On my Vado 5 SL If I discharge RE first, power/assistance drops - at anywhere between 106%-103%. It continues to stay in that dropped spot - until it comes back on full at 96%-98%. Someone here explained why it happens. I hate it. But if you plan to use two RE it is the best way to ride. If you do not set it to discharge RE first, then there is no transitional drop. That part is great, but you do not get the full power from the RE's then, if you plan to change to a second RE. Yesterday I rode 45 miles, at 70% assistance (for about 90% of the ride), with 1850 feet of climb. I started the ride with 150%. Upon return home I had 27% left. For curiosity sake I put my other fully charged RE in and the power only went up to 67%. Thus 10% more of the main battery must have drained, leaving more charge on the used RE. (That's my conclusion). I have concluded the best way to ride, planning to use two RE's; - assuming access to charging is not an issue, is to Discharge RE first on the first RE. When you have that one fully drained - at about 98% power, pull it out, put in the 2nd RE and change the settings to turn OFF discharge RE first.