Our low impedance 50AH LFP battery is the best replacement for Vextrix power kits, see http://chl-battery.en.alibaba.com
42cell just fill the Vectrix battery tunk,it is Usd68/cell FOB China including the connectors between cells.see successful example on post http://visforvoltage.org/forum/11525-50ah-li-ion-conversion-successful
Serious buyer,send mail to lfpbattery [at] gmail.com 
