2017 XC60 Low Battery Charge

[foggyjames]

As far as I'm aware the big (starter) battery is charged directly by the alternator, then excess charge is siphoned off to the smaller battery which runs everything else.

If you are routinely seeing "low battery" after only a few days (or even a couple of weeks), it does suggest that one or both batteries are getting tired, and that will happen sooner with AGM batteries than normal lead-acid. If you're still seeing it when the voltage across both batteries is comfortably above 12v, I would refer that to a dealer. It might be normal but it might not.

Be aware there might be a bit of a language barrier...but I think my guidance about rudeness stands!

cheers

James

[foggyjames]

Originally Posted by Zebster

Did you follow Tannaton's advice on resetting the BMS by following the YouTube guide?

Although it does seem like an odd sequence of actions (!) I followed it a few months ago when I became fed up of almost constant 'low battery' warnings, even after long runs and it did actually work, although admittedly now we've been in lockdown for a while I've noticed that the warnings have returned due to the car having had little use.

Interesting. Sounds like that might be worthwhile if the calibration can drift over time.

cheers

James

[moosehead74]

Originally Posted by foggyjames

As far as I'm aware the big (starter) battery is charged directly by the alternator, then excess charge is siphoned off to the smaller battery which runs everything else.

If you are routinely seeing "low battery" after only a few days (or even a couple of weeks), it does suggest that one or both batteries are getting tired, and that will happen sooner with AGM batteries than normal lead-acid. If you're still seeing it when the voltage across both batteries is comfortably above 12v, I would refer that to a dealer. It might be normal but it might not.

Be aware there might be a bit of a language barrier...but I think my guidance about rudeness stands!

cheers

James

Thanks James. Are both batteries in a parallel in which case the pd would be the same? I'm not sure if it's as simple as that. Must admit I haven't discovered the auxiliary battery yet to see if it has a battery monitor connected to it. I really don't think the main battery is on the way out as the pd would drop off a lot quicker. My 2005 Merc is still on the original battery and it drops pretty quickly after a charge 12.2-12.3V. I have new one ready to go in.

[johnnyoro]

Hi
I recently due to recommendations on these forums bought a viecar scanner and downloaded car scanner app and have been very surprised as to the range of information it is capable of displaying on the move , for my xc60 there are over 100 !!
2 of those are the main and secondary battery voltages , over a 60 mile round trip this week the main battery was 12.6 at startup and the smaller was 12.5 during the journey the main went up to 14.75 and stayed at that voltage during the journey , the smaller one went up to 12.7 in the first couple of miles and then occasionally down to 12.6 .
I think at this time both of my batteries and alternator are in good order , they ought to be at 3yrs old. However another advantage of the using the scanner is that you can record these and refer back if there are problems in the future
For under £20 it is well worth having and would give you a better idea of how you car behaves, and give you more precise info
Hope this helps

[foggyjames]

If it's in the same place as on a P3 V70, it's under the windscreen cowling very close to the starter battery. You can actually see it (just) if you take out the starter battery.

I'm not sure about exactly how they're wired, but as far as I'm aware it's not a straight parallel connection - that would defeat the object of the exercise. I believe there is some kind of charge (and I assume drain) management mechanism in place. There is some sort of sensor (or something) on one of the terminals (negative, I think) of the starter battery.

I would perhaps suggest a charge up of the starter battery, a reset of the module (as described previously), and a long drive.

I did 300 miles in mine a couple of weeks ago, and it sorted the problems right out.

cheers

James

[moes80]

Originally Posted by moosehead74

I've had the vehicle from almost new and frequently get the low battery charge message after the vehicle has been stopped a few minutes and I've been listening to the radio. I've mentioned it to the dealer every time it's been in and they assure me it's not a problem. I haven't driven the vehicle since Thursday and battery voltage measures 12.6V which suggests to me that it's almost fully charged. At the moment I periodically charge it with a CTEK Stop/Start charger via the tow electric socket.

Does the radio run from the auxiliary battery when the vehicle engine is off? How do you measure the voltage of the auxiliary battery? How does the auxiliary battery get charged? It's all a bit of a mystery after only having had previous vehicles with one battery!

Hi Moosehead74,

Not sure if this is going to help.....I read somewhere that a common fault with the xc60 is the alternator main sprocket becoming loose so not charging the battery as it should. Maybe worth a look.

[moosehead74]

Originally Posted by moes80

Hi Moosehead74,

Not sure if this is going to help.....I read somewhere that a common fault with the xc60 is the alternator main sprocket becoming loose so not charging the battery as it should. Maybe worth a look.

Many thanks for all the comments. Will check alternator. Checked charge voltage previously (can't remember of the top of my head but was fine). I think the auxiliary battery is somewhere towards the drivers side and requires a panel removed. Will pop this off at some point and see if I can measure pd and compare with starter battery. Not sure if the 'low battery charge' relates to the starter battery, auxiliary battery or both. Would be good if it did differentiate!

[foggyjames]

Originally Posted by foggyjames

If it's in the same place as on a P3 V70, it's under the windscreen cowling very close to the starter battery. You can actually see it (just) if you take out the starter battery.

I would start here - same platform, so likely to be in the same place.

cheers

James

[moosehead74]

Yes, I think the next step is to try to measure the pd of the auxiliary battery. Looking at the manual it does seem to be located on the drivers side under the windscreen. It's only rated at 8Ah so if the radio is powered from that when the engine is off I can see it would soon discharge and flag a low battery charge that's of course if this battery is monitored. If this was the case you would think the system would differentiate between the two.

[foggyjames]

Yeah, 8Ah isn't a lot, is it? The second battery is pretty (physically) small on my V70, so I'm not surprised that the capacity is quite low.

I don't know if either battery being low will trigger "Low Battery" (I assume so), but the secondary one definitely does.

cheers

James