- Thread starter
- #21
They're really really highly skilled and know the Emira and its quirks...they did my system it's awesome. They are installing a Wolfbox digital rearview mirror will get it tomorrow -
I4 Battery/Alternator Charging Behavior...batteries shutting off, dying, car not starting, etc.
- Thread starter Kaz
- Start date
They're really really highly skilled and know the Emira and its quirks...they did my system it's awesome. They are installing a Wolfbox digital rearview mirror will get it tomorrow -
@Kaz I recently installed a sodium ion 12V starter battery in my I4 Emira. It seems to work just fine. The battery is quickly charged to 100% when the car is running and stays fully charged when driving. The lower nominal voltage seems to have solved the issues we’ve observed with LFP type batteries.
The battery I’m using is 35Ah and circa 6kg or a little over.
The battery I’m using is 35Ah and circa 6kg or a little over.
Link please. I definitely want to check this out. I, Kaz and several other have run the AntiGravity Litium Ion batteries in multiple cars and were bummed when we realized we no longer could on this car. It's easy weight loss!
Plz share to me as well, thx!
It’s not a standard product at the moment, will have to speak to the manufacturer. I had a Bluetooth BMS fitted to an otherwise standard product (I wanted to be able to see what’s going on).
I’ll share some details soon, but so far it’s looking good. These Sodium Ion cells are less energy dense than LFP, but it’s still much lighter than AGM. The operating voltage of Sodium Ion is lower than LFP and 4 series of Sodium Ion pretty much matches AGM. I will get some data from the BMS to share, so you can see for yourself.
I’ll share some details soon, but so far it’s looking good. These Sodium Ion cells are less energy dense than LFP, but it’s still much lighter than AGM. The operating voltage of Sodium Ion is lower than LFP and 4 series of Sodium Ion pretty much matches AGM. I will get some data from the BMS to share, so you can see for yourself.
- Thread starter
- #27
I found this from simple search but don't know anything about the brand or the operating voltage. Looks like half the weight of AGM
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The next question, can this type of better be put on our Lotus provided battery tenders? Also, what setting, AGM or Lithium Ion?
I’m still trying to get my head around what’s going on and why the alternator reacts so differently, compared to the LFP batteries.
My car was at 100% when parked a couple of days ago. The fans seem to drain it down below 90% quickly after parking. Upon startup today I’m at circa 87% and about 12.5V (with a small drain). Once the car starts. The battery is charging at a good rate of 40A plus and fairly consistently too. It got up to circa 100% within maybe 10mins or so and it stays there, with a voltage of circa 14.4V or so.
My car was at 100% when parked a couple of days ago. The fans seem to drain it down below 90% quickly after parking. Upon startup today I’m at circa 87% and about 12.5V (with a small drain). Once the car starts. The battery is charging at a good rate of 40A plus and fairly consistently too. It got up to circa 100% within maybe 10mins or so and it stays there, with a voltage of circa 14.4V or so.
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I expect lithium ion will be fine. However, there’s no need to maintain a high voltage. A charge voltage of circa 12.8 to 13V should be ample to maintain it at a fairly high, but not 100% SOC. This battery is fully charged at circa 13.6V, but will still accept more voltage.
Unlike other cells, Sofium Ion can be discharged to 0V with no negative impact to the cells. The BMS I’ve used, does have the jump start feature.
For info, my/our company manufactures lithium ion batteries (not 12V car starter batteries, but we could). I do have a pretty extensive knowledge of batteries. Plastic cases with the standard battery sizes are available, as are suitable BMS, that can be configured to match the cells and the charging system on our cars.
The BMS is not such a key aspect of this sodium ion battery that makes it play nicely with the “Smart” Mercedes charging system we have in the Turbo. The key thing (IMO) that seems to trick the charging system in the Turbo Emira to think a regular AGM is fitted, is the charge/discharge curve of the cells, that seem to be very similar to an AGM battery. LFP cells have a very flat charge/discharge curve, and that flat area of the curve is rather high in voltage.
I don’t really understand why if I connect an LFP battery to our cars, the SOC steadily declines with use, if you don’t put it into a tender. My LFP battery was allowed to discharge recently and the battery activated the jump start function. Even though I started the car (using the jump start function ) but the car wouldn’t charge the battery and the car wouldn’t run.
I haven’t had a chance to deeply discharge the sodium ion battery and see how the car reacts, but I am fairly confident it will simply charge it quickly and get it to full charge fairly quickly.
The real answer? Someone needs to be able to alter the AMG "Smart" (i.e., dumb) charging system. I still can't believe MB/AMG went this route. I guess these are the problems you have when you buy engines from someone else.
beedobeedobeedo
Member
- Apr 10, 2025
- 12
- 4
Just following up here, but I’ve been driving the i4 on the Antigravity lithium for awhile now with only a few issues.
-No issues when doing long drives (maintains ~12.9V through 8+ hours of driving)
-loses charge pretty quickly around ~2 weeks that AGM shuts down and I have to use the Antigravity jump start button.
-No other major issues since the software update (eg limited telematics)
Anyone else still running on a lithium battery? Annoying that it doesn’t fully charge, but it seems like there isn’t yet a major issue with liberal use of the Antigravity jump start.
-No issues when doing long drives (maintains ~12.9V through 8+ hours of driving)
-loses charge pretty quickly around ~2 weeks that AGM shuts down and I have to use the Antigravity jump start button.
-No other major issues since the software update (eg limited telematics)
Anyone else still running on a lithium battery? Annoying that it doesn’t fully charge, but it seems like there isn’t yet a major issue with liberal use of the Antigravity jump start.
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I don't think anyone has had issues with AGM batteries. It's the Lithium Ion batteries that have been problematic given the unorthodox AMG alternator/charging logic inherent to the i4 variant.
beedobeedobeedo
Member
- Apr 10, 2025
- 12
- 4
Sorry I meant the antigravity lithium. Corrected the post to avoid confusion
I got caught out with my LFP battery (not Antigravity). The car had been left for a while and the battery level was low. The car started, but then it started to misbehave as soon as I had gone a short distance. Checked the app and battery was going into jump start mode, but the car wouldn’t charge the battery and maintain it. It left me sort of stranded, the car wouldn’t drive.
It seems to me, that even when these LFP batteries are very low, the car still thinks the battery has enough charge. Then other times, I’ve done a long drive (with the LFP battery) and the charge level was close to full when I arrived.
You can run a regular LFP battery, but be careful about letting it get too low, as there is the possibility it could leave you stranded.
Long and the short of it, I doubt you can get an LFP battery to play nice with the AMG charging system, the voltage curve is too different to an AGM.
It seems to me, that even when these LFP batteries are very low, the car still thinks the battery has enough charge. Then other times, I’ve done a long drive (with the LFP battery) and the charge level was close to full when I arrived.
You can run a regular LFP battery, but be careful about letting it get too low, as there is the possibility it could leave you stranded.
Long and the short of it, I doubt you can get an LFP battery to play nice with the AMG charging system, the voltage curve is too different to an AGM.
Can you comment on when you started running the AntiGravity? more specifically, was it after any recent software updates? We know the original charging logic was whacked. Perhaps they improved it a bit with recent SW updates?
beedobeedobeedo
Member
- Apr 10, 2025
- 12
- 4
Since early 2025, so a little over a year. It was one of the first mods I made to the car after hearing about the stock battery issues.
To be fair, the car has only been lightly driven (~2500 miles total). Closest to getting stranded was when I took a zoom call in the car with the engine off and it locked me out when I went for a coffee. The antigravity jump start seemed to fix that though.
Is there any damage from frequently jump starting with anti gravity that I should know about? Does that power reserve run out at all or is that charged alongside the car?
To be fair, the car has only been lightly driven (~2500 miles total). Closest to getting stranded was when I took a zoom call in the car with the engine off and it locked me out when I went for a coffee. The antigravity jump start seemed to fix that though.
Is there any damage from frequently jump starting with anti gravity that I should know about? Does that power reserve run out at all or is that charged alongside the car?
Ok, so now it sounds like the battery does get run down fairly quickly? Yay or nay? BTW, 2500 miles since early '25 is nothing. So, not sure this is confirmation that it "now works" on i4's.
And to answer your question, it's absolutely not good to use the jump start functionality on a regular basis. It was never intended to be used as a standard operating procedure. It's intended to be used in a pinch. For most, that might be once a year or less. You know, like when you go on that incredible 21+ day vacation and realize you didn't hook up the battery tender...
And to answer your question, it's absolutely not good to use the jump start functionality on a regular basis. It was never intended to be used as a standard operating procedure. It's intended to be used in a pinch. For most, that might be once a year or less. You know, like when you go on that incredible 21+ day vacation and realize you didn't hook up the battery tender...
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