Model 3 12v Battery issues, monitoring, Aftermarket replacement

[davidviolin]

Since we have triple AAA, I’ve removed the stuff I had in the cubby hole like the tire repair kit, Jack, air compressor, and left only 1 jack pad in the trunk etc. even the cubby hole cover is gone and left in the garage. All of those items I can put back when I go on long distance trips like to Las Vegas. I’ve been meaning to go to a truck weight station to see my actual weight now. Will post when I get the results.

Fred

Yeah, getting off topic here, but the main issue I have with the M3P+ is the weight. I really wish it was around 3500lb instead, and I think they could have done this by shaving off alot of redundancies, and also swapped the glass roof for carbon fiber one. Like Munroe said, its built like a tank. Oh well... here is to me wishing they made a carbon fiber version. Take the lessons learned from i3 and make a model 3 carbon fiber version. Imagine that...

 

[belanger]

The OEM acid lead battery "Atlas 85B24LS" is very close to a 46B24R.

85B24LS ~ 239mm x 132mm x 220mm
46B24R ~ 238mm x 127mm x 220mm (200mm w/o the poles)

To save weight, if you search online stores in US or China, there's a 46B24R Lithium-Iron Phosphate (LFP, LifePo4) for ~280$ on the old book store.

https://www.amazon.com/Automotive-Universal-Phosphate-Replacement-Protection/dp/B081KW6QLV/

Let's take a moment to check the specs. The Atlas one has a capacity of 45Ah while the LFP one is 25Ah. When comparing LFP capacity with acid lead batteries, the equation is : 2 x LFP capacity = 1 x acid capacity. On paper the LFP one has 50Ah "acid lead" equivalent.

LFP battery needs to be installed with a LFP charger, like this one : https://www.amazon.com/gp/product/B07B45SHHK

Ohmmu likely have a LFP charger within their battery case. The book store solution is much cheaper than Ohmmu but this last one is a US company and offers 4 years warranty.

 

[Wennfred]

One year now on the Ohmmu without any issues, will check the battery voltage tomorrow when I get home.

Fred

 

[Wennfred]

Ohmmu 1 year later, still holding strong.

 

[lUtriaNt]

i read this entire thread. i was on the fence, but spoke with the folks at ohmmu today plus your positive reinforcement, i just bought one. appreciate the yearly update.

 

[Wennfred]

Will update again in 6 months. October 2020

Fred

 

[rdskill]

Lead Acid batteries and Lithium batteries have completely different charging algorithms. They have different absorption voltages. They have different fully-charged voltages. Your Lithium battery will not be properly charged. Hopefully there isn't an automatic "equalization mode" built into the system that runs the battery up to 15v. Being on a car I doubt it has this.

You have introduced a game changer into the car's charging system that will not know its charging a Lithium battery. I hope it works out, but Tesla will probably refuse to do any work on the car's electrical systems with that battery in it. That's already happened to another owner.

 

[Wennfred]

You have introduced a game changer into the car's charging system that will not know its charging a Lithium battery. I hope it works out, but Tesla will probably refuse to do any work on the car's electrical systems with that battery in it. That's already happened to another owner.

This setup has worked very well in a years time, as far as repairs at the service center, it’s just a 5 minute battery swap to the OEM lead acid battery.

Will report back in 6 months.

Fred

 

[rdskill]

Has worked very well in a years time, as far as repairs at the service center, it’s just a 5 minute battery swap to the OEM lead acid battery.

Will report back in 6 months.

Fred

That's encouraging to know its lasted this long.

I was curious what the max voltage its taken to when charging. It would be interesting to see a graph of voltages while in use/charging if you have that data.

Having lived on a cruising sailboat for 20 years gives me some insight into charging systems as I've spent up to 3 months unplugged and no dedicated generator onboard. Plus, guys cruising sailboat always, and I mean always talk about this kind of stuff at every gettogether on the beach.

I'll be sure to watch this thread to see how you make out.

 

[lUtriaNt]

lots of cats have purchased these types of batteries over the years on this forum. last night i researched many of them and saw overall positive results. based on this data collected, i felt at ease to purchase. there have been enough of these out there in the wild now that if there were any significant issues, people would have posted about it. the fact that ive not seen any negative posts about people using these again makes me feel confident in the success of this battery.

 

[Teedub21]

This setup has worked very well in a years time, as far as repairs at the service center, it’s just a 5 minute battery swap to the OEM lead acid battery.

Will report back in 6 months.

Fred

Whats the big deal? Don't they sell this battery specifically for the model 3? I'd imagine charging requirements were taken into consideration, especially at the price they're selling these batteries for.

 

[Teedub21]

Looks like they've made batteries for Tesla for a while. Probably have the whole charging thing figured out.

https://www.ohmmu.com/product-page/12v-lithium-battery-for-tesla-model-3

 

[belanger]

Lead Acid batteries and Lithium batteries have completely different charging algorithms. They have different absorption voltages. They have different fully-charged voltages. Your Lithium battery will not be properly charged. Hopefully there isn't an automatic "equalization mode" built into the system that runs the battery up to 15v. Being on a car I doubt it has this.

You have introduced a game changer into the car's charging system that will not know its charging a Lithium battery. I hope it works out, but Tesla will probably refuse to do any work on the car's electrical systems with that battery in it. That's already happened to another owner.

True true true, all true. Ohmmu batteries come with an embedded Battery Management System to charge the cells. Many lithium batteries can be charge via alternator, each have different specs so obviously you have to read the specs. The Ohmmu batteries definitely are not an issue. The instant power they can provide compared to acid-lead makes sound systems w/ big amplifiers very happy.

 

[dmurphy]

1 year, 15k miles, zero battery issues. Using the "cheap" factory 12V AGM battery.

I'm all for pi**ing money away on silly stuff for the car, but replacing the 12V battery with a $450 lithium one seems like the silliest yet, ESPECIALLY when the car is under warranty.

This, to me, is a case of "don't overthink it"... Just drive the car and enjoy it. If you need to spend $100 every 2-3 years to replace the AGM battery, that's still 12 years before you break even on a lithium one.... Which isn't going to last 12 years either. If it had any advantage whatsoever, that'd be one thing... but there's nothing "better" about the car by having that under the hood.

 

[patrick2930]

I decided to change the 12 volt battery before it left me stranded as the car is coming up on 2 years old this summer. After much measuring I figured that an Odyssey PC1100 would fit. I perfer Odyssey
batteries as I have received 10 plus years of service in several motorcycle applications. Also with standard battery prices going out site these are now reasonable. Battery cost was 226.79
Top post lug kit was 15.25 and shipping was free. The new battery fit in with no modifications. Specs are 45ah and 500 cca.

 

[Xenoilphobe]

Lead Acid batteries and Lithium batteries have completely different charging algorithms. They have different absorption voltages. They have different fully-charged voltages. Your Lithium battery will not be properly charged. Hopefully there isn't an automatic "equalization mode" built into the system that runs the battery up to 15v. Being on a car I doubt it has this.

You have introduced a game changer into the car's charging system that will not know its charging a Lithium battery. I hope it works out, but Tesla will probably refuse to do any work on the car's electrical systems with that battery in it. That's already happened to another owner.

It doesn't matter, the OHMUU has its own BMS, unlike the dumb AGM battery it replaced. I've been running these (and the prior company) in all three of our Model S's for years. Hell Tesla even installed it for me at the SC, when I direct shipped to the SC at Tysons Corner. The OEM battery is 3rd party too... not made by Tesla..
Ohmmu 12V Battery Feedback

 

[rdskill]

True true true, all true. Ohmmu batteries come with an embedded Battery Management System to charge the cells. Many lithium batteries can be charge via alternator, each have different specs so obviously you have to read the specs. The Ohmmu batteries definitely are not an issue. The instant power they can provide compared to acid-lead makes sound systems w/ big amplifiers very happy.

It doesn't matter, the OHMUU has its own BMS, unlike the dumb AGM battery it replaced. I've been running these (and the prior company) in all three of our Model S's for years. Hell Tesla even installed it for me at the SC, when I direct shipped to the SC at Tysons Corner. The OEM battery is 3rd party too... not made by Tesla..
Ohmmu 12V Battery Feedback

Ahhhhh... I was wondering since I didn't see an external BMS. No wonder these are so expensive since you are getting a new BMS with each replacement. They should have a generous core replacement I would think.

Thanks for the info guys.

 

[Adam3]

Has anyone noticed improved audio like they insinuate? I also found a review on Amazon reporting sound quality improvement.

5. Increase power (no voltage sag, better 12v performance, especially for subwoofers/amplifiers)

Completely transformed the sound system in the Model 3
Reviewed in the United States on February 23, 2019

Great 15 minutes DIY on your Model 3 that will transform the sound quality of the sound system. The primary reason for getting this battery was the ~16lb weight saving, the boost in bass in sound system was a complete bonus.

 

[lUtriaNt]

alright gents,

installed the ohmuu yesterday. it showed up with 13.6V from phoenix to me here in LA.

replacement took less than 10 minutes - this is with turning off the car, waiting 2 minutes, opening the plastic finisher, removing/replacing batts and taking two photos.

i can tell the difference when playing music i played an old vinyl recording that i recorded in wav and the bass was tight, punchy, and the dynamics were overall better. its not placebo because ive played this song in the car a few times prior (it's one of my faves and one of the first songs i played when i picked up the car to test the sound system) . that 9 ish pound lightweight battery packs an impressive punch.

FYI: i had NO issues prior to this. this was just a mod i wanted to do on my less than 500 mile car. will keep the agm as backup.

 

[Adam3]

i can tell the difference when playing music i played an old vinyl recording that i recorded in wav and the bass was tight, punchy, and the dynamics were overall better. its not placebo because ive played this song in the car a few times prior (it's one of my faves and one of the first songs i played when i picked up the car to test the sound system) . that 9 ish pound lightweight battery packs an impressive punch.

Very interesting. If you had to guesstimate, how much "better" is the bass response? 10%, 20%...?