I am stuck on what battery to get as my second battery. I have studied all of the Li-ion packs out there, and have a good feel for the differences Li-ion 18650 cell brand, quality, and the options for voltage and amperage. WHEN I decided to look into normal deep cycle lead acid batteries, I realized I could create a 48v 100 Amp battery for about $400 (with 4x 12v 100A batteries in series). This would power my bike for 100 or more miles, EASILY. It would not take up too much space, and could easily be placed in a basket. Why do folks not use this option instead of paying $600 for a 20a 48v good quality Li-ion Samsung 18650 cell battery pack which has 1/5 of the power (amperage) of my proposed set-up? I could use my car battery charger to charge it so charging is not an issue. What, if anything, am I missing?