Where to start? This is my bike
Gio PB710 HB2-5B with 2 speed motor 350/500 true 500 not 400, with many custom mods done to wiring including all connections soldered (had problems with corrosion) and GPS/Radio/DVD all the toys you can think of, all low voltage and runs off dedicated power supply and own battery in trunk. I guess the question I would like to know is what is the max amount of amp-hours I can run? I have 16 x 12 volt 20 amp-hour batteries can I hook 2 sets up to double the amp-hours and get increased travel time. I live in a mega city and find it hard getting from one end and back on one charge. Weight isn't an issue with me as I travel on totally flat roads so no hills to climb. Any answers to my question can be send to my email edwardevbans13 [at] hotmail.com Plus I can answer any questions you have about motors or wiring as I've have rewired quite a few bikes for people in my neighbourhood. For those that want to know more about my add-ons my DVD is a 7" screen Initial GD-70X with built-in GPS very nice find at second hand store for 7 bucks, the 7 inch screen makes it easy to see where you are going while you bounce alone the street. 160 Watt amplified speaker system 2 in trunk and 1 in glove box with hookup for IPOD am looking for a radio that isn't as wide as the standard ones found on cars so I can mount it in dash. Running lights (LED) for increased visability at night from the side, all lights changed to LEDS for decreased battery usage. Custom paint Forest green with silver metal flake. Currently working on pin striping with silver airbrush work. I will post some pics when i find my camera (just moved).
There's no limit to the number of AH you can have in a pack. The biggest complication is that your pack can become unbalanced. Having one battery with less capacity can mean that the other batteries end up reverse charging the weak one.
To be clear, you now have 16 20AH 12V batteries on the scoot? Where do you sit? That's about 220 pounds of lead as it is. I would not suggest doubling the weight. You've already got 80AH @48V, so the 500W motor's maximum draw of ~13A won't put you too far down the Peukert curve.
Mark