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Old 02-21-2013, 10:43 AM   #1 (permalink)
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Best battery-swappable affordable ebike/trike?

In my exploration of alternative commuter options i'm trying to see what all is out there... and yes homebrew and DIY bikes ARE an option here/I may well build my own.

My biggest issue is range. My google maps shortest "by foot" daily commute ranges 20 miles one way, to 27 miles when it maps a bike route (why would it be longer??) or 26 miles by car if I tell it to avoid highways. One way to do it would be to get a longer range bike of at least 50 mile range, however even in that case I still have additional evening travel of another 20 miles or so shooting that idea out the window which I don't have time to charge between. So what's probably looking like the best solution is something that I can just buy 3 sets of battery packs, bring one spare (swap at my destination to get back) and use the 3rd in the evening routes. Batteries MUST be capable of pulling the range even without pedaling because I have an injury prone hobby that may leave me near unable to pedal the next few days on occasion.

Swappability also matters because I may want to have more than one ebike (like both a bike, and a cargo trike) I can swap packs between. (if not an entire motor unit if such a thing is made)

Batteries are so dang expensive anyways it's the achilles heel of ebikes, I saw someones 44 mile range bike with a $1700 battery pack and only 1000 some charges... even with free solar at that rate it'd be cheaper to ride a 250cc motorcycle at 70mpg. :-/ I don't mind a bit heavy, i'm too heavy myself as it is so a 20lb vs 40lb battery back isn't life or death to me. Even over 40lbs on the trike is fine provided the cheapness to haul the extra weight is still less. Any idea what lead acids or golf cart gel type batteries would weigh to get this range?

Fantasies of 10kw bikes are great, but almost absurd in normal street use spinning tires and such, so power needs aren't excessive. But i'd like to maintain 20mph as much as possible and even up to 30mph with pedal assist, including despite mild hills, or some light snow (yes i'd consider using it in the winter once roads are generally cleared especially the trike due to being more stable - it's also possible a front wheel assist combined with pedaling the rear be more suited to not getting stuck in this scenario too) without getting bogged down instantly, or despite heavier loads in the cargo trike. Think something stout enough to pull a pair of heavy riders two-up for the latter in weight and still go 20mph ideally. I wouldn't have a second rider, but I could see loading the cargo racks and a mini-bike trailer behind with 100lbs each EASILY like when i'm shopping for books during the neighborhood garage sale weeks that occur.

Cost of the above is a big issue - i'm already planning projects of more economical cars, and economical motorcycles, I can't buy everything. The additional gas saved over already fairly economical scooters and such isn't going to be huge, and I have to buy things outright without financing also. Things I can do for under $1000 are probably 5x more feasible than solutions costing $2000. And i'm not even sure if it has to cost over $500 (though the power/range needs of the cargo trike are admittedly harder to meet) if I did certain things myself or improvised certain things. One thing i'm willing to give up is a fully variable throttle if it's a difference of hundreds of dollars, I can use pedals to start it and most of the time to vary speed, so that could greatly simplify the need for normal controllers. Just give me a few one touch settings.

One design that I thought was neat but still more than i'm hoping to pay (because i'd still need 2 batteries probably plus its still at the utter top of feasibility anyway at $2k) was On Sale: Busettii Big 50 Mile Electric Bicycle at High5Scooters.com: Electric Moped Bikes, Electric Bicycles, Electric Mobility Scooters, Electric Tricycles, Electric Trikes, Electric Standup Scooters, Gas Scooters & Motorcycles - Always The Best Pri - they have a cargo trike but much less power speed and range. The battery is removable. Since i'm willing to DIY, and willing to compromise on battery weight to get those cheaper, I was hoping it's all still attainable.

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Old 02-21-2013, 02:25 PM   #2 (permalink)
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You could check out my project BEV. I'm planning for a 50 mile range on my LiFePo 48V pack and it will weigh HALF of what the other SLA E-bike weighed. My budget was $1500 which included everything even helmet and flashy lights.

Weight of lead acid batteries are no joke... an 12V 18aH battery is 14lbs... If you have a 48V system you are talking about a 56lb battery pack! I know that doesn't seem too bad but it isn't until you try to lift it that you realize that is a lot of weight...so swapping out an SLA battery isn't really feasible.

In your situation and only if you are stuck on electric... an electric motorcycle might be a better alternative. I only say that because with a motorcycle frame you can put on more batteries for longer range and you don't have to pedal ever. As for budget... If you could get a complete motorcycle very cheap or free it might be possible to convert it for $1000... You would have to get used batteries and a cheap conversion kit.

Otherwise you should be able to find a small older motorcycle for under $1000.
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Old 02-21-2013, 03:43 PM   #3 (permalink)
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You could build your own swapable packs and use forklift quick disconnects to ease removals and installs.
Thats what I did with my lithium packs.
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Old 02-21-2013, 07:47 PM   #4 (permalink)
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Dude I have kettlebells weighing more than 56lbs for one handed exercise and the power steering on my 2.5 ton farm truck was broken for years. >_> If I could do a 50 mile range under the conditions I described for a 56lb battery pack i'd be happy. I probably need to lose about 56lbs so after I finish that it will still perform better than an ultrabattery tech bike with a 7lb battery doing the same. :- P What I don't understand is how physically large they are or whether special handling conditions apply, like no mounting at a slant on a bike frame, obviously easier on a trike since I should be able to stick them flat and low around the axle better. I don't even know if i'm looking at something needing like half a car battery, one car battery equivalent or four basically. No idea what the math requires for older tech batteries.

I'm told golf cart gel cels is what some people seem to like for electric cars, if it saves substantial weight or has some other benefits (better safety/no acid to leak, can mount at angles, less bulk even if similar weight) i'd look at that. Are there any handy dandy rules of thumb for the different battery technologies compared side by side? Ie - what a given amp/hours weighs, it's size, it's approximate cost, it's number of charges, and unique extra info like whether you can quickcharge and such.

My biggest thing is "lowest battery pack cost for desired range/power" right now unless it's just plain unfeasible to do or takes away so much cargo from the trike to defeat the purpose. After two years of driving the cheapest battery pack I can get I might have enough money saved from not spending it on fuel to buy newer tech batteries which maybe are more affordable by then, but i'm just designing around worst case poorest person scenario right now and still hoping it to work.


Speaking of the public brainstorming bit one thing I was considering was possibly using something like a truck starter for the main assist motor on the trike rear axle (I don't know whether these can run a constant on duty cycle? but I thought I heard of someone modifying one with different bearings so that the main issue is preventing overheating, and I dont mind "pulse and glide" since in town driving is probably like that anyway), and something like an electric cordless drill motor on the front tire. The reason for the latter would be different gearing - i'd only need 3-5mph out of the front tire under power, enough to not get stuck in snow and similar at low speeds. Whereas the main motor would be expected to run me 20mph with any load I have so geared differently. Possibly even two such starters if I needed hillclimb torque, or an easy way to have 3 levels of power. (have one smaller and one big, so that I use starter 1, starter 2, or both - again since controllers seem so darn expensive)

Another plus of lead acid or gel cells would be able to use common car battery chargers for simplicity, some of the ones for big packs of laptop style batteries have sounded expensive..

Thanks for the idea of forklift quick disconnects, that seems like a good idea. I don't really want to screw and unscrew every day but even if I do sling car batteries of weight around every time that doesn't bother me at all.
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Old 02-22-2013, 07:45 AM   #5 (permalink)
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The connector described is called an anderson connector.

Using a heavier battery causes nothing but issues. Heavier battery = heavier mounts. You will NOT find an off the shelf mounting solution. I have tried... Even all of that aside using a heavier battery tires will wear faster, brakes will wear faster, you will tire more trying to pedal without using assist (heaven forbid something fails or the battery dies), its harder on axles and bearings, cargo capacity is greatly diminished (or even eliminated), and unless you mount the batteries at or below the axle you can't stand and pedal.

I know 56 lbs doesn't sound like a lot but my entire e-bike with the battery should weigh 72 lbs... Basically only 16 lbs more than just a 48v 18ah SLA battery pack!

With an 18ah SLA I seriously doubt you will get 50 miles unless you pedal a lot. If you keep adding weight eventually you will just overtax the electric motor. I am just saying instead of dropping a couple hundred dollars on batteries you may not be happy with you should take another look at lighter alternatives. Most LiFePo packs do come with a charger so you shouldn't worry about that. Basically I can carry three 48V 21ah battery packs for the same weight and size of one 48V 18ah SLA battery pack.

Honestly I don't know how far I will be able to go but I am planning on 50+ miles on a charge.
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Old 02-22-2013, 01:35 PM   #6 (permalink)
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Well, do you need a trike? If you just want to build an ebike, that's simple. Here's mine. If you want to duplicate it, I can point you in the right direction. I built this one for about $1000. It has lithium iron phospate batteries (24V/30ah). 50 miles of AER is really unachievable if you ask me. I have 16 15ah cells on my bike and 17-20 miles of AER is the best I can expect to get (and I'm only using a 500 watt motor). 50 miles would require 40-48 cells. That is an astronomical cost and amount of batteries.

I 100% guarantee you the bike in the link you posted will not get you anywhere near 50 miles AER. My guess is 6-8 miles in the real world. I don't care what the advertisement says. Its a 15AH battery pack powering up to a 1400 watt motor.

Additionally I see many drawbacks to this bike:
1) Unsprung weight of the hub motor - the motor is to the back of the bike and is unsprung weight on the wheel (causing it to be harder to pedal)
2) The battery pack is high mounted and to the back (this causes an unstable bike that will fall over easily and take bumps hard in the back. The front wheel will come off the ground easy too).
3) The motor is not geared (this limits hill climbing and assist, it also puts a severe strain on the battery and the motor (even when climbing small hills))

Here is a better set up (its called a mid mount motor). This allows you to continue to be able to shift the bike and use assist through all gears. It also reduces the strain on the battery and the motor when climbing hills. This type of setup eliminates all the drawbacks listed above.
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Old 02-22-2013, 02:10 PM   #7 (permalink)
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Quote:
Originally Posted by govman6159 View Post
I 100% guarantee you the bike in the link you posted will not get you anywhere near 50 miles AER. My guess is 6-8 miles in the real world. I don't care what the advertisement says. Its a 15AH battery pack powering up to a 1400 watt motor.
It's also a 52v system. 52v*15ah is 750 watthours. Your 24V battery is 30ah so 24v*30ah is 720 watthours.

Quote:
Originally Posted by govman6159 View Post
Additionally I see many drawbacks to this bike:
1) Unsprung weight of the hub motor - the motor is to the back of the bike and is unsprung weight on the wheel (causing it to be harder to pedal)
2) The battery pack is high mounted and to the back (this causes an unstable bike that will fall over easily and take bumps hard in the back. The front wheel will come off the ground easy too).
3) The motor is not geared (this limits hill climbing and assist, it also puts a severe strain on the battery and the motor (even when climbing small hills))

Here is a better set up (its called a mid mount motor). This allows you to continue to be able to shift the bike and use assist through all gears. It also reduces the strain on the battery and the motor when climbing hills. This type of setup eliminates all the drawbacks listed above.
Unsprung weight on a bicycle is actually good. The more weight put on the frame the less rider/cargo weight the bike can carry. It won't make it any more difficult to pedal than the weight of a motor sitting on the frame.
  • Hub motors are less complicated. There are no gears, chains or extra freewheeling hubs to have to mess with.
  • There are hub motors that are available with regenerative braking.
  • Hub motors are easier to mount, they just replace a wheel.
  • They are much quieter and they are (at least to me) more aesthetically Pleasing.
  • When choosing a hub motor one should make sure to size it correctly. You can get a hub motor that is geared...they have massive torque and you can get away with a smaller motor. However it is typically louder and not as fast.
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Old 02-25-2013, 10:51 PM   #8 (permalink)
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Quote:
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It's also a 52v system. 52v*15ah is 750 watthours. Your 24V battery is 30ah so 24v*30ah is 720 watthours.



Unsprung weight on a bicycle is actually good. The more weight put on the frame the less rider/cargo weight the bike can carry. It won't make it any more difficult to pedal than the weight of a motor sitting on the frame.
  • Hub motors are less complicated. There are no gears, chains or extra freewheeling hubs to have to mess with.
  • There are hub motors that are available with regenerative braking.
  • Hub motors are easier to mount, they just replace a wheel.
  • They are much quieter and they are (at least to me) more aesthetically Pleasing.
  • When choosing a hub motor one should make sure to size it correctly. You can get a hub motor that is geared...they have massive torque and you can get away with a smaller motor. However it is typically louder and not as fast.
Well, if we want to get technical, my system is 25.6V (25.6*30=768wh).

No gears = less efficiency or if you opt for a geared hub motor, break out the wallet and be ready to pay. Then you might get 3 or 4 gears. Use a mid mount motor as pictured above and all gears are available (21 on this bike but up to 30 on some). This allows you to take advantage of the bikes stock gearing. Some will say harder to set up but, to me, its about as complicated as adjusting spokes.
Regen braking on a bike/trike is not really practical. It produces drag that either limits coasting or top downhill speed. The net regen is almost useless and def not worth the cost or complexity it adds. I could maybe see it being practical in San Fran or Colorado but not in most of the US.

I hear your points and expected this response. I guess it just comes down to personal preference. Its funny that you see a hub motor as more asthetically pleasing. When I see one, I immediately think "that is so ugly".
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Old 02-26-2013, 07:24 AM   #9 (permalink)
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Quote:
Originally Posted by govman6159 View Post
Well, if we want to get technical, my system is 25.6V (25.6*30=768wh).

No gears = less efficiency or if you opt for a geared hub motor, break out the wallet and be ready to pay. Then you might get 3 or 4 gears. Use a mid mount motor as pictured above and all gears are available (21 on this bike but up to 30 on some). This allows you to take advantage of the bikes stock gearing. Some will say harder to set up but, to me, its about as complicated as adjusting spokes.
Regen braking on a bike/trike is not really practical. It produces drag that either limits coasting or top downhill speed. The net regen is almost useless and def not worth the cost or complexity it adds. I could maybe see it being practical in San Fran or Colorado but not in most of the US.

I hear your points and expected this response. I guess it just comes down to personal preference. Its funny that you see a hub motor as more asthetically pleasing. When I see one, I immediately think "that is so ugly".
Technically every battery peaks at more voltage than it is "rated" for. A 48V LiFe pack is about 53V (so a 21ah battery would be 1113wh by your math). The 52V pack is likely more like 56V (so a 15ah battery would be 840wh by your math). Battery condition will vary the peak voltage of your packs so that is why it is better to go by the manufacturer rating.

Any time you introduce mechanical leverage i.e. gearing you will have parasitic losses. Many hub motors are brushless which means the only parasitic loss they have to overcome is the bearings of the wheel. Up a hill the motor that uses the gears will have an advantage but on a flat the mechanical linkages will steal some power due to friction.

mid motors also put wear on your drive line and stress on the freewheeling hub. A hub motor essentially is a totally separate source of power. It doesn't rely on the bike's drive to work. The mid motor relies on the drive system of the bike. If you have an issue with the driveline of your bike like the chain derailer gets messed up, chain fails, or the free wheeling hub fails pretty much anything you couldn't fix on the road you will be pushing the bike home.

You spoke of complication... a regen system on a hub motor is totally electronic build in the controller. A mid motor adds way more complication... you need a second chain and a second freewheeling hub.
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Old 05-22-2013, 05:01 AM   #10 (permalink)
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go to endless sphere forum, there are tons of information about electric bikes.
Endless-sphere.com • Index page

Actually direct drive hub motor is not so efficient - if you run it lower speed and uphill, it draws much more current and your range suffers. Electric motor is most efficient when it runs its rated RPMs. So in real life geared hub can give you more range it you are not running full speed all time - and then you have wind resistance...

So most efficient would be direct drive hub with max speed under 20mph but then you cannot have high speed. If you pedal faster than hub motor max speed then it actually drags you down - it starts to regenerate. Lots of compromises.

So gears are good for efficiency - to keep motor at higher RPMs. And you get climbing ability and better top speed.
Check GNG mid-drive kit. I would go for that. Actually planning to buy one myself
Endless-sphere.com • View topic - GNG, 1000W 48V BB-drive, $400

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