Is it compatible with this pack: ProTek R/C 2S Li-Poly 20C Car/Starter Box Battery Pack (7.4V/4000mAh)?

Depends on the balance tap that's on that pack.

Jason

I have the Maxamp 5000 pack with the LBA10 balancer. I got my MRC 989 charger to charge after I did the plug in to a T. But as soon as the battery voltage hits 7.6 my charger goes into trickle. I really want to balance while I charge for the optimum performance. What is going on?

Let me guess, the balancer is still doing its balancing after the Charger stops charging? My MRC 989 does that with my 4S Maxamps pack.

I have found that if you balance with the balancer prior to doing this, it works much better.

Anyone experience something like this with a hyperion charger?

at 7.6 the battery isnt fully charged. 8.4 is full. The balancer seams to kick out the charger into trickle.