You need the MK group 24 with screw terminals: http://www.monsterscooterparts.com/g...-terminal.html
One thing that I found interesting when plugging my chair into the charger after the controller battery gauge is flashing one red light, is that the levels on the battery charger often read at 85%, and rarely as low as 50%. I'm not sure what this might mean, except perhaps that may be the battery charger may not be accurate?
I believe that the controller battery life remaining can be set in the controller software, I'm swapping from LA ti LiFeP04 batteries on my off road wheelchair and I'm certain that the engineer doing the swap said he could alter the red/green battery life remaining for the new batteries as they were slightly different. I've also got a power consumption meter which shows watt/hours, I reset it after every charge and never let it go above the limit I was told could damage batteries.