[Ovmsdev] 12V battery fail

Marcos Mezo mmezo at selexco.net
Fri May 30 17:34:04 HKT 2014

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.


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