Hello Nigel,
Hi, I have no idea if OVMS has any part to play other than in reporting the issue, but I've posted a full description to speakev at https://speakev.com/threads/12v-battery-flat.2373/ Basically I hit a low voltage warning - OVMS notified me via text. - why at such a low threshold when it was too late - no idea yet if ovms may be causing more drain
The OVMS microcontroller is indeed low power, but possibly the GSM modem not so much. The OVMS Twizy manual has a big warning that two or three days with the module pluged and without using or charging the car can discharge the auxiliary battery and I can attest that after two days I became a low bat warning on my phone. Admitedly, the Twizy auxiliary battery is very small. I've downloaded the modem module manual and see that there is a powersaving mode. I've scanned through the ovms firmware source and could not find anywhere where it is beeing used, but maybe I've not spent enough time. I was planning to try to modify it, so that when the car is off the modem gets in powersaving mode and maybe wakes only every 10 seconds or so to see if it has some messages. Marcos