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MKH
Gold Member
Posts: 604
Joined: Fri Nov 02, 2018 5:48 am
Location: Dallas

Re: How is your battery holding up?

Thu Jun 11, 2020 5:15 am

Why not spend $5k and get a larger capacity battery? $5k is certainly cheaper than $100k plus for a Model S.
$5K will get you a used battery taken from a wreck in a salvage yard, with a 30 day warranty. Then it has to be installed.

According to Dr. Christian Cozzarini, Head of Environmental Engineering at BMW, a 'new' BMW i3 battery upgrade is $16K, installed.
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE

alohart
Posts: 2074
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: How is your battery holding up?

Thu Jun 11, 2020 11:22 am

TheMK wrote:
Wed Jun 10, 2020 9:13 pm
A generic answer. I should’ve asked the service advisor more questions. I guess I can call him back tomorrow. I had to have a family member pick my car up so that made it hard to talk to someone about it.

Do you think I should call them back?
I would want to know as much as possible. For example, if their capacity test indicated that the capacity was just over 70% of the new capacity, I would know that I could probably get a replacement battery pack before its warranty expires.

I would want to know how they measured the capacity. I have read that BMW can use a comprehensive test that discharges the battery pack and then measures the energy required to charge it fully. Or maybe the discharge capacity is measured also. That could take a couple of days to complete although the test might continue overnight.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

TheMK
Posts: 151
Joined: Tue Sep 18, 2018 8:57 pm

Re: How is your battery holding up?

Thu Jun 11, 2020 7:24 pm

Valleeboi02 wrote:
Thu Jun 11, 2020 12:21 am
You really need to look further into it.
How many miles does your car have on it and what year is your car? A 2014 i3 with normal use should be around 17.5kw usable battery power in 2020. No way a battery as advanced as the battery in an i3 should be at 13kw, unless you've been doing lots of Level 3 charging up to 100%. That can kill a battery quickly along with lots of high temperatures.
My car has 50,500 miles on the odometer, and is a July 2014 build. I've done DC Fast Charge not too much, maybe 10 or so times, and never to 100%. My car is subject to both cold (below freezing) and hot (90-95 degree days) in the course of the year, but my AC compressor is strong still, so the heat should be managed.

TheMK
Posts: 151
Joined: Tue Sep 18, 2018 8:57 pm

Re: How is your battery holding up?

Thu Jun 11, 2020 7:43 pm

alohart wrote:
Thu Jun 11, 2020 11:22 am
TheMK wrote:
Wed Jun 10, 2020 9:13 pm
A generic answer. I should’ve asked the service advisor more questions. I guess I can call him back tomorrow. I had to have a family member pick my car up so that made it hard to talk to someone about it.

Do you think I should call them back?
I would want to know as much as possible. For example, if their capacity test indicated that the capacity was just over 70% of the new capacity, I would know that I could probably get a replacement battery pack before its warranty expires.

I would want to know how they measured the capacity. I have read that BMW can use a comprehensive test that discharges the battery pack and then measures the energy required to charge it fully. Or maybe the discharge capacity is measured also. That could take a couple of days to complete although the test might continue overnight.
Yeah, I'm not totally sure. I can't tell that anything was done except replace the fuel pressure sensor, wash the car, and charge/top off to 100%. I think the battery capacity is at around 73% if I'm understanding the information they've given me correctly. My service advisor couldn't answer those questions, after I called him today. I may try to call BMW USA corporate and see what happens. Not sure if/what will happen there, but the car is becoming almost unusable, since the REx will kick in on my (pre COVID-19) daily commute. I drive at 80MPH on the freeway for 40 miles every day, plus have to climb 1000 ft at the end of the round-trip journey home.

alohart
Posts: 2074
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: How is your battery holding up?

Thu Jun 11, 2020 9:38 pm

TheMK wrote:
Thu Jun 11, 2020 7:24 pm
My car has 50,500 miles on the odometer, and is a July 2014 build. I've done DC Fast Charge not too much, maybe 10 or so times, and never to 100%. My car is subject to both cold (below freezing) and hot (90-95 degree days) in the course of the year, but my AC compressor is strong still, so the heat should be managed.
Unfortunately, yours is not an uncommon story for 60 Ah i3 owners. The Idaho National Laboratories bought 4 new i3 BEV's and using their advanced testing equipment, measured the usable capacities of their battery packs. Three lost 7.5% of their usable capacity after only 14 months and 12k miles. The fourth i3 lost 3.5% of its usable capacity after only 3 months and 4k miles but was either not driven for 14 months and 12k miles or the results weren't reported. That's pretty disappointing and so consistent that these probably weren't outliers.

Our 2014 i3 has been driven only 10k miles in 5.5 years. Living in Honolulu, our i3 has never experienced temperature extremes. The temperature where it has been parked 99% of its life in an apartment parking garage varies between 70º F and 78º F.

It has been DC fast charged only once from a low charge level to 80% and 3 other times for ~10 minutes each time from a low charge level. It is AC charged almost always at only 16 A. I almost always charge it to only an indicated 80% - 90% rarely charging it full and leaving it fully charged for more than a few hours. I did allow it to remain fully-charged for 3 weeks to determine whether unequal cell charge levels might be responsible for its capacity loss, but this made no difference. The battery pack has never remained at a low charge level. I occasionally allow the charge level to drop very low followed by a full charge hoping that the battery pack capacity might be calibrated to a larger value, but this has never happened.

So its battery pack has had an ideal life according to best practices. Yet it has lost more than 15% of its actual usable capacity which I can estimate by driving the same 100-mile route. This is consistent with its current 15.4 kWh Batt. Kapa. max value. What I don't know is whether the cells have actually degraded that much or whether the battery management system (BMS) has decreased the usable capacity to minimize the risk of the cells actually degrading more than the 30% warranty limit.

The fact that older versions of BMW's ISTA+ software can increase the usable capacity makes me think that the (BMS) is at least partially to blame for the capacity loss of many 60 Ah battery packs. However, this doesn't explain why some 60 Ah i3 owners claim little loss of capacity over many miles driven. Maybe there were a lot of weak 60 Ah cells installed in 60 Ah battery packs with most lucky 60 Ah i3 owners not having any of these weak cells in their battery packs. With an i3 battery pack being a single string of 96 cells connected in series, the entire pack is no stronger than its weakest cell.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

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