2014 and batteries...

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EVBob

Well-known member
Joined
Apr 18, 2017
Messages
154
Looking at the market for pre owned 2014s, I've noticed some have fairly short Carfax Service history reports, and some have really long Service history reports....most of those looking like battery/electrical issues (all of them had battery charged as a listed item of service), of those some of them having multiple battery replacements.

Examples:
https://www.carfax.com/VehicleHistory/p/Report.cfx?partner=SDT_0&vin=WBY1Z4C52EVX62859
https://www.carfax.com/VehicleHistory/p/Report.cfx?partner=SDT_0&vin=WBY1Z4C52EV273054
https://www.carfax.com/VehicleHistory/p/Report.cfx?partner=SDT_0&vin=WBY1Z2C54EV284514

I am assuming it was the 12v battery being replaced. Any idea what the cause of this was? Was it resolved with software updates?

Thanks!
 
At 12,620 km and 5 months our new 2015 i3 REx 12 volt battery was found to be defective during a condition based service oil change. No symptoms. Computer check indicated faulty battery. Replaced with small agm type battery like used in many motorcycles. No subsequent problems. Currently at 39,000 km (1 year and 10 months). Not sure if they updated software to modify how 12 volt battery gets charged. In your first example the battery was replaced 6 times. Unlikely that all batteries were defective. So something else likely caused these problems.
 
EVBob said:
I am assuming it was the 12v battery being replaced. Any idea what the cause of this was? Was it resolved with software updates?
The i3's 12 V battery has a low capacity of only 20 Ah. The service manager at my BMW dealer told me that such a low capacity battery works only because the i3 connects its Li-ion battery pack to the 12 V system very frequently essentially increasing the effective 12 V battery capacity to that of the large Li-ion battery pack. This behavior can make it difficult to detect the health and/or charge level of the 12 V battery based on its voltage alone.

This connection between the Li-ion battery pack and the 12 V system is not established if an i3 is parked and left alone as might occur on a dealer's lot. Meanwhile, 12 V parasitic loads like the burglar alarm, wireless entry, etc., continually discharge the 12 V battery. If its charge drops too low and remains low for a period of time, permanent damage to the 12 V battery can occur. A more typical higher-capacity 12 V battery would not discharge as deeply with the same parasitic loads. I think that this is one of the reasons why so many i3 12 V batteries seem to be failing.
 
alohart said:
A more typical higher-capacity 12 V battery would not discharge as deeply with the same parasitic loads. I think that this is one of the reasons why so many i3 12 V batteries seem to be failing.


Hmm...is there a certain threshold of how many days one can go without the 12v completely draining? That first one looks to have gone through 8 batteries over the course of 3 years, perhaps that one is just a lemon?: https://www.carfax.com/VehicleHistory/p/Report.cfx?partner=SDT_0&vin=WBY1Z4C52EVX62859

I wonder if there are higher capacity or perhaps deep cycle marine batteries that would fit?
 
I think you'll find the battery in the i3 is an AGM type, which is better at deeper discharge than a wet cell one. You might be able to cram a larger one in there, but I'm not sure the computer has the ability to be programmed to handle it properly. Other (ICE) BMW models require you to program the computer with a few details about the battery:
- when installed (they degrade over time, it wants to know when installed (new))
- the type of battery (requires slightly different sensing and max charging voltage)
- the size of the battery

I had to go through this when I installed a new battery in my GT recently. Without reprogramming, the computer would think it was a smaller battery than I put in, and, 6-years old! I kept the type the same (AGM). I've not looked to see if the i3 has those parameters available in its programming. Someone else may know.
 
Do you have a battery code?

Our smart fortwo has a battery that is difficult to access so I installed permanent leads for our trickle c harger. Most trickle c hargers have this plug in option. I may install similar battery leads on i3 as we don't use it on icy roads.
 
TOEd said:
Do you have a battery code?

Our smart fortwo has a battery that is difficult to access so I installed permanent leads for our trickle c harger. Most trickle c hargers have this plug in option. I may install similar battery leads on i3 as we don't use it on icy roads.
From a BMW document someone posted, you CANNOT use a trickle charger for the 12vdc battery on the i3, or you will likely damage some electronics. The 12vdc battery does get charged when you are running the car and while you're recharging the main batteries, so separately trying to charge it probably wouldn't buy you much.
 
prettig said:
larger 12V battery is an option (at least in EU) so will fit....
Realoem.com shows these i3 battery options in the U.S.:

Original BMW AGM-battery 20 AH 61219321815
Original BMW battery (Warranty only) 40 AH 61217635788

A U.S. i3 owner reported that the larger, heavier 40 Ah battery would not fit in the i3's battery holder until it was modified. The windshield washer tank had to be relocated as well. So this doesn't sound like a suitable option to me.
 
jadnashuanh said:
From a BMW document someone posted, you CANNOT use a trickle charger for the 12vdc battery on the i3, or you will likely damage some electronics.
Correct.

Because I have had so much difficult trying to assess the health of the 12 V battery in our 2014 i3, I am considering installing accessible leads extending to the underside of our car from the 12 V battery charging terminals under the motor cover in the rear cargo compartment, but only to allow me to measure the 12 V battery voltage after our car has been parked for a few days.
 
Thank you ChrisColorado for your battery measurements. They correspond to an 18L AGM powersport battery used in motorcycles, scooters, ATVs, UTVs, personal watercraft, snowmobiles, boats, etc. I already have a couple of 18L batteries that I use in my snowmobile and boat. So when the warranty expires on the i3 and the battery dies, I will be swapping it for an 18L battery from Canadian Tire. P.S. The manufacturer of this battery also supplies OEM batteries to BMW. And no, I won't be programming the computer to accept this OEM battery replacement because my research indicates this is not necessary. And yes, I will be installing leads for a trickle charger as I don't see how minor fluctuations in battery voltage can damage electronics. I will let you know how these modifications work at the appropriate time.
 
TOEd said:
Thank you ChrisColorado for your battery measurements. They correspond to an 18L AGM powersport battery used in motorcycles, scooters, ATVs, UTVs, personal watercraft, snowmobiles, boats, etc. I already have a couple of 18L batteries that I use in my snowmobile and boat.
That looks like a good replacement 12 V battery because it is also an AGM battery with the same 20 Ah capacity as the original i3 battery. However, it doesn't have automotive post terminals. Hopefully, some designs allow automotive terminals to be installed.

TOEd said:
no, I won't be programming the computer to accept this OEM battery replacement because my research indicates this is not necessary.
Hopefully, BimmerCode will be enhanced to support 12 V battery registration.

TOEd said:
And yes, I will be installing leads for a trickle charger as I don't see how minor fluctuations in battery voltage can damage electronics.
Lots of expensive electronics might not be happy with power flowing from a trickle charger. It is so easy to disconnect the high-voltage system. Why would you risk not doing so?

I tried to trickle charge the 12 V battery in our i3 following BMW's procedure. Whenever anything is done to an i3 like opening the frunk or hatch, unlocking the doors, etc., multiple controllers are booted which consumes much more power than the trickle charger produces. With the high-voltage system disconnected, the DC-DC converter can't turn on to charge the 12 V battery, so the 12 V battery's charge level decreases until the controllers shut down. I finally ran the trickle charger leads up under the rear of the car to connect them to the rear 12 V charging terminals so that I could monitor the trickle charger outside the car without opening the hatch.

So to make progress trickle charging an i3's 12 V battery, one must leave the car untouched to avoid its controllers being booted which charging.
 
2014 no problem with 12v battery garaged in 60 ‘ through winter in New York .In all my gaassoline cars I always replaced them after 5years .Any suggestion to replace a 12 v battery in EV in 5 years is worth to stretch a year to have a problem.As we know you recharge battery when you charge a car . Any suggestions.


.
 
In May 2021 my 12 v battery will be 7 years old I check once a week before I start a car through cigarette outlet with modified voltmeter is still 14 ,5 volts all the time I charge a car at list once a week and in 7 years I drove only 20000 miles car is always in 60-65 “ garage I use heating or AC very seldom only radio and I lock a car in garage and on displays showing any lights at all those parasite discharge is not there just wander why I don’t have any problems with that 12 v battery Right now I ordered any way 12 v battery OM from dealer $191 already waiting 3 weeks they must ship from EU I must be lucky my battery last so long . After I get my car nobody mess up with programming or up dates maybe is still functioning so good figure out . As so many owners complains about 12 v battery and I still can make 70 -75 miles from that go cart which factory range was 84 miles
 
Lesterbmwi3 said:
In May 2021 my 12 v battery will be 7 years old I check once a week before I start a car through cigarette outlet with modified voltmeter is still 14 ,5 volts all the time I charge a car at list once a week and in 7 years I drove only 20000 miles car is always in 60-65 “ garage I use heating or AC very seldom only radio and I lock a car in garage and on displays showing any lights at all those parasite discharge is not there just wander why I don’t have any problems with that 12 v battery Right now I ordered any way 12 v battery OM from dealer $191 already waiting 3 weeks they must ship from EU I must be lucky my battery last so long . After I get my car nobody mess up with programming or up dates maybe is still functioning so good figure out . As so many owners complains about 12 v battery and I still can make 70 -75 miles from that go cart which factory range was 84 miles
The day your 12 V battery fails, your auxiliary power port voltage will still be ~14.3 V because that's the output voltage of the DC-DC converter that charges the 12 V battery, not the voltage of the 12 V battery itself. I installed a voltmeter in the auxiliary power port of our 2014 BEV more than 3 years ago hoping that it would display the voltage of the 12 V battery as an early indication of a 12 V battery failure. Unfortunately, unless the voltage of the 12 V battery is pretty high (i.e., a high charge level), the DC-DC converter will turn on to charge the 12 V battery. Because we drive so little, the average charge level of our 12 V battery must be lower than normal. A low charge level warning has been displayed once, so I charged the 12 V battery with a battery charger. During the pandemic, I've been driving only ~100 miles/month which seems to be insufficient to keep the 12 V battery charged, so I remotely unlock then lock the doors which turns on the high-voltage system for ~30 minutes during which the DC-DC converter will charge the 12 V battery, if needed. I wonder how many good i3 batteries have been needlessly replaced when all they needed was to be charged.

A better way to monitor the 12 V battery would be to install a wireless battery monitor that measures the 12 V battery continuously, even when an i3 is off and parked. That might show the battery's voltage gradually dropping as it ages, or maybe its capacity decreasing which would result in a lower average voltage. However, a monitor would add another parasitic load, although small.

The 12 V battery in our 2014 BEV is the original battery that continues to function normally. Our i3 has had its system software updated 3 times by our BMW dealer and is running the November, 2018, version. I have changed several behaviors using BimmerCode. The parasitic loads of the telematics module, the keyless entry transceiver, the entertainment system clock, and the burglar alarm, if armed, can't be avoided.

A couple of years ago, I ordered a replacement from a local East Penn Manufacturing retailer as a result of so many owners of older i3's reporting failed 12 V batteries. I didn't want to be stuck buying a replacement battery from our BMW dealer had our battery failed. It's still on a shelf waiting for the original battery to fail (I charge it a couple of times each year). This is the same battery that BMW installs in North American i3's and can be purchased for considerably less than $191. This battery is manufactured in the U.S., so your battery shouldn't be coming from a European country.
 
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