airline tech
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- Aug 24, 2022
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- Midwest - KS
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- 2022 Ranger Lariat-Super Crew, Cactus Gray
- Occupation
- Aircraft Tech
Did you perform the BMS Reset?Tried. Still test good on there test. Replaced anyway with different brand because I don't want to deal with it later. Kept the battery though.
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I do not believe the battery was bad, note just after shutting down it's normal to see 12.6 Volts - once all the modules go to sleep - Normal = 12.1 Volts. (Average)
This is what I call - Wake-Up Voltage - this reading is taken from opening the door, plugging in the meter (power-point) - Note it's not powered yet. Then cycle the Ign (On) but do not start.
You should be reading (11.9 to 12.1) volts.
Keep in mind that any reading here - You need to (add) +.1 to +.2 volts to get actual battery voltage. So, 11.9 on the meter will actually be 12.1.
The reason for the BMS Reset is to reset the calibration of the sensor - I suspect since it was not reset for the previous battery - its reporting inaccurate readings to the BCM or the BMS Sensor itself is bad and reporting false data.
So, if I am understanding you - you are shutting down the truck and immediately seeing a - System Off to Save Battery Message and or on next cab entry. (Correct)
You state you are reading 12.2 Volts on the battery - when this message is showing - (Correct)
It should not be showing (The Message) with that battery voltage - the message triggers with a lower voltage.
This is where the BMS Sensor is (Off - Drifted), it's not reading actual voltage and why it at least needs reset and or possibly replaced.
The only true way to see it - is look at the BCM Live Data PIDs, to see what the sensor is reading.
Whatever this sensor reads - it sends the information to the BCM, the BCM is controlling the Load Shed / System Off Message.
This information is also sent to the PCM as part of its control (decision) for generator output and desired Gen Voltage Setpoint - which thus affects how the battery is charged.
The new battery may work (no problem) temporally but I suspect the same issue will return, unless you address the BMS Sensor issue - (The Reason and Cause) of your post.
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