Just did the Tri cell mod but the run time sucks

[sporttracguy]

Ok, i just did the tri cell mod and its great for the 1st 20-30 seconds and then the power really drops. I tried to double charge it but the charger wont let me do it. The light just stays green,, ill even turn it off and let it sit for a few minutes and it just wont charge the truck unless its been drained a bit. Would it be better for run time if i wired it paralell instead of in cerial?

could it just be that the battery cant hold a charge? its not from a real zip zap, its from a clone.

also, what if i were to mod it to use two recharegable AAA batteries, would that fry the truck?

Thanks
Sporttracguy