[Ovmsdev] VW e-Up: 12V DCDC inverter start

Soko ovms at soko.cc
Mon May 16 18:15:04 HKT 2022

Hi Michael,

and thanks for the info. Not so good info for my project though... (see 
https://www.goingelectric.de/forum/viewtopic.php?p=1867824#p1867824 for 
So I reckon the trickle charge with ~12.9V cannot use the full capacity 
of 120A (stated in the link above) of the DCDC inverter. Only the the 
awake state with the ~14.5V might do that.

I hope I can start my investigation this week with a "regulated 
discharge test system" connected to the 12V battery. I hope that the 
(trickle) charge will start in any case when a minimum voltage is 
reached. Maybe 11.5V or so...

thanks again,

On 16.05.2022 12:04, Michael Balzer wrote:
> Soko,
> it seems many factors influence the DC trickle charge interval, 
> besides the actual voltage I think it's also at least temperature and 
> age. Chances are it also uses a load history.
> Regarding sending a command to force a trickle charge, that may be 
> possible by issuing an actuator test command ("Ausgabetest" in 
> OBDeleven), but I don't remember having seen anything like that in 
> Heiko's screenshots. I did an analysis for one of these commands 
> (unlocking / locking the charge port), see my mail "Re: Schreibzugriff 
> OBD" of june 5th 2021 on our e-Up list.
> Another approach would be to wake up the car and keep it awake as long 
> as needed. That seems to possible via Comfort CAN only -- you can keep 
> the car awake via OBD, but not wake it up (at least no method known yet).
> Be aware waking the car up sets a higher voltage level: trickle charge 
> only runs at ~12.9V, while awake it's ~14.5V. I assume the 12V battery 
> has a charge regulator so it won't take damage from a longer period at 
> that level, but the equipment you'd like to power (assumed) could have 
> an issue with that.
> Regards,
> Michael
> Am 16.05.22 um 08:03 schrieb Soko:
>> Hey guys & especially the VW e-Up ones,
>> I was wondering about the current status of writing to the e-Up.
>> I currently in "need" to start the 12V DCDC inverter when the car is 
>> off and locked. Is this currently possible or at least feasible?
>> Are there any detailed infos when this inverter starts automatically. 
>> Apparently its not just a question of the current 12V voltage...
>> Thanks heaps
>> Soko
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