Ohmmu 12v lithium Anyone purchased or have experience with this battery?

[roamtheworld]

With all the talk of 12v battery failures lately, I was looking at options that may last longer and be a better option for EVs.
I found this company ohmmu and the specs looked pretty good. The price is almost double the genuine Ford battery but it's stated it will last 4X as long as a lead acid battery. Plus it has Bluetooth and an app to monitor health and get data an bonus as a techie
https://www.ohmmu.com/product-page/12v-lithium-battery-for-ford-mustang-mach-e
Here are the specs for those who don't want to click the link
Upgrade your Ford Mustang Mach-E 12V battery with a Lithium Iron Phosphate (LiFePO4) battery from Ohmmu!

The Ohmmu 12V LiFePO4 battery is lighter, more efficient, eco-friendly, has a higher usable capacity, and lasts 4x longer than a traditional sealed lead acid (SLA) battery.

• 4 Years Full-Replacement Limited Warranty

• Replacement to OEM Battery

• Lithium Iron Phosphate Battery (aka LiFePO4 or LFP)

• Self-heating technology inside warms battery during charging in extreme cold conditions as an extra layer of protection and for continued operation.

• Proprietary 12V Lithium cell and BMS technology that is a drop-in replacement to your existing battery (no firmware changes needed)

• Compatible with the Ohmmu App, a monitoring and diagnostic tool

• Battery Management System (BMS), Bluetooth-enabled - manages cell balancing for a long service life and protects your battery from high/low voltage, overcharge, high/low temperatures, and short circuits.

Ohmmu Bluetooth App

Get valuable diagnostic and lifecycle information, State of Charge (SOC), and more from this Bluetooth-enabled battery with the Ohmmu App.

Why Go Ohmmu?

1. Increased Durability

2. Longer-Lasting Reliability

3. Decreased Weight

4. Higher Capacity

5. Better 12V Performance - Improved LED & Audio (higher nominal voltage, no voltage sag)

6. Less Environmental Waste (fewer batteries being used and less material in each battery)

7. Increased Efficiency (Ohmmu 12V charges and discharges at a higher efficiency than SLA)

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[Mach-Lee]

I don’t recommend lithium batteries, they will cause problems with the BMS:

See FAQ "Can I replace the AGM battery with a lithium or LFP battery?"

 

[roamtheworld]

I don’t recommend lithium batteries, they will cause problems with the BMS:

See FAQ "Can I replace the AGM battery with a lithium or LFP battery?"

Thanks for the link and information I'll review that and ask questions in that thread

 

[superdave80]

lasts 4x longer than a traditional sealed lead acid (SLA) battery.

• 4 Years Full-Replacement Limited Warranty

The warranty length does not quite match up with the claimed lifetime. Lead batteries typically have a three year warranty, so this company doesn't seem to have much more faith in their product to last '4X longer'.

 

[kodiakng]

they don't actually specify the Ah capacity on the unit page so you can't be sure what you're getting. their support page has a testing chart that shows a tesla replacement model getting up to 40+Ah of capacity but no actual specs for the MME or lightning versions.

while it does say it has internal heating elements they don't spec what temperature range it is useful in and what current draw the heaters have. also, adding to @Mach-Lee's admonition regarding the BMS, the heater usage won't be measured by the MME BMS so the battery could lose significant power while sitting over a cold snap and the MME won't be directly aware of it.

on the plus side, LFP batteries can reliably go down to very low SoC without problem so that might be their argument on the "usable capacity."

finally, their warranty is kind of odd when compared against other "drop-in replacement" LFP batteries for auxiliary use like this with a built-in BMS. most i've seen (battle born, lion energy, etc) give a limited lifetime warranty based on the charge cycles. since this has a time based one i'd be a bit leery on their claim of "4x longer" if they won't give you a commensurate warranty to match.

 

[dtbaker61]

With all the talk of 12v battery failures lately, I was looking at options that may last longer and be a better option for EVs.

bad idea
read the FAQ from Mach-lee

the charge curve voltages are all different, so the internal charger will not charge it properly

 

[roamtheworld]

Thanks for the feedback everyone!
The idea of being able to connect to battery and get stats is a good idea but it looks like a LFP 12v for the MachE BMS isn’t a good idea.
That’s why I love this forum

 

[generaltso]

The idea of being able to connect to battery and get stats is a good idea

You can do that now. Just get one of these:

https://www.amazon.com/gp/product/B08F9T4QC5/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

 

[SalsabyJake]

You can do that now. Just get one of these:

https://www.amazon.com/gp/product/B08F9T4QC5/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

This looks cool and a great price. I still don't understand why, for all the electronics and sophisticated software (being generous! lol) in the MachE, why don't they have such reporting and monitoring built into the vehicle?! For the car's complexity, the 12V battery is still crucial and the focus of many reported problems. So why doesn't Ford incorporated the functionality of this $28 device into the car?

 

[Mach-Lee]

So why doesn't Ford incorporated the functionality of this $28 device into the car?

They have, you just can't see it. The car knows the exact SoC, capacity, load, and temperature of the 12V battery at all times.

 

[SalsabyJake]

They have, you just can't see it. The car knows the exact SoC, capacity, load, and temperature of the 12V battery at all times.

So what's the big secret then? They must think we'd misinterpret the data and bug them... They could show it on a meter to illustrate whether it's "in range" or not...

 

[roamtheworld]

They have, you just can't see it. The car knows the exact SoC, capacity, load, and temperature of the 12V battery at all times.

Salsaby Jake has a great question.
Mach-Lee you seem to be in the know why can’t we get more data from our car. Decent charging information. More details on SOC and overall data even if hidden in a deep menu sounds like common sense for an EV. Ford is treating us like ICE customers with simple gages and limited data.

 

[Mach-Lee]

Salsaby Jake has a great question.
Mach-Lee you seem to be in the know why can’t we get more data from our car. Decent charging information. More details on SOC and overall data even if hidden in a deep menu sounds like common sense for an EV. Ford is treating us like ICE customers with simple gages and limited data.

I don't make the decisions at Ford. I would like more info too.

 

[Mark in NY]

This is an older thread but I thought I would add to it since I see there are several comments and speculations but no hands on experiences concerning a lithium replacement 12 volt battery.
I had the typical AGM battery degrade to the point where it would have been prudent to replace it. At the time I was familiar with some of the maintenance and performance issues with the Tesla model 3. Many owners had used a new lithium replacement battery and there was a fair amount of reporting/posting by owners about the positive experiences of getting rid of the AGM battery and replacing it with a lithium unit. During covid, early 2020 I took the plunge and bought an Ohmmu lithium 12 volt replacement battery. The usual deal - more electrical capacity, smaller dimensions and half the weight of the old lead battery. It is now early 2026 and the experience has been positive. Temps here have ranged from 100 degrees F in the summer to a bit below zero degrees F in several winters (and just recently). No problems and no degredation to report. My other vehicle will be coming up to 12 volt battery replacement time in another year or so. I have my eye on the newer sodium battery and possibly a battery with built in bluetooth allowing remote monitoring.
Either way I don't foresee buying another lead-acid battery.
Cheers.

 

[Maui]

This is an older thread but I thought I would add to it since I see there are several comments and speculations but no hands on experiences concerning a lithium replacement 12 volt battery.
I had the typical AGM battery degrade to the point where it would have been prudent to replace it. At the time I was familiar with some of the maintenance and performance issues with the Tesla model 3. Many owners had used a new lithium replacement battery and there was a fair amount of reporting/posting by owners about the positive experiences of getting rid of the AGM battery and replacing it with a lithium unit. During covid, early 2020 I took the plunge and bought an Ohmmu lithium 12 volt replacement battery. The usual deal - more electrical capacity, smaller dimensions and half the weight of the old lead battery. It is now early 2026 and the experience has been positive. Temps here have ranged from 100 degrees F in the summer to a bit below zero degrees F in several winters (and just recently). No problems and no degredation to report. My other vehicle will be coming up to 12 volt battery replacement time in another year or so. I have my eye on the newer sodium battery and possibly a battery with built in bluetooth allowing remote monitoring.
Either way I don't foresee buying another lead-acid battery.
Cheers.

thanks. Can you give the specs and maybe even the url for the one you bought?

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