E-Bike electronic basics

[oVxrtex]

I also choose that when I replace them, I'll be using one or more of the prebuilt ex-EV modules like those I linked (or others in my recent posts in my SB Cruiser thread here:

Those modules seem really good, it's probably going to be huge, but if I could get 20 of them (2s10p maybe) then it would be 93.6v, 64ah, which is 5990 Wh.

Oh, the discharge is also going to be 1000a peak continuous, which is genuinely insane, like 93.6v 1000a is around 93.6kw on a bike, maybe I shouldn't do this..

Anyways, that's just me thinking, because to actually do this I would need 3510 in^3 of area on my bike, which I doubt is possible in any manner, unless I figure out a way to mount it around the frame (one module on the top tube, couple in the middle, couple at the bottom of the bike maybe?)

Either way, this battery is probably going to be pretty unrealistic with these packs, even though they're actually a really good deal and I don't know why anyone else is buying them..

They'd be really good for making an EV battery maybe (Model S plaid = ~100kWh, around 325 of these packs ($6.5k) would get you to that rating, and simply getting 9s36p would give 400v 3611a, which is 1,444,400W continuous peak, and I don't know the specs of the model S but I do know that's insane for just $6.5k.. (disregarding the motors, controller, and BMS for this insane battery of course)

I think I might entertain this idea once I have the money, time, and space to do so, what do you think?

 

[amberwolf]

Those modules seem really good, it's probably going to be huge, but if I could get 20 of them (2s10p maybe) then it would be 93.6v, 64ah, which is 5990 Wh.

If you mean these that I linked in my reply in this thread

INR18650M29 LG Chem 48V 62.7Ah 2.99kWh BMZ Module | Greentec Auto

2020 48V LG Chem battery module for sale. Free ground shipping and 6 month extendable warranty. Trust Greentec Auto for your next DIY project today.

www.greentecauto.com

then 2s 10p (of the modules) is 96v 627Ah = 60kwh. (rounded numbers) Would be capable of up to a couple thousand amps; wouldn't wanna short that out by accident.

And 20 of them would weigh 35lbs x 20 = 700lbs. You're not going to carry that on a bike or even a motorcycle. Maybe in a motorcycle's trailer.

(I could carry it on my Mk IV / V trailer, which has hauled a piano, but not at normal riding speeds, maybe walking speed, so bumps and holes don't break the trailer wheels, so it would not be practical. Would probably overheat the trike's motors/etc from the repeated accelerations of all that mass in traffic, too)


If you mean the first module I posted about in the linked SB Cruiser thread post

48v 6.4ah 307.84wh Battery with Panasonic Cells - $64/kWh

This is the best deal on 48v modules that test like new. Just $20. These are absolute BEAST power modules with Panasonic cells inside. 48.1v 6.4ah 307.84wh. Built for power but at this price you will not find a better deal on batteries that have either never cycled or only cycled a few times...

batteryhookup.com

then 2s 10p would be 96v 64Ah = 6kwh. (rounded numbers) could supply up to a thousand amps.

At 8lbs each x 20 it'd be 160lbs (not counting enclosures you'd have to build), which you could put on a motorcycle, but not a bicycle. Trailer, sure, but not at the speeds you want to ride at. Even if they were lighter, at 13" x 6" x 2.25" per module, that's a fair bit of volume to find room for on a bicycle. Because they come in "smaller chunks" than the big packs like the first one in this reply, it might be possible if you're creative at building panniers for them on all "four corners" of the bike, like touring bikes can have, but it would probably change handling enough to make high speeds even less safe. I've built cargo bikes to hold stuff that way...they don't ride as well loaded up as empty, by quite a bit of difference, worse the faster they go.

But at $20 a piece, not including shipping, it's not too bad a price, at $400 for the batteries; I'd guess a third of that again for shipping costs based on the estimate I got for half that many.


If you mean some other module, you'll have to link it.

Oh, the discharge is also going to be 1000a peak continuous, which is genuinely insane, like 93.6v 1000a is around 93.6kw on a bike, maybe I shouldn't do this..

That is only the amount of current it *can* provide.

As previously noted, the actual amount of current is determined by the controller based on the load the motor puts on it based on your rider inputs and the riding conditions at that moment.

If you have a 10A controller, it's only ever going to draw a max of 10A even if you had a battery that could supply a million A.


I really think you should go visit the ebikes.ca simulator and play with it to learn how all these parts of your system interact before you go any further.

 

[oVxrtex]

If you mean the first module I posted about in the linked SB Cruiser thread post

Yeah, I meant these modules, the first ones you linked were $200 and BRICKS, so I was just looking at the other ones you posted to see how those would be in terms of pricing

Also if I go for half the kWh on the modules I was talking about, that'd be only $200 for a 93.2v~32Ah battery, and it shouldn't be nearly as big either (I'd still have to wrap around the frame somehow, but it actually sounds like a good idea now)..

Also it would be able to push 500 amps instead, but that's still an unrealistic amount of current on a bicycle that I'd never use (46.6kW).

That is only the amount of current it *can* provide.

As previously noted, the actual amount of current is determined by the controller based on the load the motor puts on it based on your rider inputs and the riding conditions at that moment.

If you have a 10A controller, it's only ever going to draw a max of 10A even if you had a battery that could supply a million A.

I meant that, if I can get a motor/controller for that power (like the stark varg-type ones) then it would be insane to strap that on a bicycle, not that I'd push power through the controller.


Anyways, I've been looking at EV batteries and found these, $20/kWh, what do you think? UR18650ZK V52A Sanyo 54V 38Ah 2kWh 18650 module | Greentec Auto

Also these, just 3 in series is really good capacity for $400 (and yes, disregarding space here) Renault Zoe NMC 24V 73Ah Battery Module

 

[docw009]

Anyways, I've been looking at EV batteries and found these, $20/kWh, what do you think? UR18650ZK V52A Sanyo 54V 38Ah 2kWh 18650 module | Greentec Auto

15S-17P and 6 years old for 50 bucks. 255 cells. Probably still capable of 100A peak? Probably great for a tourist rickshaw rig in downtown Chicago.

High speed, long range electric motorcycles? I haven't tried to figure the power requirements, but it doesn't seem possible you can do it with used 50 dollar batteries. Low speed trikes for space for these batteries. Sure.

 

[harrisonpatm]

High speed, long range electric motorcycles? I haven't tried to figure the power requirements, but it doesn't seem possible you can do it with used 50 dollar batteries.

I got close on my emoto build. But by close, I mean I went through the laborious process of testing and matching 900+ 18650s, and I still had to de prioritize top speed and acceleration in favor of range. Batteries are hard.

 

[Chalo]

Anyways, I've been looking at EV batteries and found these, $20/kWh, what do you think? UR18650ZK V52A Sanyo 54V 38Ah 2kWh 18650 module

I showed that one to AW, and he noticed that it was only rated 25A (because it's a telecom backup battery). Great value battery, but not constructed for power.

Also these, just 3 in series is really good capacity for $400 (and yes, disregarding space here) Renault Zoe NMC 24V 73Ah Battery Module

That's 108+ lbs, too. I think you're fooling yourself that you can stuff motorcycle power and energy into a bicycle and still have something worth riding. I'm at the practical limit (for me) with my biggest battery, one more or less like this in a fake Pelican case:

Jeep Cherokee PHEV 44v Battery 2.1kWh modules Samsung Cells 12s

PLEASE READ THE DESCRIPTION CAREFULLY. Shipping to Lower 48 USA states only via Ground Shipping. No shipping to PO Boxes. No international shipping including Hawaii, Guam, Puerto Rico. EV modules with high quality Samsung cells! These 44v 47Ah 2.1kWh li-ion modules are removed from wrecked...

jag35.com

And I'm 6'8" and formerly 400+ lbs, so I can handle a lot of bike with a lot of battery.

If you must go stupid fast, which on a regular bike is regularly over about 30 mph, then think in terms of using a downhill/freeride bike to manage the speed, and a high power density, not high energy density, battery. Don't try to carry 60 or 100 lbs of battery anywhere on the bike; it doesn't work. Or you could use one of those execrable ugly box bikes that's a battery case masquerading as a feeble little motorcycle with a runaway tumor. But if you start with a normal bicycle, you will end up with a result that you won't enjoy riding, and then you'll break it.

 

[oVxrtex]

15S-17P and 6 years old for 50 bucks

Oh damn, I didn't see they were 6 years old, that's probably why they're so cheap lol.

I'm at the practical limit (for me) with my biggest battery, one more or less like this in a fake Pelican case:

These seem like a really good deal actually, especially with 400A cont. discharge (w/ cooling), but you can always turn down the power a little bit.. I feel like strapping two of these in series would actually go pretty well, an 88.8v47Ah battery (4.2kWh, 35520 kW) would be pretty nice, as long as they aren’t too heavy

They’re like 60 lbs, maybe that’s fine but I don’t really know.. How heavy would most of those DIY triangle batteries (the 72v 40ah kind) be, from your previous experience?
Also the 14x6x4.5 in for one battery might work, I could probably put one on the downtube and one in the triangle, or maybe I could do two in the battery triangle if I can manage that space, or I could always just get a rack over the back tire and do it that way..

 

[Chalo]

Also the 14x6x4.5 in for one battery might work, I could probably put one on the downtube and one in the triangle, or maybe I could do two in the battery triangle if I can manage that space, or I could always just get a rack over the back tire and do it that way..

If you put them in the triangle, the bike won't be practical to pedal, if that's a factor for you.

If you put even one on a rear rack, you have to cushion it so it won't quickly break the rack. Hard things mounted to the rear rack are the equivalent of about three times as much weight hanging in cloth panniers, in terms of their ability to break stuff (rack, frame, wheel).

I use 20mm-ish closed cell foam inside the case under my heavy battery module, with more around the sides, and open cell foam on top (the foam that came with the case).

I'll reiterate what others have said: of you intend to carry a motorcycle size battery and travel at motorcycle speeds, start with a motorcycle. We have a lot of hard-won experience here, and we're not telling you this for no reason.

 

[oVxrtex]

If you put them in the triangle, the bike won't be practical to pedal, if that's a factor for you.

If you put even one on a rear rack, you have to cushion it so it won't quickly break the rack. Hard things mounted to the rear rack are the equivalent of about three times as much weight hanging in cloth panniers, in terms of their ability to break stuff (rack, frame, wheel).

You’re right, but is 4.5” really that wide? I feel like it’d still be practical to pedal, but I’ve never mounted one or seen one in person so I wouldn’t know, anyways you’re probably right about that.

I could probably find a way to mount it though, like maybe I could mount it on the side of the seat post (I think what I mean is the shortest side of the triangle frame, and putting it on the side of that tube). It shouldn’t handle too differently either, the only issue would be balancing it so it doesn’t shake around, maybe I could ratchet strap the battery or make some sort of mount for it.

Also, with the side of the seatpost idea I would put it somewhere where my legs aren’t going to touch it when pedaling.

 

[E-HP]

They’re like 60 lbs, maybe that’s fine but I don’t really know.. How heavy would most of those DIY triangle batteries (the 72v 40ah kind) be, from your previous experience?

Doing the math, assuming 5ah 21700 cells, 20S8P, 160 cells, then 25lbs for the cells, plus whatever weight is for the case, BMS, and hardware. If made with Samsung 50s cells, that would be 200A continuous when the cells are new.

 

[Chalo]

You’re right, but is 4.5” really that wide? I feel like it’d still be practical to pedal

I can ride normally with an 18650 based pack (about 3" wide) on the downtube. By the time it's up on the top tube, if I have a 12 oz can in a frame bag, my knees rub it and I have to pedal "around" it with legs slightly spread. It's awkward.

 

[oVxrtex]

Doing the math, assuming 5ah 21700 cells, 20S8P, 160 cells, then 25lbs for the cells, plus whatever weight is for the case, BMS, and hardware. If made with Samsung 50s cells, that would be 200A continuous when the cells are new.

So in other words, using those cells, it would be much lighter but also only half the amperage continuous, a kWh less, and 14v less

 

[oVxrtex]

I’m gonna make a new post asking for help on the battery build itself, if anybody from here wants to move over there to continue

 

[E-HP]

I’m gonna make a new post asking for help on the battery build itself, if anybody from here wants to move over there to continue

You could read some of the existing posts that have tons of discussion and info, like Eastwood’s battery build. He’s been planning and working on it for about a year and a half. Not done yet, but I’ve been following it off and on, since there’s good info for my future build.

Eastwood’s first battery build

-I’ve edited the title as I will just use this thread for my first battery build* So my question is, will I get more range from a higher voltage pack with discharging less amps, or lower voltage with more discharge amps that has more amp hour capacity? Battery build will be with 340 cells as...

endless-sphere.com

 

[99t4]

unless I figure out a way to mount it around the frame (one module on the top tube, couple in the middle, couple at the bottom of the bike maybe?)

You’re right, but is 4.5” really that wide? I feel like it’d still be practical to pedal, but I’ve never mounted one or seen one in person so I wouldn’t know, anyways you’re probably right about that.

I could probably find a way to mount it though, like maybe I could mount it on the side of the seat post (I think what I mean is the shortest side of the triangle frame, and putting it on the side of that tube). It shouldn’t handle too differently either, the only issue would be balancing it so it doesn’t shake around, maybe I could ratchet strap the battery or make some sort of mount for it.

Also, with the side of the seatpost idea I would put it somewhere where my legs aren’t going to touch it when pedaling.

Now that you're firming up your design parameters I highly recommend making some cardboard box mockups of the actual size and shape of your most promising battery candidates. Mount them to your bike at your chosen locations, and ride around, see if it is even workable or not. EXTRA CREDIT: Put weightlifting plates of the corresponding (battery) weights in them to really give you an accurate result. You will know almost immediately, instead of wasting precious time asking us for our opinions; what works best for us (individually) may not work for you, and vice versa.

 

[oVxrtex]

Now that you're firming up your design parameters I highly recommend making some cardboard box mockups of the actual size and shape of your most promising battery candidates. Mount them to your bike at your chosen locations, and ride around, see if it is even workable or not. EXTRA CREDIT: Put weightlifting plates of the corresponding (battery) weights in them to really give you an accurate result. You will know almost immediately, instead of wasting precious time asking us for our opinions; what works best for us (individually) may not work for you, and vice versa.

I never thought of that before, thanks for the idea.

Also, you're right about it not working for everybody, thanks for that too

I sound incredibly sarcastic here, but I genuinely mean thank you , sorry about that..

 

[E-HP]

EXTRA CREDIT: Put weightlifting plates of the corresponding (battery) weights in them to really give you an accurate result. You will know almost immediately, instead of wasting precious time asking us for our opinions; what works best for us (individually) may not work for you, and vice versa.

Brilliant! Harbor Freight sells some pretty big/strong zip ties, that you don't need to buy a boat load of. Plenty strong.

 

[E-HP]

I never thought of that before, thanks for the idea.

Also, you're right about it not working for everybody, thanks for that too

I sound incredibly sarcastic here, but I genuinely mean thank you , sorry about that..

Put a center stand down on the list for your build. Once you get over a certain weight, which appears to be in the plan, a kickstand will be useless and just a hazard. Everything needs to be stronger as you add weight. Watch out for the cheap adjustable stands if you need to extend them too much.

 

[oVxrtex]

Put a center stand

What's a center stand? Is it just a stronger kickstand or is it like one of those triangle stands that dirt bikes use?

 

[oVxrtex]

Also, forget what I was saying before with the batteries, how many watts (or just volts/amps) would I need to go 50-60mph? I want the absurdity of 30kw, but at the same time the parts are way too expensive. I could just upgrade it down the line if I REALLY want 30kw some day. I still want some torque, so id probably get a 3.5t motor, and I also want at least decent range, let's say 3-4kWh.

Sorry for switching back and forth so much with my build, I just didn't know much at the start of this thread and I've been researching a lot more after making it

 

[99t4]

I sound incredibly sarcastic here, but I genuinely mean thank you , sorry about that..

We're good-- I didn't perceive any sarcasm anywhere. It usually works best if we all show consideration for each other, and we're doing great in this thread so far.

 

[E-HP]

What's a center stand? Is it just a stronger kickstand or is it like one of those triangle stands that dirt bikes use?

This is just an example and only supports 77lbs, so you'll need something beefier. You can't use a kickstand on your build because the bike would just fall over. A center stand props the bike upright, so no leaning.

Amazon.com

 

[99t4]

how many watts (or just volts/amps) would I need to go 50-60mph? I want the absurdity of 30kw, but at the same time the parts are way too expensive. I could just upgrade it down the line if I REALLY want 30kw some day. I still want some torque, so id probably get a 3.5t motor, and I also want at least decent range, let's say 3-4kWh.

At this stage you will greatly and quickly increase your knowledge in this area by experimenting with the Grin website motor simulator (as recommended earlier by AW and E-HP).

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

 

[oVxrtex]

At this stage you will greatly and quickly increase your knowledge in this area by experimenting with the Grin website motor simulator (as recommended earlier by AW and E-HP).

What motor should I use to resemble a qs205 3kw model? Or in the custom motor section, do you know the kV of it and the internal resistance?

 

[amberwolf]

Anyways, I've been looking at EV batteries and found these, $20/kWh, what do you think? UR18650ZK V52A Sanyo 54V 38Ah 2kWh 18650 module | Greentec Auto

If you read all the specs you'll find they're useless for our purposes:
Peak Discharge Current: 25A
Nominal Discharge Current: 8.5A

If you need 100+ A you'd have to parallel like 12 of them because of that 8.5A nominal (continuous) limit (the 25A is almost certainly only good for a few seconds). At nearly 40lbs each, well....

I had those linked in my thread near the post I'd discussed the other ones in, and in a later post discarded that idea because of that limit. Woulda been nice, though.

It could just be an interconnect limit, or it could be the cells they use, or both. Either way, it would require seriously rebuilding the packs, and that makes them much much harder to use.


Similar problem with the big 12v blocks I also show in that thread--their interconnects couldn't handle the current I need, so I'd have to invent my own and rebuild the packs to use them.