Battery light on when the car is orf???? WTF

[scooters]

OK, here's one for you.
The car is an 850 T5 Auto estate with 120k on the clock, year 1996.

It's been mothballed for the last 6 months and today I put it back on the road. Sailed through the MOT, bunged a tax disc on it and had to run some errands.

Now before it was put away it was developing some electrical gremlins - especially-
indicator lights and hazard warning lights stop flashing intermittently
speedo sometimes fails but odo still works
strange things happen when you push the winter button - the arrow lights up on the dash - when you press the sport/economy switch nothing happens.

I made a metal note to look into these things over the winter suspecting a dodgey connection/earth/fues box.

SO - today, driving along start to notice warning lights flickering like a Christmas tree. I pull over stop the car. Try to restart - nothing. So I pop the bonnet only to discover that the battery isn't the battery I put the car away with 6 months ago, turns out one of my colleagues swapped it and replaced it with a 330 crank battery which looks like it might be from a 1.4 Clio - much swearing and a phone call later I hook up the jump start pack and get the engine going, drive 100 yards and once again, dash like a Christmas tree and it dies in the middle of the road. Jump pack again - this time I get 1/4 of a mile before it happens again. I'm round the corner from Unipart so pop round and spend £80 on a brand new Unipart stock battery for the 850 T5 with a 4 year warranty.

Now while I am round at Unipart, an RAC man turns up speaks to my wife, bungs on his tester and announces that the alternator is borked. However, he doesn;t know about the wrong battery or that the car has been laid up for 6 months with all the fun that entails (old petrol etc), I come back with the new battery and pop it in

I pop the battery in and no problems at all - no warning lights, every thing working fine, nothing to worry about. No charge warning light.

Except -

I switch off the car and the charge warning light/battery is illuminated.
I disconnect the battery and run to the PC -

Thoughts?

I haven't got my multimeter with me so can't test output. However, I do know enough about charging systems to know that unless you have the right size battery in the circuit to start off with you can get all sorts of readings especially with this new fangled modern 19 year old stuff.

[the judge]

Sounds like overcharging and a duff diode pack. May go away with more use, but who knows??

[scooters]

 the new battery seems to have stabilised things a bit but as you can pick up 2nd hand good alternators for these for 20 quid it wouldn;t hurt to bung on a replacement to see what happens.

 

I pointed out to my colleague that whilst one can get away with swapping batteries from old chod to old chod when you start dealing with ECUs, and power guzzling systems like climate control etc and comupterised gearboxes etc you can cause all sorts of problems by putting on a weasly battery that aint up to the job as anciliary components will start to fall over and unlike on an old land rover these components keep the car running and operating.....we're not talking about the 'lights being a bit dim'

[Mr_Bo11ox]

Scooters' special alternator masterclass required

[nigel bickle]

Scooters?

 

Alternators?

 

What could possibly go wrong?

[scooters]

chortle

tres drole chaps -

 

We will see what happens - I should really do the timing belt so might bung in a refurbed alternator in the meantime

[scooters]

Wise heads on yank volvo forum say this:

 

 

"The amount of voltage an alternator puts out is second to the amperage. If called to do so the alternator in an 850 should put out close to 100 amps, it's what they are rated at. The voltage will vary depending on the state of charge of the battery and the amount of accessories operating at the time of the test. 13.6 volts is NOT below normal, having a charge or battery light on is.

The alternator may be bad but if it were it's because one or more of the diodes had gone bad and is allowing the battery to discharge through the alternator. It's fairly rare but it's difficult to catch. The alternator will charge properly when it's running (like your light being out) but when you shut it off the battery starts to feed current back through the alternator so it acts like a big light bulb draining the battery but nothing physical to warn you it's happening (except volvo do warn you with the charge light). You need to check for a draw and find out what is causing it.

If you pull the big wire going to the alternator and the light goes out you likely have a bad alternator. If you take it in and have it bench tested it will likely pass even if it has this fault as most testers are looking at what the alternator can produce rather than if there is a "leak" !"

 

 

The sitting around outside over the winter could well have caused some diode issues - other gremlins seem to be sorting themselves out as the car is used. We will see what happens over the next few days - in the meantime I'll disconnect the battery overnight

[Charlie Croker]

My Vectra has a issue simalar to this. When i turn it off after its been running the battery light comes on for a second or two then goes out again. It runs pretty bad too but only once failed to start. It has the wrong size smaller baterry on too. Could be the alternator then...............its been like this ages and i was going to scrap it.lol.

[fordperv]

alternator is borked, replace for non borked one, i had the same problem on my saph a couple of months back

[the judge]

Seen it good few times, usually alternator. Only suggested on past experience and no real understanding of the science!! I'm not the sharpest knife..

[Conrad D. Conelrad]

My car did this too!

 

It stopped doing it on its own.

 

HTH

[holbeck]

Sounds like failure of the Alternator diode pack.

[scooters]

Tell you what though 850/mk1 V70s have to be the bargain of the moment it you can live with fuel and insurance costs. So many are being broken...2nd hand rebuilt alternator...25 quid including 24 hour courier!!! 3 years ago same part was 90 quid! Parts are rock bottom and you can pick up a 2.4 loaded estate for 500...

 

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