I have to replace my Thunder Power 2100 mAh battery pack
http://www.b-p-p.com/proddetail.php?prod=L_TP2100_11.1
for my electric ST-40 as it appears to completely dead. Balancer won’t even register it. I would like to get it from Tower Hobbies as I am already placing an order with them this week.

I know this one will work
http://www3.towerhobbies.com/cgi-bin...&I=LXMDN3&P=ML

But this one is $15 cheaper, will this one work fine? I know the rated voltage is lower and it only has two cells instead of three.
http://www3.towerhobbies.com/cgi-bin...?&I=LXMDN2&P=7

Or if I don’t want Lipo, and this is even cheaper, would this work in my Lanier ST-40 trainer?
http://www3.towerhobbies.com/cgi-bin...?&I=LXMND3&P=7

The battery pack has to have a Deans female plug installed on it.