[Ovmsdev] OVMS Power Drain?

Michael Geddes frog at bunyip.wheelycreek.net
Tue Sep 27 15:41:19 HKT 2022

Thanks Michael,

I rang the Hyundai service centre, and apparently, my BMS should not need
any updates (build date 2021 vs 2020 cars with the problem apparently), but
I'm putting it in for a checkup of the battery.  Apparently, the BMS update
was the subject of a recall for those cars affected. I'm going to take it
in anyway in case.

It seems, according to the OVMS, that the 12V is going from 13v down to 12v
over about 3hours before (generally) being recharged.  Looking at that link
you shared with me (and related
https://www.youtube.com/watch?v=lr3Z_z1C0Uk&t=965s), it should be more like
24 hours.   It still should be triggering a charge cycle - and obviously in
this case it seems to miss one and then it just goes downhill from there -
so maybe the BMS still has a bug; not helped by being forced to trigger
about 4x more frequently than normal!

Assuming nothing is wrong with the car (which unless I install some kind of
external battery monitor like that youtube clip), I can only assume that
the 3hr drain is because my Ioniq 5 module is polling too much (which,
seeing I copied the vehicle_kianiroev/src/ as my base, would mean THAT
polls too much as well).  I still have the  PollSetPidList() called with
the same data (albeit a copy) as the Kia.

So in drafting this email I think I've hit on the problem, which is when
the car is off, but a V2 or V3 client is connected (like the android app in
'background' mode), then it uses the 'Charging' pollstate element.

It has {OFF, Charging, ON} at the moment, which means there's space for a
4th which I will assign to 'off, not-charging and clients connected'.  I'll
see what I can do to drop that right down in polling frequency and the
number of modules being addressed.

At some point soon it might be worth me pushing up to a fork in case
anybody else wants to jump in!  For example, the Lock module that the kia
has is not present in the Australian version, but I suspect US ones with
key-card ability might have it.


On Fri, 23 Sept 2022 at 17:03, Michael Balzer <dexter at expeedo.de> wrote:

> Michael,
> while the OVMS draws some power, unless you actually keep the car alive
> by polling, that's normally no issue. The 12V battery will be recharged
> automatically from the main battery by the car.
> The Ioniq 5 though has a history of issues with the 12V battery.
> According to Andrew Till, a BMS update has fixed his issues:
> https://www.youtube.com/watch?v=YmfkvL_O1IA
> Also see his previous posts on that topic.
> Regards,
> Michael
> Am 23.09.22 um 09:55 schrieb Michael Geddes:
> > Hi All,
> >
> > I have just had a bit of a painful experience with my 12V being
> > drained (twice).  I'm guessing it's related to OVMS, but also
> > something seems to have happened as it was running file for a week!
> >
> > For some reason, the 12V battery graphs aren't working in the
> > (android) App.. which means I'm not quite sure of the timelines,
> > however it was most likely overnight.  This morning my 12V was
> > severely depleted (like 6v!). (Oh, it could be because I don't have
> > the app running in the background).
> >
> > I'm assuming it's likely not to be the direct drain of the device
> > itself, but maybe something it is querying on the CAN busses or
> > something that is then causing a consequential power drain?
> >
> > I got road-side assist out and they got me going, but then 20mins
> > later it was flat again! (I did see an alert in the APP and so was
> > quick to go out, but was unsuccessful in getting the car going before
> > it died!).
> >
> > I'm going to unplug it and see if that stops the card from dying.
> > Also, I might leave the car on for a bit longer.. but still I have
> > concerns!
> >
> > Also I haven't started using 'write' commands yet. Any ideas?
> >
> > //.ichael
> >
> --
> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
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