Parallel batteries

WheezyRider

Esteemed Pedelecer
Apr 20, 2020
483
198
This is the approach I've always taken. It's no big deal to charge both batteries before connecting. Why would you want to use a half-charged one if you're going on a journey that needs two batteries?
It's whatever you feel most comfortable with. But there are advantages to the diode setup, it gives you flexibility.

You could charge one pack at a time and not have to worry about things. Eg, if you are on a trip, you only have one charger and can spend an hour or so recharging one pack in say a coffee shop. You can take more advantage of opportunistic charging in this way.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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West Sx RH
For a touring cyclcist is makes sense.
For a day rider who might rides 100 odd miles using a pair of batteries one would surely have planned the ride and made sure before the off they are charged.