Katherine's E-bike!

[jonescg]

Hi all!

Well the House of Kat and Chris is now home to another electric vehicle.

Kat has been riding 11 km to work and 11 km home most days on her pushbike, and while it's not too bad, on a day like yesterday when it's 39'C it's not much fun. So we ordered an e-bike kit from cell_man at emissionsfree.com and it arrived just in time for Christmas

I'm the one who is responsible for it's construction in maintenance but whatever. I have decided to use the drink bottle holders as the battery pack frame mount.

Paul built us an awesome triangular pack with a built-in BMS. This consists of A123 green cells, 4 P 16 S.

The BMS is on the underside, so once the whole thing is placed inside a waterproof box I'll cut a few holes for the hot air to escape. Then I will put a 19 mm square ally backbone on it to support the weight of the cells, and so it can slip into the C-channels on the bike. It's a convenient setup for ease of removal prior to charging.

I figured for someone who isn't full bottle on electronics, I put a a high-current (20 A, 277 V AC) toggle switch in place with the 100 ohm resistor across the lugs. This way, once the battery pack is plugged in the Caps are charging up, and after a few seconds, the toggle can be turned on providing full current to the controller. I used those 30 A anderson style connectors. They're alright, but man they are tight to solder and fit.

The *ahem* '200 W' perfectly legal in Australia motor

I tested the switch by applying a load (my trusty 40 W 240 V bulb). It came on when the toggle was switched on, and it came on when the toggle was off :? The precharge resistor is in parallel with the switch, so when the battery leads are plugged into the controller to complete the circuit, the precharge resistor immediately draws 0.5 amps. Then when the toggle is switched, we get an e-bike that is ready for riding with minimum spark!

So is it normal for this circuit to be able to light a bulb even when there is a 100 ohm resistor in series?

 

[itchynackers]

Nice bike. I hate hairy toes.

 

[grindz145]

I love how you utilized the water bottle cage mounts. Beautifully done.

 

[LI-ghtcycle]

Ditto! That's the REAL reason they have 2 "bottle" mounts on these bikes, the designers just didn't know it yet!

 

[John in CR]

Great bike for her. What's she think? My wife refuses still due to a first ride minor mishap.

I believe that resistor is way too low. It's probably even creating a bit of spark on it's own when you connect, and would waste a lot of juice when she forgets to unplug the pack after a ride.

 

[jonescg]

She loves it, even though it's not ready yet. She got to take Adam's e-bike for a spin while we were in Vancouver. After 30 mins I was worried she might have had a crash... nope, she was just grinning and riding

So you think I should go for a bigger resistor? 1kOhm?

 

[dingoEsride]

Cool, maybe another partaker in our local river ride

 

[John in CR]

She loves it, even though it's not ready yet. She got to take Adam's e-bike for a spin while we were in Vancouver. After 30 mins I was worried she might have had a crash... nope, she was just grinning and riding

So you think I should go for a bigger resistor? 1kOhm?

Yeah, I think somewhere in that 1kOhm range is what the electrical guys recommend. The one I use for manual precharging is 3.5kohm and it does take a few seconds to charge the caps, a bit slow, so that's too high. A fairly low resistance like yours, maybe even lower, is probably appropriate only for a connector with the built-in precharge circuit kicking in as it's plugged together.

One other possible issue....What do you have to prevent her from connecting the plug and trying to take off before flipping the switch? That seems like a common and easy thing to do, and will fry something, the resistor or its wiring, which is a significant fire hazard? You can solve the fire hazard with a small fuse in the precharge circuit, but what will solve the fuse getting blown all the time? I think you need dual switches with a single throw flipping both on. The 2nd circuit being switched is the controller power, so the controller can only be on when the main power switch is on.

No doubt Kat will love the bike. Then after dealing with the pain of disconnecting and (I guess) removing them for charging, you get her rigged up for just park and plug-in with just a single key switch to turn it on and off. I have some RC packs on the way, and I don't know how I'm going to take to going back to battery hassles before and after rides. The only thing easier than I have now will be the solar charged bike that I will very rarely have to plug in to charge. Getting her to park and plug will net you plenty of extra hugs and kisses too. 8) . Paying her dues with some battery hassles at first is a good thing anyway, so she'll appreciate the greater simplicity later instead of taking it for granted.

 

[jonescg]

I've been looking into a 3 position ignition switch for my e-motorbike, and I wonder if a smaller, simple version of the thing might exist for an e-bike. It uses three spots - off / Acc / on. Off - nothing is completed. Acc - pole one and two are connected, enabling the precharge circuit to complete, then On - the main circuit / contactor circuit is engaged. This would make life a lot easier I think.

Edit, just bought two of these Geez I love internet shopping!

 

[jonescg]

As mentioned elsewhere on the forum, my Shimano 7 speed freewheel seems to screw on to the hub a bit too far. Do I need a washer / spacer? And where would I get such a specific washer or spacer? 35 mm ID 44 mm OD. :?

http://s285.photobucket.com/albums/ll53/jonescg/?action=view&current=hubissue.mp4

 

[AussieJester]

As mentioned elsewhere on the forum, my Shimano 7 speed freewheel seems to screw on to the hub a bit too far. Do I need a washer / spacer? And where would I get such a specific washer or spacer? 35 mm ID 44 mm OD. :?

http://s285.photobucket.com/albums/ll53/jonescg/?action=view&current=hubissue.mp4

I would get a scrap of 1.5-2mm ali and simply make a spacer/washer/shim whichever
one likes to call it, pop it on before screwing on the Shimano cluster
'washer' will obviously need to sit inside the cluster as per depicted below-->



Be good as a bought one mate I have HEAPS of scrap ali
suitable if you wish to try making one. The 1.5mm can be cut
with a sharp box cutter several times and snapped...

KiM

 

[jonescg]

I was in Malaga today, so I shopped around all the bearing places. They had lots of 47 mm OD and 35 mm OD, but no 35 mm ID. Anyway, a bloke at Apollo Bearings gave me a shim which would soit the OD but need honing out in the middle. Not sure how frocked I can be, but maybe the dremmel will get some use again

Still, must have been a dud out of the factory :? The threaded part is just 1.5 - 2.0 mm short of what it needs to be.

 

[voicecoils]

Yes you need the washer. I've seen the same thing happen before on a Golden Motor Magic Pie.

I've seen the spacers come with Golden Motor and Crystalyte motors when they're needed however.

If I find one I'll let you know...might have something in a box of parts somewhere.

 

[jonescg]

That would be awesome! Thanks man!

 

[AussieJester]

I just remembered what fits the thread, the locking nut
from the European style bottom brackets they screw straight
onto the freewheel adapters are about 3-4mm wide wil give you the required
spacing....

KiM

 

[jonescg]

That's good to know. I might rummage through Balcatta Recycling Depot for a few hours and find one. 4 mm sounds like a lot, I thought I'd only need about 2 mm. Anyway, the 7 speed is still a tight fit in the frame. I'll look into it

 

[cell_man]

Hi Chris,

what's up, still not got it fitted. I would have had that pack gaffer taped in there in 5 mins. Where there is a will, there is a way to get that motor fitted in an afternoon

Sorry I haven't been able to get back to you with any info on the freewheel issue. As these are a ready built kit and they've been pretty good so far I don't really mess with them other than spend some extra time making the packing a bit more secure than it comes from the factory. I did try the kits out in my bike previously but there may be some small differences between the kit I tried and what came in later. It may be that some kits are only good for a 6 speed freewheel, or there may be an error on the side cover. I don't keep my stock of these motors and my tools and parts in the same place since I now have a workshop, but will try to have a look at another motor and see if I work out what may be going on. AJs suggestion of a shim sounds like it will work just fine, you may need to add some washers to the axle if the 7 speed extends too far and fouls the frame. If I've misinformed you or anyone else about the freewheel compatatability, sorry, I'll work out what's going on with them.

Regarding the pre-charge resistor on the battery pack. It is perfectly safe if you forget to connet the main positive as all that will happen is that the current will cause a voltage drop and the controller will hit LVC, nothing will happen, try it. If you put the pre-charge resistor too high it will cause excessive voltage drop and will not do it's job properly. Even a 100ohm resistor causes about a 3V voltage drop on my 36V pack due to the quiescent current from my controller and a CA. That 100ohm 3W gets shorted outed across the supply, it will just pop in a flash, no hazard IMO. A slightly higher resistance and a higher power could handle a short across the battery, so I'll look at that soon. It's difficult to find a good switch that can handle any descent DC current, so I don't bother, plus they will likely be expensive and to be honest unless people are willing to pay for these additional parts, it's an unnecessary part of the pack. AC switches will be significantly de-rated operating with DC current.

I think the way the connectors were shipped is about as straighforward as it gets with having a precharge circuit and it's perfectly safe. There really is no reason to go with a switch, especially when it was your intention to have a removable battery not a permanent installation. Nobody else seems to bother with a pre-charge, but I just am not happy letting them ship that way as I feel it is very hard on the BMS and the connectors get trashed quite quickly. Those Anderson type connectors are supposed to be 45A by the way, not 30A, but it's difficult to get genuine 1s here in China so I can't be sure. For your setup they are more than adequate IMO. If connecting some plugs in the right order is a concern, I can't see how a stack of RC LiPo with a rats nest of cables is even a consideration. There is more than a little spark if you make an error with the connections on the LiPo and there is a very real possibility of them bursting into flames if they are not treated right.

1 last thing, I wouldn't rely on just the captive nuts in the frame to hold the battery. If the bike falls over there is a possibility that they could break and damage the frame. They weren't designed to be holding that sort of weight, so I would be tempted to make plates that use the bottle holder mounts but are also clamped to the tubes of the frame as well using U bolts or even just big jubilee clips. When I have a free afternoon I plan to knock up something like that for my bike and hopefully have a complete battery in case with mounts for the frame to offer for sale at some time in the not too distant future. Unfortunately these things take a lot of work as they are not mass produced and everyone seems to want everything for nothing.

BTW I ordered 700C rims weeks ago now but I'm still waiting on their arrival. When I do have them I will be able to offer the MAC motors in a 700C rim as well as 24" and 20". SS spokes for these awheel sizes are coming in any day now, but already have them for the 26" rim. If the performance of the DD kit isn't up to what you want, a stronger controller would add a bit of pep and I've got 6 to 12 Fet Infineon EB2xx with IRFB4110 fitted in stock or could go with a MAC in the future. You wouldn't loose much selling the DD kit on to someone in Oz, and anyway you can't have too many ebike parts or ebikes sitting around The Mac would have been my first choice for you but you'd till be waiting for it if we took that route.

Cheers
Paul

 

[jonescg]

Hey Paul! Thanks for the brain-dump :lol: always good advice in there. Katherine is a big scaredy cat and jumps at even small sparks, so she wouldn't have a bar of it. Simple as that. So the switch was the next best idea. With high voltages contactors make the most sense, but I mean, for an e-bike? Probably not worth it. The drink-bottle holders are pretty damn convenient, but like you say if it tips it could be an issue. Being weighted snugly in the V of the bike should give it more strength I think.

We are getting a waterproof polycarbonate box fabricated with air vents where the BMS is. So when all is said and done it should be a pretty mean machine Hey - those controllers. Are they water proof?

I will hone out a big washer I got at a bearing shop, and that should sort the freewheel issue out. Will the BMS get hot when charging? Just wondering if we should take them out of the box to charge?

Cheers mate,

CHRIS

PS Voltron is almost ready Check out my thread -->

 

[cell_man]

Hey Chris,

sorry, got a bit carried away there

No need to worry about cooling the BMS IMO and vents will only let in water. Keep an eye on it in the hot weather and see how it does. If necessary yo could leav the aluminium sheet exposed bit sealed around the edges to keep it waterproof, but I wouldn't bother unles it's necessary. I would say the controller is pretty waterproof, they are pretty well sealed from what I've seen.

48V is not gonna hurt anyone unless you make a real effort to do something daft. The contacts on the andersons are not exposed, I can't see how you could possibly get a shock. Just as likely to forget to flick the switch back in the off position when she connects as she is to plug 2 connectors in the wrong order. Result of either error is a small spark and it's hardly worth worrying about IMO.

Cheers
Paul

 

[MikeFairbanks]

So, your wife has an eleven-kilometer ride to work.

As Rich Sanchez would ask, "what is that in English?"

A little under 7 miles, of course.

Sounds like just the right commute.

Now, that celcius thing has me perplexed. Not only do I struggle to spell celcius and Farah's height, but converting is a chore. So 39C is probably about 95F, right?

If only Australians knew how to speak English like we Americans.

 

[AussieJester]

As Rich Sanchez would ask, "what is that in English?"

Now, that celcius thing has me perplexed. Not only do I struggle to spell celcius and Farah's height, but converting is a chore. So 39C is probably about 95F, right?

If only Australians knew how to speak English like we Americans.

OR... America could catch up with the majority of the world and switch to the Metric system.
39C is actually 102.2F

The missus will be chuffed Chris....if you ever get off the e-bike so she can ride it herself that is hehehe

KiM

 

[MikeFairbanks]

As Rich Sanchez would ask, "what is that in English?"

Now, that celcius thing has me perplexed. Not only do I struggle to spell celcius and Farah's height, but converting is a chore. So 39C is probably about 95F, right?

If only Australians knew how to speak English like we Americans.

OR... America could catch up with the majority of the world and switch to the Metric system.39C is actually 102.2F

The missus will be chuffed Chris....if you ever get off the e-bike so she can ride it herself that is hehehe

KiM

That's a good one. We're Americans. If you look up stubborn in the dictionary you'll see a picture of one of us. Why would we want to take a meter and simply divide or multiply by 10, 100, or 1000 when we can take an inch, multiply it by 12, then multipy it by 3 to get a yard, 6 to get a fathom, or 5280 (I had to look that up) to get a mile?

There are 8 ounces in a cup, 2 cups in a pint, 2 pints in a quart, and four quarts in a gallon. There are three gallons in a hogshead, and fifty gallons in a barrel.

You metric-lovers and your simple multiplication and division by 10! Where's the challenge?

 

[jonescg]

Overheating is a real concern for most electrical equipment here in Perth. Our summer has been the driest on record and the maximums are rarely below 32'C. The record for Perth was 46.7'C! Although, being a Queenslander originally I have concerns for my friends and family who are currently under water, or about to be

Oh, I stopped in at a bike shop and I think I got the right spacer for the 7 speed freewheel.

Katherine can't wait! After I've had a go on it

 

[AussieJester]

Overheating is a real concern for most electrical equipment here in Perth. Our summer has been the driest on record and the maximums are rarely below 32'C. The record for Perth was 46.7'C!

I went past the Mundaring Weir (not far from home) last Friday its the lowest i have seen it in my life
Howz the diversity of climates in OZ....one side of the country is literally meters underwater
while the other side is in a heat wave... ;-S

VIDEOS of you smokin the missus bike up soon to come i hope ChriS hehe...

KiM

 

[MikeFairbanks]

Overheating is a real concern for most electrical equipment here in Perth. Our summer has been the driest on record and the maximums are rarely below 32'C. The record for Perth was 46.7'C! Although, being a Queenslander originally I have concerns for my friends and family who are currently under water, or about to be

Oh, I stopped in at a bike shop and I think I got the right spacer for the 7 speed freewheel.

Katherine can't wait! After I've had a go on it

Perth!

Now there's a place I'd like to visit. Western Australia....some of the best hidden surf on the planet, and home of Keith Ledger. I had no idea it could get that hot there.