12V battery

First check that Aux Battery Saver is checked in the menu options controlled on the steering wheel, sounds like it isn't. Second, once your 12V battery suffers a discharge you may want to purchase and use a proper calcium-compatible charger, otherwise have it professionally charged.

crofter said:
Is there a simple test I can do to check this, other than putting a voltmeter on it every few days?
Click to expand...
There's no other practical test but you could attach a bluetooth BM-2 monitor, mentioned in various threads.

crofter said:
...some contributors to this thread talk about leaving the car in 'run' mode to charge the 12v battery. What is 'run' mode? Presumably not the one where the little green car is ready to move
Click to expand...
Yes, but ... from Run mode go into Utility mode from the same dash menus as above. That way the car can be left relatively secure and 12V charging will carry on for the entire duration.
 
Proposing another experiment: could any of you who keep having this
recurrent dead-12V trouble try *disabling* the battery-saver for a while?
And is there some way to set things up for less bluelink-related traffic,
without excavating the cell modem? But primarily the "saver" which seems
to wind up doing the opposite.

_H*
 
hobbit said:
Proposing another experiment: could any of you who keep having this
recurrent dead-12V trouble try *disabling* the battery-saver for a while?
And is there some way to set things up for less bluelink-related traffic,
without excavating the cell modem? But primarily the "saver" which seems
to wind up doing the opposite.

_H*
Click to expand...
You can disable all but one notification(emergency messages) in the Bluelink app.
 
hobbit said:
Proposing another experiment: could any of you who keep having this
recurrent dead-12V trouble try *disabling* the battery-saver for a while?
_H*
Click to expand...
In my experience with monitoring ABS events the aux battery always ends up at a higher voltage than it started with, normally leaving it at 13.0V. I think turning off the ABS will have the expected result.
 
Last edited:
crofter said:
I joined after reading this interesting thread. I think my 12v battery is not being charged, despite having the Aux Battery Saver + set in my Other Features, except when I am charging the main battery.
Click to expand...
I first posted this on 27 May. Since then I bought a BM2 and after fitting it I noticed from its app that the voltage was slowly declining until 5pm each day when it shot up from 12.5 to nearly 15v for 30 mins or so, after which it went back to 12.75v. Today I went to check and sure enough at 5 pm the graph shot up and the little light came on in the front emblem. Problem solved, but how? All I did was loosen the negative connector from the battery post to try to fit the BM2 (it was a mistake - you have to stack another nut on the bolt instead because not enough room in the connector). I have to assume that retightening it (at 5pm!) was what solved the problem. Battery connectors not tight enough is common so I suggest that others try that remedy. For the record the battery first went flat after about 110 starts when the traction battery was at 75% i.e. I had done 70 miles since charging. Obviously most trips were between drive and garage, this being during lockdown. Anyway thanks to all for the BM2 advice, an amazing little gadget that works out of the box.
 
Left the Kona parked for 16 days in a 50 degree garage, no change in available range or SoC.

Also, I had the "Aux. Battery Saver+" deactivated as per the US owners manual page H57-58 so no charging of the 12V battery from the traction battery. 12V battery voltage when I left it was 12.4V, upon return, 12.1V.

Never have the Aux Battery saver on....have not had any problem.
 
My guess is that provided you don't do a ridiculous number of short trips (i.e. about 100) between charges of the traction battery (at which time the Aux 12v battery also gets charged), you won't need the "Aux Battery Saver +"
 
There are certainly case scenarios where the ABS is not needed but there is no downside to leaving it 'on'.
 
This is an interesting change since I had the BMS recall/ TSB done, every four hours now the charge rate jumps up, not sure if this is increased monitoring of the 12 volt battery or something else that comes on in the BMS system and causes a charging event. I've attached before and after pictures:

After TSB.webp Before TSB.webp
 
Last edited:
The checking (dips in voltage) is likely primarily for the traction battery (insulation resistance) and perhaps the aux battery SoC at the same time. The higher frequency of checking is what I gathered from the campaign docs. If the aux battery tests OK perhaps it won't bother with an automatic 12V charge?
 
The June 10 graph is what my car looks like when it's trying to run ABS+ but not succeeding. But it could also be the car waking up and checking the high voltage battery, as KiwiME suggests, or doing any random function, or just opening the door every once in a while. In any event, it's not charging. The June 5 plot is what ABS+ looks like.
 
Toolworker said:
The June 10 graph is what my car looks like when it's trying to run ABS+ but not succeeding. But it could also be the car waking up and checking the high voltage battery, as KiwiME suggests, or doing any random function, or just opening the door every once in a while. In any event, it's not charging. The June 5 plot is what ABS+ looks like.
Click to expand...
And yet the residual 12 V level still drops at the same rate, thanks for the update, hopefully it starts to work as its supposed to - or I might be putting the update off a little longer.
 
I should have added that both these graphs were on days where the car was not used , just parked and no charger connected. To me it looks like that on the June 10th plot after the TSB that the car now checks in more frequently for some reason, I speculate this may be to make sure we don't have as many 12v battery issues? or BMS software changes?. My main point was that it is definitely a change around battery monitoring of some type. To this day I have never seen a dash warning mentioned in the owners manual saying battery saver was activated even though the battery has been charging on my graph. I have only had one instance of the dead battery and that was after many hours of fitting floor mats and the rear hatch open, the battery is fairly small!
 
I'd be interested in seeing more BM2 graphs to get an idea of what the changes are, particularly from days when your Kona is not driven, and the one day prior to those when driving to figure out what the triggers are. You seem to be the first owner with both a BM2 and the update.
 
Last edited:
Daily Charge - Parked.webp Parked -Charger On.webp Startup.webp So here are a few more graphs as requested, we just had the car parked for a few weeks and it went into a recharge 'once a day' mode, of around a 25 hour period. Each time it hits 12.73 volts the DC to DC charger steps in and brings the 12 Volt battery back up to 14.78. We have also lost the Aux Battery Saver function after the TSB install, though we never got a warning since the cars was new that this had been activated even though we saw the light on the grill lit.

Thanks BTW KiwiME for the BM2 heads up , us engineering types just love it. I have two friends with the same car and we all have them now!
 
Konan the Explorer said:
View attachment 8679 View attachment 8680 View attachment 8681 So here are a few more graphs as requested, we just had the car parked for a few weeks and it went into a recharge 'once a day' mode, of around a 25 hour period. Each time it hits 12.73 volts the DC to DC charger steps in and brings the 12 Volt battery back up to 14.78. We have also lost the Aux Battery Saver function after the TSB install, though we never got a warning since the cars was new that this had been activated even though we saw the light on the grill lit.

Thanks BTW KiwiME for the BM2 heads up , us engineering types just love it. I have two friends with the same car and we all have them now!
Click to expand...
Really excellent graphs. Thanks for that.
Its nice to see some additional action to attempt keeping the 12V battery charged due to the update.
After I get mine done, I will probably still keep up my usual habits of leaving the car "on" for a couple of hours ( if I find the resting voltage less than 12.65 v) every once in a while and monitor with voltmeter as I don't have BM2 .
I wonder how much additional drain is actually happening now for the car to check status more often?
 
You must log in or register to reply here.
Back
Top