My car's had to be recovered!

[Zebster]

Went out tonight and suffered widespread electrical problems. When getting near my destination about an hour away from home warning lights began coming on, first the ABS warning light, then the tyre inflation warning, then the engine warning light, then various messages such as 'low coolant' and 'steering failure'. So then I stopped!

After stopping the problems continued to increase... Although the engine continued to run fine the dash went completely blank, the central locking ceased working, the radio wouldn't turn off, etc etc. So I called my recovery service and had it brought home.

Now home, it starts normally and the headlights work fine - I had to drive it off the recovery truck and up our driveway. The dash is now working ok, but several warning lights are on and the radio cannot be turned off (until the key is removed). Some doors are locked, some are not. Only one door mirror has folded... It's a mess!

It's definitely a widespread electrical issue. My thoughts are that one of the batteries has failed, but obviously not the one that affects starting.

Has anyone else had this happen? I know where the largish battery is at the back of the engine bay, but where is the other (smaller?) one? I assume it's 12v, but are they both AGM types?

I've got a multimeter and I'm actually an electronics engineer, but I'm rather in the dark with the specifics of this car! So any advice gratefully received.

TIA
Jon

[Tallpaul82]

I had an old Honda which did similar. It was the alternator in the end that was outputting just enough to keep the engine running but all instruments died. New alternator and a charge of the battery and all was good. Do you have a multimeter to check battery voltage when running?

[Tannaton]

What you have described broadly reflects what most Volvos do if the system voltage falls... it always starts with the abs warning.

Suggest you check the voltage with the engine running - should be circa 14.1v.

Some of the warning lights might need resetting after you have fixed it.

[Zebster]

Please can anyone explain which is the main battery and which is the support battery? And which functions does each perform? Do they both need to be AGM types?

[SwissXC90]

Originally Posted by Zebster

Please can anyone explain which is the main battery and which is the support battery? And which functions does each perform? Do they both need to be AGM types?

Battery type is in the Owners Manual, likely are AGM
But check before replacing, and ensure it is a battery problem before replacing,.
Don't just guess!

[Tannaton]

If you can still start the car normally, I would suggest it is unlikely (though not impossible) that your main battery is the cause.

Some alternator issues can damage the battery.

First test is to start the car and check the voltage of the battery with the engine running.

I recall a similar post recently from a member who had similar issues and the problem turned out to be a bad/corroded joint on one of the battery/power cables.

[Clan]

Originally Posted by Zebster

Please can anyone explain which is the main battery and which is the support battery? And which functions does each perform? Do they both need to be AGM types?

don't worry about the support battery that is hidden away under the windscreen that is only used when stop/start is stopped . Sounds as if alternator may have failed I would get it towed to the volvo dealer it cant be far out of warranty and it needs professional investigation , there is a lot of data stored on what may have happened ! If you do need a battery for whatever reason get the genuine volvo one they are competitively priced and 20% off until the end of the year .

[Zebster]

It's almost a year out of warranty. Nearest Volvo dealer is some way off. I worry that a local garage would know a lot less than this forum and would merely embark on replacing both batteries and the alternator.

I'm quite happy to work on cars and would describe myself as a very experienced DIY mechanic... I just have absolutely no technical info on this vehicle!

[Zebster]

I've now been out to investigate.

The car appears to have magically (and suspiciously) recovered... without starting it up, the central locking and door mirrors are now operating normally. With the ignition on (I) the radio can be operated and turned off (which it couldn't last night). I accessed the larger battery and it's on 12.2v with the ignition off... this drops quite noticeably when the ignition is turned on (II) (falling towards 11v) but the car starts as normal and, with the throttle held at 2000rpm, the main battery terminal voltage rises to 15v. This suggests to me that the battery was somewhat discharged, but that the alternator is working fine (at the moment).

I assume this could point to a failing main battery, but don't understand why the alternator wouldn't have maintained the battery terminal voltage last night whilst driving along an A-road when gremlins first began appearing?

Is there really no chance that the smaller battery could somehow be to blame?

I still do not understand what functions each battery is responsible for... can anyone explain?

Is it a known thing for the main batteries on these models/related models to fail at around 4 years? I'm tempted to try a new one on the basis that this could solve the problem but, if not, the original battery was probably becoming weak anyway?

[Clan]

Originally Posted by Zebster

It's almost a year out of warranty. Nearest Volvo dealer is some way off. I worry that a local garage would know a lot less than this forum and would merely embark on replacing both batteries and the alternator.

I'm quite happy to work on cars and would describe myself as a very experienced DIY mechanic... I just have absolutely no technical info on this vehicle!

you are only 20 miles from a dealer ! They are the only people who can read the stored information about the true state , condition and usage information of the battery and carry out the built in Battery test process . , It could be that there is an intermittent problem with the alternator if the battery checks out ok . Volvo goodwill is pretty good if you have had the car serviced properly ..