Quote:
Originally Posted by Effduration
so to be clear, the 2 of the 3 key fobs still start the car fine, but they no longer lock/unlock the car, right ?
They start the car because the valet key is fine
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The key fobs don't start the car. But the keys do
, and all 4 do so with no problems at all, as they have done for 5.5 years. The EWS chips (3 of them in the 3x valet keys, 1 in the full diamond key), etc. all work just fine.
The 3x EWS chips in the key fobs are still there but are not relied upon by the EWS, and do not confuse the EWS as long as a valid key is present. The only problem is with the rechargeable batteries in the key fobs (2 of the 3). Because those batteries are bad, the fobs will not work consistently to be programmed or work to use the remote entry functions.
And again, to maybe clarify, those key fobs all began their lives as BMW diamond keys, then found their way to eBay where I bought them, cut the keys off, thus creating fobs out of the diamond keys. Then I reprogrammed them to do the keyless entry, programming all keys consecutively using
Qsilver7's often posted instructions on here.
Over the 5.5 years I've had this car and these keys, I have periodically "manually" charged them by putting them in/near the ignition key cylinder, held in place with masking tape on a key in there to the ON position, left there for a day or so, with the car on a charger to maintain the 12V battery. From paying attention to them working or not, and the behavior coming and going slightly, I'm fairly convinced the batteries themselves are due for replacement. With 4 keys/fobs, sometimes one would not work, which I'd attribute to insufficient use/charging, so I'd do this procedure. Lately, after doing this, the two failing fobs have not worked consistently.
Good point by
wpoll above about the key+fob arrangement being less exposed to the induction field than with a diamond key. True, but it has worked well enough for a few years, and in my forced charging setup, it is right within the cylinder of the charging coil. So I don't think weakness of charging is the problem here.
BTW, so far, the following youtube video solution is looking like the leading candidate, and it looks easy enough to do, so I think I'll just do it. Was expecting there was a guide here on xoutpost somewhere that I was somehow unable to find.
https://www.youtube.com/watch?v=imyB6_F2u0o
(but I'm not sure if he uses the right battery. Panasonic VL2020 appears to be the spec as long as it has the right connection geometry - 90 degrees apart)
Also, found an interesting comment on a not-so-good youtube video:
"Hi there. I worked for BMW for many years. as an engineer. Can confirm our diamond key fob introduced in 2000 models (as used on e53, e46, e39 etc) most certainly contains a rechargeable (vanadium pentoxide) battery, charged through electromagnetic induction (via EWS ring antenna as shown in the video). Like all rechargeable (secondary) cells, capacity decreases as charge cycles occur. Most diamond fobs will last 10-15 years with normal use. Full recharge (ignition must be in position 2 or 3) from empty takes ~30 hours. 1 hour of charge typically gives 15 lock/unlock cycles (on completely flat battery) depending on age of course. Replacing with a primary cell (non-rechargeable) not recommended."
And more on the vanadium pentoxide cathode he mentions:
https://www.sciencedirect.com/scienc...05829717302295