Hello

I have a Hoppecke Trak Basic Premium Charger that i got with my reack truck in the past. Recently i got another electric forklift same voltage (48V) without charger, and i used this one to charge the battery. It seems that the charger is set to charge for about 6h and 39min, and it start to count down, them it stop to 4 min and keep charging with low amp (around 29ah and i got 2.4v reading/cell) till it give E05 error and stop charging, it not give me full charge. If i unplug the charger from the socket and wait around 30 min, it can start to charge the battery again and start to countdown the same amount of time 6hours and 39 min. What that mean? E05 error as far i understand is over discharged battery, what can i do to fully charge this battery, or to equalize this battery. As far i understand i can set the charger to do that, pls help me.
Thx in advance