Ive never seemed to have this problem. But my new 7.2v 3800 packs make my sv run like 5..10 mph less than my older 7.2v 3500mah packs. I emailed the guy to see if they were defected and he said the batteries need to be cycled 3-5 times. What does that mean and how do i do so?

so how fast were the 3800's running? cus I am running Duratrax 4200's and they are great,did you balance the batteries,and mine are in shrink wrap if that means anything? try that,and make sure they are on a FULL charge!

if your chargewr has a cycler then use that(read the manual) or if it doesnt then you can discharge them using a lightbulb set up.
cycling simply means charging and discharging but dont discharge at full amps until they are cycled. i am pretty sure you dont want to charge them real fast either.

hmmm ok. thank you guys ill give it a shot. do you think that will be a solution? To be honest, i dont quite know how fast it goes i would say mid 30s easily with the grim prop. But with these new batteries its much slower. Guess i should order a gps too.

that happens with all batteries. your runtime will be shorter and not as fast until you have cycled them.