XC70: Electrical intermittent Dead Battery

[TillM]

Hi all,

I have searched the threads and Googled my issue and I cannot seem to find an answer.
I had my XC70 serviced (108,000 ) at a main dealer before we left for our holiday in France.
Everything was fine until late in the day on the second day of driving down the 700miles to the midi pyrenes . Then the air con packed up, no big deal I thought these things happen and I will get it looked at when we get back, then the rear park assist decides to display a warning " Park Assist Requires Service" upon restarting the car this message goes away and has not come back, but I am down one sensor. (I am including this in case its relevant).

Ok, car is still working, then out of the blue the following happens.

Pull into a garage to refuel, turn off the ignition leave the keys in the slot and fill up with diesel. Get back in the car and nothing, no electrics at all. cannot eject the fob the car is totally dead. So I think maybe its a fuse (dumb I know, but let start with basics), Pop the bonnet open and no fuse is blown that I can see, close the bonnet and everything springs back to life.

We drive off and everything is fine, still no aircon and only partially working reverse sensors. OK, I treat it as a one off.

Today I see a nice view that I want to take a few photos of, stop the car leave the key in the slot, wife is in the car. Step outside for about 5 mins and exactly the same thing happens, car is totally dead np electrics. So I open the bonnet, do not do anything its still dead, close the bonnet and hey presto everything springs into life.

So is this a "security feature" or is there something more bizarre going on?

Any help would be appreciated.

It will be going into the garage when I get back, but that not until the 11th August.

A brand battery was fitted to the car a year ago.

I have RAC European breakdown cover, but I am crossing everything in the hope that this will not be needed.

My wife went to get into the car, pressed unlock the alarm goes off, remote appears to be Thinking its a dead battery in the remote, I manage to get a new battery from a friendly Englishman living close by, try the new battery car is still dead. Manually open the car with the key, no alarm. Everything is dead. Pop the bonnet, check the battery is not loose, nothing go to close the bonnet and everything springs back into life. Remote is working fine, can lock and unlock the car. Now I am even more confused.

Thinking this is an ECU problem, but how does it cut the battery power out completely !

[Tannaton]

It's likely corrosion on the battery terminals and connections on the high current leads, or a loose battery terminal (strong clue - a mechanic was under the bonnet before you went away...)


Most unlikely the battery, it wouldn't fully recover.

[TillM]

OK, An update is that it was all working and we drove 5k this morning to a small town and it cut out again. lifted the bonnet and closed it, nothing. Then decided if it was the slamming of the bonnet causing it to kick back into life that its probably something not connecting properly. So I thumped the fuse cover with my fist and it sprung into life.
Have taken it to a small garage, where the garage owners wife speaks English. they tested the battery and the connections, everything as it should be. checked the fuses and everything OK, Then it cut out again, so did the trick on the cover of the fuse and it kicked into life again. The owner phoned the Volvo Dealership in Agen and just our luck the technician is away on holiday. So after some more testing and it cutting out 3 more times. Started looking at the fuse cover diagram, the thinking is that the problem is one of the two grey relays at the top end of the fuse box. These have been ordered from a supplier and , I am getting a lift to the Volvo dealers in Agen to collect them in the morning.
Hopefully this will cure the problem.

[TillM]

The garage has found the problem, there are two connections to the positive terminal of the battery, the one feeding the fuses etc has a cover over the middle of the connection and a thin piece of metal between the two halves, this has a hair line crack. So as a temporary fix, that garage has soldered it together, not ideal I know. But it will hold (I hope) until we get back to the UK and I can get it replaced. Probably the whole cable.

I have also found this on a similar issue.

https://forums.swedespeed.com/showth...rminal-problem

I have attached a picture from the site showing the same problem, that I have.


Thanks for all your suggestions.

[Tatsfield]

I don't know if it really is but that section looks like it's been designed to be fusible. Why else would they reduce the width of the connecting metal? If that is the case, what blew it?

[SwissXC90]

Originally Posted by Tatsfield

I don't know if it really is but that section looks like it's been designed to be fusible. Why else would they reduce the width of the connecting metal? If that is the case, what blew it?

It didn’t blow. It’s metal fatigue. Stress fracture.

[Tatsfield]

Fair enough but I'd still be interested in what the narrowing of the metal component is supposed to contribute to the design of the part. It looks deliberate. Why shape it that way when it could run full width? I does seem deliberate. Could it have a built-in fusibility? Would that serve any purpose?

[tommyweaves]

Originally Posted by Tatsfield

Fair enough but I'd still be interested in what the narrowing of the metal component is supposed to contribute to the design of the part. It looks deliberate. Why shape it that way when it could run full width? I does seem deliberate. Could it have a built-in fusibility? Would that serve any purpose?

If not a hefty fuse, could it be designed to separate in a collision?

[kzu]

Hi
Turned out battery is damaged in some strange way.
Won't take charge at all.
Strange because it's VARTA silver 85Ah, 800A, max18 months old and I just a month ago did 3000mile trip to Europe.
Supplier of original battery refusing to exchange it even though it's been tested by 3 different places all tried to charge it and all confirmed something is wrong with it as it is not taking the charge.
Anyway, Alternator is providing 14.2V, with all possible electrics in the car switched on. Can't measure current as misplaced my clamp meter.
Will see how it goes.
Only issue after battery was out of the car for few days is that windows do not go up and down automatically after pulling switch to the end and mirrors do not fold every time when I close the car with remote but will need to get it sorted on next service.
Unless you know the way to make it work without visiting the workshop.

[tommyweaves]

The window issue is a simple one: when the window is down pull the switch up until window's fully closed and hold it there for 10 seconds. Do that for each window in turn.