When you buy your battery, the seller may specify the amp rating. It may be a big lie, as the ratings were on the betrbattery I bought from Amazon early 2018. 50 A specified, would not deliver 3 A to a 15 ohm load.
The battery I bought from lunabikes was specified at 50 A rating, and delivered 26 A reliably above 20% charge as long as that controller worked: 3 years. The battery still works after 4 years but I have a 10 A controller now. Yeah, shanghai shutdown 2022.
AH (amphour) does not have to match on batteries. That just tells you roughly how far you can get on a charge. Voltage has to roughly match, although I'm using a 39 v LIfePo4 battery on a controller specified for 36 v LiIon battery.
As long as you have some standard connector like andersn or XT90, and the + and - match up between the batteries, you can swap to extend range. If the connectors don't match up and you are electrically trained, you can change connectors. I use insulated .250 flag crimp terminals on my battery, dorman brand. 3m, TE connectivity, Ideal, T&B, Panduit are also 30 amp capable connectors. Not the ****ese connectors from RadioShack or Amazon, they melt at 30 amps. My Luna battery came with XT90 but the XT90 I soldered on the controller end wouldn't stay on. So rather than buy a $300 soldering iron I cut both XT90 connectors off and crimped on the flag terminals. I put male & female opposite sex on + and - so I couldn't reverse the polarity when charging. 3 years, no problems.
