This is a known issue with the Hobbico Field Charger MKII. It charges lipos to only a little over 4V per cell, instead of the normal 4.2V per cell.

This doesn't necessarily mean it's a bad charger, but you won't be getting full capacity from your lipos -- more like 80-90%. You'll have shorter flight times than if you use a charger that fully charges your lipos.

There have been numerous threads on the topic over on RCGroups.com.

- Jeff