I like my "ping LiFePO4 48v15ah V2.5" (standard size from his website-300x105x150mm) it arrived in a week after ordering it directly from his website. First impressions – it was light, durable battery pack it had 4 wires protruding from it (one big red wire, one little red wire, one big black wire, one little blue wire). No instructions inside the delivery box, you can download the pdf file at ping's website - "Wiring Guide for V2.5 Products.” The size of the battery pack fits perfectly in my Topeak MTX Trunk Bag DXP.
SLA batteries are in the Stone Ages: high maintenance, must plug in immediately or suffer sulfation (battery damage); heavy; low mileage, that every decreasing power curve until you just get only 4 miles per charge.
When I replaced my SLA batteries, it was like installing a new high performance engine. I upgraded from a 36v to a 48v, there is certainly a "kick" to my bike now, and the top speed feels
faster (25-30MPH), and the mileage is FAR superior to SLA . Before, using my SLA 36v 18AH, I was getting about 15 miles per charge declining to about 5 miles per charge after 6 months of using. My ping battery I can easily do 15 miles (my normal fun route) plus 5-10 more miles to test the range: bottom line, I feel I can go ~ 30miles on a single charge.
Because the LiFePO4 battery pack is so light, it took about 13lbs off my bike's weight: that’s like not carrying a bowling ball around with you on each bike ride. So, if the battery pack died or you just want to ride un-assisted, the bike's drop in weight was very noticeable. With my LiFePO4 battery, my bike's weight feels like a regular bicycle again.
After owning my LiFePO4 battery pack for 6 months, I notice I have more peace of mind while riding. I know that I have the range to go anywhere (i.e. work route, fun route, chore route all combined), I can leave it un-charge at a friend’s house or at work, and know that the battery is not being damaged while sitting there. The long lifecycle means I can own one LiFePO4 battery pack for 3 years (instead of a pack every 6 months using SLA). The worry about having enough juice to get back home (SLA who knows if you just lost a couple miles permanently the night before) is gone from the back of my mind. In conclusion, my LiFePO4 battery pack is small, has at least double the range, light weight, safe, powerful, long life, gives me peace of mind: LiFePO4 is simply awesome!