Dual Battery Parallel connector

Perfect. I use my bike to commute to work and appreciate a little assurance I will get there and back with battery charge left. Very easy to install to add a second battery.

If one does real hills, this thing helps reduce dreaded voltage sag on the big/long ones. I regularly do one ~50 mile loop where the display on my Rad with stock OEM controller and single active battery dropped 2 bars during climbs in three different places, but no more after adding this thing and a 17.5 Ah battery alongside the original Rad OEM 14 Ah one (13S9P now!). You DON"T get that benefit if you manually switch/swap batteries one at a time. Don't let some flatlander nincompoop tell you that if your bike drops 2 bars there's something wrong with it just because they can't pull ~750 Watts for more than the 6 seconds it takes to get to the 20 MPH limiter cutout (unless they ride with the brakes on or in quicksand). I suppose it's now time to start worrying about battery/controller/motor/wiring/connector thermal overload or cutout instead of voltage sag on those 2+ minute ~750 Watt climbs, it's always something... I tried two other parallel battery adapters before this one, both of which were cheaper and had smaller 3D printed plastic cases with NO heatsink. They both failed within 100 miles. I'm at 1000+ miles and counting on this one so far with zero problems/glitches! I do centuries on my bikes so reliability is especially important when a long way from home. Even so, it's best to carefully plan plug and wiring configuration when installing any component like this so it can be easily removed/bypassed if necessary or when troubleshooting.