I4 Battery/Alternator Charging Behavior...batteries shutting off, dying, car not starting, etc.

Lotus F1 · Aug 4, 2026

Livert said:
Anyone know if the charging logic is different for the emira 420 as they have lithium batteries? I'm hoping a simple software upgrade can fix our issues.

It would 100% have to be.

Milk242 · Aug 4, 2026

Lotus F1 said:
Did you put in the Sodium Ion battery voltage profile in the BM200. You have to do that or the reading will not be correct. From what I see you did not do that.

I only saw lead acid or lithium as my choices. Should I be choosing lithium?

Lotus F1 · Aug 5, 2026

Milk242 said:
I only saw lead acid or lithium as my choices. Should I be choosing lithium?

Neither would be appropriate. You have to go into the settings for the profile you created and in there you will see a custom mapping and in there you put in all the voltage and percentages. It will completely change the readout you are getting

That said make sure you do not use the AGM mode of a battery charger as you will ruin the battery. You can use the lithium profile to charge the battery

dbjames · Aug 17, 2026

lynchy73 said:
That “Solid State Buttery“ is just a name/BS. It’s almost certainly LFP. Semi solid batteries are available, but their nominal voltage isn’t suitable for a 12V starter battery (typically 3.6Vnominal).

I’ve been using a Sodium Ion battery in my I4 for months. It charges fine, it charges strongly as soon as the car starts and quickly gets up to 100%. It works as the voltage curve is pretty much identical to AGM. LFP voltage curve is quite different and doesn’t play nicely with the alternator algorithm in our cars.

What's the advantage of the sodium ion over sticking with OEM?

lynchy73 · Aug 19, 2026

dbjames said:
What's the advantage of the sodium ion over sticking with OEM?

Lighter weight, about 1/3rd the weight of the AGM battery. My battery has Bluetooth, so I can turn off the output if I want/need to.

Sodium ion versus LFP. Voltage curve matches AGM closely, so the I4 charging algorithm just works, LFP doesn’t. NA (sodium ion) can be discharged to 0V with no issues. NA energy density is lower than LFP, so for our H6 you get maybe 35 to 40Ah, but it’s enough, just means it will not hold charge so long without usage, maybe 10 to 14 days IME.

Kaz · Aug 19, 2026

H6/Group 48 - Sodium 12V Battery

The Adventure Series Sodium 12V batteries are built for the places maps don't cover. It's engineered for overlanders, off-road builds, and anyone who needs a battery that simply will not quit — no matter what the terrain, temperature, or conditions throw at it. Most batteries have a breaking...

ohmmu.com

Looks great...so seems coast is clear for these? Cheap too

Milk242 · Aug 23, 2026

Kaz said:
H6/Group 48 - Sodium 12V Battery

The Adventure Series Sodium 12V batteries are built for the places maps don't cover. It's engineered for overlanders, off-road builds, and anyone who needs a battery that simply will not quit — no matter what the terrain, temperature, or conditions throw at it. Most batteries have a breaking...

ohmmu.com

Looks great...so seems coast is clear for these? Cheap too

So far no problems. I didn’t drive it for 2 weeks and still started up fine with no tender on. I don’t know how to customize the battery profile in the ancel app so just left it on lead acid. Nice characteristic of sodium ion batteries is that it can go to 0v without detriment to the battery capacity.

Kaz · Aug 23, 2026

Milk242 said:
So far no problems. I didn’t drive it for 2 weeks and still started up fine with no tender on. I don’t know how to customize the battery profile in the ancel app so just left it on lead acid. Nice characteristic of sodium ion batteries is that it can go to 0v without detriment to the battery capacity.

going to order right now

Kaz · Sep 8, 2026

Milk242 said:
So far no problems. I didn’t drive it for 2 weeks and still started up fine with no tender on. I don’t know how to customize the battery profile in the ancel app so just left it on lead acid. Nice characteristic of sodium ion batteries is that it can go to 0v without detriment to the battery capacity.

ok OHMMU wrote back and said that their own charger will be coming out this winter and it will be a compact unit with bluetooth built in the charger for remote diagnostics. They said I can use my existing Antigravity charger in lithium mode for now and it will be fine to charge the battery that way. Will report back once it's all installed and I go through some cycles...will save around 30lbs and it's much cheaper than lithium. $11/lb of weight loss is actually very cheap compared to carbon fiber or mag wheels, etc. (dude math)

Kaz · Sep 10, 2026

16lbs, will install and report back - should have no news other than it works

docron · Monday at 5:42 PM

Twinsies!

spats · Monday at 8:15 PM

docron said:
Twinsies!

View attachment 88459

Are these just plug n play without issue on the i4?

Lotus F1 · Wednesday at 4:14 PM

spats said:
Are these just plug n play without issue on the i4?

dude did you not read the thread?

spats · Wednesday at 7:30 PM

Lotus F1 said:
dude did you not read the thread?

in this case I was on my phone and did not. my bad. All caught up now

Beachbum · Thursday at 2:57 AM

Lotus F1 said:
dude did you not read the thread?

I have, but dont remember what has been said over the last 18 months of it, it did start in May 2025 and is now 4 pages long
A quick yes/no would have sufficed.

docron · Thursday at 5:26 AM

Kaz had his installed yesterday. I'm installing mine tomorrow.

And yes, this should be easy plug and play with no issues for the i4. Will monitor SOC behavior with battery tracker and report back.

Milk242 · Thursday at 1:14 PM

I’ve had no issues so far starting the car. I only drive it basically once a week. Ancel always tells me battery is low but that’s because it thinks it’s a lead acid battery.

Lotus F1 · Thursday at 11:07 PM

Milk242 said:
I’ve had no issues so far starting the car. I only drive it basically once a week. Ancel always tells me battery is low but that’s because it thinks it’s a lead acid battery.

You can fix that in the ancel settings and change the percentages

lynchy73 · 2026-09-18T08:32:55-0500

Milk242 said:
I’ve had no issues so far starting the car. I only drive it basically once a week. Ancel always tells me battery is low but that’s because it thinks it’s a lead acid battery.

What is the voltage after you’ve been parked up for a week? TBH, I’d expect the battery voltage to be fairly low (circa 12.5V give or take is no problem). These Sodium Ion batteries have a fairly low capacity, you might get 2 weeks parked up if you’re lucky, but I’d say it’s best to run it weekly and if you can’t, then I’d charge it. Additionally, the voltage does drop down when it’s slowly discharged/drained. The fans running when you park up does drain a fairly significant percentage of the capacity.

Don’t Select LFP voltage curve for these sodium ion batteries, the voltage drops down linearly as the state of charge reduces, similar to an AGM, it’s very different to an LFP battery. A sodium ion battery is not deeply discharged, even if the voltage is on the low side and it should still start your car.

These Sodium Ion batteries seem to quickly get charged to full once you are running the I4 and maintain a full charge. My battery has a Bluetooth BMS, I can monitor the charge current, SOC etc so I was able to immediately see it plays nice with the AMG charging algorithm, unlike the LFP (have a Bluetooth BMS on that battery too).

Milk242 · 2026-09-18T21:47:32-0500

lynchy73 said:
What is the voltage after you’ve been parked up for a week? TBH, I’d expect the battery voltage to be fairly low (circa 12.5V give or take is no problem). These Sodium Ion batteries have a fairly low capacity, you might get 2 weeks parked up if you’re lucky, but I’d say it’s best to run it weekly and if you can’t, then I’d charge it. Additionally, the voltage does drop down when it’s slowly discharged/drained. The fans running when you park up does drain a fairly significant percentage of the capacity.

Don’t Select LFP voltage curve for these sodium ion batteries, the voltage drops down linearly as the state of charge reduces, similar to an AGM, it’s very different to an LFP battery. A sodium ion battery is not deeply discharged, even if the voltage is on the low side and it should still start your car.

These Sodium Ion batteries seem to quickly get charged to full once you are running the I4 and maintain a full charge. My battery has a Bluetooth BMS, I can monitor the charge current, SOC etc so I was able to immediately see it plays nice with the AMG charging algorithm, unlike the LFP (have a Bluetooth BMS on that battery too).

11.67v after sitting for a week