Shimano Di2 Battery Charger USB Connection (SM-BCR2); – Di2 charger for the internal battery that will keep your Di2 system shifting – Di2 uses a powerful long-life 7.4V Li-Ion battery: keep it in top condition and ready for shifting with this specific Shimano Di2 charger – 1.5 hour charge time – Plugs in directly to the SM-EW90 handlebar junction A – Can also be used for completing firmware updates when linked to E-tube software on your PC