RESET "LOW BATTERY" in Volvo - disconnect BMS plug

If you often see "LOW BATTERY" warning despite regular long drives, you can disconnect the cable at Battery Monitoring Sensor (BMS) for 20 seconds. It will force BMS to recalculate the battery % SOC overnight. If your battery is low indeed, LOW BATTERY will reappear next day.


Press START button to put ignition in position I (short press START, without touching any pedals) and disconnect BMS plug for 20 seconds. Reconnect, ready. Now you can drive as usual.

This trick doesn't reset internal timer for battery age, trick can be performed on older battery.

LOW BATTERY
"Low battery" warning appears below 50-60% SoC (battery State of Charge). 50-60% SOC seems quite a lot, right? But lead-acid batteries should not be discharged below 50% SOC, due to lead acid chemistry (lithium ion batteries are different).

"Low battery" warning protects battery from getting fully discharged - for example when you sit and listen to music in the car.

"Low battery" is not the source of your problems - it is a symptom of other problems, maybe you are not driving enough, installed a dashcam, keep doors or locks open when car is parked? Find the source of battery parasitic drain - if battery is quickly drained, a new battery will soon be empty, too!

If you often get "LOW BATTERY" warning:
- always close the doors and lock the car when parked, because open doors and locks keep the electronics awake for much longer
- do not listen to music with engine off - it quickly drains the 12V battery
- if you use webasto, drive at least as long as webasto was running.
- drive more to let the battery replete the State of Charge
- check the standby "quiescent current" in Car Scanner, maybe too much parasitic drain?

Did you install any electronic gadgets - dashcam, LED lights, Bluetooth dongle? Quiescent current should not exceed -25mA.

After 2010 Volvo cars use 12V battery to get lower fuel consumption and CO2 emissions. Battery Monitoring Sensor (BMS) charges the main battery only to 82-85% SOC, the rest is left for brake energy regeneration (battery charged during engine braking). But it means that 15-18% of battery is left unused - only to reach marginally lower consumption and CO2 emissions.

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CAR SCANNER ELM OBD2 app

how to check 12V battery on smartphone in Car Scanner ELM OBD2 app:    • Bad design? Volvo alternator charging...  

Car Scanner ELM OBD2 shows:
- main battery state of charge (% SOC)
- battery voltage
- quiescent current average (parasitic battery drain when car is off, value from last 10 hours)
- main battery current (amps)
- battery charge balance Ah
- battery temperature
- alternator current (in some engines)
- BMS sensor reliable - after this trick sensor will show 0 for several hours, then 1 (reliable) again once car recalculated the battery SOC.
- secondary battery parameters (in cars with Start/stop)

In video after disconnecting BMS sensor the SoC dropped from 79 to 32%, then next morning jumped to 90% SOC. A few days later I repeated the trick and filmed using Car Scanner ELM OBD2 app - battery SoC dropped from 85 to 40%, next morning jumped to 80%SoC.

If you drive a lot, BMS keeps battery at 82-85% SoC, to allow for brake energy regeneration. Battery is desulphated three times a year (according to VIDA):    • 12V battery desulphation in Volvo 🔋 A...  

Good advice again: lock the car when in garage and don't listen to music with engine off - it rapidly drains the battery!

Battery temperature and battery charge voltage in Volvo:
60°C - 13.55V
50°C - 13.60V
40°C - 13.90V
30°C - 14.20V
20°C - 14.50V
10°C - 14.90V
0°C - 14.90V

If you charge battery with CTEK or other battery charger: negative (black) charger cable must be connected to any metal part of engine or car body, never directly to the battery terminal! BMS must see and register charge delivered by battery charger.

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IMPORTANT
use other trick when new 12V battery is installed to reset battery age timer in BMS    • VOLVO HACK for new 12V BATTERY - BMS ...  

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How the BMS works in Volvo:
https://automotivetechinfo.com/wp-con...

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Volvo 12V battery - my playlist:
   • Volvo 12V battery and Start/Stop batt...  

video on Volvo "low battery" warning - Car Scanner    • Bad design? Volvo alternator charging...  

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Car Scanner ELM OBD2 app for Android and iOS
https://play.google.com/store/apps/de...
https://apps.apple.com/us/app/car-sca...
https://www.carscanner.info

VIDA 2014d
Volvo V70 D3 diesel 2012 Geartronic, Volvo EFB battery, no start-stop

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*Technical Journal in video:
TJ28159 - 2013-09-13 - “LOW BATTERY” message and high stand-by current, 2014 P3 vehicles
S80 II (124), S60 II (134), XC70 II (136), XC60 (156) - MY2014
Production: 20 week of 2013 to 36 week of 2013
“LOW BATTERY” message may appear even if the battery is in good condition. There may also be high standby current ("quiescent current")
SERVICE: Perform a CEM SW Upgrade