Ohmmu Announces BT19 Sodium 12V Batteries for Rivians: Thoughts?

[SwampNut]

Incoming battery failure...

In my experience, that’s Rivian’s perpetual state, lol.

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[xinaes]

Thanks everyone for your insight and inputs.

I've decided to pull the trigger and pre-order a set of the Ohmmu sodium batteries.

I have a big trip coming up at the end of the month, and I absolutely don't want any surprises with my 3.25+ years old OEM 12V AGMs.

Will give an update to this thread when I do the change out.

 

[UnsungZero_OldTimeAdMan]

I'm already skeptical because of the odd name.

Ohm, unit of resistance… Mu, greek for micro? I’m more interested in what exactly they’ve done in the past to lead to some concluding they are not trustworthy. All I see is hearsay. A name is just a name. Does your name define who you are? Or everything you’ve done in life thus far?

 

[iansriv]

Ohm, unit of resistance… Mu, greek for micro? I’m more interested in what exactly they’ve done in the past to lead to some concluding they are not trustworthy. All I see is hearsay. A name is just a name. Does your name define who you are? Or everything you’ve done in life thus far?

It's a joke mate. I would like to think I'm a bit different than a battery though.

 

[UnsungZero_OldTimeAdMan]

It's a joke mate. I would like to think I'm a bit different than a battery though.

We kinda are. Biological functions are in effect chemical reactions; cycles of charge and discharge.

 

[SwampNut]

I would like to think I'm a bit different than a battery though.

Dunno, you seem all charged up.

 

[SwaziCAR]

I have a 2 battery R1T and changed to Ohmmu a few months ago. I had no issues with the first set, changed speculatively before any failure. Easy to do following their instructions. It's nice being able to monitor the battery health and count cycles over Bluetooth. I think better and cheaper than the Rivian solution

To clarify, you have the Ohmmu LFP batteries, or you somehow have the new sodium batteries?

Thanks!

 

[scottf200]

So my concern is that this battery has its own BMS for charging and battery temp. Anyone have any thoughts on how the Rivian HV batt to LV batt inverter and battery charger will handle the BMS.

The BMS on the replacement battery is just to protect the battery and maintain balance of the cells. Actual shut down protection should never happen save for the battery dropping below -30. A few will limit the charging amps. None of this is an issue to the vehicle DC converter.

I had the Ohmmu battery in my Tesla Model X (TMX) for a few years. The BMS and circuitry in the Ohmmu have to simulate what the Tesla (or Rivian) are expecting. I had the TMX get strange error message about the 12v as the "checking" it was doing on the battery to determine if it was going bad was confused. I had to hard reboot my TMX several times (disconnect 12v and firemans loop (eg., HV battery contact)).

I eventually got tired of that and replacd it with an OEM battery (which triggered other events to now show up). In any event, YMMV. The simulation is not trivial it seems and OTAs changed over the years and confused it. New Ohmmus had firmware updates so they could keep up.

 

[xinaes]

My 2 x Ohmmu 12V sodium batteries arrived yesterday, and I was able to install them today.

I followed their video instructions, and it went off without a hitch. After replacing the batteries and a hard reset of my 2022 R1T, all my errors cleared, and I was able to drive it around all day with no issue.

For the curious, here are some photos of my Ohmmu batteries before I installed them in my vehicle:

I wish a took a photo of it before dropping them in, but I had a 12V battery tester that I tested the Ohmmu batteries with, and they were able to crank out 500+ Amps as advertised (not that that's needed, being Rivian seems to only pull about 30 Amps from the 12V batteries).

For those curious, here are some photos of my old Rivian OEM 12V batteries that the Ohmmus replaced:

I ran my battery tester on both my old OEM Rivian 12V batteries. Here were the results:

Conclusions:

• The installation went pretty smoothly. It took me just over 1.5 hours, and that includes grabbing tools and watching/pausing the video instructions along my install. I was going pretty slow to make sure I wasn't shorting anything.
• The hardest part was getting a good grip and pulling out the old OEM batteries from that cramped space.
• You will also need to sit on the front lip of the frunk with your legs in the frunk to more easily unbolt and remove/replace the batteries. Try not to bang your head against the frunk cover's metal latch 10 times....
• If I'm reading my battery tester correctly, my old OEM Rivian 12V batteries seem to be in good health, despite them being 3.5 years old. I'd expect another year or 2 of life out of them. This is surprising to me since I've certainly been taxing them quite a bit by leaving Gear Guard persistently on (even when parked outside at home) and hence theoretically having higher cycling of the batteries, and they are subjected to some hot summers here in Alabama. Guess I lucked out compared to some other Rivian owners with bad OEM batteries.

 

[Kunzene]

My 2 x Ohmmu 12V sodium batteries arrived yesterday, and I was able to install them today.

I followed their video instructions, and it went off without a hitch. After replacing the batteries and a hard reset of my 2022 R1T, all my errors cleared, and I was able to drive it around all day with no issue.

Thanks for sharing! Will be ordering a pair soon.

 

[Viper D-Day]

I’ve had the Li battery and now their sodium version. Ohmmu didn’t fail with the Li battery, A Rivian software update changed the charging parameters to try and fix their problems with the Lead batteries and it cause a nuisance fault with the Li. It never stopped working, it was just an annoyance to look at. They sent me a sodium replacement for free and I’ve had zero issue with it. I’d absolutely recommend them.

 

[jollyroger]

I got the dreaded replace 12v battery warning earlier this month, I was out of the battery warranty for only 2 months when it failed. So I was going to be on the hook for all $800 despite having asked for some relief. (By they way, I heard they were only charging for one battery in the two battery vehicles, but they seemed to have stopped doing that too, or people are just telling stories)

After they told me that I went ahead and looked at the Ohmmu sodium battery pair. They seems to work fine after install, but I am a little worried that when these start to wear out, the failure might be more sudden. I'm less worried about charge curves, or optimizing sodium battery charging with a system designed for AGM.

As long as they last longer and give me enough warning when they fail. I'm calling it a win!

 

[xinaes]

I got the dreaded replace 12v battery warning earlier this month, I was out of the battery warranty for only 2 months when it failed. So I was going to be on the hook for all $800 despite having asked for some relief. (By they way, I heard they were only charging for one battery in the two battery vehicles, but they seemed to have stopped doing that too, or people are just telling stories)

After they told me that I went ahead and looked at the Ohmmu sodium battery pair. They seems to work fine after install, but I am a little worried that when these start to wear out, the failure might be more sudden. I'm less worried about charge curves, or optimizing sodium battery charging with a system designed for AGM.

As long as they last longer and give me enough warning when they fail. I'm calling it a win!

If we are to take Ohmmu at their word, hopefully our sodium batteries will last for the full 10 years.

I also considered buying and installing a Bluetooth monitor on them so I can track their life. Might get that later.

 

[VSG]

If I'm reading my battery tester correctly, my old OEM Rivian 12V batteries seem to be in good health, despite them being 3.5 years old.

Well you're not alone. My R1T is also 3.5 years old with the two original OEM batteries. I put them on a tester last month and they're still in great shape.

 

[DuoRivians]

My 2 x Ohmmu 12V sodium batteries arrived yesterday, and I was able to install them today.

I followed their video instructions, and it went off without a hitch. After replacing the batteries and a hard reset of my 2022 R1T, all my errors cleared, and I was able to drive it around all day with no issue.

For the curious, here are some photos of my Ohmmu batteries before I installed them in my vehicle:

I wish a took a photo of it before dropping them in, but I had a 12V battery tester that I tested the Ohmmu batteries with, and they were able to crank out 500+ Amps as advertised (not that that's needed, being Rivian seems to only pull about 30 Amps from the 12V batteries).

For those curious, here are some photos of my old Rivian OEM 12V batteries that the Ohmmus replaced:

I ran my battery tester on both my old OEM Rivian 12V batteries. Here were the results:

Conclusions:

• The installation went pretty smoothly. It took me just over 1.5 hours, and that includes grabbing tools and watching/pausing the video instructions along my install. I was going pretty slow to make sure I wasn't shorting anything.
• The hardest part was getting a good grip and pulling out the old OEM batteries from that cramped space.
• You will also need to sit on the front lip of the frunk with your legs in the frunk to more easily unbolt and remove/replace the batteries. Try not to bang your head against the frunk cover's metal latch 10 times....
• If I'm reading my battery tester correctly, my old OEM Rivian 12V batteries seem to be in good health, despite them being 3.5 years old. I'd expect another year or 2 of life out of them. This is surprising to me since I've certainly been taxing them quite a bit by leaving Gear Guard persistently on (even when parked outside at home) and hence theoretically having higher cycling of the batteries, and they are subjected to some hot summers here in Alabama. Guess I lucked out compared to some other Rivian owners with bad OEM batteries.

How are the sodium ion batteries holding up so far?

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