Indubitably
100 W
- Joined
- Jan 9, 2010
- Messages
- 126
I'm in the akward position of having 60v (18s) worth of thundersky 40ah hour batteries on a 70 lb recumbent with a crystalyte 5302. Needless to say, it does pretty much make for the ideal death trap of unstoppable kinetic energy at speed on the flat (think 320lbs at 60 miles an hour with nothing but coaster brakes and regen between you and certain doom), but the moment it so much as looks at a hill with a grade over 5% it stops dead in its tracks and starts whining for its mommy.
The build was clearly put together before I really understood exactly what I was getting into, but I'm pretty much stuck with these components now, so I need to figure out an upgrade to the build that will make it viable. My target is a 35MPH top speed on the flat with peak efficiency in the 20 to 30 mph range, the ability to sustain a 20% grade for 45 mins without danger of overheating, and 30% grades for 10 mins. The options as I see them are...
Build up:
Turn my bike into a low speed motorcycle with a Hubzilla wound for torque and as many thunderskys as it takes to hit the voltage I need in order to simply brute force the hill without bogging down. I'm allready at 330, so we may be talking about a gross weight approaching 400lbs if I go this rout.
Pros: More power than I know what to do with, the ability to tow a trailer on the flat (or perhaps even a passenger), enough range to travel a couple hundred miles on the flat without pedaling.
Cons: Fortunately I've already upgraded the bike with air adjustable dirtbike shocks that have a mount for a nice beefy hydrolic disk brake, but it will still be heavy as all hell and dangerous to ride, and bothering to pedal at this point is pretty much useless beyond its comedic value. We're talking about some pretty serious cash for that matter too, I'm probably going to need another $900 worth of thunder skies, a $600 motor and a controller that can handle at least 120v at 100a is going to be more than $300 any way I slice it.
Build Down:
Strip every last pound of weight I possibly can off the build, abandon the full suspension recumbent frame (that I worked so hard to get on the road) and move everything to a 20lb bmx with standard bicycle front suspension. I'd probably go for a HS3540 or the like, and keep the 18s thundersky set up.
Pros: Probably the most efficient build for hills at or under a 10% incline, convenient size, still has pretty awesome range with those 40ah batteries, hits my target speed on the flat, and is by far the cheapest option available to me.
Cons: Even at this weight (should come in at around 280 gross lbs) I'm not going to be charging up any steep hills any time soon. I'm guessing my limit will be in the 15% grade range with occasional sub 30 seccond spikes in incline that approach 20%. My weight will be high up on the bike, and my wheel base will be short, which is just asking for trouble if hit any snags, not to mention that it will create much more drag from wind resistance which will hurt my efficiency on the flat.
Build... Sideways?
The other option is to go for something in between, pick up two hs3540s and a seccond controller, but keep the 18s thundersky set up.
Pros: Get to keep my fancy suspension recumbent, reasonably decent performance / efficiency on hills at less than 20%, improved traction, and still a lot less expensive than building up.
Cons: It might be less expensive than the absurdly expensive build up option, but isn't going to be cheap either. It will require me to make some minor modifications to the front end fork so I can fit a standard 100mm dropout and will require the construction of some pretty hefty torque arms because the dirtbike forks take a through bolt.
So what do you guys think? I'd be sad to see the recumbent frame go, but it seems like the smartest thing to do is build down. Cheap but strong aluminum bmx frames are easy to come by on craigslist, and it wouldn't be too difficult to get one ready. I could conceviably also add a bmc torque motor to the recumbent, loose regen, and just resign myself to crawling along at a top speed of 25mph, but that doesn't seem terribly appealing either. If I was smart about it, I would have just gone for something like the build down option from the get go, loaded up on lipo or a123s untill I hit about 100v at 16ah, and ran an ht3525, but alas it appears highly unlikely that I am going to find anyone who wants to trade $900 worth of thundersky cells for $900 of lipo.
The build was clearly put together before I really understood exactly what I was getting into, but I'm pretty much stuck with these components now, so I need to figure out an upgrade to the build that will make it viable. My target is a 35MPH top speed on the flat with peak efficiency in the 20 to 30 mph range, the ability to sustain a 20% grade for 45 mins without danger of overheating, and 30% grades for 10 mins. The options as I see them are...
Build up:
Turn my bike into a low speed motorcycle with a Hubzilla wound for torque and as many thunderskys as it takes to hit the voltage I need in order to simply brute force the hill without bogging down. I'm allready at 330, so we may be talking about a gross weight approaching 400lbs if I go this rout.
Pros: More power than I know what to do with, the ability to tow a trailer on the flat (or perhaps even a passenger), enough range to travel a couple hundred miles on the flat without pedaling.
Cons: Fortunately I've already upgraded the bike with air adjustable dirtbike shocks that have a mount for a nice beefy hydrolic disk brake, but it will still be heavy as all hell and dangerous to ride, and bothering to pedal at this point is pretty much useless beyond its comedic value. We're talking about some pretty serious cash for that matter too, I'm probably going to need another $900 worth of thunder skies, a $600 motor and a controller that can handle at least 120v at 100a is going to be more than $300 any way I slice it.
Build Down:
Strip every last pound of weight I possibly can off the build, abandon the full suspension recumbent frame (that I worked so hard to get on the road) and move everything to a 20lb bmx with standard bicycle front suspension. I'd probably go for a HS3540 or the like, and keep the 18s thundersky set up.
Pros: Probably the most efficient build for hills at or under a 10% incline, convenient size, still has pretty awesome range with those 40ah batteries, hits my target speed on the flat, and is by far the cheapest option available to me.
Cons: Even at this weight (should come in at around 280 gross lbs) I'm not going to be charging up any steep hills any time soon. I'm guessing my limit will be in the 15% grade range with occasional sub 30 seccond spikes in incline that approach 20%. My weight will be high up on the bike, and my wheel base will be short, which is just asking for trouble if hit any snags, not to mention that it will create much more drag from wind resistance which will hurt my efficiency on the flat.
Build... Sideways?
The other option is to go for something in between, pick up two hs3540s and a seccond controller, but keep the 18s thundersky set up.
Pros: Get to keep my fancy suspension recumbent, reasonably decent performance / efficiency on hills at less than 20%, improved traction, and still a lot less expensive than building up.
Cons: It might be less expensive than the absurdly expensive build up option, but isn't going to be cheap either. It will require me to make some minor modifications to the front end fork so I can fit a standard 100mm dropout and will require the construction of some pretty hefty torque arms because the dirtbike forks take a through bolt.
So what do you guys think? I'd be sad to see the recumbent frame go, but it seems like the smartest thing to do is build down. Cheap but strong aluminum bmx frames are easy to come by on craigslist, and it wouldn't be too difficult to get one ready. I could conceviably also add a bmc torque motor to the recumbent, loose regen, and just resign myself to crawling along at a top speed of 25mph, but that doesn't seem terribly appealing either. If I was smart about it, I would have just gone for something like the build down option from the get go, loaded up on lipo or a123s untill I hit about 100v at 16ah, and ran an ht3525, but alas it appears highly unlikely that I am going to find anyone who wants to trade $900 worth of thundersky cells for $900 of lipo.