I replaced the dead original battery, the best Lithium chemisty LiFePo4 RC battery.
LiFePo4 lifePo4 lifetime over 2000+ charging cycle. (theoretically 10000)
4cell life pack cell voltage same the original pack, but necessary protect the cells overcharging and over discharging. I buyed the ebay
the small BMS (battery management system) and 2 pieces 2 cells cheap RC LiFePo4 pack from rc shop.
battery: 2 pieces.http://www.hobbyking.com/hobbyking/stor ... duct=14077
2 cells BMS protection: 2 pieces.http://www.ebay.com/itm/ws/eBayISAPI.dl ... 2313wt_954
package must be connected in series between the two (after the BMS).
The packages have only used the balancer plugs. (plus, common, minus)
NTC soldering directly the temperature pins. (this pack not warming the charging cycle)https://lh4.googleusercontent.com/-FFjA ... 000139.JPG
I not modification the charging system.
First test is very good. Roomba running time more 1:30 hours with all time green the status LED.
I test more later.
The original charging system is working well
images are placed tomorrow. Sorry.
This BMS is only switched normal operation when charging takes place at least once.
Otherwise, not voltage the chargin/discharging pins..
At first I thought it was broken or destroyed.
Sorry the worst English.
pictures:https://picasaweb.google.com/1074543900 ... Conversion