Ohmmu 12V Battery Feedback

[android04]

i bought the Ohhmu battery for my Performance Model 3. It worked great until there was an update from Tesla. Apparently, Tesla is aware that this battery is not OEM and through the software quarantines it. Ohmmu tells me they are working on it, but no solution yet. I bought a Tesla battery (which had i known there was a 50K warranty on and would have been free) battery for an additional $119, but feel a little taken. Ohmmu has stopped communicating with me, so i think i am out the 439 i paid, but you might want to think about that before purchasing...

I don't think Tesla is quarantining it. It just has different charging behavior than what Tesla programmed to detect for the OEM battery. A wise man once said "don't attribute malice to what can be explained by incompetence". I wouldn't say that incompetence applies with regards to the Ohmmu though. I don't expect Tesla to try to program in detection and different behavior for different types of batteries. It's great if they do, of course.

 

[Wennfred]

i bought the Ohhmu battery for my Performance Model 3. It worked great until there was an update from Tesla. Apparently, Tesla is aware that this battery is not OEM and through the software quarantines it. Ohmmu tells me they are working on it, but no solution yet. I bought a Tesla battery (which had i known there was a 50K warranty on and would have been free) battery for an additional $119, but feel a little taken. Ohmmu has stopped communicating with me, so i think i am out the 439 i paid, but you might want to think about that before purchasing...

If you read their email correctly, they said they will be swapping out the battery for free soon.

Fred

 

[RayK]

I just signed up on the Ohmmu site and asked them to keep me up-to-date on the status of the Model 3 battery (I don't have one of theirs yet). They said that the Rev2 variant should be shipping out in 4-5 weeks.

 

[Flybyglass]

Update 2020.36.10 finally updated today after repeated attempts. According to the Ohhmu site, there is an incompatibility with Model 3 software until they release a new battery in October. I removed my Ohhmu battery and replaced with the factory battery that I had removed when I first purchased the car. Software version 2020.36.10 would not go past 60% until I swapped and put the factory battery back in. Update progressed as t should and now after 4 weeks of failed installs it works as advertised. Now idea what a 12 volt battery would be an issue but it is a Tesla.

 

[Flybyglass]

Contacted Ohmmu about the battery issue. Since my battery was purchased in late Jan.2020. Took about 2 weeks but they sent out a Rev 2 battery no charge with a return shipping for the rev 1 battery. Have not done any software updates yet but after replacing rev 1 with the original factory battery (that I still had since it had only been used a few days) 2 software updates installed successfully. So far no issues with the rev 2 battery. Good customer service with Ohmmu. They had a problem, corrected it and made good with previous buyers.

 

[SageBrush]

I'd appreciate some feedback here whether I am understanding LiFP chemistry correctly when used in my Tesla Model 3:

So far as I can tell, the Tesla charging algrorithm charges up the 12v to 13.1v. In a LiFP auto battery, 13.1v is about 50% SoC

Dos this sound about right ?

 

[FurryOne]

I'd appreciate some feedback here whether I am understanding LiFP chemistry correctly when used in my Tesla Model 3:

So far as I can tell, the Tesla charging algrorithm charges up the 12v to 13.1v. In a LiFP auto battery, 13.1v is about 50% SoC
Dos this sound about right ?

The Ohmmu Model 3 battery has it's own Battery Management System that optimizes whatever the Tesla gives it. Ohmmu came out with a battery with their V2 BMS back in October. That's what I have since October in my Model 3 AWD.

Tesla should charge their battery (SLA/AGM) at 14.4v, and charging should be kept below 14.7v (Nominal SLA/AGM battery voltage should be 13.1v). LiFEPO4 battery nominal voltage should be 13.4v, and charging should not exceed 15.2v. So there should be no problem with LiFEPO4 batteries in a Tesla. Worries about cold-weather charging LiFEPO4 batteries should be taken care of by the BMS.

 

[DAS CO]

This thing costs $439????

Same, 3 yrs & 63,000 miles ….I would’ve changed it out @ 49,000!! Oh well, live & learn!

 

[Robert Sansone]

My question is if I want to replace my 12 volt original battery with the new lithium battery, I was told that the car computer would have to be reprogrammed or updated for this new battery. None of the videos that I have watched on replacing this battery with the new lithium talked about this. I was told this by a tesla tech.
Is this true?
Thank you
Robert

 

[Candleflame]

no

 

[Stanwood Steve]

I replaced my OEM Battery with the Ohmmu battery with absolutely no issues (about six months ago). The OEM battery was still working fine, but this was a preemptive move given all the issues being mentioned on the forum and my desire not to be left stranded anywhere. The replacement was very straightforward (instructions with battery were very clear), and no reprogramming was required. Pretty simply swap out and I've experienced no issues whatsoever.

 

[Pied]

I'm starting to have constant 12v warnings with my ohmmu battery. It'll work fine for a few days after doing hard reset, then the warning pops up. Started after getting the 2021.40.x update.

Anyone else having the same issues? I'm tired of doing hard resets, may go back to OEM.

 

[sunhelm]

I'm starting to have constant 12v warnings with my ohmmu battery. It'll work fine for a few days after doing hard reset, then the warning pops up. Started after getting the 2021.40.x update.

Anyone else having the same issues? I'm tired of doing hard resets, may go back to OEM.

Yes! Getting this too, no issues for 2 weeks after I installed the Ohmmu. Now an issue after the 2021.40.6 update. Sent an email to Ohmmu support and hope to hear from them soon.

 

[Silicon Desert]

Aside from the reduced weight is there any benefit?

I'm even having trouble understanding that reduced weight is a significant benefit. Please enlighten me.

 

[Pied]

Yes! Getting this too, no issues for 2 weeks after I installed the Ohmmu. Now an issue after the 2021.40.6 update. Sent an email to Ohmmu support and hope to hear from them soon.

Glad I'm not the only one. The issue is pretty new, so they can figure it out quickly. It's good to let them know so ohmmu can see how many people are affected or if it's just a small batch of people.

 

[Pied]

I'm even having trouble understanding that reduced weight is a significant benefit. Please enlighten me.

It's aftermarket part. The significant benefit is if you like putting aftermarket parts on your car to make it significantly better or a little better.

A lot of people are fine with stock suspension. You won't be able to convince them to spend $3k on better aftermarket suspension.

 

[sunhelm]

Glad I'm not the only one. The issue is pretty new, so they can figure it out quickly. It's good to let them know so ohmmu can see how many people are affected or if it's just a small batch of people.

So they said they're aware of this issue for 2021.38.x and 2021.40.x owners and actually have a new battery design for it that so far have not returned this error. They're offering to swap out my recently purchased battery for the new one. Meanwhile, I measured the voltage of the new battery and it is down to 10.75V! Definitely a concern which I think means the car is not charging it at all! Luckily, I still have the old battery and swapped it out.

Recommend you measure yours just to be sure. If it's dropped, then I would not recommend driving it as you might get stranded.

 

[android04]

Hopefully Ohmmu designs newer batteries with a USB port and the ability to reprogram the BMS in the future. That would save them some time and money in shipping customers a newer version of the battery and having the customers ship the old one back. The customers can just update the BMS programming themselves on their computers any time Tesla tweaks the monitoring and charging behavior of the 12v system. But maybe that kind of updateable BMS system doesn't exist commercially and it's cheaper and easier just to replace the BMS board or repurpose the older batteries for something else.

 

[Pied]

Is the new battery design you're talking about the rev. 2? Support hasn't mentioned a new revision to me. I started the conversation with them around Thanksgiving. Been doing hard resets every 7-9 days since then.

 

[Xeux]

I just ordered one for my X. Is this unresolved on the latest revision?