OVMS causes 12v battery to run flat

OVMS ice causing the 12v battery to run flat on my Kona EV

Hi David,

Sorry to hear your having issue with OVMS. Could you provide some more info about happened?

  • How long was the car sitting when the 12V was depleted?
  • Did you receive a push notification from the OVMS mobile app to alert you that the battery was running low?

OVMS android app has an integrated graph to keep a track of the 12V battery voltrage, could you try to use this to monitor the battery voltage and post some screenshots:

The car was standing for 5/6 hours before the battery fell below 11V. I did receive a push notification, but the Battery Saver function on the Kona did not kick-in to recharge the 12V battery. I’m using the iOS App

Is this the first time this has happened?
How long have you been using OVMS?
Could something else on the car caused the battery to be depleted on this particular evening?

OVMS only consumes 0.1A (1.2W), which should not be any problem for the 12V battery, at least for a couple of weeks.

I have no experience with a Kona EV myself, however searching on Google for Kona 12V battery reveals lots of threads with people having issues with the 12V battery without using OVMS. The Kona EV OVMS sub-forum does not seem to have any posts about 12V battery. It may be worth getting the health of your 12V battery tested.

If you decide you no longer want to continue using OVMS we would be happy to offer a full refund on return.

Hi Glyn,
I’m getting the battery checked tomorrow (Friday) and will let you know the outcome.

Would disabling features like WiFi and GPS reduce the power consumption ?



Great, interested to hear the result of the check. I’ve just measured the power consumption of the OVMS module again, power consumption will drop slightly if the modem (3G + GPS) is switched off, but not that much.

Wifi + 3G + GPS: 85mA
Wifi only: 49mA

As I mentioned the energy consumed by OVMS is very small, there must be some other issue that is keeping the car awake. This is a possibility that OVMS is keeping the CAN bus awake for some reason which results in a higher current draw since the cars systems are not going to sleep. The only way to know for sure would be to measure the DC current draw on the 12V battery in situ. I would have thought if this was an inherent issue with OVMS and Kona that we would have heard of other users reporting it.

How long was OVMS installed before the 12V battery went flat?

In the meantime it may be useful to carry a jumper pack e.g


Hi Glyn,
Update - The garage claims there is nothing wrong with the battery, but I’m not convinced - even the dashcam flattens it overnight (never used to do that). What I don’t understand is why the Battery Saver function is not charging the 12V battery when the
voltage gets low. When I asked the question, just got blank looks - I don’t think they’re very familiar with EV’s.
In its current state, I am unable to leave the OVMS connected when the car is off, so I am seriously considering returning it for a refund.



Hi David,

Sorry to hear the issue has not been resolved. We would be happy to issue a refund if you do decide to send the OVMS module back. However, it sounds like there is some other issue at play here if the dashcam also drains the battery overnight.

Looking at the Kia eNiro user group, it seems clear that I’m not the only one having battery problems

Which user group is this? Please post a link, so I can take a look. I think it would be a good idea for you to post on the Kia eNiro sub-section of the OVMS user forum: Kia e-Niro | Open Vehicles


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I now get an intermittent fault where it reports the main battery at 0%, rebooting the unit doesn’t fix it, power cycling does - Any ideas ?