BMW i3 auxiliary battery sizes

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I suspect the post-drive fans and cooling loops are driven by the 12V battery. This would wear down the 12V battery faster than if these post-drive loads were not there.

Bob Wilson
 
bwilson4web said:
I suspect the post-drive fans and cooling loops are driven by the 12V battery.
The A/C compressor is powered by a high-voltage motor. I'm not sure about the front heat exchanger fan motor.
 
Apparently the OEM i3 12 V AGM battery is made by East Penn Manufacturing under the Deka brand. Its model number is AUX18L. Local dealers can be found here for those of you interested in replacing the battery yourselves. I have just sent my local dealer an email message requesting availability and price. If this dealer can sell a battery to me, I would have another source than my BMW dealer, hopefully at a lower price.

Now I need to figure out the best way to register the battery. The Carly tools apparently require a Windows operating system to install BMW software. I don't do Windows, so Carly is not an option for me. An independent BMW mechanic would likely charge less than my BMW dealer, but I would like to be able to register the battery myself. What's the least expensive tool that could register a new battery?
 
You should be able to do it with the Bimmercode app, assuming you have iOS devices. The license for the app and the OBD device to talk to the car should easily be available for about $50. Some other BMW driver near you might do it for you for free.
 
jadnashuanh said:
You should be able to do it with the Bimmercode app, assuming you have iOS devices.
I have BimmerCode. Unfortunately, it is currently unable to register a new battery.
 
Very interesting topic and hopefully my question is not too far off;

I'm going on vacation from Saturday to Saturday and was thinking of leaving the i3 plugged into the standard 110v wall charger while I'm gone. I have a 6:00am climatize schedule set for weekdays as well. The i3 will be in the garage with expected minus (Celcius) temps next week.

Would that be ok or is there a better way ?
 
tman66 said:
I'm going on vacation from Saturday to Saturday and was thinking of leaving the i3 plugged into the standard 110v wall charger while I'm gone. I have a 6:00am climatize schedule set for weekdays as well. The i3 will be in the garage with expected minus (Celcius) temps next week.

Would that be ok or is there a better way ?
Just park it with climatization off, the battery pack charge level ~50%, and the EVSE not plugged in. The 12 V battery won't discharge enough in 7 days to cause problems, the Li-ion battery pack won't discharge enough to be noticeable, and you won't waste energy climatizing a car that won't be driven.
 
alohart said:
tman66 said:
I'm going on vacation from Saturday to Saturday and was thinking of leaving the i3 plugged into the standard 110v wall charger while I'm gone. I have a 6:00am climatize schedule set for weekdays as well. The i3 will be in the garage with expected minus (Celcius) temps next week.

Would that be ok or is there a better way ?
Just park it with climatization off, the battery pack charge level ~50%, and the EVSE not plugged in. The 12 V battery won't discharge enough in 7 days to cause problems, the Li-ion battery pack won't discharge enough to be noticeable, and you won't waste energy climatizing a car that won't be driven.

Hey Art, thanks for the suggestion. It makes more sense than what I was thinking. Newbie EV owner paranoia I guess.

Is there any particular reason why the battery should be at ~50% and not let’s say 100%?
 
The car won't turn on the EVSE until the battery level drops. There is no possibility that power will be applied continuously and potentially damaging the batteries. BMW suggests to leave it plugged in. The level must drop a few percent after charging before the car will turn the EVSE back on again. The system is pretty smart in that regard.

Long-term, the biggest issue is the 12vdc battery getting discharged and, if it's really cold, potentially freezing. That can't happen if it's charged or connected to an EVSE. An i3 isn't your laptop of cellphone...the battery management and EVSE combined are a lot smarter.
 
tman66 said:
Is there any particular reason why the battery should be at ~50% and not let’s say 100%?
A Li-ion battery cell degrades more rapidly as its charge level varies from ~50% (i.e., more rapidly at very low or very high charge levels compared with mid-range charge levels). The i3's battery management system doesn't allow its cells to reach 0% or 100% charge levels to protect them from rapid degradation. According to the excellent book Electric Vehicles and the BMW i3 (60 Ah and 94 Ah) by David J. Bricknell, a 60 Ah battery pack can't be discharged lower than ~10% (a displayed charge level of 0%) or charged higher than ~95% (a displayed charge level of 100%). So if a battery pack is allowed to remain at a displayed charge level of 100%, the actual 95% charge level is still quite high and results in cells degrading more rapidly than at lower charge levels.

Many of us who plan to keep our i3's past the battery pack warranty period do what we can to minimize the inevitable battery cell degradation rate. Minimizing the time a battery pack is allowed to remain at a high charge level is one of these strategies.

For those leasing an i3 or who don't plan to keep their i3's for many years might feel that manually managing the battery pack's charge level is more trouble than they want to endure, so they just leave their EVSE's plugged in to their i3's whenever they're parked at home.
 
BMW is running the Chargeforward program in some places in US, and it encourages to charge to 100% every time , and when ever possible.
Most people are the Lease , so they could also care less .



alohart said:
tman66 said:
Is there any particular reason why the battery should be at ~50% and not let’s say 100%?
A Li-ion battery cell degrades more rapidly as its charge level varies from ~50% (i.e., more rapidly at very low or very high charge levels compared with mid-range charge levels). The i3's battery management system doesn't allow its cells to reach 0% or 100% charge levels to protect them from rapid degradation. According to the excellent book Electric Vehicles and the BMW i3 (60 Ah and 94 Ah) by David J. Bricknell, a 60 Ah battery pack can't be discharged lower than ~10% (a displayed charge level of 0%) or charged higher than ~95% (a displayed charge level of 100%). So if a battery pack is allowed to remain at a displayed charge level of 100%, the actual 95% charge level is still quite high and results in cells degrading more rapidly than at lower charge levels.

Many of us who plan to keep our i3's past the battery pack warranty period do what we can to minimize the inevitable battery cell degradation rate. Minimizing the time a battery pack is allowed to remain at a high charge level is one of these strategies.

For those leasing an i3 or who don't plan to keep their i3's for many years might feel that manually managing the battery pack's charge level is more trouble than they want to endure, so they just leave their EVSE's plugged in to their i3's whenever they're parked at home.
 
EVMan said:
BMW is running the Chargeforward program in some places in US, and it encourages to charge to 100% every time , and when ever possible.
Most people are the Lease , so they could also care less .
That's true. I fear that the i3 will get a poor reputation down the road as battery degradation reduces range to unusable levels for many people while the cost of battery pack replacement remains a significant portion of the total value of an i3.
 
Bawareca said:
jadnashuanh said:
The charging routine for an AGM battery is different than one for a typical lead-acid battery. When BMW sweated every gram of weight on the car's design, there obviously were some compromises, but the vast majority of people get by fine with the stock battery. That new battery may not have the same life since an AGM typically uses a slightly higher charging voltage that would shorten the life of a typical one. On some BMW models, you can adjust the charging routine depending on the battery installed, but I do not know if they are accessible with the right software on the i3.

My car came with a completely dead battery and that upset me a bit (10k miles). Browsing REaloem I found the upgraded 40Ah battery and instead of buying another laptop battery (the original one :p ), I bought the upgraded without doing much research. At the end I had to modify the battery tray and I had to change the position of the windshield washer reservoir.
There has been many cases when the main battery shuts down completely at low state of charge and the small "laptop" battery will be sufficient for only a few minutes before it is completely exhausted, let alone to start the REX. The 40ah battery has some real energy stored in it and if one needs it only 1 time it is worth it (for me).
From what I see there is no "charge routine". The moment the car wakes-up 14-14.5V from the main battery thru the DC/DC inverter is supplied to the 12V system, to the moment the car goes to "sleep". Actually the original AGM battery is very fragile when fully discharged (partially because of the low capacity), lead battery should fare much better in these conditions.

Do you mind to share how did you modify the battery tray and where did you relocated the washer tank? Thanks
 
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