Ohmmu Model 3 12v Lithium Battery

[RandyS]

Selling a November 2021 Ohmmu 12v Lithium battery for Model 3 as-is. Purchased for $433 and installed in November 2021 and removed from service in October 2022. Asking $175 OBO plus $20 shipping or local pickup in San Diego. I want to be open/honest/transparent about the product, so you should know this if you don't already: There are compatibility issues with this product and Tesla's new 12v management software. It is best suited for someone that is familiar with the product; wants to experiment, knows what they're doing, or wants to use it for another purpose, etc. See the full story below...

Full story: I ran the Ohmmu battery for 11 months with no issues in my Model 3. After updating my FSD beta software in October while on a road trip, one day later I got a 12v battery low voltage error message on the car. I read about the issue on Ohmmu's website and contacted them.

Link to Ohmmu support page: Tesla | All Models | "Replace 12V Battery Soon" Alert - Ohmmu Support

The issue is caused by a change in Tesla's 12v battery management software. There is a work-around suggested by Ohmmu that involves charging the battery manually and resetting the car to eliminate the error. Down the road, there could be a more robust hardware solution available; I don't know what the timeline is for that.

I decided to purchase a 12v lead-acid replacement battery from Tesla and move on. After I replaced my battery, in my correspondence with Ohmmu, they offered me a $250 refund/settlement on my earlier purchase, which I accepted. The battery is fine, it's just that Tesla changed their software that manages and monitors the battery. There is some good life left in this battery and I'm hoping that someone can get some good use out of it, perhaps in another application or with a Tesla if you have skills and patience to work through the issues.

If you have any questions, please let me know...

 

[RandyS]

Bump.

 

[Anthony1960]

Selling a November 2021 Ohmmu 12v Lithium battery for Model 3 as-is. Purchased for $433 and installed in November 2021 and removed from service in October 2022. Asking $175 OBO plus $20 shipping or local pickup in San Diego. I want to be open/honest/transparent about the product, so you should know this if you don't already: There are compatibility issues with this product and Tesla's new 12v management software. It is best suited for someone that is familiar with the product; wants to experiment, knows what they're doing, or wants to use it for another purpose, etc. See the full story below...

Full story: I ran the Ohmmu battery for 11 months with no issues in my Model 3. After updating my FSD beta software in October while on a road trip, one day later I got a 12v battery low voltage error message on the car. I read about the issue on Ohmmu's website and contacted them.

Link to Ohmmu support page: Tesla | All Models | "Replace 12V Battery Soon" Alert - Ohmmu Support

The issue is caused by a change in Tesla's 12v battery management software. There is a work-around suggested by Ohmmu that involves charging the battery manually and resetting the car to eliminate the error. Down the road, there could be a more robust hardware solution available; I don't know what the timeline is for that.

I decided to purchase a 12v lead-acid replacement battery from Tesla and move on. After I replaced my battery, in my correspondence with Ohmmu, they offered me a $250 refund/settlement on my earlier purchase, which I accepted. The battery is fine, it's just that Tesla changed their software that manages and monitors the battery. There is some good life left in this battery and I'm hoping that someone can get some good use out of it, perhaps in another application or with a Tesla if you have skills and patience to work through the issues.

If you have any questions, please let me know...

View attachment 886151

I had alert issues too mostly when it got really Hot or really Cold.They ended up sending me a newer version last month. Still have old battery which is fine. They never sent a call tag for the old battery so I have two now. BTW it still didn't solve the problem. Ended up carrying a 10mm Ratchet with me so I can reset the battery when this happens. Its a pain in the ass but have gotton really good at the procedure. Anyone in Connecticut interested in my other Ohmmu let me know.

 

[Flybyglass]

I had alert issues too mostly when it got really Hot or really Cold.They ended up sending me a newer version last month. Still have old battery which is fine. They never sent a call tag for the old battery so I have two now. BTW it still didn't solve the problem. Ended up carrying a 10mm Ratchet with me so I can reset the battery when this happens. Its a pain in the ass but have gotton really good at the procedure. Anyone in Connecticut interested in my other Ohmmu let me know.

If you have the V4+ with bluetooth there is a reset procedure where no tools needed and can be done from the drivers seat.

 

[Anthony1960]

If you have the V4+ with bluetooth there is a reset procedure where no tools needed and can be done from the drivers seat.

V4+? My car is a 2018 2.5HW what are you talking about? Tell me the procedure

 

[Flybyglass]

V4+? My car is a 2018 2.5HW what are you talking about? Tell me the procedure

The 12 volt Ohmmu battery with Bluetooth is a V4+. From the Ohmmu.com support section:

Tesla | Model 3 / Y | Rev4+ Reset Procedure via Ohmmu App​

RESET PROCEDURE for Tesla Models 3 / Y Rev 4+ via Ohmmu App​

Reset Procedure (Est. Time to Complete: 10 mins)

1. Download and install the Ohmmu App from the App Store for iOS or Google Play for Android.
2. Open Ohmmu app and verify your Ohmmu 12V battery is listed in the devices list. Your battery needs to be a Rev 4+ or greater to connect with the Ohmmu App.
3. Follow the reset procedure below (future versions of the app will streamline this process).

Power Cycling the Vehicle
If your vehicle demonstrates unusual behavior or a nondescript alert is present, you can try power cycling the vehicle to potentially resolve the issue.

• Shift into Park.
• On the touchscreen, press 'Controls' > 'Safety & Security' > 'Power Off.'
• Wait for five minutes without interacting with the vehicle. Do not open the doors, touch the brake pedal, touch the touchscreen, etc. Once all courtesy lights have turned off, you should be able to proceed.
• Launch the Ohmmu app to connect to the battery and ensure your battery's state of charge (SOC) is >15%. If not, wait for your 12V battery to charge up above 15% before proceeding.
• Toggle OFF 'Enable Charge' and 'Enable Discharge' on Home screen.
• Wait 60 seconds and then press brake pedal to ensure that the car does not wake up and is fully powered off.
• Toggle ON 'Enable Charge' and 'Enable Discharge'.
• After two minutes have passed, press the brake pedal to wake the vehicle.

**Please note the enable charge and enable discharge switches will tell the BMS microcontroller to, in effect, "block" charging or discharging or "allow" it. If charge is enabled, for example, the BMS will leave the battery internally connected when current is at 0.0A or anything higher (positive current going into the battery), but if charge is disabled, the BMS would react to any current greater than 0.0A and internally disconnect it. If charge is disabled, then, the battery can't charge but it can discharge and will eventually be dead. Please be mindful toggling these switches in the app as they may leave the battery in a state where it is blocking all charging.