Ross' bike pusher (trailer) project...

[rossfree]

I cleaned up some wiring a bit and got the new brakes on the bike. Temperature hit the 50's (F) over the weekend. Wierd! Had to get the bike out. The shifter needs some work but I was able to get it into a higher gear so I could pedal a bit with the throttle open.

Got salt-water all over everything! Ha! Lucky I got back at all! Have to put some priority on protection from the elements.

I found my new avatar! Can you guess which picture???

I am very pleased with this trailer connection arrangement. I feel no side loading on the back wheel. I don't take sharp corners with the throttle open... so that's no big deal. But I do accellerate through reasonable curves without concern. This is not what I would consider an off-road bike. The smoother the roads the better. Trailer bounce is not significant but it's there when the road gets bumpy. Three lines of traction means you don't miss many bumps. And I stay away from pot-holes. The wet, icy, sandy roads makes biking precarious at best. I can't really "dodge and weave" to get the full feel of the trailer behind the bike. When the sand and ice go away and the roads dry up I'll be experimenting more. But I LIKE IT!

Rear View: (4) 12v 19amphr AGM batteries from Walmart... note the 30amp automotive fuse in series with the pack. The fuse sits in the recess of the batteries so I can put a flat top across the trailer. Once I mount the controller and charger below, the whole top will be flat (except for the screws and washers mounting the motor).

The tape in the other battery recess hides a spare fuse! 8)

I built a utility trailer several years back. My Dad told me to you never have enough places to tie things down with ropes or bungees. So by his suggestion, I put 12 or 14 welded loops around the bottom perimeter of the utility trailer and love them. The loops are bent down so that you could hook a length of rope around it. Or you could connect bungee hooks or strap hooks to it. I'll be doing something similar with this trailer for tieing things to it. I won't need quite as many. :wink:

When I remount the trailer tongue, the trailer will be parallel to the ground (no tilt).

The beer came from a buddy down the street. Those wire thingies come in handy!

Here's some more pictures:

Ross

 

[fechter]

Nice!

Looks like you need some kind of fender or cover to keep the spray off the electricals.

 

[TylerDurden]

Excellent proof of concept for a stealth electric-assist bike/rickshaw setup.

 

[Rassy]

Way to go Ross! With those 19AH batteries you should get some pretty good range. I am hoping to replace the 12AH SLA in the one-wheel trailer with 20AH of LiFePO4 when the right battery at the right price is available.

When you get your platform/carrier on top it should be real stealthy. The Lycras will think you are a superman as you pass them on the hills.

 

[rossfree]

Thanks for the comments guys!

It's official... I dusted off a schwinn speedometer/odometer that I picked up for my teenage son some years back and hooked it up. Dead battery. Ahh ha! I'll take the ole bike and trailer to the drugstore down the road and get a new battery!

A mile down the road, peddaling all the way (with assist of course) I had to pull over and rest. My head was pounding and I'm thinking this is it... I'm gonna have a heart attack and die. Man am I OUT OF SHAPE!!! Took way to long to get my wind back and I'm still realing from the head pounding. Sheesh... it's down right embarrassing!

Anyway... not to be deterred, I sally forthed to the drug store and obtained the necessary voltage container. On the way back I clocked in at 20mph on flat ground with no pedaling! With human assist I brought it to 24mph. Not bad at all for a winded, overweight, dieing man seeking oxygen. This is after I've been playing with the trailer off and on for the past couple of weekends. It hasn't seen a charger yet! The trip there and back was 3.2 miles. And it went quick! I like the speed. It's a good speed with the trailer and stil has nice pickup. I don't think I'd want to trade the pickup for more top end.

I did make an attempt to wrap the controller in plastic to keep it a wee bit drier.

I've got my 48 volt charger now so I have all my pieces parts. I'll be looking for a suitable container to keep the charger and controller dry on the trailer.

Having fun!

Ross

 

[kyakdiver]

Ross,

Thanks for the build report! I've been watching and reading your progress from the start and I'm impressed with the final product. Good work!!

 

[rossfree]

Thanks Kyak,

The Lycras will think you are a superman as you pass them on the hills.

8)

...I'm looking for a good superhero outfit...

NO CAPES!!!

 

[fechter]

Here you go-

http://www.coolest-gadgets.com/search/dee-three-oh

 

[rossfree]

Was thinking about something like this!

 

[rossfree]

It's been a while since my last update... we've had snow snow snow! No chance to ride. **Bother**

While waiting for things to thaw, I dissassembled the trailer and painted it. It was starting to rust from the salt water roads around here. I also got the brakes on the bike replaced and worked a bit on the gear changers. Still have some work there. I think I screwed up the "thumb clicker" to change gears.

Anywhoo...

I threw the thing back together to catch a beautiful spring day... dry roads, cloudless sky...

Hooked everything up, jumpered the disconnect... and decided to give it a quick test before taking off. Standing next to the bike, I gave the throttle a gentle little nudge. Nothing happened. Hmmm... I nudged it a bit more. Nope.

So I pushed the throttle it all the way forward...

As I stood there, the TRAILER TRIED TO TAKE OFF LIKE A SCALDED DOG! I'm holding on to the bike and the trailer wheel is laying rubber in my garage. Only two words were going through my mind.

"HOLY CRAP... HOLY CRAP... HOLY CRAP..."

But that wasn't helping...

I reached down and yanked the throttle cable connector. It disconnected and changed absolutely nothing.

"HOLY CRAP... HOLY CRAP... HOLY CRAP..."

Now I manged to get a hold of the trailer frame and lift the drive wheel off of the ground. I could feel the wind off of the studded wheel inches away from my arm and the high pitched "ZZZZZZZZZZZZZZZZZZ"screaming off of the chain drive. It's really hard to think when your brain keeps repeating...

"HOLY CRAP... HOLY CRAP... HOLY CRAP..."

I grabbed the "disconnect" jumper and managed to yank it out. Nothing!

"ZZZZZZZZZZZZZZZZZZZZZ"

I reached over and grabbed the automotive fuse in series with the four batteries. It resisted but by that time survival instincts were taking over... the trailer or ME! I yanked the fuse and the thing settled back to earth.

Now I'm managing three words in my brain.

"What

tha

hell"

!!!

I checked all the wiring. It looked right. I left the throttle and disconnect jumper out, put the trailer on blocks and briefly engaged the fuse in it's socket. Molten metal and sparks shot out and the motor and tire jumped to "scream" speed in an impressive billionth of a second. I pulled the fuse back out (or what was left of it). The arcs had taken a chunk out of the fuse ends. Wow.

SO... something blew in the controller. It's an LB37. I took it apart looking for possible dammage from salt water. Nothing looked wrong. I inspected the solder joints and traces. Nothing to indicated overheating. It looked fine. So I'm figuring that one or more of the FETS blew.

So... do I replace the bad part or go with another controller?

It has three FETS and three power schottky rectifiers. Can anyone advise me on this. I'm handy with my solder station. No fear replacing things. Is it likely I blew a FET or one of the rectifiers? Can you advise me on better replacements from Digikey or the like? I'll do it.

Anyone?

Thank you!

Ross

 

[Lessss]

It's a brushed motor and IF you engage it only after the you have the bike going so you could do without the controller but only if you are willing to go from no assistance to FULL assistance. Otherwise brushed controllers are cheap. Upping your Fets to better ones is a project worth doing. Since Brushed controllers are cheap I say do both. That way you have a spare.

 

[rossfree]

I'd prefer to keep the controller and not go with just on/off switching. Can somebody recommend replacement FETS?

Thank you,

Ross

 

[fechter]

IRFB4110 are the best. If you're cheap, you could try IRFB4310's (or IRFB3808's if you never go over 60v). Be sure to check the freewheel diodes to make sure they didn't short.

While you're at it, you should consider upgrading the main capacitors too. If they fail or get weak, that will blow the FETs too.

With brushed motors of any kind, it is very important to have a kill switch that will completely disconnect the batteries from the controller. I was seriously injured by a runaway controller and I even *had* an easy to reach kill switch. It just happens too fast to react.

 

[rossfree]

Fechter,

Thanks for your reply. I'll go with the 4110's. Can you also recommend diode upgrades or do you think I need them. I've checked the ones I have out of circuit. They're still good. Don't remember how to check the FETS... will look that up online.

Also... you recommended a Capacitor upgrade. Higher voltage? Higher capacitance? Can you suggest?

Many thanks!

Ross

 

[fechter]

For diodes, you might try:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=V30100S-E3/45GI-ND
or
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=V30120S-E3/45GI-ND

The capacitor voltage rating needs to be higher than the battery voltage and as big as you can easily stuff in there. A "switching grade" or "low ESR" type is best.

You can get some other ideas here:
http://www.theworkshop.ca/energy/dirt_e/2/2.htm

 

[rossfree]

Thanks again Fechter,

All parts ordered... ya gotta love Digikey! Under $35... the same as the controller new... but I expect it will last a LOT longer.

I looked at the link on upgrading the controller. Nice information. If I had time, I think I'd lay out the entire controller with updated components... and maybe include the circuitry necessary for plug braking. Doesn't look all that complicated for brushed motors. A bit more complicated for brushless. I've made boards before. Lots of fun.

I still want to try a coil of stainless steel wire for braking (instead of a long length of coiled copper wire as others have done). I think it could be really small (about the size of a 'C' battery or so). Alas... for now... I don't have the time.

I've got to find a good water tight box for the electricals on the trailer. It's holding me up. Since I have the controller apart, I think I'll desolder all of the wires I'm not using on my setup. I also want to get the honkin relay I purchased into the main lines. No more rasslin with an out-of-control trailer.

I'll let you know as things come together.

Thanks again,

Ross

 

[ngocthach1130]

I found that those YiYun controller are very prone to blow fets. Esp when you mod them then pump high voltage in. What then to happen is they don't the "starting from zero" I think your trailer is so heavy the motor is pulling massive current at start and blowing the fets. I have the same thing happen on the scooter. When it went crazy i grabbed the brake and spike the current again. Then it blow the fuse to stop. Make the connection between battery 1 and 2 on the left side of the trailter anderson, i'm talking about the copper wire you use to connect them. Put anderson on both side and tie a string to that. If your trailer went nuts pull on the string to disconnect the battery.

BTW after modding my controller the scooter jump too much. So what i had to do was flintstone the scooter the first few yards to get it up to speed and engage the throttle.

 

[rossfree]

Thanks for the reply ngocthach,

What mods did you put in? I've ordered the 4110's to handle the current better and went ahead and ordered beefier diodes and four 470uf caps to replace the 300uf caps on the board.

I don't plan to over drive the board with higher voltage. It's a 48vdc controller, and I'm using (4) 12v glass matt bats. I'm sure the motor is drawing a lot of current at start up... not because of the trailer weight... but because of MY weight! Ha! I'll put in a current meter someday and find out just how much.

I have a high amperage relay that I plan to put in that should act as a good cut-off. It's beefy. And I'd like to put in a resistive circuit that pre-charges the caps in the controller before closing the relay. I hate those sparks!

Can someone tell me what EXACTLY limits the current on these controllers? The shunts provide feedback to the comparator? I'd like that explained a little better.

Thank you,

Ross

 

[fechter]

When the current gets high enough, the voltage across the shunt reaches the trip point for a comparator. The output of the comparator basically pulls the throttle signal down to keep the current at or below the limit.