VW Polo. Weird 'battery' problem

[Scoby_Beasley]

SWMBO was returning from work one night last week in her S reg. Polo when (I quote) "it was like the battery n everything died, the clock reset and battery light came on". Then she drove home OK.

So I go out a couple of days later, check battery connections, looking good n clean. Yet to find where the earth connects to the body though! (Oh for the old days when you could stand in the engine compartment to do stuff!!). Alternator has two small leads (dash indication?) and a larger cable which I suspect is the output cable. That's a bit rusty and has some green corrosion (verdigris) on it.

Has anyone come across anything like this before and has any pointers as to what to look for? Just got a new Haynes so I can delve a bit deeper.

I had something similar happen to me in an old Beetle many years ago when all the power just disappeared from the electrical system. Mind you, that was when a lightning strike hit the ground less than 25yds away! Had to change undies as soon as I got home!!

 

[Burnerman]

It sounds just like total battery failure, doesn't it - so do go over all the connections at the battery and where the negative battery lead contacts the engine and bodyshell. The engine connection is usually on the gearbox somewhere, and the bodyshell one on the inner wing.
However, the Polo of this vintage did suffer from ignition switch failure which would give the same symptoms. Usually this prevents the car from starting from time to time.
John

 

[Mursal]

When you are at the alternator cleaning the + connection, might be worth checking the alternator earth strap, as its mounted on rubber (I think).

 

[Scoby_Beasley]

Any ideas where the main (from battery) chassis connection is?? I was expecting it to be next to the battery. It looks like a cable lug is near there but can't see any connection. I'm thinking its maybe on the bulkhead after it comes off the gearbox? Haynes manual is telling me nowt!!

 

[mfarrow]

I would just keep trying, eventually you'll find it.

At 12V, a poor connection won't necessarily track across enough to maintain an electrical connection, and I would advise removing and replacing both battery to body, and body to engine connections and smearing with an electrical compound.

As an example my sister-in-law's 206 temperature gauge kept shooting into the red for no apparent reason, and the above treatment sorted it.

 

[Agile]

In usual;ly manage to track these problems by measuring voltage from an independent chassis connection to the neg and pos battery connections.

But a small load like side lights is needed to create a current.

Trouble is sometimes those faults are intermittent. Even so can usually show up as a slight voltage discontinuity.

Tony