if you want the features Nicd give you
(fast charging, high dischargecurrents,
long lifetime, no firerisk like on (many) Lipos,
very resistante against deep-discharge,)
without some of the dissadvantages
(memory effect,
high selfdischarging compared to Lipos,
heavy for given capacity,
toxic cadmium)
there is already an alternative:
Fepo4
they combine the advantages of Nicd
without heaving there disadvantages
you get for about halve the weight the same capacity of Nicd
you can run them for 1000cycles at 10C load !
they are said to live for 10years which only Nicd are able to do so far
(NiMh rated for ~6years, Lipo/LiIon rated for ~2-4years)
you can charge them very fast (up to 10C charing !!.. filled to 95% in 5-6min with the right charging device)
and when lying around full charged you the selfdischarge is very low, so your bike can always be ready
and they are no miracle cells only spoken about in www and not seen in real world, not in use..
you can realy buy them..
i already use them for 1 year now with great success.
until now there is the original cell from A123 systems
(they will also equip the new GM VOLT with Fepo4-Cells from a123 systems)
with all the good features..
there are also some chines made cells with Fepo4-technologie..
but many are far of there claimed features... some are only rated for 2C !
at least: the technologie is here andn buyable for endusers now since about 1 year
and there are already some competitors coming...
this sounds promissing, because different cells-sizes become availabe..
iam waiting for the first tests done by a college
Advanced Battery Factory
if they inherit the features of the original A123 Fepo4 (cyclelife, easy handling, robustness,...) this cells should be suitable for electric bikes..
i think the 7500mah and the 12.000mah-cells should be worth to have a closer look
the cells are not that powerfull than the original A123 Fepo4
but 160A continouse from the 12Ah-cells should be still enough for an electric-bike ?!?
1700-1800g weight for 33Volt 7500mAh-cells sound not that bad
of course: with Lipos you can get a better weight/Energy-rating, but with all the disadvantages of Lipos/LiIons