Are they any good

[zvizdic]

 D Ni-MH 11000mAh Rechargeable Battery Ultra cell


To assemble a battery bank at 48 v 

[joestue]

well like any NI-MH battery you have to put in 1.5 amp hours for every amp hour you get out.

D cells are generally reliable, they stick them in hybrid cars so YMMV.
what are you intending to use them for?

[zvizdic]

Storage for windmill probable to assemble 5 x 48 v banks .

 Is it to mach for 1 controller?

I hate Led acid batteries,  they are garbage usable only at .6v discharge to gate any life out of them.

[fabricator]

With a good controller and proper care you can use "Junk" lead acid batteries for 15-20 years or more, and they are pretty much completely recyclable.

[Madscientist267]

The only issue I've noticed with NiMH is that they don't like to be float charged.

Something about them causes their overall capacity to reduce rapidly when left on a charge, although I have no idea what. 

This might become an issue with a windmill scenario. Personally, I've tried to avoid them unless they are on some kind of timed charge.

One thing is for sure, 5x48V bank of them can crank out some power when you want it!

FWIW

Steve

[zvizdic]

If they use them for hybrid cars and not charged  with constant voltage, then logically thy can be used for RE(windmill ).

I know it is best to charge to 80% .

[joestue]

until this gets fixed http://en.wikipedia.org/wiki/Patent_encumbrance_of_large_automotive_NiMH_batteries
I wouldn't waste my time or money on ni-mh.

you don't need to charge them all the way up or all the way down, it doesn't matter if you use CC or CV, provided you stay below 90% SOC.
i don't think there's any reason not to charge them to 100%, other than the fact that they absorb any overcharge by recombination of hydrogen and oxygen.
as the cells age there may be an imbalance, and the cells will vent oxygen, why? IIRC they make the negative plate bigger so it can't vent hydrogen

they do make ni-mh cells designed for float charge, just like they did ni-cd cells back in the 1990's (you will find these in surplus fire escape lights)
but the smaller cells will be destroyed by cheap chargers with no temperature correction.

[zvizdic]

So NO NO 

Thanks for pointing on issues

[joestue]

So NO NO  

Thanks for pointing on issues

you have to evaluate what they are worth to you.
unless you can get those cells for less than 10$ each, you might find lithium to be cheaper.