Sigh...

Right. Let me explain a bit about Li-Ion packs, then, since you seem a bit lazy to check the thread Shane posted a while back. I won't explain everything, just the basics for vapourbots.

Lithium-Ion cells are a relatively new discovery in combat robotics, so people aren't too keen to use them. They have advantages over NiCads and NiMH in that they have a higher voltage count. The Li-Ion packs themselves give out 3.3-3.6 volts per pack (we take the base voltage, 3.3v), and weigh ~700g. This means that you would not be able to run your vapourbot's motors in increments of 1.2v as you would with NiCads or NiMH packs. Instead, you would run them near recommended voltages for the motors. In the case of the S28-400 Magmotor, that would be 24v.

24v / 3.3v = 7.2727

Since we can't use 7.2727 packs (lol), we have to round that off to the nearest whole number. Thus you would need 7 packs.

3.3v x 7 = 23.1v

So, you would run your motors at 23.1v.

Do you understand now, Mark? Show me you understand by doing what I just did with the S28-400s, with LEM130s. (recommended voltage for LEM130s is 36v, according to the manufacturers' page) I'm sure you could do it.