to long or it will explode . 4 of the cell went caboom.They sound like a shot gun when they blow up. I pulled the batt off the charger and put it in my crawler......I smelled somethin burning but the batt wasnt that hot......i started to play and noticed that the batt started to smoke. I took it off the crawler right away and set it down on the porch....as i walked away the batts blew up .Glad i got them off the axle in time as the batts blew a chunk off my porch. Time for a new batt now.