Ohmmu 12V Battery Feedback

[Flybyglass]

I received a response from Ohmmu this morning. As expected they ARE standing behind the product. They understand how these error messages are occurring and even who the Tesla engineer is behind them. Tesla did NOT engineer a method of blocking after market batteries. The latest Tesla revisions have 12 volt overcharge protections that are conflicting with the Ohmmu BMC logic. The Ohmmu still works and will charge OK. On the Ohmmu website is a reset procedure to clear the error(s) and a there is a Hardware fix coming for existing owners Jan/Feb. and a redesign ready Mar/Apr. Here is the link to reset and where you can report the issue. You will need to set up a login during the process which helps with communications. Tesla | All Models | "Replace 12V Battery Soon" Alert

 

[MasterC17]

I'll just share my experience as a reference point.

I've replaced several Ohmmu Lithium 12V batteries on S, X, and 3 due to early failures. Most of the time they just stop holding a charge, but I've also seen cells expand and break open the casing. I would not consider them to be reliable. The cells are made overseas and the quality control does not appear to be very high.

I'm running MPP Lithium 12V batteries in my 2021 Model 3 Performance and 2021 Model Y Performance, both on the latest firmware updates, neither currently have, or have had alerts. The battery in the Model 3 is about a year old, and the one in the Y is about 4 months old.

For anyone curious, here's photo's of one of the expanded cells from an Ohmmu. Not saying this will happen to them all, but worth mentioning.

 

[Jschwind]

Last month I received the errors about the electrical system is unable to support all features, schedule service to replace low voltage battery etc. I live far from a service center, had a trip coming up and was unable to schedule a service appointment due to work, so I purchased an Ohmmu battery and replaced it myself. Problem went away until today and error messages came back. I scheduled a service visit for next week. Is there anything I can try in the meantime? I had tried the car reset by holding brake and steering wheel buttons to no avail. Thanks.

 

[thesmokingman]

The Ohmmu probably got firewalled. Refer to the big Ohmmu thread?

 

[jjrandorin]

The Ohmmu probably got firewalled. Refer to the big Ohmmu thread?

(moderator note)

Thread moved to one of the threads on ohmmu battery, which is why you will now find your post in one such thread.

 

[Jschwind]

After the update yesterday, my car got the message and is now the car won’t even turn on.

 

[lasdj]

I'll just share my experience as a reference point.

I've replaced several Ohmmu Lithium 12V batteries on S, X, and 3 due to early failures. Most of the time they just stop holding a charge, but I've also seen cells expand and break open the casing. I would not consider them to be reliable. The cells are made overseas and the quality control does not appear to be very high.

I'm running MPP Lithium 12V batteries in my 2021 Model 3 Performance and 2021 Model Y Performance, both on the latest firmware updates, neither currently have, or have had alerts. The battery in the Model 3 is about a year old, and the one in the Y is about 4 months old.

For anyone curious, here's photo's of one of the expanded cells from an Ohmmu. Not saying this will happen to them all, but worth mentioning.

Based on your experience, how long ago or when did you purchase the batteries? Was there a new update design that maybe resolved this issue?

 

[Flybyglass]

Based on your experience, how long ago or when did you purchase the batteries? Was there a new update design that maybe resolved this issue?

A fix is coming. Sounds like a module for exiting owners and a redesigned battery a couple months later.

 

[MasterC17]

Based on your experience, how long ago or when did you purchase the batteries? Was there a new update design that maybe resolved this issue?

Some were older (3 years), but others were fairly new (six months or so). I'm not privy to the design changes/cutoffs they have made, but I would certainly be cautious about getting one of these, especially for the money.

 

[Flybyglass]

Some were older (3 years), but others were fairly new (six months or so). I'm not privy to the design changes/cutoffs they have made, but I would certainly be cautious about getting one of these, especially for the money.

The fix for existing battery owners should be out within a month (Jan/Feb time frame). A new battery should be out in the Mar/Apr timeframe. My understanding is for existing owners there will be a module used to solve the issue and right now if you check the Ohmmu site they are not selling Model 3/Y batteries during this transition. The batteries coming out in Mar/Apr will incorporate the changes needed. Based on what I'm hearing, the battery itself is the same but changes needed to be made to the built in BMC (Battery Management Computer). Tesla DID NOT block the battery use. Tesla made some software changes to protect Lead batteries from overcharging and it was causing conflict. The temporary reset procedure above and on the Ohmmu site clears the messages. Ohmmu is very aware and working quickly to correct the problem.

 

[JSNH1919]

The reset procedure barely works. I went thu it and it did clear the error message but by morning it popped up again. I put Ohmmu battery in in December since my lead acid was 3 years old. I might put the lead acid one back in this weekend since it is still serviceable. I don't like annoying messages on screen that prevent software updates especially being on the beta FSD.
Understand the issue but disappointed with the Ohmmu at this time.

 

[citywide4100]

I attempted a hard reset several times (Ohmuu Model Y Battery) and my Y Perf never came back on. Jumped my OEM battery, put it back in, worked fine. Good thing I kept it. The Ohmuu was reading 10.88 amps, which apparently isn't enough to re-engage the connector or fire back up the lights, or touch screen. It's been 4 days now and Ohmuu hasn't responded to my email. Starting to consider other options. I wonder if you can safely recharge the Ohmuu with one of these jobbies...
Dakota Lithium Battery Charger.

 

[citywide4100]

I attempted a hard reset several times (Ohmuu Model Y Battery) and my Y Perf never came back on. Jumped my OEM battery, put it back in, worked fine. Good thing I kept it. The Ohmuu was reading 10.88 amps, which apparently isn't enough to re-engage the connector or fire back up the lights, or touch screen. It's been 4 days now and Ohmuu hasn't responded to my email. Starting to consider other options. I wonder if you can safely recharge the Ohmuu with one of these jobbies...
Dakota Lithium Battery Charger.

Pretty sure that's volts, not amps. Not many good 12v lithium options out there, it seems.

 

[Flybyglass]

I attempted a hard reset several times (Ohmuu Model Y Battery) and my Y Perf never came back on. Jumped my OEM battery, put it back in, worked fine. Good thing I kept it. The Ohmuu was reading 10.88 amps, which apparently isn't enough to re-engage the connector or fire back up the lights, or touch screen. It's been 4 days now and Ohmuu hasn't responded to my email. Starting to consider other options. I wonder if you can safely recharge the Ohmuu with one of these jobbies...
Dakota Lithium Battery Charger.

Ohmmu told me a battery charger is OK to use. The internal BMC would prevent any overcharging. Do a chat message they do return it may take a day or so. The Ohmmu site under support has some information. I had the same messages you posted. I was able to clear using the Ohmmu procedure I went a step farther. I noted my Ohmmu was at 87% charge (using my Diehard charger) and I charged it to 91% reconnected it to the car using the procedure in the reset. The Ohmmu then charged to 95% (I disconnected it to do the measurement.) I then decided since I had the original OEM battery on the shelf with low miles to swap while waiting for the fix. My OEM still had 95% after sitting on the shelf for a year. What I do notice is at cold temps (near zero) my M3 is much slower to wake up. So I am waiting for the fix like everyone else. The only other Lithium battery I have seen is from Mountain Pass Performance and like the Ohmmu it also has an internal BMC. They claim no issues but since they cost more and sell far fewer I wont move to that version. Plus there is a bunch of hardware to do the swap. Ohmmu knows what the issue is, has a fix coming (most likely a module you add which will be quicker than a battery replacement as the battery itself is fine). They wont have an actual replacement battery until the Mar/Apr time frame but the replacement will be the same as adding the module just internal from manufacturing. The model solution Ohmmu says is the fastest way to correct the issue. As I had mentioned in previous post, Ohmmu know the individual engineer that made the software change at Tesla and what the change was and the corrective measures.

 

[Flybyglass]

This is from the Ohmmu web site. On their site at the bottom is a report button to keep informed on progress for resolution. Put yourself on the list.



Known Issue Working on it

Tesla | Model 3 / Y | "Schedule service to replace low voltage battery" Error​

If you wish to follow and receive updates on this Known Issue, please sign up or login (support.ohmmu.com) and click the "Report" button at the bottom of this page.
Otherwise, this article will be updated and we will provide additional information and status updates as we monitor and work on this issue, so please check back regularly.

Support Notice Information​

A potential issue has been identified for customers with Tesla Model 3 and Model Y vehicles, running software updates 2021.36.x, 2021.40.x, and 2020.44.30.x.

Tesla has pushed several new features with their recent updates, which appear to alter the method and extent that the vehicle utilizes its 12V battery. Due to these changes, it is possible that you may receive error alerts for your 12V battery on your Model 3 or Model Y vehicle when it updates to these software versions.

IMPORTANT NOTES:

1. We have identified the issues causing these errors.
2. Ohmmu is currently developing a hardware revision to resolve this issue for existing customers, which should be available in January/February 2022.
3. Ohmmu began developing a revised battery design in December 2021, which will also resolve and prevent these issues from occurring in the future. The revised batteries will be available in March/April 2022 for new customers and potentially existing customers on a case by case basis.

If you're experiencing error alerts, your battery is most likely healthy and your vehicle will continue to operate (some features may be turned off by Tesla software, such as USB ports and seat heaters).

However, if you receive this error alert and experience any other issues, please contact Ohmmu Support and we will walk you through a reset procedure or assess your situation and provide the necessary assistance.

To clear the error alerts and perform a software update (which may resolve these issues), please follow the RESET & SOFTWARE UPDATE PROCEDURE provided below.

RESET & SOFTWARE UPDATE PROCEDURE for Tesla Models 3/Y with Software Versions 2021.36.x, 2021.40.x, 2021.44.30.x​

Support Notice For:
Vehicles: Tesla Model 3, Model Y (Does not apply to other makes/models)
Software Versions: 2021.36.x, 2021.40.x, 2021.44.30.x

Reset & Update Procedure (Est. Time to Complete: 15 mins)

1. If possible, drive your vehicle for ~10 mins prior to performing this procedure
2. Confirm that next Tesla software update version is staged for installation (12V alert does not effect this update from downloading to your vehicle)
3. Unplug all USB devices in vehicle cabin
4. IMPORTANT: Roll window down and leave the driver's door open for the ENTIRE PROCEDURE (Model 3: Also leave passenger side rear door open)
5. Open Frunk
6. On MCU (Tesla computer touchscreen in vehicle cabin), tap "Power Off" under "Safety and Security" menu and confirm
7. Exit vehicle (be careful not to close driver's side door) and lift open Frunk
8. Model 3 (All) and Model Y (2020 - Early 2021): Remove upper trim panel in Frunk by pulling up edges gently
9. Model Y (Late 2021+ w/ HEPA Filter): Remove the 2x 10mm bolts securing the HEPA filter, remove filter assembly, and then remove upper trim panel in Frunk by pulling up edges gently. You can watch a video of this process here: Watch Video
10. Locate (DO NOT disconnect yet) High Voltage (HV) disconnect method for your vehicle - see below:

Model 3: Located under passenger side rear seat (to access, slide seat lock tab toward center driver side to unlatch, then lift seat cushion up, remove black foam block, and locate grey plug underneath)

Model Y: Located in Frunk on passenger side above wheel well (red/black connector near First Responder Loop w/ orange tag)
11. Using a 10mm wrench, loosen the negative terminal of the 12V battery (this is the terminal nearest the drivers side, without a red cover and no fuse attached)
12. Remove negative terminal -- be careful not to drop lead spacer! Position the negative connector lug so that it doesn’t fall back onto the negative battery terminal.
13. Disconnect HV

Model 3: Unlock Grey/black header by pinching top and rotating locking arm downwards, then pull up to disconnect

Model Y: Slide red lock open, then squeeze end of plug while pulling apart to disconnect
14. Wait 10 seconds
15. Reconnect HV

Model 3: Reconnect Grey/black header by pushing firmly back into place and then rotate locking arm upwards into locked position

Model Y: Push together connectors and slide red lock into closed position
16. Wait 20 seconds (Don’t need to wait any longer than this)
17. Reconnect negative terminal lug -- again, be careful not to drop the lead spacer!
18. Tighten negative lug connector using 10mm wrench
19. Model 3: replace foam block, then push rear seat down into position firmly, lift up to confirm it has latched
20. Model Y (Late 2021+ w/ HEPA Filter): Reinstall HEPA filter using 2x 10mm bolts
21. All Models: Secure top trim panel in frunk by placing into position then pressing along edges to snap together (will hear/feel snap)
22. Wait for vehicle to reboot
23. Disable sentry-mode under "Safety and Security" menu
24. Wait 1 hour (this gives 12V battery time to recharge before initiating update)
25. Update software

For Additional Support, Please Contact Us at:

Email: [email protected]
Chat: ohmmu.com

Our Commitment to You

Ohmmu is committed to our customers and the excellence of our products, and we apologize for any inconveniences you have experienced due to the recent Tesla software updates 2021.36.x, 2021.40.x, and/or 2021.44.30.x.

Please know that we are continuing to evaluate this issue and working hard on further developing solutions that will prevent occurrences like this from happening in the future.

Thank you so much for your patience and support -- if you have any questions or require additional assistance, please contact: [email protected]

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[citywide4100]

Ohmmu told me a battery charger is OK to use. The internal BMC would prevent any overcharging. Do a chat message they do return it may take a day or so. The Ohmmu site under support has some information. I had the same messages you posted. I was able to clear using the Ohmmu procedure I went a step farther. I noted my Ohmmu was at 87% charge (using my Diehard charger) and I charged it to 91% reconnected it to the car using the procedure in the reset. The Ohmmu then charged to 95% (I disconnected it to do the measurement.) I then decided since I had the original OEM battery on the shelf with low miles to swap while waiting for the fix. My OEM still had 95% after sitting on the shelf for a year. What I do notice is at cold temps (near zero) my M3 is much slower to wake up. So I am waiting for the fix like everyone else. The only other Lithium battery I have seen is from Mountain Pass Performance and like the Ohmmu it also has an internal BMC. They claim no issues but since they cost more and sell far fewer I wont move to that version. Plus there is a bunch of hardware to do the swap. Ohmmu knows what the issue is, has a fix coming (most likely a module you add which will be quicker than a battery replacement as the battery itself is fine). They wont have an actual replacement battery until the Mar/Apr time frame but the replacement will be the same as adding the module just internal from manufacturing. The model solution Ohmmu says is the fastest way to correct the issue. As I had mentioned in previous post, Ohmmu know the individual engineer that made the software change at Tesla and what the change was and the corrective measures.

Thank you for your response. I'll follow up with Ohmuu using the chat, instead. The Mountain Pass battery kit is on backorder. I found this thing somewhere:
Kepworth 12v Lithium Batteries 40ah - 54ah. I like that it has that LED readout of the battery's current voltage built in. I've never heard anybody using a Kepworth in their Tesla, and I'm rightly apprehensive. It's good to know the Ohmuu can be recharged in a pinch with the correct type of charger. Especially if support is several days wait.

 

[Flybyglass]

Thank you for your response. I'll follow up with Ohmuu using the chat, instead. The Mountain Pass battery kit is on backorder. I found this thing somewhere:
Kepworth 12v Lithium Batteries 40ah - 54ah. I like that it has that LED readout of the battery's current voltage built in. I've never heard anybody using a Kepworth in their Tesla, and I'm rightly apprehensive. It's good to know the Ohmuu can be recharged in a pinch with the correct type of charger. Especially if support is several days wait.

The issue becomes would the built in BMC conflict with the Tesla charging DC-DC converter? I suspect it would that is probably why even the MPP battery is on "backorder". It may also be undergoing a BMC update.

 

[MagnusMako]

Zero issues with the EarthX MPP 12v Li-Ion battery here other than a loose terminal connection a few weeks ago that required me to jump the car to pop the hood and use a washer to tighten the terminal cable clamp.

 

[android04]

The issue becomes would the built in BMC conflict with the Tesla charging DC-DC converter? I suspect it would that is probably why even the MPP battery is on "backorder". It may also be undergoing a BMC update.

The reason that the MPP battery is backordered is probably that they are waiting on the machine shop to make more mounts for the battery. The battery is from EarthX in the USA and they are in stock (ETX900 EarthX Lithium Battery for experiemental aircraft!), and MPP had nothing to do with the battery or the management system. MPP sends the machined custom mounts to EarthX, and EarthX actually ships out the order for the battery and mounting kit when you buy from MPP.

 

[android04]

Thank you for your response. I'll follow up with Ohmuu using the chat, instead. The Mountain Pass battery kit is on backorder. I found this thing somewhere:
Kepworth 12v Lithium Batteries 40ah - 54ah. I like that it has that LED readout of the battery's current voltage built in. I've never heard anybody using a Kepworth in their Tesla, and I'm rightly apprehensive. It's good to know the Ohmuu can be recharged in a pinch with the correct type of charger. Especially if support is several days wait.

That Kepworth battery has no warranty, so you are on your own if it fails. Also, the voltage display isn't really useful because it will be hidden behind the frunk trim and will be upside down when you install it.