Have a baseline, where next?

[20Lush]

Hello, I'm a college student building up an ebike to commute to school from(when we return to campus that is)

What I have so far is the absolute bare minimum you can get for mere instant ramen dollars:
- 1000W 48V unknown max A ebay hub motor china special
- 48v 14ah battery with peak discharge either 50A or 30A the dude who wrote the ebay page has both up there
- A real bastard of a steel frame, bottom drop out, mech disk brake, folding mountain-bike with full suspension that is surprisingly good for $300 (having ridden full suspension 1k+ mountain bikes, I couldn't believe it either when I rode on it)

It weighs in at about Too Heavy without the rider and Way Too Heavy with the rider(160lbs).

All this totaled up to about ~$550USD.

And I love it! I could seriously take this thing to school and ride it until the cheap lugs fall off and the back wheel drops out. I can really hammer it around the block taking corners like a champ and going aggressive on the uphills and the motor will end the day sort of lukewarm.

But unfortunately I also feel the potential. Just today I clocked 34mph on a downhill WOT and pedaling and I felt that the frame still had it in her to keep pushing. Obviously I'm not going to be at the speed while turning, due to these nice and thin 26" bicycle wheels, but in a straight line with minor traffic corrections, this frame can definitely handle more than its BARELY ~20mph cruising speed and frankly anemic loaded performance(uphills and launches and the sort)

So where do I go? 60V? 72V? 2000W? I can't say I really, fully, understand the wattage measurement in the context of ebikes, or even the relationship between the battery, controller, and motor. I have heavy experience in electromechanical systems but I'll be honest our equipment only went as far as our giant lead acid 12v batteries and 1.4hp brushed motors took us. Brushless, gearless, high voltage hub motors are a whole other can of worms that I'm working to learn about. Should've just gotten a mid-drive. Oops.

I would like to be able to squeeze every last bit of performance out of the components I have however I realize that scaling up from here means a new battery and a new battery means I have to toss the dinky little 48v controller and that means soldering and pinning and crimping and running more wires. I'm ready for it, I've got nothing but time and stimulus checks.

TLDR: Something fast, only needs to run for a relatively short distance.
-> Commute Distance: No more than 4 miles total. 3+ definite stopping points(traffic reasons)
-> Desired Speed(Cruise): >25mph
-> Desired Speed(Max): >35mph (If I join the 40 club I'll go get my motorcycle license. Not that I would need one officer.)
-> Local Terrain: Flat for miles until its suddenly 10-12% gradients(willing to actually pedal). No extended gradients over 8% on commute path. Some short little hops but thats it

 

[amberwolf]

- 1000W 48V unknown max A ebay hub motor china special

The motor itself can probably handle twice that power for bursts, how long depends on how much and under what conditions.

You can go to http://ebikes.ca/simulator to play with different systems and conditions to see the relationships between things, and how motor power "actually" works. Just make sure you read the entire page first, so you know what everything is and how it works.

- 48v 14ah battery with peak discharge either 50A or 30A the dude who wrote the ebay page has both up there

My guess is "peak" is probably 50A, for a few seconds, and 30A is max continuous, making it a "2C" battery (current delivery ability of twice it's capacity). But that depends on what it's actual capacity *really* is and what kind of cells are in it. 2C isn't uncommon in the cheap stuff, but there *are* worse ones, and a battery that is only part of a $250 motor/controller/battery setup is likely to be pretty dang cheap (possibly made of recycled garbage cells, which isn't uncommon).

If you link to this and your other ebay/internet-acquired bits, we might be able to tell you a bit more about them.


Before we get into making it faster, a caution: If the area you ride in defines electric bikes as less than the speed you want to go, you could run into issues with others when exceeding the speed. Some places that can get expensive.

That said:

The 20mph speed you get could be simply insufficient voltage (or power), or it could be a speed limiter. I suspect the latter because many of these 48v 1000w kits will easily reach 25mph on the flats.

If you flip the bike upside down and run the motor, and it spins at the same 20MPH it does when on the road, then it's speed limited by the controller. If it has a display it may have a settings menu where that can be changed. Otherwise you may have to replace the controller, or do modifications to it (not always possible). If it spins faster, like 21-22MPH+, then it's not speed limited.

If you ride up a hill and it slows down from 20MPH, it's power limited, either from battery voltage sag, or from insufficient controller current. If it stays at 20MPH, there's probably enough power and the battery isnt' sagging too badly.

So if neither of the above is a problem, then you could use a higher voltage battery and controller for a faster speed. Or you could use a different motor that is meant for 20MPH at a lower voltage like 36v, and it will spin faster at the higher voltage you already have, though it won't get you your max speed (you'd need one that did 20MPH at 24v for that, most likely, along with a higher current limit controller, and potentially a better battery).

TLDR: Something fast, only needs to run for a relatively short distance.
-> Commute Distance: No more than 4 miles total. 3+ definite stopping points(traffic reasons)
-> Desired Speed(Cruise): >25mph
-> Desired Speed(Max): >35mph (If I join the 40 club I'll go get my motorcycle license. Not that I would need one officer.)
-> Local Terrain: Flat for miles until its suddenly 10-12% gradients(willing to actually pedal). No gradients over 8% on commute path.

If you simulate that on the site linked above with a motor like the Crystalyte H2425 that only goes 20mph with a 48v battery and a 20A controller, it can only get you up to just under 11MPH, so you'll be doing most of the work yourself with your present system on the 12% grade.
https://www.ebikes.ca/tools/simulator.html?motor=M2425&batt=B4814_EZ&cont=C20&hp=0&mass=75&axis=mph&grade=12
If your present system already gets you faster than that on the 12% grade, then some part of your system is better than what I listed. That could be any of the three, or all of them. If your present system doesn't even go that fast up the 12% grade, then some part or all of the system isnt' even as good as what I listed.

Knowing which of those is the case would be helpful in figuring out what you'd need to change out.


Using a 40A controller with the same motor/battery only gets a couple MPH faster up that hill, and probably would overheat the motor.

But using the same 40A controller with the 3548, which is even worse on that hill with only a 20A controller, will go 22MPH up that hill, and take about 3/4 of an hour doing that to overheat.
https://www.ebikes.ca/tools/simulator.html?motor=M3548&batt=B4814_EZ&cont=C40&hp=0&mass=75&axis=mph&grade=12
and will go 34mph on flat ground without overheating.

So, it depends on what motor you actually have, and what the controller current limit is (and any speed restriction), and how well your pack actually performs under load (how much voltage sag), as to what bits you have to change out to get what you want.

 

[dogman dan]

Well,,, Don't know how starving, starving students are these days. Back in my day I actually had to go hunt rabbits if I wanted to eat meat. That was not common even then, but that's where I was on student job pay.

So this ancient old fart says save your money and run what you got. As you get more, do get that small, dirt cheap used, motorcycle or scooter. Pretty much what I did. As I went into the low pay student job I could not keep my truck running anymore. One year I rode a bike, the next a moped, and was on a honda 125 by 1980 when I graduated. My only mistake was the moped. It was supposed to last till I graduated, about 5 semesters, but it died in 2.

Buy a used honda when you can afford it is my advice. Save money now by riding the e bike as long as the battery lasts. The other stuff on the e bike is cheaply fixable, like repairing halls in the motor, or a completely new controller. Once that battery dies, have your cash for a beat up old honda.

If you can scratch up 2000 now, shop for the motorcycle now. Or shop longer and find something more like only a thou.

 

[20Lush]

If you link to this and your other ebay/internet-acquired bits, we might be able to tell you a bit more about them.

Gotcha, here's everything except the frame for which I assume the seller made a quick buck then dashed:

-> Hubmotor kit
https://www.ebay.com/itm/Voilamart-Electric-Bicycle-E-Bike-26-Front-Rear-Wheel-Motor-Conversion-Kit/322247604604?ssPageName=STRK%3AMEBIDX%3AIT&var=511147989364&_trksid=p2057872.m2749.l2649

-> Battery
https://www.ebay.com/itm/48V-14Ah-Lithium-li-ion-Battery-Pack-1000W-ebike-Bicycle-E-Bike-Electric-Charger/293213345157?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

The more I look at the listings and ride the bike the more I'm inclined to agree that the motor can take more than what the battery and controller give it, however I don't have the diagnostic wattmeter or temperature readings to back that up. Nor have I tore into the controller to see whats going on with the caps, but hey I just built the thing a day or two ago so it'll happen soon.

I'm having trouble with the simulator as I really dont know what the hell the hubmotor is, or is based on, or is cloned from. So I can't really run an accurate one until that riddle is solved

Today I relearned a valuable lesson from doing maintenance on my Integra, Dont touch the brake discs when you just hammered them.

As for real world mobility, back in highschool I saved up and got myself a nice Acura Integra to get me from school to work, work to home, and to run errands with. I'm meticulous about oil changes, brake pads, tires, spark plugs, starter motors that for some reason are mounted behind the screaming hot exhaust manifold, so I don't expect the beater honda to die on me for a while. The trouble is that I've become attached to the jeezlus thing and so the beater has become the halo car and the new beater is the bike I just burned my finger on this morning. That and, while I do get reserved parking in the university's apartment complex, I'm going to have to pony up $400 for a parking pass for campus, so a nice little zippy bike that can be set and forget on a bike rail would be better than giving my yearly top ramen budget to the man.

So I should be fine, the car and the bike are coming with me. Bike for school, car for everything else. I realize that my need for speed is irrational, but my mistake of spending a half years salary on a good condition honda turned into a calculated win as far as mobility needs. I don't necessarily need to save up for a good motorcycle, just a rainy day fund for anything that happens to the car and the rest of my transportation allocation can go to the bike. I've had a bad experience with a moped too though, never seen a twostroke conrod punch through the crank case, through the rubber fender lining, and then through the aluminum body before. However, that may or may not have been due to the governor system mysteriously ending up outside of the engine and on my workbench. Later sold it on ebay for "as-is"

 

[Tommm]

-> Battery
https://www.ebay.com/itm/48V-14Ah-Lithium-li-ion-Battery-Pack-1000W-ebike-Bicycle-E-Bike-Electric-Charger/293213345157?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Battery looks like the China special (bottom of barrel). You won't get an ounce more power without sacrificing battery life/reliability/usability unless you buy a battery that cost almost as much as your full setup cost.

I would suggest you enjoy what you got and plan on some 4-5kw beast with a good used frame from the ground up.
That way you don't end up with an endless suboptimal project build and a bunch of parts that are impossible to resell.

 

[amberwolf]

-> Hubmotor kit
https://www.ebay.com/itm/Voilamart-Electric-Bicycle-E-Bike-26-Front-Rear-Wheel-Motor-Conversion-Kit/322247604604?ssPageName=STRK%3AMEBIDX%3AIT&var=511147989364&_trksid=p2057872.m2749.l2649

That's a pretty commonly used kit, even some threads on it like this one
https://endless-sphere.com/forums/viewtopic.php?f=2&t=97810&hilit=Voilamart+kit
So most likely you could easily use it for twice the power in bursts, and the 1000w constant. 1000w on a typical 26" dd hubmotor will easily get you 25mph on the flats, up to 30 depending on conditions. (IIRC I got 31.something MPH out of a 500w motor run at ~1000w on CrazyBike2 at the DeathRaces several years ago, on the straights.)

The specs on their page say you should be getting a lot faster max speed out of it, at least 28MPH:

Specifications:
* Wheel Size: 26" * Spokes: Steel, 12G×2.6mm
* Max load capacity: 150kg (36V500WR、36V500WF)
* Max load capacity: 200kg (48V1000WR、48V1000WF、48V1000WRC)
* Max load capacity: 250kg (48V1500WR)
Model Wheel Power Max speed Torque
36V500WR Rear 500W / 36V 22 mph 35 N.M
36V500WF Front
48V1000WR Rear 1000W / 48V 28 mph 45 N.M
48V1000WF Front
48V1000WRC Rear 1000W / 48V 28 mph 45 N.M
48V1500WR Rear 1500W / 48V 34 mph 48 N.M

So I think there must be a speed limit set in the display settings, or a jumper wire. The website refers to:

Upgraded Intelligent Motor Controller:（For 48V1000WR、48V1000WF、48V100WRC、48V1500WR）

* Allow you to swap two power modes between the full 1000W/1500W power or 750W power by a single blue switch wire is embedded in controller.

So I would recommend looking for a single blue (or other) wire that comes out of the controller and plugs into another blue wire going right back into the controller. Unplug it, and then retry it on a ride.

If it still doesn't work, and there are no speed limiter settings in the display menus, then it could be battery voltage sag.

-> Battery
https://www.ebay.com/itm/48V-14Ah-Lithium-li-ion-Battery-Pack-1000W-ebike-Bicycle-E-Bike-Electric-Charger/293213345157?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

At 14s5p, to get 14Ah it's have to have almost 3Ah cells. But it doesn't specify which actual cell model and brand they are.

They even say things like:

* No voltage sag - faster cranking for motors and higher voltage for continuous consistent power.
* Does not heat up during use

and other claims that I doubt are true. Basically it's a bottom-end battery that probably can't realistically sustain even the 20A it claims, much less enough more to do extra that you may want to ask of it. It'll work to run the kit...but the harder it's pushed most likely the worse it will perform and the shorter it's life will be. PUshed near the 20A regularly, especially if a lot of capacity is used each time, it will likely become unbalanced, and require leaving on teh charger overnight (at least) each time it is used. If not immediately, as it ages.

The more I look at the listings and ride the bike the more I'm inclined to agree that the motor can take more than what the battery and controller give it, however I don't have the diagnostic wattmeter or temperature readings to back that up. Nor have I tore into the controller to see whats going on with the caps, but hey I just built the thing a day or two ago so it'll happen soon.

Wattmeters are cheap, and useful for diagnostics, especially when you have battery issues, which will happen eventually (probably sooner rather than later with this particular battery).

I'm having trouble with the simulator as I really dont know what the hell the hubmotor is, or is based on, or is cloned from. So I can't really run an accurate one until that riddle is solved

It doesn't matter. The point of the simulation suggestion is just so you can play with systems to learn the relationships between the different things, so you can use it to figure out which part(s) you need to change out to do what you want to do with the bike. It's very unlikely taht the Voilamart motor is in the simulator--but any of the ones that are DD (not geared) and about the same physical size are approximately equivalent. H3540, or 3548 are probably similar, if not the 9c 2706 (or 7, etc) would be, etc. Ther'es others too I just dont' recall the numbers for, in the MXUS stuff and others.

Today I relearned a valuable lesson from doing maintenance on my Integra, Dont touch the brake discs when you just hammered them.

Well, only if you like your fingerprints.

 

[20Lush]

Did some testing today and redid the harness for the 5th time(I got looms over looms over looms now), this time leaving the blue jumper disconnected. I'm definitely getting more power out of it, but I'm going to get the wattmeter to get some data. Hopefully it comes in when the final bags and things come in. I also learned that the "LED light" header on that controller has the full 52V just ready to go, one probe slip with the multimeter and you got yourself the basics of welding. I do want to peek at the 18650's in the batter to see whats going on but I also dont want to break the blue plastic seal. Maybe once I have actual voltage/amperage/wattage data I can go from there, decide whether its worth it to find out if I just got recycled laptop batteries.

To give the battery some credit I really didn't feel much temperature change but I have yet to really put it through the ringer, due to the battery mount not being finished yet.

The now discovered 1000W mode has fulfilled my speed requests for the most part, though I dont have hard numbers quite yet. I wish I had a little bit more power on the hills but damn if this thing isn't super fun to ride. If there is voltage sag, and I do indeed have retired vape batteries in a box, do I just shell out for an actually good battery, or can I go up in voltage? I guess what I mean to ask is, once this battery gives up, will I get meaningful speed gains from going to say 60V with a nice battery, or even 72V? Im going to test this in the simulator but maybe there is some real-world catch that I wouldn't see coming.

EDIT:: wow okay I didn't think a jump to 60v would make that much of a difference on paper. Maybe 72V isn't a great idea. Yet.

 

[john61ct]

Going to higher voltage is for increasing top speed

which drastically increases

the need for a very powerful battery (in reality, not seller specs, therefore much more costly)

and also drastically reduces energy efficiency, Wh per mile used

thus reducing range