Peter, Are you sure you are using Lithium rechargeables? Could they be Ni-Mh? I bought some Ni-Mh rechargeble N-size cells through ebay, and they work pretty good, their charge capacity is very high. There is one problem, they are the 'flat-top' version, and the contact from the batteries is not as reliable as with the 'button-top' battery we are all used to.
The Lithium rechargeables are not sold to consumers outside of a package containing sophisticated charging logic. Whereas Ni-Mh batteries can be charged much like Ni-Cds, and will stay safe, lithium rechargebles will explode, catch fire, and burn ferociously if over-charged. They are very light, with very high charge densities, so they have become almost universally the only laptop battery designed today, but even in those applications, if the charge logic faults, or if the battery package gets damaged, things can get pretty exciting if the battery overcharges! There have been recalls of millions of Lithium batteries over the past 5 years as a result, and many fires.
Do your batteris have the button top, where the positive contact extends significantly from the battery top?
Dan
