Safe's Electric Bike Project #002

[safe]

Anyway, I found they fit perfectly into 3/4" Class 200 sprinkler pipe. Seems like it would make a convienent and light holder with glued and threaded fittings available.

Bingo!

That's the plan... and then use spring loading on both ends.

The tubes will also fit perfectly inside my frame and create an additional protective layer between the cells and the steel of the frame so that I don't have to worry about electrical shorts.

PVC pipe is about a dollar for an eight foot section... that's my kind of price scale.

 

[z_slo]

I just thought of a possible problem, heat. I've melted PVC pipe but that was with my solar panel water system and it gets pretty hot. My laptop's batteries get lap scalding hot, how about nicds? Maybe holes drilled in the pvc where the batteries touch would ventilate heat.
These subC batteries are way sturdier than D cells. I doubt they would crush if they were held together with strong springs. I'm going to have mine horizontal so vibrations from the road wouldn't make em jump up and down.

 

[z_slo]

Another benefit is that you can shake them out of the tube and toss out the "runts" easily. I've found a few of my old cells that go to 0V sooner than the others.

 

[truckerzero]

safe those are about the same price as 2600mah aa nimh but have a c rating 10 times higher never new there was actally a real use for nicad plus nicad you can run flat dead with out hurting them or at least thats what i hear

 

[TylerDurden]

So... we've concluded SLA is not the "Most Cost Effective Battery".

:lol: :lol: :lol:

 

[safe]

So... we've concluded SLA is not the "Most Cost Effective Battery".

We've concluded that I built a bike for "D" cells and can't change course very easily. Go to the "Most Cost Effective" battery thread... the deep discounts in these NiCads make them cheaper than you might think.

Regular price: $2.00 per cell (and up)

Sale price: $1.25 per cell

I'm a bargain shopper...

This price ends up almost eqaul to SLA and over time they will end up cheaper. Even LiFePO4 becomes cheaper after about 3,000 - 5,000 miles.

 

[safe]

Maybe holes drilled in the pvc where the batteries touch would ventilate heat.

I've been thinking about that... if the heat transfer is fairly rapid through the PVC pipe it should be okay. Hot water is sometimes run through these pipes, so they need to be able to handle at least 150 degrees F in case of some hot water heater that is running a little hot.

I guess I'll just have to see how well it works.

My experience is that everything is incremental... you build something, test it, make changes, test some more. It takes a long time to refine to a level that you can say you are "done".

Update - This is some text about PVC pipe heating:

"Temperatures necessary to heat the pipe are dependent on pipe size and the severity of the desired bend radius. In general, PVC pipe should be heated from 225°F to 275°F for the minimum amount of time necessary to achieve uniform softening. Care should be taken to avoid exposing the pipe to bending temperatures for an excessive length of time, as irreparable distortion and deformation will occur. Localized overheating must be avoided. Successful minor bends (< 30°) can be achieved with minimum distortion in the lower temperature range (225°F) without internal support. Sharp bends (> 30°) require higher temperatures (250°-275°F) as well as internal support to prevent wall distortion/collapse."

 

[safe]

Another benefit is that you can shake them out of the tube and toss out the "runts" easily. I've found a few of my old cells that go to 0V sooner than the others.

That's the biggest advantage that I see. By people being able to eliminate the "runts" you keep the overall pack going better.

Hmmmm... a filtering theme seems to be on my mind these days... :wink:

 

[z_slo]

I made a PVC holder for 10 cells for testing purposes.
Hmmm... bike rack stacked with pipes with capped ends and red and black wires sticking out? I'd be shot by Homeland Security before I got to the end of the block! Better keep yours well hidden in your frame.

I'll try overcharging at 1C to see if I can melt the PVC. Maybe do it out in the yard and tell the kids and dog to stay away.

 

[safe]

I'll try overcharging at 1C to see if I can melt the PVC.

225 degree Fahrenheit = 107 degree Celsius

275 degree Fahrenheit = 135 degree Celsius

My guess is that NiMh and NiCads go up to about 70 degrees Celsius at most so the PVC should never melt unless the cell has already suffered complete failure.

 

[TylerDurden]

Well...? Stalled-out? Nothing new on this project since 5/11. (#003 is totally MIA.)

 

[JennyB]

I made a PVC holder for 10 cells for testing purposes.
Hmmm... bike rack stacked with pipes with capped ends and red and black wires sticking out? I'd be shot by Homeland Security before I got to the end of the block! Better keep yours well hidden in your frame.

I'll try overcharging at 1C to see if I can melt the PVC. Maybe do it out in the yard and tell the kids and dog to stay away.

Try ABS pipe. http://clevercycles.com/?p=123

 

[TylerDurden]

Looks like 'safe' (Eric) crapped all over the comments there too.

 

[safe]

"Eric Says:
July 8th, 2006 at 7:14 am"

...well that would be about the time I started researching ebikes.

Maybe he's my "evil twin"?

Given that "solderless packs" are the new "rage" in fashion I have to say that whoever this Eric fellow is happens to be rather prophetic in his ideas... just how did he get it right like that?

I'm impressed... :wink:

 

[z_slo]

The ABS battery packs aren't solderless, it's just a container for premade nicd packs.

I haven't been able to melt my PVC/spring loaded packs but I haven't found a high amp 48v power supply to really test them.
I used pinned wood blocks in the ends instead of PVC fittings so that the tubes can be closely bundled together.

 

[safe]

Mountain Bike Comparision

Just so people realize that I've got a long mountain biking past this is a comparison of my old mountain bike that I've rided forever with my new projects. After so much time on the mountain bikes I just got bored with it and now all that interests me is the road racers.

Notice the differences in the wheelbase and the amount of frontal area I manage to get.

Without a side by side picture like this it's easy to not really realize what I'm doing here... it's a very different experience to be on a road racer bicycle than to be up in the air on a mountain bike. These days it's all I want to do. (I haven't even ridden the bike for a few years now)

The damn thing cost me $1000 dollars new... but it's a great bike...

I've thought about becoming "normal" and turning this into a typical hub motor ebike... but at this point in time I'm just not excited about that geometry. I'm more interested in the street than the dirt because (unlike California) in Missouri off road riding is not so great. The soil is too clay like... I like more sandy soil that is hard packed.

 

[safe]

Front Disc Brake Mount (Reversed)

If you want to have dual disc brakes in the front and you already have a disc brake lying around (that happened to have been partially broken) the only thing you can do is create a new mount that is upside down and backwards from the stock part. It's going to be a little weird because the cable will pull to a fixed location and the outer cable will need to move in order to make it compress. So a little care in making sure the cable is the right length (and properly guided) will go a long way towards making everything work right. There's also going to have to be some kind of cable splitter, but I suspect tandems use such things and I'll be able to either order one or make one myself.

The mount I created is on the left, the identical part in it's stock configuration is on the right. It's a cheap no-name cable driven disc brake that came with the "Toys R Us" bikes.

This represents two full days of work and about another day just thinking how the heck I needed to do it. :lol:

 

[safe]

Armature Current Limiting - First Test

I'll actually be using this on this Project #002 before #003 so I might as well post it here.

I assembled the Armature Current Limiting circuit and connected it into Project #001 (the one that has been working for two years) and rode around a little. You can really tell the difference because that low end torque that one gets so addicted to isn't there any more. The high end is still there, but the overall feel becomes very linear rather than the usual "grunt" that the non-limited controller produces.

It was kind of fun accellerating slowly with a full throttle and then turning up the "boost" and feeling how the torque came back again. Higher "boost" power is lower quality (because it's causing higher heat) so when you reduce the "boost" you lower the motor temperature. Even with the Armature Current Limiting Circuit set to full on (40 amps) you still have less low end torque than stock, so for the #001 bike it makes no sense. Only on #002 and #003 will it make sense. (my gearing on #001 is way too high to use this) It does make one think about more "boost" (60 amps) because the motor can handle more power longer with this. Of course then I need to switch controllers and my old SLA cells are already sucking wind just to deliver 40 amps as it is, so the higher "C" rate SubC NiCads will be better suited to this type of system.

The voltage coming out of the controller is surprisingly accurately 5 volts. My multimeter suggested 5.04 which is so close to 5 exactly that it's effectively right where it's supposed to be. I've got a trim pot that needs to be set based on the controller voltage, so there is some fine tuning yet to be done.

In the picture:


...I connected the system up to the Project #003 and tried it too. The motor still revs high like a 48 volt motor should, but you can tell that it won't "lurch" to get there, it has a constant accelleration.

So far (lacking any negative problems so far) this seems to be working correctly.

Of course, I can't control the weather, so now it's raining and I can't ride...

 

[johnrobholmes]

Depending on the amount of travel you need, just get a cable splitter for a BMX bike. Or make one yourself.

http://www.danscomp.com/512039.php?cat=PARTS

 

[safe]

Bigger Motor - Higher Heat Capacity

On Project #002 the motor is bigger to begin with (MY1020Z3 with geardown) so it has a higher heat capacity, so running 40 amps all the time makes sense. In fact going up to 60 amps might be a good idea, so I might want to use one of my 100 amp current sensors on it. For now I'll just start off at 40 amps and go up from there.

This is the motor performance chart: (very similiar to Project #003, but the rated heat is higher)


At 50 amps:


At 60 amps:



P.S: Thanks johnrobholmes I knew there had to be some kind of cable splitter somewhere.

 

[recumpence]

Depending on the amount of travel you need, just get a cable splitter for a BMX bike. Or make one yourself.

http://www.danscomp.com/512039.php?cat=PARTS

Cool. Perfect for my dual caliper front brake arrangement I am looking at. :wink:

Matt

 

[johnrobholmes]

Just measured mine, it will give you 1" of travel with the stops threaded out all of the way. Make sure you can have the pads off the rotor and go to full lock with less than that.

 

[safe]

Top Speed

The top speed is a crazy 50+ mph (8th gear) on the flat.

(that's going to depend a lot on how good the aerodynamics get of course)

 

[dirty_d]

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

 

[TylerDurden]

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

About 2kW at the wheel, for a typical bike.