I know many of us have suffered from the starting issues across many of the BMW bikes.
Pukmeister found these new hybrid batteries from Mottobatt (yes you know of them) that can be charged via a normal charger as they are both AGM and Lithium technology giving way more cranking amps (350) than the BMW OEM or the Yuasa high powered battery
www.motorcycleproducts.co.uk
I also noticed a part from the massive weight saving and more room you now have in the battery area that the voltage on the bike sits at 12.7v where as my previously brand new Yuas HP battery (and the original OEM one before that) would drop to 12.3/4 volts within seconds of turning the bike on with nothing turned on.
£127 delivered next day
Pukmeister found these new hybrid batteries from Mottobatt (yes you know of them) that can be charged via a normal charger as they are both AGM and Lithium technology giving way more cranking amps (350) than the BMW OEM or the Yuasa high powered battery

Motobatt MHTX16 Hybrid Lithium Battery
Shop Motobatt MHTX16 Hybrid Lithium Battery at Motorcycle Products Ltd. Replaces: GYZ16H, GYZ16HL, KMX14-BS, YTX14, YTX14H, YTX14L, ETX14-BS, AGM12-12M, LTX14-BS, ENTX14-BS, NTX14-BS, YTX12-BS, CTX12-BS, TTX12-BS, PTX12-BS, GTX12-BS, FTX12-BS, 6E12, ATH12-12B, B12-12B, 510-012-009, DTX12-BS...

I also noticed a part from the massive weight saving and more room you now have in the battery area that the voltage on the bike sits at 12.7v where as my previously brand new Yuas HP battery (and the original OEM one before that) would drop to 12.3/4 volts within seconds of turning the bike on with nothing turned on.
£127 delivered next day