Hi,

Do you have a voltmeter in your dash or have you used one on the battery to see what the alternator is doing?

I suspect, because I really don’t know, but you will probably have to leave a traditional incandescent bulb in the battery light window portion of the instrument clusters circuitry.
LED’s operate on almost nothing for current draw and at the same time they are a diode, of which, those regular diodes do not emit light. They will act like a one way-check valve in normal circuits.

The original light bulb allows is designed to allow enough current through to excite a magnetic inside the alternator
Upon startup it needs that current to get it going. Otherwise, it could take some time, at a higher RPM’s for the output TO RISE.
The RISE shuts down a path to ground for that bulb and it goes out!
You maybe getting feed back, within the cluster, that is coming back to the other bulbs and leaves them on.

Again, I’m totally guessing on this. I’m just flying from the seat of my pants to how the LED’s are affecting things, but at least you know, it was something you just did, that will help others trying the modification.
Definitely me!

Watch for posts from those that are in the know, here on the BB!

Phil