12 volt Battery Warning

[Hengus]

My 120Ah i3 has got very little use in the past 9 months during lockdown. I leave the car plugged in to a 7kW charging point. Yesterday, I got the 12 volt battery off auxiliaries message. Is there anything that I can do to increase the state of charge in the 12 volt battery. Would leaving it plugged in and pressing start work, or do I need to take the car out for a long run which is difficult at the moment? Thanks

 

[keepgoing]

I read from other post that every time you press the Start/Stop button to start up the car, it will charge the 12v battery by the inverter. So you may try that without taking it out for a drive.

 

[jadnashuanh]

Lead acid batteries, even AGM ones, can be damaged if they're discharged and sit too long at that state. AN AGM one can handle it better, but at low temperatures, a discharged AGM or plain lead acid battery can actually freeze and split its case. So, yes, setting the vehicle into ready state should attempt to recharge the battery, but depending on where it is in its life cycle, it may not restore it. Depending on its age, it may be time to replace it.

Depending on the MY and current software version, you may be able to install a trickle charger and keep it maintained. On the earlier versions, you have to disconnect the HV battery first.

You can buy the battery for about $140 or so, give or take a little, but it will cost you a lot more from the dealer, and if you have them install it, quite a bit more. The logic needs to know when the battery was installed, so you should do that. If you don't have the software/hardware to do that, some places will do it for you (Pep Boys around here will do it for about $30 or so). That will keep the battery charging logic functioning at optimum performance, but it will work regardless, just won't last as long.

 

[alohart]

I read from other post that every time you press the Start/Stop button to start up the car, it will charge the 12v battery by the inverter. So you may try that without taking it out for a drive.

Even easier would be to unlock then lock the doors, even with the BMW Connected app. That would also start the high-voltage system including the DC-DC converter which will charge the 12 V battery if its charge level is too low. I've seen the high-voltage system remain on for at least 30 minutes. Doing this periodically should help keep the 12 V battery's charge level from dropping too low.

 

[alohart]

My 120Ah i3 has got very little use in the past 9 months during lockdown. I leave the car plugged in to a 7kW charging point. Yesterday, I got the 12 volt battery off auxiliaries message.

Further evidence that leaving an EVSE plugged in won't keep the 12 V battery charged. About 30 minutes after the battery pack becomes fully charged, the high-voltage system and the DC-DC converter that charges the 12 V battery turn off.

 

[Hengus]

Thanks guys. I have been out this morning and Pressed Start. No 12 volt battery warnings appeared, and apart from a slight hum (with the doors closed/unlocked) there was nothing unusual. After about 20 mins, the car started to charge again from my charging point. I will 'rinse and repeat' over the next few days.

A further question if I may? I will need to check tyre pressures before my next drive. If I use a 12 volt air compressor with Stop/Start set to Start will inflating tyres deplete the 12 volt battery?

 

[Anonymous]

I will need to check tyre pressures before my next drive

(While Driving) Using the iDrive MENU button, choose:
“Vehicle Info”
“Vehicle status”
“Flat Tire Monitor”
The tyre pressures will be displayed.

Once the car is in "Ready" state, the 12v sockets should be powered by the DC/DC converter and the HV battery pack.

 

[alohart]

During the pandemic, our i3 has been driven only ~100 miles/month. Last week when I started our i3, the dreaded "Excessive battery discharge while stopped. Start the engine" message (paraphrased) was displayed. This must occur when the 12 V system voltage drops too low which could be due to a failing 12 V battery or a low 12 V battery charge level due to our driving too infrequently and for too little time. Our 12 V battery is over 6 years old, so it could be failing. However, rather than replacing it (I have a replacement already), I decided to charge the 12 V battery with a battery charger to learn whether it would hold a charge. So far, so good…

Before connecting the battery charger, I disconnected the high-voltage disconnect to prevent both the DC-DC converter and my battery charger from potentially charging the battery simultaneously. The module responsible for 12 V battery charging would sense the voltage of the battery charger and probably would not turn on the DC-DC converter assuming that the battery didn't need charging, but I don't know for certain and didn't want to risk damaging anything. However, unlike in the past, I didn't wait for the high-voltage system to turn off on its own (can take over 30 minutes) before disconnecting the high-voltage disconnect. As a result, the ConnectedDrive Website sent me the following email message :

Dear BMW ConnectedDrive Customer,

The battery of your vehicle WBY1Z2C50EV285093 cannot be charged due to a malfunction!

Please pay attention to the remaining range and contact Roadside Assistance.

Kind regards,

BMW ConnectedDrive
https://connecteddrive.bmwusa.com

Typical poor BMW message. No indication which battery the message is referring to. Because the message was sent immediately after I disconnected the high-voltage disconnect which prevents the DC-DC converter from charging the 12 V battery, I assume this refers to the 12 V battery.

 

[alohart]

During the pandemic, our i3 has been driven only ~100 miles/month. Last week when I started our i3, the dreaded "Excessive battery discharge while stopped. Start the engine" message (paraphrased) was displayed. This must occur when the 12 V system voltage drops too low which could be due to a failing 12 V battery or a low 12 V battery charge level due to our driving too infrequently and for too little time. Our 12 V battery is over 6 years old, so it could be failing. However, rather than replacing it (I have a replacement already), I decided to charge the 12 V battery with a battery charger to learn whether it would hold a charge. So far, so good…

More than 2 weeks after charging the 12 V battery, no additional 12 V battery warnings have been displayed, and the 12 V battery seems to be holding its charge despite our i3 not being driven much. So I won't be replacing our original 12 V battery yet but will be doing more to prevent vampire loads from discharging it too much.

 

[Deutsch100]

During the pandemic, our i3 has been driven only ~100 miles/month. Last week when I started our i3, the dreaded "Excessive battery discharge while stopped. Start the engine" message (paraphrased) was displayed. This must occur when the 12 V system voltage drops too low which could be due to a failing 12 V battery or a low 12 V battery charge level due to our driving too infrequently and for too little time. Our 12 V battery is over 6 years old, so it could be failing. However, rather than replacing it (I have a replacement already), I decided to charge the 12 V battery with a battery charger to learn whether it would hold a charge. So far, so good…

More than 2 weeks after charging the 12 V battery, no additional 12 V battery warnings have been displayed, and the 12 V battery seems to be holding its charge despite our i3 not being driven much. So I won't be replacing our original 12 V battery yet but will be doing more to prevent vampire loads from discharging it too much.

Great news

 

[Lesterbmwi3]

Can someone tell me when I should replace 12v battery on my 2014 MAY BMWI 3 EV no REX in MAY will be 7 years old nothing wrong so far is original battery car in NY is sitting in heated garage is driven short distance 2-3times a week in snow too and charged fully once a week .? If I’m going to see on display battery is going dead 12 v or bc of age I should replace now to prevent problem in near future need advice car is only 20000 miles Thanks

 

[alohart]

Can someone tell me when I should replace 12v battery on my 2014 MAY BMWI 3 EV no REX in MAY will be 7 years old nothing wrong so far is original battery car in NY is sitting in heated garage is driven short distance 2-3times a week in snow too and charged fully once a week .? If I’m going to see on display battery is going dead 12 v or bc of age I should replace now to prevent problem in near future need advice car is only 20000 miles

We also have a low-mileage (13k) 2014 BEV with its original 12 V battery although it has never experienced cold weather (tropics). If you plan to replace the 12 V battery yourself or know an independent mechanic who would do this, buy a replacement AUX18L battery now to have it ready when needed. I bought mine from a local East Penn Manufacturing retailer for ~$60 less than our BMW dealer's price. Be sure to fully charge the replacement battery before installing it.

A 12 V battery low charge message was displayed on our instrument panel recently. This could occur when a 12 V battery is failing and needs immediate replacing or when the 12 V battery hasn't been kept charged (e.g., if an i3 isn't being driven often or far enough). In our case, charging the 12 V battery with a battery charger seems to have fixed the problem, so my replacement battery is still waiting to be installed.

 

[Lesterbmwi3]

Thank you you right I m buying replacement and keep fully charged in garage