Battery charge after long periods

BMW i3 Forum

Help Support BMW i3 Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

nernm

New member
Joined
Feb 1, 2017
Messages
1
Location
Scotland
Received this yesterday and the day before:

"Dear BMW ConnectedDrive Customer,

Please check the battery charge when your vehicle V58**** has been left parked for longer periods."

What's it about? Does it mean traction battery or 12V battery? What's a long period? Any modern car with immobiliser and other power draw thingies will eventually drain the 12V battery if left long enough.

How do I check the 12V battery charge? I can do the traction one though the app.

nernm
BMWi3 Rex
 
from the manual

Do not park the vehicle for longer than 14 days
if the electric range is less than 6 mls, approx.
10 km.

also

With storage times of up to three months, if
possible plug the vehicle into a suitable power
source or park it in a nearly fully charged state.

i believe the batteries are connected and the larger one will help maintain the smaller one
 
If the 12v battery is low, it will be shown on the instrument display.

Just put the car on charge and it will charge the main battery and the 12v battery.

I accidentally left the 13 off charge while away for over a month. When I came back the car was fine and put it back on charge at low rate to give the 12v battery enough time and no issue.
 
nernm said:
Received this yesterday and the day before:

"Dear BMW ConnectedDrive Customer,

Please check the battery charge when your vehicle V58**** has been left parked for longer periods."

What's it about? Does it mean traction battery or 12V battery? What's a long period? Any modern car with immobiliser and other power draw thingies will eventually drain the 12V battery if left long enough.

How do I check the 12V battery charge? I can do the traction one though the app.

nernm
BMWi3 Rex

This is just a generic reminder email sent out to all BMW i3 owners - four others I know received these last week.

The word ‘when’ is the giveaway. It’s not suggesting the battery is flat or that it has been left parked for a long period.

However, this same communication channel WILL send you a reminder email (or SMS) if your battery is too low and it has been parked for a long time. This setting is under ‘Battery Guard’ for your car in your ConnectedDrive profile. You can also choose to receive an email or and SMS.
 
justanotherdrunk said:
With storage times of up to three months, if
possible plug the vehicle into a suitable power
source or park it in a nearly fully charged state.
No need to leave the battery pack nearly fully charged. Li-ion battery experts know that degradation is less likely at lower charge levels but not too low; ~50% would be ideal.

No need to worry about the Li-ion battery pack discharging significantly. It isn’t connected to anything electrically when the car is off and not being charged. We have parked our BEV for 6-9 months in each of the past 3 years with no more than ~5% self-discharge during each storage period.

The 12 V battery could discharge enough to prevent the car from starting, so it must either be disconnected or charged while the car is parked (e.g., by charging the car with an EVSE).

justanotherdrunk said:
i believe the batteries are connected and the larger one will help maintain the smaller one
This is not true when an i3 is off and not charging.
 
The car disconnects the EVSE when it senses it has reached it's optimum charge level. It's not like many consumer electronics where the charger continues to operate, trying to pump power into the batteries generating heat which can damage them. IOW, you cannot overcharge the battery in an i3. If, over time, the level drops enough, it will try to top it off, but in reality, that's likely to be months unless the battery temperature drops significantly with the weather. The 12vdc battery OTOH, may be damaged if it sits too long...it doesn't have a huge load, but the clock and alarm system, and probably a few other things will continue to run, and those are powered by the 12vdc battery. I don't think that is explicitly monitored, and the HVDC battery may not try to top that off until it's level drops and the main HV batteries need power...that part is a little fuzzy.

Toyota's latest prototype battery is said to handle 5000 power cycles and retain at least 90%...that's over 14-years of daily charging. That tech may be better than that in the i3, but the i3's is better than most out there today. FWIW, sometimes, the weather can change quickly, and the ambient temp of the battery pack is probably the second biggest thing on the readout of range...the first is how you drove it the last few miles which may be nothing like what you will drive in the future, and thus, be way off, at least for awhile. Range is a trend indicator, not an absolute. My ICE might say 500-miles to empty when I just finished a trip...drive around town for maybe 20-miles, and it could drop to 400, way more than you'd think (100 lost verses a real 20 driven).
 
Back
Top