[Yaesu] HT rechargable battery questions

[Tom WA9WSJ]

Hello Gents,
In going through a bunch of my nm-hi rechargeable batteries I find they are failing allot, even after a proper charge. They must close/at the end of their life cycle.
I'm using the Imedion brand 2100 mAh AA type. They really did work well for a long time. The problem is that I cannot find this type any more. The only ones available are the 2400 mAh type, but that type is bigger in its outside diameter and will not fit well into the Fb-25A case, (for the FT-60). 
Any size over .562" OD is a fit problem.

So I'm asking those that are using some other comparable 2100 amp hour size and same outside diameter size, what are you using?
I've seen some forums that talk a little about this but none that seriously mention using HT's.
Yeah I know that the fb-25a says use only alkaline type but I believe they don't want you to recharge them in that holder/pack, which I haven't and they worked very well.
Thank you!
Tom