Motorola MC3090 mobile computers draining battery fast when used with HP E-MSM430

We used to use a consumer-grade stand-alone Linksys WRT54GL with our Motorola (Symbol) MC3090R mobile scanners, and the battery life would be about 6 hours of continuous wireless scanning.

Now we are using a centrally-managed enterprise wireless using HP E-MSM430 access points controlled by a central MSM760. Since changing the have found that the battery life on the scanners has halved to around 3 hours continuous use.

It doesn't seem to make any difference what encryption type I am using (I have tried both WPA2 and open (no encryption)).

Any ideas what might be happening here and how to resolve this?

Thanks!