Volvo Owners Club Forum - View Single Post - 2013 T4 Stuck in Battery Refresh/Overcharging

pettaw · Nov 7th, 2018, 09:17

As thread title. My car is 5 years old and has done 80,000 miles.

I had noticed for quite some time that everytime I plugged in my scan tool and looked at live data in the CEM the battery mode was "battery refresh," with the charging voltage being super high, well over 15V. When I looked into it further, even if I did a really long journey and got the SOC up to 100%, when the car sat overnight the SOC would drop into the high 80s or low 90s. I have a CTEK battery tester which is basically a very low function Midtronics machine which tested the CCA at 525 rather than the rated 760, so I reckoned the battery was probably past it and replaced the battery.

Using my scantool I reset the BMS to 0 days and fitted the new battery and performance returned to normal, with the alternator only charging the battery up to the required level and then switching to floating voltage etc. After the battery was approximately 60 days, I happened to plug in my scantool to diagnose something else and I noticed the system had gone to "Battery Refresh" again. So I kept an eye on it for a few days and it continued to be stuck in this mode, even though the battery was completely fully charged, and maintaining it overnight. (When I started the car after sitting for 2 days it would still be at 99% SOC)

I thought, maybe the BMS is playing up, so I replaced the BMS and again, as per procedure, reset the BMS with the scantool. Again, performance returns to what I would expect according to the literature.

However, once again, after approx 3 months, I noted that the "Battery Refresh" mode was activated once again, even though, as I said the battery was already fully charged. Now, I monitored the battery using my scan tool on every commute to work and every drive home. I did note that it did kick out of "Refresh" mode, but once the car was turned off and sat, the refresh cycle kicked in again the next time the car was started. I know that AGM batterys are very sensitive to the charging requirements, one of the reasons all this smart charging was invented, so I'm worried that its overcharging my battery and will boil it into submission soon.

Does anybody know whether there is a software glitch in the car or CEM? I believe that the CEM controls the charging voltage requirements, using the BMS as a guide to the health of the battery. I can't think that there's any hardware failure, I'm much more inclined to think that the software is glitchy.

I will say, for completeness of information, that my journey to work is over an hour each way, of mixed traffic and dual carriageway driving, with plenty of runs so that the engine is running to charge things and not that much start-stop, where the engine is off all the time, so I can't believe that its short journeys.

Help please!

Nov 7th, 2018, 09:17	#1
pettaw Forum Support Team Last Online: Jul 23rd, 2023 15:29 Join Date: Jan 1970 Location: Glasgow, London	2013 T4 Stuck in Battery Refresh/Overcharging As thread title. My car is 5 years old and has done 80,000 miles. I had noticed for quite some time that everytime I plugged in my scan tool and looked at live data in the CEM the battery mode was "battery refresh," with the charging voltage being super high, well over 15V. When I looked into it further, even if I did a really long journey and got the SOC up to 100%, when the car sat overnight the SOC would drop into the high 80s or low 90s. I have a CTEK battery tester which is basically a very low function Midtronics machine which tested the CCA at 525 rather than the rated 760, so I reckoned the battery was probably past it and replaced the battery. Using my scantool I reset the BMS to 0 days and fitted the new battery and performance returned to normal, with the alternator only charging the battery up to the required level and then switching to floating voltage etc. After the battery was approximately 60 days, I happened to plug in my scantool to diagnose something else and I noticed the system had gone to "Battery Refresh" again. So I kept an eye on it for a few days and it continued to be stuck in this mode, even though the battery was completely fully charged, and maintaining it overnight. (When I started the car after sitting for 2 days it would still be at 99% SOC) I thought, maybe the BMS is playing up, so I replaced the BMS and again, as per procedure, reset the BMS with the scantool. Again, performance returns to what I would expect according to the literature. However, once again, after approx 3 months, I noted that the "Battery Refresh" mode was activated once again, even though, as I said the battery was already fully charged. Now, I monitored the battery using my scan tool on every commute to work and every drive home. I did note that it did kick out of "Refresh" mode, but once the car was turned off and sat, the refresh cycle kicked in again the next time the car was started. I know that AGM batterys are very sensitive to the charging requirements, one of the reasons all this smart charging was invented, so I'm worried that its overcharging my battery and will boil it into submission soon. Does anybody know whether there is a software glitch in the car or CEM? I believe that the CEM controls the charging voltage requirements, using the BMS as a guide to the health of the battery. I can't think that there's any hardware failure, I'm much more inclined to think that the software is glitchy. I will say, for completeness of information, that my journey to work is over an hour each way, of mixed traffic and dual carriageway driving, with plenty of runs so that the engine is running to charge things and not that much start-stop, where the engine is off all the time, so I can't believe that its short journeys. Help please!