V70: Electrical Stop/Start & Battery Charging

[DaiRees72]

My Stop/Start hasn't worked for ages, which I don't mind but it's got me thinking about the state of my battery. I do a lot of short trips and can appreciate that isn't great for the battery. However when I do a longer trip I'd expect the battery to get a good charge and for the stop/start to start functioning again, but even after a few hours of motorway driving it doesn't come back to life and the computer reports that stop/start is unavailable because the battery is charging.

So I was wondering whether I should charge the battery at home? My previous car was a Peugeot with notoriously flaky electronics so I'm still a bit apprehensive. Firstly is it a good idea to charge the battery at all or should I just let the car sort it out? Secondly, would I have to disconnect the battery it or is it safe to charge it while it's still connected, if so I'm guessing +ve to terminal and -ve to chassis earth? Finally, I understand that my car has a second battery to "assist" the stop/start system, so which one needs charging and where's the additional battery located?

[Sasha94]

I also thought there was a second battery but an AA patrolman I was chatting to told me there wasn't. I am sure I read there was a second battery. I have also heard a figure of 76% charge being needed to get the stop/start going but there is much misinformation on the system so I don't know. As far as changing the battery goes I'd do it at home, take the old one and just install the new one.

[Boatie]

Originally Posted by Sasha94

I also thought there was a second battery but an AA patrolman I was chatting to told me there wasn't. I am sure I read there was a second battery. I have also heard a figure of 76% charge being needed to get the stop/start going but there is much misinformation on the system so I don't know. As far as changing the battery goes I'd do it at home, take the old one and just install the new one.

There is! It's under the plastic trim to the left of the main battery. My Stop/Start hasn't worked for months and for this I'm grateful. It saves me having to turn it off each trip. 'orrible function.


Frank

[Sasha94]

I knew there was!! I was certain of it, thought I was going mad when he said it didn't have one! I like the stop start, it works really well on my car

[andyg]

I have a 2013 S80 D3 with start/stop that did not work reliably when I first got the car 11 months old from Motorpoint. It may have been sitting around for several weeks was my guess. After research on this Forum and advice in particular from Clan (always very helpful) I purchased a modern battery charger from CTEK that among other things is suitable for AGM batteries found on most recent cars. I put the battery on a trickle charge for 24 hours and the problem was sorted. The stop/start has worked to spec since then.

Yes, the Volvo manual states that the negative / ground lead of the charger should be connected to the chassis, not to the negative terminal of the battery. Something to do with sensors on the battery connector I think. The positive lead clamps straight onto the battery. I did not disconnect either battery terminal. I cannot give any guarantees but this procedure worked for me.

[DaiRees72]

Thanks for that info Andy, I wasn't aware of AGM batteries and would probably have stuck my standard charger on there at some point! I've been having a google and reading up on AGM (and EFB) batteries.

The battery part number is 31255132 and although it doesn't say so on the label, I believe it is an AGM battery. I also found the smaller "assist" battery hiding under the scuttle panel as Boatie said, that one's definitely AGM because it says on the top, right next to the FoMoCo logo.

So now I'm off to search for a charger suitable for AGM batteries...

[Rooster]

72% is cut off for stop start,

Also the battery monitoring system does benefit from been reset every so often,

The earth lead has a little black 2 pin connector on it with ignition off unplug said connector for a minute then plug back in again,

As said above never put a battery charger lead on negative battery terminal on any car with stop/start as it will screw the system,

Ctek are quiet a well known make in the kitcar and motorbike world altho i have a couple of cheaper oxford chargers altho i don't own anything with an AGM battery on it

[DaiRees72]

Thanks for your help guys. I've ordered this CTEK charger

https://www.amazon.co.uk/CTEK-MXS-5-...s=ctek+mxs+5.0

Should be here in a couple of days so I'll let you know how I get on

[andyg]

Just in case you had a concern.... the main and secondary battery are connected in parallel as part of the car's wiring. If you make the connections to charge the main battery that also charges the secondary battery. You do not have to go looking for additional terminals under the plastic trim! Hope the CTEK works for you.

[Tatsfield]

The CTEC I have came with a set of connectors which are permanently bolted to the battery terminals and enable you to just plug in the charger without having to make any connections when you want to charge the battery. The unit is quite compact and could be fitted permanently in the engine bay so that it is always there when you need it.