Doc_Wui

After enjoying the ride on my wife's new store bought e-bike, I thought I'd try to do a cheap conversion on my Diamondback mountain bike . I have a 500w geared rear wheel coming in this week from an ebay vendor. Seller says it has an external 36/48V controller, plus pedal sensors, brake lever cut off, throttle button, and a LCD panel.

My plan was to use my Ryobi 40V weed whacker battery to test the connectivity on the components when I install the kit. It should spin the wheel, no? I could also use jumpers to connect the dolphin battery pack off my wife's bike, but I want to avoid that.

In the meantime, I was considering a cheap battery from China. Risk an alibaba experience maybe, or buy one off ebay of unknown quality. Then I decided to get a quality 48V10AH dolphiin pack from EM3EV. Costs $500, but they appear to be highly regarded for quality. It also might fit the dolphin bracket on my wife's bike. Then if my ebay wheel is no good, at least I have a spare. Long term, I really want to try a mid mount Bafang on my old Trek , and this would be a good battery.

Then I saw that lunacycle.com has a new dolphin pack with 3000ma Samsung cells for the same money shipped as EM3EV. So I ordered one. I hope I didn't screw up here.

So much for a cheap conversion, but everyone says the cheap batteries will just break my heart and wallet. Will post pics as the project moves along.

InTheRain

Have fun with that project. I'm not a great wrench. I don't have the patience for that type of project. Whenever I try something like that... it ends up costing me more than if I had just had a professional do it for me with the top of the line components. Thus, I have a $2200 BionX conversion kit on my touring bike. I love it! I'm a "jump on and ride it" kind of person.

Denver commuter

EM3EV is good but I believe Luna is better. Luna is in the US so everything is easier. I especially like the triangle bags they have for batteries!

Doc_Wui

The wheel is in. It's from Dongdian ebikes. It seems pretty sturdy. I didn't expect to see such a thick rim. It has 1/2" high hollow structure to hold the spoke ends. Spokes are .10" diameter and all seem tight.

I ordered new tubes, tubes, and rim tape so I won't start til those arrive.

Been thinking about the controller. I understand most can be over volted. I plan to put a 48 volt battery on this one since the ebay seller says the kit runs 15mph max at 36v and up to 24mph at 48v. . Will I blow it out? Also wondering about low voltage cutout. That would have to be in the battery circuit?

chas58

Bummer!

so, it is a 36v controller, which means its high and low voltage cutoffs are for a 36v battery (say from 42v to 28v for example). YOu need a 48v controller (I'm assuming this one is not programmable).

Keep an eye on those spokes. Chinese mass produced wheels have a habit of falling apart after a few miles. You'll need a spoke wrench than can handle those oversized spokes.

your speed numbers are a little off. If it is a 200 rpm motor (likely) it will run around 15 mph at 36v. at 48v it will run 15 *48/36= 20mph. Still a nice boost.

You should really read about my build here or on endless sphere, as documented a lot of what you will be going through. Its fun if you like to build things, and at $500 (+ bike), my bike is pretty cost effective.

chas58

I think it depends on what you need as to who is better. EM3ev has a good choice of base batteries, and will custom build a pack for just like you want. Luna is great, but only stocks certain packs. If they have what you want great, if not, go to EM3EV. Your choice.

Denver commuter

That is true I don't believe that Luna is building custom packs as of yet. They are offering loose cells so if you have the ability you could build any configuration that would work for your frame. They are both solid and respectable vendors with great customer service. You really can't go wrong with either of them.

Doc_Wui

I ordered a Headway 36V10AH battery from ElifeBike.com, but I paid a little more to get it via ebay/Paypal. Should be here by 9-16, if Fedex tracking is correct. Meanwhile, got to convert the bike. Here's my old Diamondback.


Mounted the tire. I used a long valve Presta Tube, because a Presta valve was needed on the front wheel that I bought, but the hole in the rim would have taken a Shrader valve. Tire and wheel at a little under 12 pounds.


Wheel fits into the frame OK. I am happy that the chain fits too.


My bike doesn't have an optimum shifter and control layout. The new brake levers have to go on before the gear shifters. The throttle they gave me was a motorcycle twist type, and this might be awkward.

I mounted all the parts, except for the PAS and the controller. I want a clean look, so I will get a luggage rack and mount the controller under the rack.

2old

Aluminum frame and no torque arm?

Doc_Wui

I read torque arms were not absolutely required on the rear, as this is a small hub motor. If not then I will fix.

You know, I need to grind out the slots so the axle fits lower anyway. The washers with the tabs don't sit very deep in the slots.

chas58

Looks like you are doing the right things!

What kind of motor is that? Looks like a Q100. If so, it is designed for 15 amps. 17 amps max if you want to push it (and keep an eye on heat issues). The 22 amps is going to burn it out - that controller may be a problem.

You sure the motor and the controller match?

FYI, at 36v 15-20 amps, a torque arm isn't really needed on the rear in genera;l (I don't use one). You will need one if you can't get that motor to seat deeper and more solidly in the rear drop outs thought. Either way, torque arms are an easy bit of insurance.

Doc_Wui

I believe the controller is matched to the wheel. The kit appears to be from dongdianebike.com and their website shows people in white lab coats surrounded by motor windings.

I was going to cut up a piece of 1/4" steel and make my own torque arm, as I wonder how a two piece universal kit held on by hose clamps would be any better. The longer I looked at the rear, the more concerns I get. Not a lot of aluminum there, and what there was cast to save weight.


I have a very old Trek 800 mountain bike, which has a steel frame. I believe I may stop with this one and move the components over to the Trek. The handlebar controls are more conducive to the new brakes and throttle anyway.That one has a lever shifter inside the brakes levers. This one is opposite with the brakes are inside a twist shifter. After I add the twist throttle, the brake lever is pretty far away, porbably too far, and it will be hard not to twist the throttle and shifter at the same time.

.

chas58

Yeah, the steel mountain bike is pretty well suited to what you are doing. Bigger drop outs would definitely help.

I can't tell for sure, but that really looks like the ubiquitous Cute Q100 motor. I don't know what else it could be with that size, shape, and looks. If so, its not going to take much more than 15 amps. 22 will kill it.

Doc_Wui

I restored my Diamondback bike back to stock and started converting a Trek 800. It's a steel frame mountain bike. I checked with a magnet. I believe we acquired it in 1994.


I found the rear dropout was too small to accept the wheel. I grabbed a scissors jack and expanded the frame a little. Don't be trying this on aluminum.


The wheel still took some finesse to mount. I hope I don't get a flat tire. It would be an awkward roadside fix. Bearing in mind that the Trek has not been ridden since 1996 when my son went off to college, I spent the rest of the day getting the gears, brakes, and shifter levers adjusted. The shifters were gummed up and stuck, I had to take them apart, degrease and relube. Then I rode it around unpowered to make sure everything works. I needs new rubber on the V-brakes. I sure do miss the front suspension that I have on my own bikes. So much of this bile is old and outdated components, but the tires and wheels are new and true, and it rides nice. I'll be able to get home if I run down the battery.

Here's the battery that just came in.


I plan for the controller and battery to go on the down tube, mounted with plumber's u-straps from Home Depot. I could almost hook up power and see if it spins the wheel, but first I want to mount the PAS sensor. Darn, I have to pull the crank arms off to mount the PAS, don't I. That means I gotta order a crank puller. Bu the way, here's another picture of the motor. It has no markings. I figure the label on the controller exaggerates and it won't deliver 22A. In any case, I do have a clamp-on ammeter and I can monitor the current.



Should mention also that the spokes I thought were so taut now seem a bit loose with a tire mounted on the rim. Will have to buy a spoke tool too.

chas58

Nice to see it coming together, keep the updates coming!

Doc_Wui

Today I mounted the battery and controller and connected everything except power.

I've seen where some owners clamp the dolplhin battery to the bottom tube using existing water bottle mounts. I didn't feel that was very robust for a 5 lb battery, so I added a front and rear clamp. The rear is just a u-clamp and I had to put two holes in the rear mount for it. The front is a hose clamp that I pinched so it could be attached to the battery holder with a screw.



So the battery is held by two metal circles around the tube, plus the two screws for the water bottle. It's good. If I had two more hose clamps, I would have added them. It rides OK with the battery mounted, except I still need to replaces those hard brake shoes. Won't stop.

U-clamps on the controller were pretty simple. I mounted it with the wires facing down in case it rains. I was too lazy to go inside and get the instructions, but the sockets are all distinct, although throttle and PAS are the same, so it was easy to connect.


What keeps me from powering it up? Battery wires need to be longer, so I need to make a splice. I can't find my wire strippers, and I don't have any stranded red/white wire that is heavy enough. It also turned out to be a really hot day, so I'll go find the instructions, my soldering tools, and some wire and connect it up this evening.

After I make sure it works, then I will shorten all the cables and figure out how to hide the tangle under the controller. Maybe a cover. Will also paint all the mounting hardware black.

Doc_Wui

Connected the battery. Nothing happened. Checked all the connections. Then saw the ON/OFF on the handlebar controls.

It lives.

chas58

its coming together!

I had a hard time as the wires on my throttle didn't match the controller, and it took me a while to narrow it down do that.

You have a LiFePo4 battery that weighs only 5lbs? Mine weighs 10lbs. I'm missing something in that equation.

Ever ride on a wet surface? consider putting that controller behind a fender or something where it will not be soaked with the water coming off the rear tire. do you have something to keep the battery from sliding down the downtube?

Doc_Wui

I'm not worried about the battery mount moving. Two bottle holder bolts hold it to the frame, with two extra clamps, and they are gripping metal-against-metal, front and rear. The plastic end of the dolphin battery mount uses an o-ring to keep the interior dry. That houses the battery connector plug.

The controller box appears weather resistant with rubber o-rings in the two end plates. However, there are some extra holes in the grommet where the wires pass thru. I have that facing downward. When I cover the wire harness, it will stay dry.

The crank puller should arrive by the weekend in the mail, plus a speedometer. That's when I will cut all the wires to the proper length. It's a rat's nest right now.

I took a 7 mile ride to test it on a nearby hill. The motor has more power than I thought. We have a 500W 48V LG cruiser which pulls very well. This is not as strong, but still feels like it has enough speed. The Trek 800 is a nice handling bike too, but the brakes still stink. Maybe a new fork with a disk brake would be nice. A plastic fender ought to be easy, and hopefully inexpensive.

With throttle only, the bike moves pretty slow on the first power level, but it's turning the motor. More noticeable at mid power, and easily discerned at the third and last power level. After my 20 minute ride, the battery felt cool, and the hub did too.

I believe it's LiMnO4, but it probably does weigh 9 pounds.

chas58

Disk brakes are over rated. You just need new cables and new pads ($20). With either disk or drum brakes you need good parts - either will work fine with quality pieces.

A new fork, new wheel, and hardware for disk isn't gonna be cheap.

Doc_Wui

Final tweaks done today. I shortened all the wiring and hid them in an automotive wire loom. I used a plastic tube from a broken toilet fill valve to hide the connections under the controller.


I also got my crank puller, so I installed the PAS sensor. I did not glue it on the bike, as suggested in the instructions, as it would probably fall off. I put the sensor on a small bracket bolted to the frame.


I retested operation after I cut and resoldered each cable to make sure I didn't goof up, but I didn't test the PAS until its wire was shortened and the sensor mounted. I was very pleased that it all works.

The three level PAS seems overly strong in mode 1. One pedal push on starting off will activate the motor for about 10 feet. Watch out! I guess my wife's bike is like that too.

It also seems faster with PAS than with throttle/pedal. I'll get a speedometer this weekend.

Only thing left is to paint those copper brackets black, and put some invisible paint on the battery. .. maybe a silver image of a bottle. Oh yeah. Gotta put new shoes on the brakes. Grinding off the top layer of rubber doesn't work.

350htrr

Beg to differ... Good hydraulic disk brakes are waaaayy better than any other type of brakes I have had, In every way a hands down winner, power, consistency, modulation, reliability, and never needs adjusting, and more... I wouldn't even consider any other type of brakes any more for my next bike...

EDIT; Nice build Doc_Wui, But PAS to me means using a sensor that measures pressure the rider puts on the pedals and then it adds 25%, 50%, 75%, 100% 200% of that to the riders effort. Any other type is just another throttle...

chas58

Well, if we are talking hydraulic, yeah - I agree.

Doc_Wui

The e-brake handles that came with the kit must be designed for disk brakes or maybe cantilever brakes. There's very little lever travel before the pads close on my v-brakes. Guess I have to order non linear handles?.

350htrr

Only quality hydraulic discs are worth thinking about changing to IMO, The dumbed down cable versions are garbage IMO... Even some hydraulic ones, the cheap ones are not worth it.