factor and he will check everything for you.a factor not a garage who will just sell you a battery . g

Check all connections first. Then hook a multi meter onto the battery with the engine running. It should read circa 14 volts. If it doesn't this points to the alternator. If it does its likely the battery.

Charliefarlie wrote:Check all connections first. Then hook a multi meter onto the battery with the engine running. It should read circa 14 volts. If it doesn't this points to the alternator. If it does its likely the battery.

Don't know how to use a multimeter then pop into LIDL they do a simple charge tester similar to a multi-meter but has leds telling you charge issues in a simple form. 

Hi

I had a car in the 1970s which was intermitted not charging. So had the Regulator replaced and was still not charging. Then I had the Alternator replaced still the same. Anyway my Dad looked at it took the terminal wires off peeled back the insulation cover on the connecters which was all green and corroded inside. But to look at the connections they looked clean on the outside. I felt a right idiot after spending £88.00.  

Hi Troika

            As you have had previous earth prob's it might be worth checking all connections to earth and chassis cleaning them up and coating in grease or Vaseline after being reconnected, give the same treatment to the positive connections also.
If the alternator/regulator is OK you should as previously stated get approx' 14 volts on the DC volts scale on your meter with the engine running if not it points to possible alternator/regulator failure. 

Cheers John

Thanks everyone for your comments and advice.
I had a look at connections and they all seem clean / tight etc.
It's def looking like the alternator is the problem according to the multimeter readings.
I'm just surprised it can fail with pretty low mileage.....45,000.
What sort of bill should I be expecting to pay for a new one inc fitting?

Charliefarlie wrote:Check all connections first. Then hook a multi meter onto the battery with the engine running. It should read circa 14 volts. If it doesn't this points to the alternator. If it does its likely the battery.

I'm just getting a reading of 12.20  with engine running so looks like it's the alternator. I could understand if it had done major mileage but 45,000!

Hello.

Hope this helps a little, first clean your terminals and make sure all connections are clean and tight, start your engine and test the battery (should read 14 volts or over) if this is not the case then the alternator is suspect. on the reverse of the alternator there is usally a small cap/cover of some kind that hides small bushes (carbon) these may be worn or have a poor conntact. I dont know what type of alternator you have but take a look as it may only be this small part you need and not the whole unit. it is very easy to replace them, only pop it out and new one in. Also check your battery ampage if you can, battery will take a charge but it wont hold if ampage is not maintained. best of luck  

Before you go and buy a new alternator just do a couple of things:

1: Check that the alternator is connected to the battery! It definitely won't work if it isn't. There should be a fat-ish cable to the back of the alternator - with the ignition off or on it should be at the same voltage as the battery. If it isn't then follow it and find the break. Not an uncommon problem.

2: Some vehicles have a switched feed to the alternator - if the fuse blows then that can stop it working. Have a look at the fuses.

I would be surprised if the alternator has failed at 45k. It's possible that the free-wheel pulley (if it's got one) has failed, but normally they make a racket first.

It won't be the earth if it starts OK - the starter takes far more current than the alternator supplies.

Hi
I had the flashing battery light last year when returning from a trip.
Did all the usual checks and didnt initially suspect the alternator itself as the van had only done about 38,000 (2003 boxer)
However, after taking it to a local starter/alternator firm, they confirmed that the 'slip ring' on the alternator was badly worn.  The cause was a very tiny diesel leak from the pump that had found its way along a lead and into the alternator. Apparently, a strange electro-chemical reaction takes place that erodes the copper !

Anyway, new alternator fitted and problem solved.  Cost was around £100 fitted from memory, so not too bad.

It was the cost of removing and repairing the diesel pump that made my eyes water

Well, you learn something every day. I can honestly say I've never heard of anything like it, but could certainly be the cause of the OP's problem.

Be grateful for small mercies op! The "dreaded red battery light" is a breeze compared to having the engine management light flick on which last year cost me an aborted trip to the Baltics and relieved me of £650!

Thanks as always for your replies!

Here's an update..............I've had a new alternator fitted and I tested it with a multimeter etc and now getting 14v plus when engine being revved which I wasn't before (11v) so that's great but....................the red battery light is still on!!!
It appears I did have a faulty alternator but any ideas what is causing the red light to stay on?

In all my years in the motor industry (40yrs or more)including motor racing, manufacturing and building prototypes, servicing, curcuit and proving ground test and development work, crash testing at MIRA etc I have never heard of a "slip ring " on an alternator. An alternator belt slipping, yes but a slip ring. Sounds like a bucket of steam or a sky hook to me.

biffobear wrote:In all my years in the motor industry (40yrs or more)including motor racing, manufacturing and building prototypes, servicing, curcuit and proving ground test and development  work, crash testing at MIRA etc I have never heard of a "slip ring " on an alternator. An alternator belt slipping, yes but a slip ring. Sounds like a bucket of steam or a sky hook to me.

?? [You must be registered and logged in to see this link.]

biffobear wrote:In all my years in the motor industry (40yrs or more)including motor racing, manufacturing and building prototypes, servicing, curcuit and proving ground test and development  work, crash testing at MIRA etc I have never heard of a "slip ring " on an alternator. An alternator belt slipping, yes but a slip ring. Sounds like a bucket of steam or a sky hook to me.

In all your 40 years, you cannot have stripped many alternators down then?

Frank

Hi  

I've repaired several of my own alternators over the years.  Seems to be the diodes that fail more often than not but I always replaced the slip rings and brushes at the same time because they looked knackered even if they were working and it only cost a few quid extra.

The thing that strikes me in the current thread is if the garage opened up the alternator to the point that they could see the slip rings why didn't they replace them instead of the whole alternator?

troikafloyd wrote:It appears I did have a faulty alternator but any ideas what is causing the red light to stay on?

Difficult so say for  sure but it sounds as if the lamp is connected to the wrong point, are the alternator connections identical?  The lamp should be connected to a dedicated connection on the alternator.  Whatever, if you've paid garage to replace it then take it back to them and get them to fix it.

Brod.
P.S. A knowledgeable old member returns, nice to see you back Frank.

brodco wrote:Hi  

I've repaired several of my own alternators over the years.  Seems to be the diodes that fail more often than not but I always replaced the slip rings and brushes at the same time because they looked knackered even if they were working and it only cost a few quid extra.

The thing that strikes me in the current thread is if the garage opened up the alternator to the point that they could see the slip rings why didn't they replace them instead of the whole alternator?

Brod.
P.S. A knowledgeable old member returns, nice to see you back Frank.

BIB.....time, plus its a lot easier for a Garage to order a new one and slap that on than faff around repairing. Some Garages like the one i use will outsource repairs such as alternator strip/rebuild to local auto electricians.

Even during my years of 'messing around' with cars, if an alternator or dynamo was playing up it was easier to go to a local breaker and pick one up which he'd charge around a fiver or couple of quid if you took it off yourself, or of course you could take your old one to an auto-electrics place doing service exchange units though that would cost you more.

Your right I haven't so what is a slip ring? What does it do? & has it ever been called something else? Please enlighten

troikafloyd wrote: Thanks as always for your replies!

Here's an update..............I've had a new alternator fitted and I tested it with a multimeter etc and now getting 14v plus when engine being revved which I wasn't before (11v) so that's great but....................the red battery light is still on!!!
It appears I did have a faulty alternator but any ideas what is causing the red light to stay on?

To check the red light wiring & bulb. Engine switched off. Remove the small wire from the back of the alternator . This being the wire that
feeds 12 volt power to the field windings. With this wire know now disconnected to anything, Switch on the ign the, the red light now should Not be lit. Now with the ign still switched on earth the wire, the red light should now come on. This test proves that the bulb holder & the wiring from your red light is Not faulty.

Carry out this check first before you guess other possible faults.

Gren.

biffobear wrote:Your right I haven't so what is a slip ring? What does it do? & has it ever been called something else? Please enlighten

Slip rings are what the carbon brushes bear on to 'excite' the field winding and control the output of the alternator. Don't think that they've ever been called anything else.
Google 'alternator slip rings'

HTH
Frank