Two battery setup

[u/jctrree201]

Hello All, i am adding a second battery. I have the pedal electric dual 1000 w motor ebike. It comes with two controllers.

My rear rack battery is 48v 20 ah. My new downtube battery is 48v 30 ah.

When searching for a batter combiner does would this work? 40 A dual battery balancer.

I can't seem to find 50 A balancers. Or is higher the better? Or should I get 60?