Electrical issues

Toby_HDi · Unread post by **Toby_HDi** » 11 Jul 2009, 19:35

My apologies if I should not be posting this on here and if I shouldn't, please remove. However, I seem to be getting nowhere with a couple of Vauxhall forums and thought I may pick the brains of some of you here.

My Omega has a flat battery everytime I go to it. Now I've measured alternator output and it stays within 13-14v even with accessories on. Static charge is usually 10v after being left for a few mins. I've tried to measure any discharge and there appears to be none (which is strange as I thought even with engine off there should be a small amount drawn for alarm gubbins etc.

I tried another known good battery and I got same readings. Now other than a loose aux belt or a duff alternator (which it doesn't appear to be) what could be causing this? Are there any other tests I can carry out?

I believe this has something to do with an issue I'm having with a flickering speedo (flickering on zero) and a dead rev counter.

Again, apologies if this shouldn't be here, am at a loss with it

Please remove if felt necessary.

Thanks

admiral51 · Unread post by **admiral51** » 11 Jul 2009, 21:50

Hi Toby
Sorry i cant really help you with the problems you are having electrics are not my strong point

I dont see any reason why it should be removed as its proof posative that its not only Citroens that have electrical gremlins

i can only offer these thoughts on your problem
I was led to believe that the output from the alternator should be a little higher than you are getting somewhere in the region of 14.5V
Assuming (Guessing really) that the speedo/rev counter is electronically driven then would a short to earth give you a zero reading and in effect shorting the battery to earth

Sorry to hear you are not having a joy with the Vauxhall forums from previous experience they seemed to be quite good but have not frequented them for a couple of years

Colin

Toby_HDi · Unread post by **Toby_HDi** » 11 Jul 2009, 22:22

Thanks Colin.

When it stops raining I need to check the aux belt, I guess its possible that the belt may be a tad slack. I don't think it is the problem though, not unless the alternator has very suddenly decided to die. I was led to believe they do so gradually.

Its not strictly reading zero. It sits at zero but it flickers a small amount (barely noticeable at a glance), the rev counter does just sit there though. Strange thing is, temp and fuel gauges are fine and the odometer is still working.

Just been out to car now and it's flat again. Putting a dampener on V6 RWD ownership

admiral51 · Unread post by **admiral51** » 11 Jul 2009, 22:34

Hi Toby

I know its probably a long shot but as you say both batteries are giving the same readings and i presume both going flat could it be that the alternator is charging whilst running albeit a little lower than normal but when the engine is switched off its actually draining the battery.

I know its a rare occurance but im aware of atleast 2 people that have had this problem on different makes of car.I cant remember what the actual reason the alternator does this but as its the source of recharging the battery it wont take long to drain it if there is an internal fault.

Hopefully someone with more knowledge than me(must be thousands

) will be along to shoot me down in flames or tell me im not totally mad

Colin

wheeler · Unread post by **wheeler** » 11 Jul 2009, 22:56

admiral51 wrote: I know its a rare occurance but im aware of atleast 2 people that have had this problem on different makes of car.

Was'nt a VW/audi/skoda by any chance was it ? maybe even a rover ?(sorry for swearing). VAG cars & rovers seem to be quite common for the alternators causing a discharge. You say there is no drain on the battery ? Sorry if im teaching you to suck eggs here but are you checking it properly ? are the leads on the multimeter set in the right position ? are you putting the meter in series with one of the battery leads ? has the multimeter fuse blown for the ammeter ? Usually caused by people trying to start the car with the meter in place or putting it across a battery & forgetting to set the leads back to volts. Confirm the meter is actually working properly by setting it up then switching the interior light on & you should have a draw of around 0.5 amps. If you can get access to an amp clamp this is ideal for checking charging/drain faults. When checking the charging do it under load, turn on lights, hrw, blowers then rev it to 2000 rpm, over 13.2v is acceptable.

Toby_HDi · Unread post by **Toby_HDi** » 11 Jul 2009, 23:01

Meter is brand new, fuse is fine. Trying to check current in series,

Both batteries are giving the same reading when on the car and engine running. Just that my one reads 10v static and the other one is healthier at 13v.

Have checked charging under load and it never dips below 13.2v

To all intents and purposes everything seems fine except that my battery reads 10v

wheeler · Unread post by **wheeler** » 12 Jul 2009, 00:45

Have you left the new battery in overnight ? is it flat in the morning ?

admiral51 · Unread post by **admiral51** » 12 Jul 2009, 01:52

Having had a little time to reflect on what i posted earlier i think ive remembered what the problem with the alternator was

To all intents and purposes when running the alternators were showing a healthy charge output approx 14V and when the car was switched off no unusal current drain was visible.

I believe that the problem was that whilst running and charging the battery the alternator was in fact draining the battery due to a short/fault internally by more than what it could recharge.The end result was that the car was effectively being run off the alternator and once switched off would not restart

maybe even a rover ?(sorry for swearing).

How uncanny one was a metro

Colin

Toby_HDi · Unread post by **Toby_HDi** » 12 Jul 2009, 10:44

Wheeler, I only have to leave it 10mins or less and it won't restart.

That sounds very likely Colin, shame the alternator is not easily switched for one I can use for testing purposes, I wonder how this can be tested for in situ?

DickieG · Unread post by **DickieG** » 12 Jul 2009, 10:48

Toby_HDi wrote:That sounds very likely Colin, shame the alternator is not easily switched for one I can use for testing purposes, I wonder how this can be tested for in situ?

As soon as you stop the engine disconnect the alternator for a few hours then reconnect and check the battery voltage/see if it starts having reconnected the alternator.

wheeler · Unread post by **wheeler** » 12 Jul 2009, 11:20

Toby_HDi wrote:Wheeler, I only have to leave it 10mins or less and it won't restart.

10 minutes

sound like there is something heavy draining it , Possibly out of the range of the multimeter you have as most will only do 20 amps max. Disconecting the alternator is a good idea, if you have no joy with that you will really need an amp clamp to find this problem quickly. There aint many things on the car that would cause the battery to discharge so fast that you wouldnt notice working, the HRW aint stuck on is it ?

Toby_HDi · Unread post by **Toby_HDi** » 12 Jul 2009, 11:39

Thats what I thought, but the meter shows 0.00 rather than the usual '1' overrange reading. I will try disconnecting the alternator if I can get to it

I believe I have an amp clamp that came with the meter. Thing is, how do I use it!

Toby_HDi · Unread post by **Toby_HDi** » 12 Jul 2009, 21:18

All fine. Am beginning to suspect battery. Put the battery from the other Omega one for a bit and had no problems.

Not only that but a running issue I've had reappeared with the good battery. It hasn't cured the flickering speedo though

wheeler · Unread post by **wheeler** » 12 Jul 2009, 23:42

Had'nt you already tried another good known battery

Toby_HDi · Unread post by **Toby_HDi** » 13 Jul 2009, 00:02

For 5 mins yes. I had not run the car anywhere with it as it was too tall to close the bonnet.

Tbh I haven't got a clue. I've tested what I know and all seems fine. I've probably missed somethign though