Astravan electrical problem.

moneysavingplumber

I have an ongoing problem with my 17TD 1997 Astravan. The battery keeps draining. I'm suspicious of the alternator and earth straps. With the engine running I get no more than 13.5 volts accross the battery terminals (it was only 13 when I just refitted the battery after charging indoors), but from the positive accross to the alternator casing I get 14.1, it doesn't fluctuate when revs are added. The belt is as tight as it can go and there are no bulbs remaining on, although a mechanic i know did identify a drain using a neon screwdriver that seemed to be on the radio/lighting circuit, it has a Meta alarm fitted and I wonder if that has anything to do with it. Any ideas from any electrical mechanics?

Thanks in advance.

vansboy

Ask in https://www.honestjohn.co.uk clik on The Backroom - Technical forum.

Alternator is usually first plcace to check, but as you've done the obvious, unless the (red) dashboard alternator is on, or glowing slightly, with ignition off OR on, you'll need someone to do a bit of trial n error testing.

VB

ohreally

moneysavingplumber wrote:

IThe belt is as tight as it can go

Firstly, back off the tension on the belt.All you will succeed in doing is puting a strain on the alternator bearings.Try adding another -ve strap from the block to the battery -ve terminal and possibily another between chasiss and battery -ve terminal.

wazza

i normally ask if you have changed anything before this problem occured. if you have then that may be the cause. if you reckon its the alarm then disconnect it and see if the battery still drains.

how old is the battery? could be its on its way out and need replacing. if you have access to another battery then fit it and see if the drainage problem remains. if not then the battery is gone. if it drains then you have a short somewhere.

on my diesel the car would start straight away but if left for a few days the battery was flat. the battery was on its way out. it was 6 years old.

moneysavingplumber

Thanks for all your input. I'll take a bit of tension out of the belt.

My electrician reckoned if the alternator's working correctly that the voltage should fluctuate with the revs. Is that correct? I can pick up a reclaimed alternator for £10 and try that so I may well do that if it's suspect.

I might try another battery in there, it's supposedly only two years old according to the Arfur Daley i bought the van from, but it's always had a slight problem with this, it's gradually got worse. I've been down the new battery, new starter-motor route before with my old van, only to find it was an earth strap. Should there be a difference in readings between battery and body and battery and alternator?

I'll also try honestjohn.

Thanks again.

ohreally

moneysavingplumber wrote:

My electrician reckoned if the alternator's working correctly that the voltage should fluctuate with the revs. Is that correct?

The voltage regulator should be set to deliver around 80% of it's available output almost from tick over speed so it shouldn't really fluctuate too much. There are quite a few alternators that may claim to fit so be vigilant when sourcing a used part that it looks the same appearance wise. Does it look like it has an internal fan,viwed from the front?

moneysavingplumber

I'm not sure about the internal fan, but the guy I get my spares from dismantles Astras and Vauxhalls only, I've had everything off of him from alternators, radiators and power-steering pumps, and they've always been spot-on, he knew the difference between the models of my van that have Isuzu lumps and some that have GM lumps and dug out the correct power steering pump just by glancing under the bonnet.

AlanCollier

How old is the battery?
The battery voltage can only reliably be tested under load so simply using a multi-meter across it isn't enough.

--Alan

moneysavingplumber

Thanks for all the replies. I paid a fiver and had it diagnosed by an auto-electrician, it took him about 20 seconds to find it! The strap from alternator to block was attached to the clamp as opposed to the alternator itself. i disconnected it and cleaned it up as advised and reconnected it and it's been fine since.