What's with the Ohmmu 12V battery?

[camalaio]

I see a lot of strong recommendations for the Ohmmu 12V battery. It's a Lithium-based 12V replacement. Plenty of statements of this being a life-altering change to their vehicles, feeling lighter, etc.

But I'm not getting it. $720 (Canadian) off Amazon can pay for a lot of typical lead-acid battery replacements, certainly more than I'll need over the life of the car. And it only has a 4 year warranty. I've not exactly bought expensive lead-acid batteries but always had at least a full replacement 3 year warranty on them (and prorated after). What gives? If they're only warranted to last an extra year but cost 5x more, that doesn't make a lot of sense to me.

Any insight, or is it just a novelty thing?

 

[dmurphy]

I see a lot of strong recommendations for the Ohmmu 12V battery. It's a Lithium-based 12V replacement. Plenty of statements of this being a life-altering change to their vehicles, feeling lighter, etc.

But I'm not getting it. $720 (Canadian) off Amazon can pay for a lot of typical lead-acid battery replacements, certainly more than I'll need over the life of the car. And it only has a 4 year warranty. I've not exactly bought expensive lead-acid batteries but always had at least a full replacement 3 year warranty on them (and prorated after). What gives? If they're only warranted to last an extra year but cost 5x more, that doesn't make a lot of sense to me.

Any insight, or is it just a novelty thing?

There are people that are hyperfocused on vehicle weight, and this battery shaves a few pounds. They swear they can feel it in the acceleration.
There are also people who swear this makes the radio sound better.

I, personally, believe the vast majority of that is confirmation bias, but I have no empirical data one way or another.

 

[camalaio]

There are people that are hyperfocused on vehicle weight, and this battery shaves a few pounds. They swear they can feel it in the acceleration.
There are also people who swear this makes the radio sound better.

I, personally, believe the vast majority of that is confirmation bias, but I have no empirical data one way or another.

Ohhhh... the stock radio? This is reminding me of audiophile insanity all over except every audio source available to the car is compressed audio, so this is especially... funny?

This does seem like a product depending on confirmation bias -- I do see now that their website mentions amplifiers and efficiency due to weight. Big yikes from me.

Perhaps someone does have a well-tuned butt accelerometer and can feel the maybe 0.5% difference in acceleration.

It's weird though, because it seems so many people are getting it, not just the ones concerned about raw performance and... audio? performance.

 

[Knightshade]

I doubt anybody could tell the weight difference in an A/B blind test- but I'd bet you could hear the audio difference with the right (fully uncompressed high quality from a USB key) music.


Also isn't the factory 12v already a somewhat pricier (though not lithium pricey) AGM, not a lead acid?

 

[camalaio]

I doubt anybody could tell the weight difference in an A/B blind test- but I'd bet you could hear the audio difference with the right (fully uncompressed high quality from a USB key) music.


Also isn't the factory 12v already a somewhat pricier (though not lithium pricey) AGM, not a lead acid?

I'm 90% certain they're typical flooded cell lead acid, but maybe not all are the same. They're vented in Model 3, usually AGM are sealed (at least the numerous ones I've dealt with, but I've never met an AGM in a car application).

 

[Knightshade]

I'm 90% certain they're typical flooded cell lead acid, but maybe not all are the same. They're vented in Model 3, usually AGM are sealed (at least the numerous ones I've dealt with, but I've never met an AGM in a car application).

12 Volt Battery Compendium | TeslaTap

The Model 3 uses a 45 Ah, AGM Battery. One supplier is AtlasBX with the model 85B24LS.

 

[dmurphy]

It's weird though, because it seems so many people are getting it, not just the ones concerned about raw performance and... audio? performance.

I'm completely the wrong person to talk to about this stuff. I don't even have PPF or a ceramic coating. I'm just idly waiting for my doors to rust off.

 

[ItsNotAboutTheMoney]

I'm 90% certain they're typical flooded cell lead acid, but maybe not all are the same. They're vented in Model 3, usually AGM are sealed (at least the numerous ones I've dealt with, but I've never met an AGM in a car application).

Apparently except for the Prime, all Prius 12V batteries are AGM.

I think AGMs have become increasingly common due to hybridization and heavier system loads. Might be about 10%.

 

[SSedan]

The lithium following is based on belief in their salesmanship period.
It might be good but they have not been in use in volume long enough TO PROVE that.

When I contacted them a couple years ago about my concerns with using a lithium in my very cold climate without full temp control system I got a lot of salesman speak about how it won't shorten life that much to charge at sub-zero fahrenheit..........

For those who claim handling or sound system benefits please explain the the mechanism for that benefit. 20lbs is half a percent on a 4000lbs car and battery isn't rotating weight and the weight is inside the wheelbase and not particularly high so it doesn't have a lot of leverage on suspension.

 

[animorph]

The audiophile claim is undoubtedly more instantaneous power from the lithium battery, with less voltage sag, than the usual AGM battery.

The ohmmu lithium is a lithium iron phosphate battery, suitable for more discharge cycles than our big Tesla batteries, and recommended for this type of application. It has its own BMS.

For the Model 3 at least, the ohmmu was less than 2x as expensive as getting a battery replacement through a Service Center. The OEM AGM battery is not cheap. Given that our original 12V battery lasted about 18 months, that makes the ohmmu a good deal. I chickened out on ohmmu because I wasn't positive all the problems we were seeing were due to the 12V battery and wanted the SC to check it. Turns out ohhmu would have been fine.

 

[Rocky_H]

@camalaio Your location says you are in British Columbia, Canada, so this would certainly be a bad idea for you.

concerns with using a lithium in my very cold climate without full temp control system I got a lot of salesman speak about how it won't shorten life that much to charge at sub-zero fahrenheit

...because of that. Recharging a lithium ion battery in very cold temperatures is very damaging for it. With my electric motorcycle, and the batteries for my Black & Decker leaf blower, they have temperature monitoring on them, and they will just blink a red warning light and refuse to charge so it doesn't destroy the battery until it just naturally gets warmer. But without an active warming system for the 12V on a car that is outside, who knows when it could get warm enough to recharge?

 

[Sam1]

Perhaps someone does have a well-tuned butt accelerometer and can feel the maybe 0.5% difference in acceleration.

no one is 'feeling' a 20 pound reduction of sprung weight on a car that weighs over 4000 pounds.

 

[jjrandorin]

I'm completely the wrong person to talk to about this stuff. I don't even have PPF or a ceramic coating. I'm just idly waiting for my doors to rust off.

View attachment 570618

Thanks for making me spit coffee on my laptop, reading this post

 

[Rocky_H]

no one is 'feeling' a 20 pound reduction of sprung weight on a car that weighs over 4000 pounds.

Tesla's cars are so much lighter from not having a printed manual in the glove box!

 

[ra88it]

For the Model 3 at least, the ohmmu was less than 2x as expensive as getting a battery replacement through a Service Center. The OEM AGM battery is not cheap.

80$ USD isn't cheap for an automotive 12v AGM battery? damn... Volkswagen and BMW have been charging 10x that for batteries for years. Better yet, look up what a 2020 BMW M4 battery costs (1/4 the cost of a used model3 traction pack).

 

[SSedan]

@camalaio Your location says you are in British Columbia, Canada, so this would certainly be a bad idea for you.

...because of that. Recharging a lithium ion battery in very cold temperatures is very damaging for it. With my electric motorcycle, and the batteries for my Black & Decker leaf blower, they have temperature monitoring on them, and they will just blink a red warning light and refuse to charge so it doesn't destroy the battery until it just naturally gets warmer. But without an active warming system for the 12V on a car that is outside, who knows when it could get warm enough to recharge?

I have a decade old Craftsman C3 cordless tool set and the lithiums with that also will not charge near freezing.

The salesman actually tried to tell me the 12volt is close enough to the main pack it won't get that cold. At work in particular my car is exposed to probably 1/2mile of cleared land to the west so the sub-zero F wind gets right down to the ground. Suffice to say the car gets chilled and I have seen -25f a couple times here, -15f every winter.

Just to be clear I am not saying a lithium 12volt is bad, I am saying the belief they are so great is based on good salesmanship.

 

[SSedan]

I went back and dug thru my spam account and found the salesman email from a Rudy at n4power and he copied in sscherer. 2 years ago

 

[Kevy Baby]

...except every audio source available to the car is compressed audio...

This is not true: you can listen to FLAC files from a USB thumb drive.

 

[camalaio]

12 Volt Battery Compendium | TeslaTap

Huh. My battery does not look like the one in the link, and says nothing about being an AGM battery. Might dig it out at some point to check for other labelling. Wonder if this is a regional thing for whatever reason?

The audiophile claim is undoubtedly more instantaneous power from the lithium battery, with less voltage sag, than the usual AGM battery.

The ohmmu lithium is a lithium iron phosphate battery, suitable for more discharge cycles than our big Tesla batteries, and recommended for this type of application. It has its own BMS.

For the Model 3 at least, the ohmmu was less than 2x as expensive as getting a battery replacement through a Service Center. The OEM AGM battery is not cheap. Given that our original 12V battery lasted about 18 months, that makes the ohmmu a good deal. I chickened out on ohmmu because I wasn't positive all the problems we were seeing were due to the 12V battery and wanted the SC to check it. Turns out ohhmu would have been fine.

Wait, I had really never thought of this. Getting the battery from Tesla? Is this common in the US, to get batteries from the car manufacturer? Here, I'd just go to Interstate Battery (I assume that's in the US too?) or Walmart or something. I think the battery on our Honda Fit, from Honda, is something stupid like $300. From wherever we got it, we paid $120 or so instead.

If everyone's comparing to Tesla 12V battery prices, I can absolutely see how the Ohmmu's price might start to sound sort of reasonable.

@camalaio Your location says you are in British Columbia, Canada, so this would certainly be a bad idea for you.

...because of that. Recharging a lithium ion battery in very cold temperatures is very damaging for it. With my electric motorcycle, and the batteries for my Black & Decker leaf blower, they have temperature monitoring on them, and they will just blink a red warning light and refuse to charge so it doesn't destroy the battery until it just naturally gets warmer. But without an active warming system for the 12V on a car that is outside, who knows when it could get warm enough to recharge?

In my specific case it would be mostly isolated from the cold (and it really doesn't get that cold here most Winters), but is a good point. I understand it has a BMS to manage itself and would maybe limit charging, but that itself seems problematic if Tesla is depending on it to be charged. 99.99% of days it would probably be OK, but I'd hate to have that 0.01% case.

0F is -17.8C. That... yeah that doesn't really happen where I live. Would be a daily low, and the car would be in the garage for that time. It might be -20C up on the ski hill if we decided to brave such a cold day.

This is not true: you can listen to FLAC files from a USB thumb drive.

Right, I did forget about this. Early in ownership, USB ports would die often so USB music was unusable for us. Too fussy for something as "simple" as music.

 

[jjrandorin]

Huh. My battery does not look like the one in the link, and says nothing about being an AGM battery. Might dig it out at some point to check for other labelling. Wonder if this is a regional thing for whatever reason?



Wait, I had really never thought of this. Getting the battery from Tesla? Is this common in the US, to get batteries from the car manufacturer? Here, I'd just go to Interstate Battery (I assume that's in the US too?) or Walmart or something. I think the battery on our Honda Fit, from Honda, is something stupid like $300. From wherever we got it, we paid $120 or so instead.

If everyone's comparing to Tesla 12V battery prices, I can absolutely see how the Ohmmu's price might start to sound sort of reasonable.



In my specific case it would be mostly isolated from the cold (and it really doesn't get that cold here most Winters), but is a good point. I understand it has a BMS to manage itself and would maybe limit charging, but that itself seems problematic if Tesla is depending on it to be charged. 99.99% of days it would probably be OK, but I'd hate to have that 0.01% case.



Right, I did forget about this. Early in ownership, USB ports would die often so USB music was unusable for us. Too fussy for something as "simple" as music.

Lots of people get batteries from the car manufacturer. My views might be colored a bit because of my long history with BMWs, but BMW has used AGM batteries for quite a while, AND a battery change also required "re registering" the battery with the car with a specific process that required either a computer with an ODB to ethernet cable and specific BMW software, or later, a wireless ODB adapter and specific iPhone apps.

"Regular" BMW AGM batteries (for lowly 4 series) are like 500-600 installed at the dealer, but the battery itself is like 300 ish even if you go after market, and then spend the money on the items to register it yourself (did you look at the price for the BMW M4 Battery @ra88it listed? its about 2k.. yeah 2 thousand dollars). So yeah your not "cruising down to nappa auto" for your typical BMW AGM battery. No idea on the tesla, but I would likely go to tesla for it at least until the car is out of warranty.

I know tesla does not = BMW, but coming from that brand, the thought of an AGM battery does not surprise me, and 2-300 for a battery sounds actually cheap to me...