Recumbent - Velomobiles with batt/electric assist.

I was wondering if anyone had any experience with these and li-ion, nimh, or nicd battery packs. I've seen specs for the zap epod/aerorider, and the range is just bad given the size of the vehicle, which I'm guessing is because of Puekret's effect when using lead acid batteries, but anyway, I was hoping someone had some info on using batteries that don't suffer from this decrease in capacity wrt increased current draw.

A few simple rules about electrifying:
Li-Ion is the way to go for weight and durability. They put out fewer amps but last a LOT longer
Size the motor for the power you need. Why use 750W if 250W of power assist is plenty.
Regenrative power is the BOMB... You want the ability to charge your batteries while you're riding as an option. This is not common on many systems and the system has to be designed for it.
Lead acid batteries die slowly on a non-linear rate. Their charge will be less than half within a few months.
NiMH batteries are a compromize between Li-Ion and Lead Acid. Their limit is that you have a lot of cells and one bad one can trash your whole pack.

If electrifiesd is something you want to explore, I'd say that BionX is ahead of the curve in this technology field for cycling.

You best bet for cost/performance right now is NiMH. They have resonably high capacity, are lighter than lead-acid, and safer & cheaper than Li-Ion. In a few years, this may change (and swing towards Li-Ion).

As far as finding a battery that can output high current, you need to find just that: Most batteries you'll see have their capacity based on a much lower current draw than what an e-bike application will subject it to. The key is to look at the capacity when the current draw is 5, 10 or 15A (not 0.5A). These are the ones that you want to use on your bike.

I was actually thinking about putting together something using ~140 3.7v 2000mah li-ion batteries in 14 37V ten battery packs. The Max. Discharging current is 1.5C ma (for continuous discharge), so each should deliver ~3ah for 45min max, 2ah for 1hr, 4ah for 30min, etc...
Now at 37V, with each pack providing 3ah, that's ~111wh/pack, and 1554wh total. Of course motor/controller efficiency will probably be ~75%, so that's ~1.150kwh for 45min? Or ~1hp for an hour? I wonder how hot they get during this time? Probably not hot enough to blow (~130C?), but at $600 for 140 batteries it's a pricey pack... Assuming ~1kwh per 50mph cruising speed, then this is ~$650 per 25,000miles, compared to a car@100mpg it's $750, car@20mpg is $3750. So gas is still too cheap and batteries too expensive for seriuos auto use (aside from the $100k tesla roadster with the $30k pack). After checking out NiMH (Saft) it seems like the price of both per kwh is the same, if not more for nimh? Maybe it's the difference in brands, French versus Chinese? Well, nope, Tenergy NiMH's run $280 for 360wh, and LG 18650s are $500 for 814wh from all-battery dot com... Looks like li-ion out-cheaped nimh?
Of course there's also load balancing since each unit isn't the same... but I think that applies for both types.

Ideally I'd like to make something that's highway (~55mph) capable, but will probably used at low speed for a significant portion of the time, so if I build it for all highway, then the battery lifetime/cost per kwh will be much better than the "worst" case senario. I was wondering if the crappy range in LA powered velos was because of Puekert's or some huge error in calculating energy need at some speed on my part, but then I saw the Twike and it's capacity/size/range, which seems to fit pretty nicely compared to my calculations.

This is more my style of electric assist Velomobile.
http://www.waw-bionx.blogspot.com/
But for the speeds you want the WAW may be a better bet as well, much more areo and lighter, and you can get it with a boot hatch to stick the batteries in.
The Aero rider weighs about 100kg's with the minimum standard battery pack, I know thats not the specfication but I have heard that at least one dealer admitted to them being a lot heavier than expected.
Don't under estimate the benefit of better aero as it will drop current consumption massively, especially at the kind of speeds your after, and disc brakes will be necessary at those speeds as Velo's don't like slowing down

I was looking at the aerorider and it's just too big in terms of CdA and W. Unfortunately the WAW's too expensive, so I may just see what I can make myself. If I can build something WAW'ish, and have it pull down ~80miles@55mph all electric that just might tide over my commute needs... depending on where I end up. Of course the basic platform is what I really need, I can always add batteries and a motor later. And disc brakes, definitely disc brakes! :D

55mph on a bicycle? You're asking for trouble. And carrying 6 large batteries is nothing to laugh at.

I have electrified a Schwinn Cruiser with a Go-Hub kit. Although I added another 12V battery for 48V total. When I'm doing 30mph on this bike it's faster than I care to go on a bicycle. But nice to know it's possible.

Remember, pick the speed at which you want to slide on asphalt.

Yes it's pushing the limits but we are talking about a fully enclosed 3 wheeler with suspension and the battery pack if Li-on will probaly be lighter than yours.
See pic.