roomba 560 LiFePo4 upgrade

[njozsef]

Hi.
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.

notes:
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.
Best Hacking.
Sorry the worst English.
Jozsef Nagy

pictures:
https://picasaweb.google.com/1074543900 ... Conversion

[mfortuna]

Very nice. Does this battery charge OK when the roomba is docked? There is a known 500 series problem that occurs when the battery protection system terminates charging.

[njozsef]

Hi Mfortuna.
YES Roomba OK is Docked charging mode.
Tomorrow measure the cell voltage level (full charging/discharging).
so far 2 cycle charge/discharge. No problem the protection circuit not activated with charging or discharging time.

My BMS no way does the balancer mode.
Need to more cycles to control the cell packs balanced/unbalanced.

[vic7767]

Very good mod ! Waiting for final result of charging/discharging tests. I hope the package will fit well inside the Roomba.

[njozsef]

Thank you for charging defect information.

[njozsef]

this new battery pack over the 20 running cycle. No running and charger problem. (except one ERROR 5 (this is Irobot 560 BUG))

But.... small elecrical problem.... (or not)
.... two BMS not symmetrical charging. If one pack BMS disconnect when overcharge, then secondary pack not charging (charge current=0).
I planning the two "power-zener" circuit the two BMS output (parallel bridge). This circuit working if the BMS disconnect .


Zener is 6.8V (BMS disconnect the 6.6-6.8V)
NPN transistor changeable other Si power-transistor.
Cooling is needed.


Better BMS pcb for 4 cells life:
http://www.ebay.com/itm/PCB-Protection- ... 099wt_2646

[dasankir]

Hi!

This mod is very useful. Any news about the balancing problems?

[vic7767]

I have dis-assembled the pack that was originally posted in this thread. Opening two of these packs will provide you with 4 cells each of which are 3.2 volt LI-Fe 2500 mAH Using the 4 cell PCB also listed in this thread, a 4 cell pack can be built to power a Roomba. This configuration can fit both the 500, 600, 700 Roomba as well as fit inside a stock 4XX, 4XXX, Dirt Dog battery. There is no auto balance performed so battery cell balancing must be accomplished manually prior to assembly into a manageable pack configuration.