The 12v Ohmmu issue with 2021.44.30 update

Truav8r

Active member
Joined
Aug 5, 2017
Messages
35
Location
Albany NY
Country
Country
Tesla Owner
Model 3
I installed the Ohmmu 12v battery about 4 weeks ago. Today, I got the “replace low voltage battery” and associated warnings before ever leaving the house. Did some quick reading, was preparing to contact Ohmmu with details, when I came across their support document outlining how this error might come about with a few recent software updates from Tesla. I’m on 2021.44.30 but it covers a couple other versions preceding that. Ohmmu’s support article says they are working on a fix and it will involve some kind of hardware fix/replacement. In the meantime, the article implies that the 12v is most likely fine (I’m surmising mine is fine, as it’s only been in service for 4 weeks). For anyone else that is seeing this issue with the Ohmmu and the recent software updates… are you more or less continuing to drive like normal until the fix is available? I see the USB ports and heated seats don’t work in this condition, and I’m fine with that, but wondering if anyone in the same situation is going about business as usual until the fix is ready?

For reference, here’s their document on this issue:
 
  • Informative
Reactions: TrevP and iChris93

Perscitus

Top-Contributor 👍🏻
TOO Supporting Member
Joined
Feb 22, 2017
Messages
517
Location
New York City
Country
Country
Tesla Owner
Model 3
Thanks for sharing. We've been here before with the 1st gen Ohmmu batteries for the 3 about 2-2.5years ago. At the time Tesla also changed something in their diagnostics and/or 12v monitoring and charging logic which caused issues and false positive alerts pre or post MCU software updates.

Now theyve done it again and are bound to do it again after the fleet of 3/Ys switch to the 18v for the 2022 refresh.

Now Ohmuu is indeed great but this game of cat and mouse with Tesla changing things (diagnostics, CAN bus messaging, v8/9/10/11 GUI, etc.

Its just a matter of time until old aftermarket auto frunk/trunk and self presenting doors start to malfunction depending on what Telsa does?
 

TrevP

TOO Founder / Technoking
Founder
Joined
Oct 20, 2015
Messages
8,213
Location
Toronto
Country
Country
Tesla Owner
Model Y
Tesla's charging system for the 12V seems to be rather touchy if anything changes. Changing to the lithium battery would likely throw some errors as evidenced by problems in the past. Personally I wouldn't mess with it.
Tesla is transitioning all their cars to CATL lithium 12V systems now anyhow
 

msjulie

Top-Contributor 👍🏻
TOO Supporting Member
Joined
Feb 6, 2018
Messages
790
Location
Monterey Pennisula
Country
Country
Tesla Owner
Model 3
Tesla's charging system for the 12V seems to be rather touchy if anything changes. Changing to the lithium battery would likely throw some errors as evidenced by problems in the past. Personally I wouldn't mess with it.
Tesla is transitioning all their cars to CATL lithium 12V systems now anyhow
Unexpectedly not backward compatible either - makes sense though, now all the cars' batteries and BMS one big cooperating family.
 
  • Like
Reactions: TrevP

Perscitus

Top-Contributor 👍🏻
TOO Supporting Member
Joined
Feb 22, 2017
Messages
517
Location
New York City
Country
Country
Tesla Owner
Model 3
The 2022 refresh will run a 15.5V Li-ion battery with a VC_Front / BMS and control/diagnostic functions configured to suite that. Sadly looks like retrofits to earlier fleet cars will either be hard or maybe entirely impossible.

Back on topic, any further updates from Ohmmu? Are v3 batteries or some type of v1/v2 retrofit or BMS-only update the solutio I haven't heard back in a few months.
 

Attachments

  • FHul8bjVEAElXu1.jpeg
    FHul8bjVEAElXu1.jpeg
    168.1 KB · Views: 9
  • 2a2a937b80e4096fcbadf8b28e8f3a3c0f32a4fd.jpeg
    2a2a937b80e4096fcbadf8b28e8f3a3c0f32a4fd.jpeg
    104.6 KB · Views: 8

Mr. Spacely

Top-Contributor 👍🏻
TOO Supporting Member
Joined
Feb 28, 2019
Messages
709
Location
St. Petersburg, FL
Country
Country
Tesla Owner
Model 3
This is not an 80's Ford. With the most aggressive technology in the world in our cars, I would never buy third party electronic accessories or add a third party app. It is just a matter of time that a software update isn't compatible with your fancy puddle lights...
 

shareef777

Legendary Member 🏆
TOO Supporting Member
Joined
Mar 9, 2019
Messages
2,052
Location
Chicago
Country
Country
Tesla Owner
Model 3
Thanks for sharing. We've been here before with the 1st gen Ohmmu batteries for the 3 about 2-2.5years ago. At the time Tesla also changed something in their diagnostics and/or 12v monitoring and charging logic which caused issues and false positive alerts pre or post MCU software updates.

Now theyve done it again and are bound to do it again after the fleet of 3/Ys switch to the 18v for the 2022 refresh.

Now Ohmuu is indeed great but this game of cat and mouse with Tesla changing things (diagnostics, CAN bus messaging, v8/9/10/11 GUI, etc.

Its just a matter of time until old aftermarket auto frunk/trunk and self presenting doors start to malfunction depending on what Telsa does?

Hadn't thought about the aftermarket kits. I've been using my powered frunk/trunk on my 3 for 2+ years now without issue through all the updates. As far as I'm aware, they have pass-thru connections for all the connectors so it should work just as if they weren't there. Did get the "replace 12V battery" message and mobile tech blamed the frunk kit for that, but replaced the battery anyway. Luckily I saved the original hydraulics for both my 3 and Y so if it really comes down to it I can just go back to the "old school" manual method.
 

Sjohnson20

Active member
Joined
Mar 8, 2018
Messages
176
Location
Orlando, Fl
Country
Country
Tesla Owner
Model 3
I just got the error the other day. I couldn’t update the software so I followed Ohmmu’s instructions to reset the car. After I did everything the car was completely dead. I had to hook up my jump start battery pack to get the car booted up. Now I’m wondering if the battery wasn’t charging at all and the warnings weren‘t just errors. I think I may buy a regular battery and put it back in. I didn’t know that adding this lithium battery could cause problems like this or I would have never ordered it.
 

buggaboo

New Member
Joined
Jan 23, 2022
Messages
1
Location
CO
Country
Country
Tesla Owner
Model 3
Watching this conversation... having the same issue with my recently purchased ~half-month old Ohmmu battery. When the errors were thrown, Teslafi showed that the car had essentially stopped sleeping so that the car would keep from bricking itself. Not an ideal behavior for avoiding battery drain while the car sits idle for extended periods - one of the major draws of the Ohmmu option. I tried the reset procedure, but it just went back to reporting battery issues within 12 hours (this time, initially, just the warning that the battery needed service) and was still staying awake most of the time. Decided to uninstall the Ohmmu and put back in the lead-acid. Can't wait for a fix.

I feel bad about the cat 'n mouse game that Ohmmu has to play with Tesla - I love that they're willing to offer a superior aftermarket product that fixes a weakness in Tesla's design, and wish that Tesla would find a way to work with aftermarket solution providers that are true improvements the the original vehicle.
 
Last edited:

michigantesla

Active member
Joined
Mar 9, 2019
Messages
45
Location
Chelsea Michigan USA
Country
Country
Tesla Owner
Model 3
I just got the error the other day. I couldn’t update the software so I followed Ohmmu’s instructions to reset the car. After I did everything the car was completely dead. I had to hook up my jump start battery pack to get the car booted up. Now I’m wondering if the battery wasn’t charging at all and the warnings weren‘t just errors. I think I may buy a regular battery and put it back in. I didn’t know that adding this lithium battery could cause problems like this or I would have never ordered it.
Same here. Got error that battery was degraded. Car stayed drivable by not going to sleep but this of course leads to some battery drain overnight. I tried resetting per the ohmu instructions and this led to a dead car. I measured the voltage on the ohmu and it was 1 volt so I swapped the lead acid battery back in and this brought the car back to life. In talking with Ohmu they said that the car thinks something is wrong with the ohmu battery and stops charging it. They said I can swap the ohmu back in after charging it but I am going to wait for a more permanent fix. They have good support and seem to want to fix it but Tesla software is such a moving target that it may never happen 100%. Too bad because I hate carrying around that extra weight. PS I did charge the ohmu back up and it seems fine.
 
  • Like
Reactions: Perscitus