What NiCads are you using Gary? We just did another test with the Lithiums, running THz round on a nice grippy tarmac carpark for four mins, doing a fair bit of heavy pushing. Pulling up to 150 amps (briefly). And we accidentally only had three out of the four Lithium packs connected. They were only warm at the end.

With the A123 Lithiums, you will dramatically shorten their life if they get over 60 degrees C.

You should connect a 100 amp shunt (or a whattmeter - http://www.westlondonmodels.com/product1836/Astro-Super-Whattmeter/http://www.westlondonmodels.com/prod...er-Whattmeter/ or http://www.alshobbies.com/shop/lookupstock.php?pc=4870http://www.alshobbies.com/shop/lookupstock.php?pc=4870) to your battery pack to see what sort of currents you are drawing.