We have a keyless bike, Yamaha Grand Filano hybrid ABS.
You just keep the fob in your pocket, belt, handbag...????
Not long after we bought the bike the battery went totally dead, it seems Mrs. T didn't turn the dash nob to off...
Took the battery out and went to Yamaha dealer, they tested the battery and said 1200bht for a new one, battery isn't guaranteed, so we walked out, took it to get it charged, they said it's dead, but we don't sell those.
Went to a bike shop and bought a no name brand battery for 500bht.
Up and running again. I bought one of those battery chargers that do stuff to liven up batteries, but it needs a minimum of 7 volts, We had 2 volts.
Took the battery off the car, linked the poles from it to the dead battery, gave it an hour, think the dead battery showed 10 volts, something like that, then connected it to the charger to do its thing.
The dead battery ended up fully charged and is still fine in the bike 2.5 years later. Seems these folk don't know or want to know how to revive a dead battery,
The 500bht battery is back in its box, for 2.5 years, every few months I charge it up, a good spare..................