Those who swapped in a 12V lithium - how are things going?

Greetings All,

For those that installed a 12v Lithium battery to replace their 12v SLA/AGM battery - how is it working out for you?

Can you share which make/model of battery you used and for how long?

In South Florida, we are lucky if we can have our 12v batteries last 3-4 years - going to be due to swap out soon...

Thanks in Advance!

I haven't changed my AGM but did come across this on facebook

https://dakotalithium.com/product/dakota-lithium-12v-20ah-amp-hour-23ah-lifepo4-battery/

These two blurbies are from the Dakota Lithium FAQ and worthy of consideration:


With a former Audi, I recall in VCDS there were different coding values to input for SLA and AGM batteries, and I also recall their being a Li-Ion setting but don't remember if it was available as a selection in my 2013, or if it only applied to other models. Does anybody know whether BMW has such a setting?

Anyway... despite all that, here's a thread on Reddit where the author just "dropped one in" tp his i3 and it has been doing fine for him for at least 3 years.

eNate said:

With a former Audi, I recall in VCDS there were different coding values to input for SLA and AGM batteries, and I also recall their being a Li-Ion setting but don't remember if it was available as a selection in my 2013, or if it only applied to other models. Does anybody know whether BMW has such a setting?

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When I installed a LFP 12 V battery in our i3 6 months ago, I tried to change the battery type during battery registration. However, the battery type and capacity cannot be set when registering the battery with BimmerLink. BimmerCode can set the battery type and capacity but only from a fixed list of types and capacities which doesn't include any lithium type. The battery manufacturer told me that the capacity of my LFP battery is equivalent to a 40 Ah AGM battery, so I set the type and capacity to 40 Ah AGM. I don't believe that this makes much, if any, difference on an i3.

My LFP battery's performance seems good. Its voltage is ~0.5 V higher than an AGM battery. The DC-DC converter keeps this battery fully charged. The battery's output voltage doesn't sag nearly as much as the OEM AUX18L. Living in the tropics, I don't have to worry about my LFP battery not charging well at cold temperatures. However, my battery has its own internal battery cell heater which is claimed to make it perform normally at cold temperatures.

alohart said:

When I installed a LFP 12 V battery in our i3 6 months ago, I tried to change the battery type during battery registration. However, the battery type and capacity cannot be set when registering the battery with BimmerLink. BimmerCode can set the battery type and capacity but only from a fixed list of types and capacities which doesn't include any lithium type. The battery manufacturer told me that the capacity of my LFP battery is equivalent to a 40 Ah AGM battery, so I set the type and capacity to 40 Ah AGM. I don't believe that this makes much, if any, difference on an i3.

My LFP battery's performance seems good. Its voltage is ~0.5 V higher than an AGM battery. The DC-DC converter keeps this battery fully charged. The battery's output voltage doesn't sag nearly as much as the OEM AUX18L. Living in the tropics, I don't have to worry about my LFP battery not charging well at cold temperatures. However, my battery has its own internal battery cell heater which is claimed to make it perform normally at cold temperatures.

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Could you please share what battery you installed/provide a manufacturer link? I have another couple of years on my current AGM, but I would then be able to report on cold weather performance of the lithium setup. (I’m located in Colorado). Thanks!

eNate said:

This is because Dakota Lithium iron phosphate (LiFePO4) technology charges and is full at a higher voltage then traditional batteries (Dakota Lithium charges at 14.4 Volts).

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Since I've been shaking down my recently-installed BM2 monitor, I can report (as I think others will echo) that during DC-DC charging, the voltage jumps to 14.4V, falling off only slightly during these DC-DC charging sessions. So it seems spot-on for Li-ion, actually.

I installed the Moseworth 20Ah LFP in mine this winter. No issues with it, and fit is perfect after moving padding from the top of the hold down bracket to the front. It accepts SAE adapters for a no hassle install. No problems yet!

ksnax said:

I installed the Moseworth 20Ah LFP in mine this winter. No issues with it, and fit is perfect after moving padding from the top of the hold down bracket to the front. It accepts SAE adapters for a no hassle install. No problems yet!

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$54 is an incredible price for any battery that fits an i3, much less a LFP battery. The Ohmmu LFP battery that I installed is 5 times the price! I was sent 2 of these batteries for testing in our i3, but I would not have paid so much more for it compared with the Moseworth LFP battery. Unfortunately, most batteries won't be shipped to Honolulu including the Moseworth.

The Ohmmu battery includes a Bluetooth radio that allows its BMS to communicate with the Ohmmu smartphone app to report all sorts of data as well as to turn charging and discharging on and off individually. It also seems to have a larger capacity than the Moseworth battery, but the Moseworth's capacity seems sufficient for an i3. It includes a battery cell heater that enables charging at low temperatures which might be an advantage in cold weather over a Moseworth battery that claims to be chargeable down to only -5 ºC.

I'm disappointed that Ohmmu hasn't prepared one of its batteries specifically for an i3 including screw-on SAE posts that fit well. The Rivian battery is slightly taller than the AUX18L which requires modifications similar to what's required to install the Moseworth battery.

Enate

Thanks for the info. My AGM charges at 15v? Does that sound right? I am basing this from the graph on my battery monitor and it may not have enough granular data to show me more precision.

Lito

tongsli said:

Thanks for the info. My AGM charges at 15v? Does that sound right? I am basing this from the graph on my battery monitor and it may not have enough granular data to show me more precision.

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Next time you open the Battery Monitor app and access the graph, tap somewhere with your finger and slide back and forth. You will see the precise voltage readings in a little popup window

EvanstonI3 said:

Next time you open the Battery Monitor app and access the graph, tap somewhere with your finger and slide back and forth. You will see the precise voltage readings in a little popup window

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thank you!

tongsli said:

Thanks for the info. My AGM charges at 15v? Does that sound right? I am basing this from the graph on my battery monitor and it may not have enough granular data to show me more precision.

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I have what appears to be the same 12 V system monitor. For our former 2014 i3 and current 2019 i3, the DC-DC output voltage has never exceeded 14.4 V and the AGM battery's resting voltage was ~12.7 V, both ~0.4 V less that what your monitor is logging. I've confirmed these voltages with 2 different voltmeters. Maybe your higher voltages are due to cooler temperatures or maybe your 12 V system monitor is reading high. If you search the Internet for AGM battery voltage vs. charge level, I don't think you'd find any reference that states that the AGM resting voltage at a 100% charge level is the 13.0 V that your monitor is logging.

Nevertheless, the value of your monitor isn't the actual voltage that it logs but how the voltage is changing over time. In that respect, your 12 V battery seems to be in very good health because its voltage is remaining quite steady over many hours unlike what a failing battery could do.

alohart said:

I have what appears to be the same 12 V system monitor. For our former 2014 i3 and current 2019 i3, the DC-DC output voltage has never exceeded 14.4 V and the AGM battery's resting voltage was ~12.7 V, both ~0.4 V less that what your monitor is logging. I've confirmed these voltages with 2 different voltmeters. Maybe your higher voltages are due to cooler temperatures or maybe your 12 V system monitor is reading high. If you search the Internet for AGM battery voltage vs. charge level, I don't think you'd find any reference that states that the AGM resting voltage at a 100% charge level is the 13.0 V that your monitor is logging.

Nevertheless, the value of your monitor isn't the actual voltage that it logs but how the voltage is changing over time. In that respect, your 12 V battery seems to be in very good health because its voltage is remaining quite steady over many hours unlike what a failing battery could do.

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Yeah, thanks. It's fairly cool still in MD on the east coast. I'll look again in July. I do keep my car in a garage so it likes living inside. When I bought the car, I asked the dealership to check the battery and they said it was fine. I need to see if I can find a production year on the battery, it may have already been replaced. But, the original owner was from California. I have seen your posts on the failing battery logs and I look every few weeks to see if I find the dreaded failing pattern.

There is an East Penn Manufacturing distribution center 15 minutes from my house where I can pickup the Deka Aux 18L battery for the same price REMY sells if for online with shipping. So I will purchase it from there if I start to see a failing condition. I am open to switching to Lithium Iron Phosphate but would like to see what happens with your test.

Had a friend do it for me. Very easy.