Will my XC90 start, after leaving it parked for 4 weeks?

[Boatie]

Left my v90 for 4 weeks plus. Started first attempt. Start Stop didn't work for several days, exactly as my V70 in similar circumstances. Draw your own conclusions.

[Philip Fisher]

Originally Posted by gaby

You assume that since your car didn't survive, no car will?

It isnt an unreasonable assumption......

[KNVXC90]

Thanks all for your opinions and suggestions. I don't have access to any sort of chrargers at the moment. So I will be back here in four weeks time to report on my XC90's fate.

[luggsey]

Originally Posted by KNVXC90

Thanks all for your opinions and suggestions. I don't have access to any sort of chrargers at the moment. So I will be back here in four weeks time to report on my XC90's fate.

Haven't you got a neighbour that will start it up once a week for you?

[Lexman8]

I'd certainly want and expect the car to be okay after 4 weeks. However, a simple calculation shows why it might not be the case.

The XC90 (D5 and T6) has an 80Ah battery; i.e. it can supply 80 amps for an hour, 40 amps for 2 hours, etc. Over the 672 hours in 4 weeks it can supply an average of 120mA which at 12 volts is 1.4 watts (not much).

So, throughout the 4 weeks the alarm system has to be powered continuously, VoC is fully active for the first 4 days before dropping back to hourly mode until day 27 and the keyless entry system is awake (I don't know how long for; on my Merc the keyless system switched off after 72 hours). Also, this calculation assumes the battery will fully discharge and in practice the car will not start some time before that.

So with only 1.4 watts available to power (at least) 3 systems over 4 weeks it's understandable why a car might not start. On the other hand, if the alarm draws a very small current and the keyless system switches off after a few days then maybe 4 weeks would be achievable. These figures also suggest that even a low power (~2 watts) solar charger could be enough to maintain the battery at a sufficient level to allow the car to start . However, I've no experience with these.

I assume the T8's electrics are completely different.

[neon]

The longest I have left my car is twice for 2 weeks at a time in an airport carpark. Interestingly very shortly after leaving the airport car park the auto stop/start engaged, which would suggest a high amount of charge in the battery.
Over the winter though I did experience quite a few times when the auxiliary heater would not warm the car before a journey due to low battery power.

[Lexman8]

Off topic... I sometimes think the stop/start algorithm needs a bit more tuning. For example, the other evening I drove 20 miles each way on mostly minor roads with lots of junctions and stop/start didn't operate once in the 40 miles and 80 minutes of driving. It was a mild evening and everything was normal but the READY indicator remained off throughout. The next morning I'd barely gone 100m when the engine stopped. Go figure.

[gaby]

I think it must be female...

[KNVXC90]

Originally Posted by KNVXC90

Thanks all for your opinions and suggestions. I don't have access to any sort of chrargers at the moment. So I will be back here in four weeks time to report on my XC90's fate.

Just got back from 4 week holiday. My XC90 D5, started up fine, at the first attempt. Keyless entry/boot kick opening all worked fine too.

Happy ending

[ulstrup]

I just don't understand the problem.
I don't know with the Volvo since I don't have it yet but I very often leave my other cars for 3/5 weeks and I never had a dead battery.