Safe's Electric Bike Project #002

[safe]

huh? it takes like 2800W to go 50mph does it?

The human powered speed record is 80 mph and he wasn't producing more than about 1000 watts in the sprint. It all depends on how aerodynamic the fiberglass ends up. We will see. You really start to hit a "wall" of air at about 45 mph.

Don't forget I'll be in a tight tuck behind front and rear fairings... and that's when I would be running at 60 amps (1900 watts at the rear wheel) which is a lot more that I would use normally... it will heat up the motor in a hurry. 40 amps is a better heat profile for normal use. 20 amps is it's peak efficiency level.

 

[recumpence]

Wow, so are TD and Safe agreeing on something? TD, I like the new pic. You look better than I thought!

Now I have seen it all. Maybe I sould go out and buy a lotto ticket and see how my luck holds up! :wink:

Anyway, yes it does seem like there is a wall up over 40. Heck, even at 40mph I have a huge reduction in efficiency versus 30 or even 35mph.

Matt

 

[dirty_d]

so whats the story on the tenergy sub-c cells? have you tested them, whats the voltage drop like at different current draws, im curious as to how long these will last at around 10A drain per string. it says "Up to 20A discharge" on the specifications, but is that continuous or what?

 

[safe]

so whats the story on the tenergy sub-c cells? have you tested them, whats the voltage drop like at different current draws, im curious as to how long these will last at around 10A drain per string. it says "Up to 20A discharge" on the specifications, but is that continuous or what?

Need to finish the bike first. I haven't even started on the fiberglassing (well I have the male molds, but have not started on the female) and there are bunch of other things to get finished as well. I'm hoping to get these running by the end of the summer. Fingers crossed.

I'm only planning on pulling 4.4C (max at 40 amps) so I won't be able to know if they are able to go up to 10C or not. (even if I bump the controller up to 60 amps it's still only 6.7C)

The batteries have been built and charged and once I removed the wrappers from the cells there was a 100% success rate for the cells to deliver a voltage. (which means there is electrical contact)

 

[markcycle]

huh? it takes like 2800W to go 50mph does it?

Last Friday I did a speed run on my motorcycle
For those who know Long Island NY I ran RT 107 between 25 and 25A
53.2 MPH @ 3800 watts 48 volts @ 80 amps
There was a 10 MPH head wind
Just confirming some real world testing at 30 MPH I only draw 20 to 25 amps. You definitely hit a wall at over 40

Mark

 

[dirty_d]

safe i said 10A not 10C, at 4.4C thats 10.6A per string.

 

[safe]

safe i said 10A not 10C, at 4.4C thats 10.6A per string.

I'll have 8 sets of 24 volts combined together so that I have four sets of parallel 48 volt strings at 2.4 Ah each. So that means 9.6Ah in total.

2.1C makes 20 amps (this is the motors efficiency maximum)
3.1C makes 30 amps
4.2C makes 40 amps
5.2C makes 50 amps
6.3C makes 60 amps (normally I'd think this would be enough)

2.1C equals 0.5 the motors rated heat (using ACL)
3.1C equals 1.0 the motors rated heat (using ACL)
4.2C equals 1.8 the motors rated heat (using ACL)
5.2C equals 2.7 the motors rated heat (using ACL)
6.3C equals 3.7 the motors rated heat (using ACL)

I'm pretty sure my motor heating issues will be more important than the battery "C" rate.

If I were to maximize the current that the battery can theoretically provide I could pull about 100 amps at 48 volts. That would be pretty insane because your range would be next to nothing, but it's an option. (maybe set some speed record doing such a thing) I do have a 100 amp controller, so I suppose one day I might try it. :?

 

[John in CR]

Safe,

Are you using any of the tube packed batts yet? I want to order some batts , and would like to avoid soldering and go the tube route for all the reasons you've mentioned, however, nagging in the back of my mind with the bumpy roads down here is the issue of batts coming separated at all causing major problems. Help me make up my mind with tabs or without tabs.

John

 

[safe]

Are you using any of the tube packed batts yet? I want to order some batts , and would like to avoid soldering...

Yes, I'm currently testing some of them on my #001 Project which is in my avatar picture. (the gray tubes underneath) So far they have been flawless and I hit bumps hard at speeds of 50+mph without suspension and the solderless tubes are working perfectly.

As long as you get the length of the tubes correct so that the right tension is on the spring (you want the springs moderately compressed, but not excessively) and you use real copper as your contacts and don't otherwise make any mistakes they work great. Don't forget that you are going to need to build something to grind out the inner lip of the PVC coupler jount so that the battery and spring can clear past them. That little lip needs to be removed. I used a drill and something that I had fashioned with a welder and some sand paper, but you could buy something to grind it out too, like maybe a big grinding bit for the drill.

The RC crowd discovered solderless tubes a while ago and I suspect that like everything else we are a little slow on switching over.

Be sure to make up your own thread and do a better job than I did in making a project build thread. If you make it look really good then everyone will come to your thread and learn from it.

And shop around for price... Lowe's was cheaper than ACE Hardware by a large margin overall...

 

[John in CR]

I'm in Costa Rica, so no Lowe's and the Ace that went out of business didn't have squat. At this point, if I go tubes I'll just roll them out of thin aluminum sheet. I want the aluminum so I can easily monitor for thermal charging, as well as dissipate the heat really well. It wasn't the sprung ends I was worried about losing connection, but more in the middle of strings and the contact from one battery to another. If it works with the acrobatics of RC, and you aren't having issues going fast with a suspensionless ride, then my worries are probably without merit. Now to figure out how to make the tubes an integral part of the strength of the frame to save weight in that structure, hmmm.

Thanks,

John

 

[safe]

I think the only way you can screw up is to not get a spring that is of the right amount of tension and also neglect the idea of having a screw to preload the spring because the springs need to be set right. On mine all I needed was to have them set at a firm twist and it was fine. Don't forget that I REMOVED THE PACKAGING around the cells in order to guarantee electrical contact. That's the nice thing about an insulator like PVC plastic you don't have to worry about electrical problems. The heat is not a problem from what I've been able to tell. Upon finishing a charge they are slightly warm. The tubes dissipate heat very well. (and on the bike I actually have air cooling running past them, so they never are warm)

 

[Toorbough ULL-Zeveigh]

*bump* to help slo u down.
just as with your bahnndough, ur spreading yourself a little too thin.
to quote inspector harry callaghan; "a man gots to know his limitations."


how long do u plan an living til u reach mk101 that u needed 3 digits?

 

[TylerDurden]

how long do u plan an living til u reach mk101 that u needed 3 digits?

 

[safe]

This project was largely abandoned because an ebike without pedals can never satisfy the Federal Ebike Law which defines something that is "legal" (viewed as identical to a bicycle) as:

750 Watts of Power
Must Have Pedals
Top Speed (as sold) must be 20 mph on the flat

...since this project is not a pedal bike it does not advance my "new" goal of creating a product that has universal appeal. (it would be legal in Missouri)

But you never know... maybe an RC motor might make sense with this and then open the power up to 5000 watts. :lol: (the frame is strong enough to handle as much as you could ever throw at it)

This frame is just sitting around doing nothing in the garage.

The fairings will go on and have a life in Project #003. (and beyond)

 

[Bobocop]

This project was largely abandoned because an ebike without pedals can never satisfy the Federal Ebike Law which defines something that is "legal" (viewed as identical to a bicycle) as:

750 Watts of Power
Must Have Pedals
Top Speed (as sold) must be 20 mph on the flat

...since this project is not a pedal bike it does not advance my "new" goal of creating a product that has universal appeal. (it would be legal in Missouri)

Did you take your medicine today ? :lol: (just kidding)

I remember that for months people were trying to tell you (which i agree) with your #001 build that a bicycle has peddles, but you kept insisting that that was a Missouri bicycle.

what made you now realize that a bicycle is known all over the world to have peddles ?

 

[safe]

...but you kept insisting that that was a Missouri bicycle.

It was a Missouri bicycle... that's all I had planned for at first.

What happened is that as I rode the Project #001 bike more and more I started to realize that there was a lot of potential for something that could be sold nationwide. I only learned of the Federal Law after I had gotten started on #002.

Basically I did not initially realize how good these things could be. (and with things like RC motors things just get better and better every day)

So #002 might still be of value... but like in the Southpark episode... one never wants to be a number two.

http://en.wikipedia.org/wiki/More_Crap

Note: One Couric is approximately 2.5 lbs [1.13 kg] of excrement

 

[safe]

Getting Rid Of The Crap (002)

I live in Missouri. The Project #002 was started as a "Missouri Special" bike in the beginning and I've been thinking I should just accept that and finish the bike so that it completely obeys the Missouri law... to the letter. (it's actually pretty close to being done)

The Missouri law states:

30 mph top speed
Maximum horsepower is 3hp (2250 watts)

So I have 120 NiCads from the Project #001 bike hanging underneath giving it extended range, but I could get this #002 bike running at 72 volts using two strings of 60 cells. This means a 1C load would be 2 * 2.2Ah = 4.4 amps. 10C would be 44 amps.


Maximum power would be about 2000 watts. (legal in Missouri)

By running the bike at 35 amps I would be under the maximum C rate of the cells and be able to deliver some impressive power. I would make the bike a simple direct drive one speed geared so that it would hit a maximum speed of 30 mph. Also, I would use Armature Current Limiting to keep the heat really, really low.

------------------------

This would allow me to make a bike where I could use up a lot of my old parts (add a fairing set too) and be able to sell it and recapture a little of the money I've spent on this stuff. Maybe I might get someone to ride with too.

 

[Mathurin]

Remember that Missouri moped regulations prohibit manual gear change.

 

[safe]

Remember that Missouri moped regulations prohibit manual gear change.

Actually they prohibit a clutch lever for the left hand. The logic was that little kids have troubles being coordinated enough to use a clutch while learning to ride a moped. You need one of those "centrifugal clutches" to be legal on a gas powered moped.

Besides... if you read closely this one will essentially be a "hub motor" because it will be direct drive without even a freewheel.

I'm finally going to have a true one speed.

(a three horsepower monster of a one speed, but a one speed all the same)