mike21070
Posts: 2
Joined: Thu Jul 25, 2019 12:03 pm

Battery charging questions for new owner

Sun Jul 28, 2019 2:39 pm

Made the leap and bought a 2016 BEV. Great car deal on the car and we're happy.

The question I have is regarding charging the battery: My wife only uses about 30 miles a day, which means there's about 40 left over at the end of the day. What do you suggest we do--still charge it to full overnight, or use it the second day before fully charging. I'm wondering about what people say about the damages of constantly charging a battery. Should you let it get down to almost nothing and charge again, or keep charging when there is plenty of charge left?

Thoughts/opinions?

Thanks

Fisher99
Posts: 403
Joined: Sun May 12, 2019 6:24 pm

Re: Battery charging questions for new owner

Sun Jul 28, 2019 5:25 pm

With an i3/BEV, If it was my wife, I'd charge it every night. There are too many variables that can eat up an extra perceived 10 miles of range and I wouldn't want to run the risk of leaving her stranded.

However, with my 2014 i3/REX, I usually don't charge it if I have 40 miles left showing, but then I've got the REX as a security blanket, so no range anxiety here... 8-)
2014 BMW i3 with Range Extender Engine, Capparis White/Frozen Black, 20" wheels,, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, TurboCord EVSE

jadnashuanh
Posts: 5196
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Battery charging questions for new owner

Sun Jul 28, 2019 6:42 pm

The logic doesn't actually charge it to full and once it's at its peak, it disconnects the power so it's not like it sits on the charger forever, potentially frying the batteries. From what I've read, charging once from zero is the same 'wear' on the batteries as charging from 90-100% ten times...IOW, I don't worry about it. Nearly 5-years of that on my 2014 BEV and the battery capacity is only slightly less.
Jim DeBruycker
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)

Obioban
Posts: 100
Joined: Wed May 22, 2019 6:16 am

Re: Battery charging questions for new owner

Mon Jul 29, 2019 4:27 am

Charge it every night. It only charges to ~80% so you're not hurting it. Charging it every night allows for the unexpected, which will inevitably occur. Traffic jam, closed road, emergency shopping need, emergency hospital need-- it's good to have to car functional/ready to go.

alohart
Posts: 2431
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Battery charging questions for new owner

Mon Jul 29, 2019 8:36 am

Obioban wrote:
Mon Jul 29, 2019 4:27 am
Charge it every night. It only charges to ~80% so you're not hurting it.
Actually, the maximum allowed charge level is ~95% of the actual full charge level with ~10% being the minimum allowed charge level. So there's ~15% total unusable charge split between upper and lower charge levels.

Leaving a Li-ion battery cell at ~95% of its maximum possible charge level potentially results in faster degradation than when left at lower charge levels. That's simply an electrochemical fact. Likewise, leaving a Li-ion cell at 95% charge level results in slower degradation than when left at the maximum possible charge level, so the i3's battery management system will likely prevent more than 30% capacity degradation during the battery pack's warranty period. However, many of us planning to keep our i3's past the battery pack warranty expiration date want to minimize the degradation rate by not charging to an indicated full charge more often than necessary.
Aloha,
Art

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

Fisher99
Posts: 403
Joined: Sun May 12, 2019 6:24 pm

Re: Battery charging questions for new owner

Mon Jul 29, 2019 10:38 am

alohart wrote:
Mon Jul 29, 2019 8:36 am
Obioban wrote:
Mon Jul 29, 2019 4:27 am
Charge it every night. It only charges to ~80% so you're not hurting it.
Actually, the maximum allowed charge level is ~95% of the actual full charge level with ~10% being the minimum allowed charge level. So there's ~15% total unusable charge split between upper and lower charge levels.

Leaving a Li-ion battery cell at ~95% of its maximum possible charge level potentially results in faster degradation than when left at lower charge levels. That's simply an electrochemical fact. Likewise, leaving a Li-ion cell at 95% charge level results in slower degradation than when left at the maximum possible charge level, so the i3's battery management system will likely prevent more than 30% capacity degradation during the battery pack's warranty period. However, many of us planning to keep our i3's past the battery pack warranty expiration date want to minimize the degradation rate by not charging to an indicated full charge more often than necessary.
I like the idea of stretching battery life, but have not found a good way to regularly limit charging to, say, 80%, without running out and looking at it while it is charging. Even with best intentions, I will forget. And often I charge at night so I'm sleeping while it is charging. Perhaps some of the more expensive EVSE's can be set to stop charging at a certain percent? I know that my TurboCord can't.
2014 BMW i3 with Range Extender Engine, Capparis White/Frozen Black, 20" wheels,, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, TurboCord EVSE

alohart
Posts: 2431
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Battery charging questions for new owner

Mon Jul 29, 2019 11:48 am

Fisher99 wrote:
Mon Jul 29, 2019 10:38 am
I like the idea of stretching battery life, but have not found a good way to regularly limit charging to, say, 80%, without running out and looking at it while it is charging. Even with best intentions, I will forget. And often I charge at night so I'm sleeping while it is charging. Perhaps some of the more expensive EVSE's can be set to stop charging at a certain percent? I know that my TurboCord can't.
Because of extensive roof-top solar in Honolulu, the off-peak period of our time-of-use electricity rate plan occurs between 9 am and 5 pm daily. Being retired makes it convenient to charge between 9 am and 5 pm so that I can just set an alarm on my Apple Watch to remind me to stop charging.

However, the software on my old JuiceBox kit allows me to set charging start and end times, so I could prevent charging to full using my JuiceBox if I charged overnight.

Too bad the i3's charging software does not support setting a maximum charge level. BMW apparently does not want i3 owners to be inconvenienced by having to manage charging.
Aloha,
Art

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

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