VPX Battery System (Black & Decker)
I was in Lowes yesterday and noticed that B&D has a line of battery power tools which appeared to be new. I just did a bit of research and found these are built using A123Systems cells using the M1 chemistry but in an 18650 form factor. The cells used in the DeWalt packs are 26650 form factor. There's a few other differences.
An 'official' announcement from A123Racing contains details.
Neither A123systems.com nor A123racing.com have posted any data on the cells in question. However one of the rcgroups.com postings contained a link to this PDF:
And stated it is '12-10-07 Official A123 Racing specs'. It uses the product designation, APR18650M1. The is a dicharge graph showing these cells would radically dip when used at a 20C rate. It also claims 1.1 AH capacity per cell.
The price for a pack is approx $20, or $35 with a charger.
A typical use we EV nuts might put this to is for a bicycle battery pack...? Well, that's what I would do anyway, for my WE 36BD bicycle. It would require 36V 10AH or so. That means a 6S and 10P arrangement (6 cells in series, 10 of those strings in parallel). It means 60 of the VPX packs and some hairy wiring. At retail price the packs would run you $1200 and it's not clear how to manage charging.
For charging perhaps it will work to wire the packs in parallel then connect the paralleled packs in series. It would require 6 chargers. Fortunately the B&D chargers are small and are constructed to be daisy chained.
Don't have any actual experience - just some speculation.
I think in general it will be better to have LiFePO cells in a larger format so that there are fewer cells. Stringing together lots of small cells to make a full size pack leads to lots of wiring. I just wanted to make some use of the research I did, and maybe someone else is interested in this...