I left my roadster plugged in and in storage mode three weeks ago. I check its state occasionally with OVMS and noticed today that the app reports a voltage of 11.5V on the 12V battery. If I wake the car, the reading changes temporarily to above 13V before it goes back to 11.5V again when, I believe, the car goes back to "sleep". Should I be worried?
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Storage mode and the 12-V battery
- Thread starter einhalv
- Start date
The difference in voltage is due to two sources of power for the 12V system. When awake, the 13V you see comes from the APS (auxilliary power system) that is a DC-DC converter from the 400V coming from the traction battery down to ~12V. When sleeping, the 11.5V comes from the 12V battery behind the right front wheel if your car is a 2.x Roadster or if your car is a 1.5 Roadster then it comes from the secondary 12V system powered by just two sheets of the traction battery.
11.3v reported here when asleep, 13.0 when awake. I note that the calibration of the OVMSv3 measurement isn't super accurate. The reported reading is measured by OVMS itself from what it is being fed from the Diagnostic port under the dash, not a digital value that the car is reporting on the CAN bus. The module's calibration can be adjusted, if needed.
I should note that the 12v battery in my car was replaced in 2015, so about 4 1/2 years old, however the voltage measured at the battery itself is 13.77, plus or minus a few millivolts, regardless of whether the car is awake or asleep. That means that it's being kept at a nice float charge by the DC-DC inverter. The no-load voltage of a fully charged lead-acid battery is about 12.6v.
One last note is that the voltage reported by the in-dash JVC unit is yet different. "A man with a watch knows what time it is. A man with two watches is never quite sure..."
I should note that the 12v battery in my car was replaced in 2015, so about 4 1/2 years old, however the voltage measured at the battery itself is 13.77, plus or minus a few millivolts, regardless of whether the car is awake or asleep. That means that it's being kept at a nice float charge by the DC-DC inverter. The no-load voltage of a fully charged lead-acid battery is about 12.6v.
One last note is that the voltage reported by the in-dash JVC unit is yet different. "A man with a watch knows what time it is. A man with two watches is never quite sure..."
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