how to charge x5 key battery
 

My batteries are dead on both my key's. Can anyone tell me how to charge them. I think I did this before by putting the key in ignition & turning on the ignition, letting it sit overnight. Thank you in advance.
jay

You replace them not charge them. If you did that car battery would be drained.

May not be a battery issue, check this site out: https://www.bmwgm5.com/

The new style (diamond shaped) remote keys do charge while they are in the ignition and the car is on (from ignition position 1-upward)...but to fully charged a discharged key can take up to 30 hours.

Leaving your key in the ignition in position 1 or 2 will kill the battery...and can also kill the key after it remains on and the battery dies.

In order to do what you propose...you would need to hook up a battery charger or trickle charger to the pos & neg jump start terminals in the engine bay...or directly to the battery. This would prevent the battery from draining and possibly killing your key while its in the ignition during the time of the battery drain.

If you have an induction charger (like many cordless tooth brushes have)...you can place the key close to the induction charger...some have claimed it will charge the key's battery...but some also suggest not to do this, too...it's your call.

TIP: KL R = ignition position 1

If your handy with a soldering iron you can replace the battery.

The key fob takes a Panasonic ML2020 or VL2020 battery.
Brand New PANASONIC ML2020 VL2020 Battery fits BMW E46 E60 E90 Key Fobs | eBay

You need to carefully separate the front and back covers of the key. I did 2 keys using a putty knife. Start from the key ring and then work your way around the edges. You want to keep the knife blade on the perimeter of the key other wise you could damage the circuit board. It should open up fairly easily. Desolder the old battery and solder in the new one.

To reassemble the two halves you can use some plastic epoxy which should provide a water resistant seal. Or you can get silicone key fob covers. Since my 2 keys are backups I just put a strip of duct tape on each side to hold the key together and put the cover on.

Silicone key cover protection case for BMW X3 X5 Z3 Z4 3 5 7 SERIES E38 E39 E46 | eBay

Thank you everyone for the details. Have a good holiday.
j

I just place the second set of keys in a cordless touch brush charger and switch between the two set of keys every other week.

A fully charged remote key should be good up to 1.5 years stored in a drawer.

I swap remotes at daylight saving time change in the spring & fall...it makes it easy (for me) to know how long the one in the drawer has been sitting unused...plus it gets put back into service long before its battery completely discharges. :)

Better use recharging batteries not ordinary! Ordinary batteries are swating... rechargeable lasts about 12 years! My car is 2002. and my batteries died 2 years ago!
I decided to change my key fob for new design

I use the electric toothbrush charger trick all the time- it works like a dream!

right now i have two keys, one to start the car and one to operate the doors. I am planning to merge these functionalities into a single key.... it's just a little complicated, (as I think anyone who has rolled their own key will attest!)

chris