XC70 unusual issue(s)

[Tannaton]

With regard to the battery, if the car was stood for a while before you bought - it can cause this issue in a number of ways. Personally I would removed the battery from the car (or disconnect it) and charge it for 24-48 hours using a traditional (I.e. not smart) battery charger - this will fully saturate it. And disconnecting the battery for this long will reset the BMS.

In normal circumstances you would not disconnect the battery during charging as you would want the BMS to register that charge, but when the BMS and battery are out of sync, this becomes irrelevant.

After you have done the above the BMS system will recalculate the state of charge and this can take a few days, it does it by monitoring the battery voltage when the car is not used (and locked) for periods of 8 hours or more, so if you keep it in a garage, you should still lock it…..

The battery issue may explain your freezing problem, if the car thinks the charge is too low it disables certain functions to preserve enough charge to start it again - including lighting, and being able to use the radio without the engine running.

If the above does not solve the problem - I would change the battery. Don’t take it for granted that because it’s nearly new and/or a good brand that the problem must be the car - we see maybe 2 or 3 new members on here every year with strange problems that go away when the main battery is replaced. The in-car BMS system continuously monitors the battery under charge and under load and if uninterrupted, develops a more accurate assessment of battery health than even a intelligent test device ever could in a 30 second test. If you do not have start/stop - then you don’t have an additional battery.

[SignumGB]

However, when I get to my destination, turn off the car and get out, only the driver's door unlocks

Every XC70 I have owned has been like this. Perhaps it's a standard European feature. I am now in North America, same thing. But what they have got here is keyless entry (2012 XC70 T6 - unless optional extra) so when I go to the rear door it will unlock when I open it. Child locks are on so kids can't get out themselves anyway. It's nothing to fret about as you have the unlock button on the arm rest anyway. I'd rather be in control than being automatic. Safer too! You don't want some random jumping in your car....

[yostumpy]

Also worth remembering, is the fact that it's probably fitted with a smart alternator, providing minimal voltage whilst driving, but spiking to around 17 volts on overrun, to reduce emissions, and load on the engine, so a long run at high revs wont bang in a charge, but coasting down big hills probably will. What I can't find out is does it charge normally with a load on it (other than the driving lights) I was talking to a chap a while ago, whilst I was contemplating buying a Subaru Forrester, and he said he drives around with the lights on to create a load, otherwise the alternator won't charge until the engine is at operating temp, similar thing to smart one I suppose. o switching on the lights might overide the 'smart' bit.

Interestingly I have 2 new batteries (max 1 year old), and do lots of short trips, then nothing for a week, and s/s doesn't always work. Had battery low come up, and went to fill up with diesel, 3 miles away, cleared the trip and mpg readout, and set off again, but the green s/s IS available light was back on? and continued to function normally on the way home (This is the second time this has happened, making me think it's linked to clearing trip or mpg?) But 2 days later the warning is back on, now with a red triangle. It has a mind of it's own, it does.

[apersson850]

Although I don't let my car lock the doors automatically when driving, I can set how the car should work when I unlock. That is, all doors, driver's door only and some other combinations.

[Jdizzle]

Hi all,

Thanks for the various replies - such a refreshingly helpful forum / community!

I think that the combined advice dispensed has resolved all of the issues, so thank you! The only thing I'm unsure of is if anything happened / changed when I pressed the button combinations to reset the BMS... but that being said I don't seem to have had any further low battery warnings so I'm optimistic!

Thanks again!