Battery Chemistry: LiFePO4

After some research on batteries the advantages of the more advanced chemistries became clear quickly. Each time one upgrades from lead-acid, to NiMH, to Lithium the battery becomes about half the weight for the same energy storage capacity. As some say "lead is dead", at least in the world of e-bikes where weight is of greater importance.

Though it may seem a bit of a risk, I chose to go with a LiFePo4 battery from the eBay seller pingping227. I was less intimidated by its duct tape shroud due to the fact that others on the ebike forum "endless sphere" have reported good luck with them. Time will tell as far as long term longevity of the battery, but to an extent I am happy to try out new technology. With shipping the cost was $550, which included a free 2A charger. Note that I added the Anderson Powerpole connectors to it as seen in the photo, it does not come with these. This brand of connector seems to be the standard in ebiking now.

Here are the manufacturer's specifications for my battery:

Voltage: 48 Volts
Capacity: 20 Amp Hours
Dimension: 150x220x220 mm ( 6 x 8 1/2x 8 1/2 inches )
Weight: 9.00 kg ( 20.00 lbs)
Charging Voltage: 61 Volts
Charging Current: <5>1000 times

A Home for a Battery: The Rack

I spent a considerable amount of time debating where I might put the battery on the bike. A full suspension bicycle does not offer many options. This ZED DS also does not have eyelets anywhere on the rear. I closely considered a seat-post mounted rack, but was scared off by reports of them cracking under heavy loads. One seat post rack which did look promising was one made by Headland, as it boasts a 40lb capacity (most others are 15-25 lbs max). It is a little on the expensive side though.

In the end I settled on a rack made by Old Man Mountain called the White Rock. The LBS where I purchased it installed it for me, which required drilling and tapping above the rear dropouts due to the lack of eyelets. The upper struts fasten to the rear brake bosses.

Though I am happy with this rack, as it is a strong setup (40lbs capacity) on a bike that was never meant to take a rack, it does pose one problem. If I mount the battery too close to the seat, the seat will hit against it as the suspension flexes. This issue makes my original plan of a large Topeak MTX DXP bag look unlikely, as the height and length (9"-13"x12.5") will surely pose interference problems. I will have to find some kind of suitable box for the battery that is short enough to not conflict with the motion of the seat.

The Unadulterated K2 ZED DS

Here is my recently purchased base for my future electric bicycle. It's a K2 ZED DS 21 speed low-end type bicycle. I had in mind a full suspension from the start, as I plan to use this bicycle as a commuting vehicle and would like it to be as comfortable a ride as possible. It cost a bit more than I had planned to pay for the base, but I couldn't bring myself to buy a Mongoose after looking at them in person. This one also came in multiple sizes, so I think it fits me a bit better. I also liked that it looks more like a "normal" bicycle, as I don't care for the aesthetics of the Y type frame.

The frame is aluminum and the rear suspension arm unit is steel. The rear dropouts appear to be nice and sturdy for the electric motor torque, as this will be a rear wheel drive bike.

It does not have disc brakes, which I thought I might need. However, the disc brakes that come on the low-end bikes do not appear to be much of an improvement over v-brakes. I may upgrade the front wheel to a disc in the future if it turns out to be a necessity.