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The eBike thread

unkel

A quick look seems that this doesn't really seem to fit in the cycling forum. So starting a thread here about all things eBike

I'll get the ball rolling. I have zero experience with eBikes. But I was going to build myself a battery anyway, for various reasons (like in bringing with me in my EV as a "petrol can")

I'm going to buy a solderless kit to make the battery (with 18650 cells I have removed from dead / old laptop batteries). This kit cah handle 20A max, and I would like the battery pack to produce 1kW constant. P=V*I so 1000W = 50V * 20A

This dictates that my battery needs to be nominal 48V (was thinking of making a 24V battery pack, but that won't be able to charge my car)

A quick browse on eBay and Amazon shows that you could buy a powerful 1000W bike conversion kit with everything needed except the battery for about GBP120 (a bit more from Amazon but peace of mind)

What to buy though, front wheel or rear wheel kit? Pros and cons? Any other advice?

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[Deleted User]

unkel wrote: »

That is a great resource. Thanks for sharing!

Welcome, yes it's a great resource. Enjoy !

unkel

My first Vruzend battery build this evening from 18650 cells forcefully removed from dead laptop batteries I got for free

Look mama, I made a 10S 36V battery!

unkel

What seems to be the standard yoke that everyone uses to determine 18650 capacity: LiitoKala Lii-500 is ordered and on the way.

Last step is to measure battery internal resistance. Could of course buy another tool for this, but I thought this would be an easy measurement. Measure voltage of cell. Stick in a 1 Ohm resistor in series and measure voltage again. Resistance is then voltage drop / voltage under load, like this:

https://www.youtube.com/watch?v=av38iBxcOgQ

When I stick in the 1 Ohm 11W resistor I bought today in RS Radionics, nothing happens, voltages are the same. What am I doing wrong here? Sir Liam?

[Deleted User]

Well done no stopping you now !

What way are you supposed to connect the radiator?

unkel

So made it into a 10S2P pack, crimped a fuse and an XT60 on it and charging...

Bypassed the existing battery and hooked it up to the controller. Working fine. Getting decent bit of range from it too, even though it is tiny. Which strengthened my feelings that the existing battery was toast and that there was nothing wrong with controller / motor

Took the existing battery apart (not without shorting it once or twice LOL

), measured all 40 cells and indeed, there were 9 cells not charging beyond 3.6V, causing the BMS to cut off the battery very early (particularly under full load) and explaining the poor range. The vast majority of the Samsung cells were charged to around 4.15V, so will be re-used :cool:

Deleted User wrote: »

What way are you supposed to connect the radiator?

The resistor? Looks like they have it in parallel, maybe I went wrong there, must try again

unkel

Put a watt meter between battery and controller. Tested it in the park and getting max 300W draw so not much more than 250W at the motor, LOL! That controller wasn't joking with the "7A" sticker on it 7A * 42V = about 300W. This eBike is 100% road legal (for the moment) :pac:

As soon as I get my 30A 48V controller, this original 36V controller will be ripped out anyway, so I might as well have a bit of craic with it. Increased my vruzend battery pack from 10S2P to 13S2P, 54.4V yeah!

Hooked it up and surprise, surprise it works just fine and the eBike is now a whole lot quicker

[Deleted User]

unkel wrote: »

Put a watt meter between battery and controller. Tested it in the park and getting max 300W draw so not much more than 250W at the motor, LOL! That controller wasn't joking with the "7A" sticker on it 7A * 42V = about 300W. This eBike is 100% road legal (for the moment) :pac:

As soon as I get my 30A 48V controller, this original 36V controller will be ripped out anyway, so I might as well have a bit of craic with it. Increased my vruzend battery pack from 10S2P to 13S2P, 54.4V yeah!

Hooked it up and surprise, surprise it works just fine and the eBike is now a whole lot quicker

Is 7 amps and God knows what Peak current not a lot for those old Laptop cells ?

unkel

Remember I put 25A through those hover board packs? They were essentially 10S2P packs made with cheap 18650s

7A through this pack and the batteries didn't even warm up at all

New controller is 30A but I will take it handy enough as long as I have only one 13S2P pack. Micah calls it a "mighty mini"

Have nearly enough cells now for another one, now that I can re-use about 26 cells from the dead battery. But even this mighty mini should be able to occasionally take 15A no bother for 800W (3.8C) and the vruzend kit is rated at 20A. If I'll make another pack (have to buy another vruzend kit for that), I'll parallel them and I might be brave enough to do a quick top speed test. Should be fun with 1600W

unkel

Tested the bike with the new battery today, getting 520W. That's better but I can't wait til I get my new controller

[Deleted User]

unkel wrote: »

Tested the bike with the new battery today, getting 520W. That's better but I can't wait til I get my new controller

Wait til you're at 5 Kw ! lol

unkel

Maybe I'm a bit greedy, but I thought, if I'm using a 48V battery, I might as well go 52V, right? I have the cells and it fits the Vruzend kits. So 14S BMS ordered and a 58.8V charger.

I ordered a cheap 48V Chinesium inverter yesterday too (max input 60V, so the 58.8V of a fully charged 14S pack is within spec), pure sine wave and 1000W continuous (2000W peak). So the 14S4P pack that I am building should be able to give my car a 3-4km range in about 20 minutes. Can't wait to try this

This is handy to know, a site that will suggest the ideal groups in your pack when you are using not perfectly capacity matched cells:

https://www.youtube.com/watch?v=hXYf1r62vqc

Can't wait to get all this stuff and get going to my next steps in the eBike project.

[Deleted User]

Lol you got the bug now no stopping you !

unkel

Waiting for all the stuff to come from China is a bitch though

[Deleted User]

unkel wrote: »

Waiting for all the stuff to come from China is a bitch though

I usually got stuff in a week bit more.

unkel

Deleted User wrote: »

I usually got stuff in a week bit more.

But you paid about 10 times as much for your stuff compared to what I'm paying :pac:

[Deleted User]

unkel wrote: »

But you paid about 10 times as much for your stuff compared to what I'm paying :pac:

My stuff was built to handle a lot of power so naturally cost more but I was given different postage options.

unkel

My 30A 48V controller that cost €17 including shipping is gonna take a month to get to me from China. Beggars can't be choosers

I presume it can handle up to 58.8V otherwise I'll have to order another one and wait another month :pac:

You ever go 72V or 90V for your high power eBikes? Either that, or use a massive 18650 battery pack or go LiFePo4?

Low Energy Eng

unkel wrote: »

My 30A 48V controller that cost €17 including shipping is gonna take a month to get to me from China. Beggars can't be choosers

Hey, can you link me where you got that?

unkel

Low Energy Eng wrote: »

Hey, can you link me where you got that?

I did already, a few posts back. Here it is again!

unkel wrote: »

Or just do it the cheap way with this 30A controller for €19 including shipping :eek:

Linky

Damn it was €19 shipped, not €17

[Deleted User]

unkel wrote: »

My 30A 48V controller that cost €17 including shipping is gonna take a month to get to me from China. Beggars can't be choosers

I presume it can handle up to 58.8V otherwise I'll have to order another one and wait another month :pac:

You ever go 72V or 90V for your high power eBikes? Either that, or use a massive 18650 battery pack or go LiFePo4?

At one stage I was running around 90 odd volts yes, at this voltage it's ridiculous, I was hitting 90 Kph. Can't remember which motor this was but I quickly knocked that on the head, it was causing a lot of distraction to drivers as they were matching my speed looking in amazement as I was whizzing along in the shoulder coming out of Carlow Town. Distracting for them and dangerous for me.

One other thing at high voltage is that you'll have to make up a pre-charge circuit for anything over about 60 volts because of the spark from the current surge , it comes from charging the capacitors so the Resistor will limit the current flow to the cap, if I remember correctly it was about 100 Ohms. Can't remember exactly, again, endless sphere.... once your cap is charged after a second or two then you can connect the main battery lead, otherwise the sparks will eventually kill your connectors, same if you use a switch.

Anyway, with LiPo I could have a tiny pack for my long cycles and just use it for boost because no other chemistry offers this kind of C rate from a battery about twice the size of a large box of matches. Incredible, I was pulling over 40 amps at about 60 volts, around 64 hot off the charger from an amazingly small battery.

If your controller can do 50 volts it should do 60 volts but the key here is the hot off the charger voltage must not exceed the value on the capacitors or the FET's, open it up and look and get the model of the FET's.

unkel

Deleted User wrote: »

At one stage I was running around 90 odd volts yes, at this voltage it's ridiculous, I was hitting 90 Kph.

:eek: You indeed are a Mad_Lad

Deleted User wrote: »

One other thing at high voltage is that you'll have to make up a pre-charge circuit for anything over about 60 volts because of the spark from the current surge , it comes from charging the capacitors so the Resistor will limit the current flow to the cap, if I remember correctly it was about 100 Ohms. Can't remember exactly, again, endless sphere.... once your cap is charged after a second or two then you can connect the main battery lead, otherwise the sparks will eventually kill your connectors, same if you use a switch.

Yeah I already had sparks connecting the tiny 36V 2S10P pack to both controllers I have used. No plan to go above 58.8V off the charger, so I'll take my chances here

[Deleted User]

unkel wrote: »

:eek: You indeed are a Mad_Lad

I certainly am , I agree !

Yeah I already had sparks connecting the tiny 36V 2S10P pack to both controllers I have used. No plan to go above 58.8V off the charger, so I'll take my chances here

Yeah even at 60 volts it's a good idea to use a pre-charge resistor, connect the lead the resistor is on first, then connect the main lead, then remove the resistor lead, no more sparks and your connectors will last forever.

unkel

I'm not too worried about the connectors. Ordered 5 pairs of MT60 for the 3 phase connection between motor and controller for under €3.50 including shipping

Linky

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704450c413d6e616ec0424c90b16e00c05401f442f48cae08e9ae846e4822e65.jpg.jpg

]

I've ordered more XT60 connectors too

unkel

Yay, my Liitokala Lii-500 from China that wasn't due until Oct 31st, is customs cleared in Amsterdam. Hopefully have it by Friday so I can dismantle my vruzend battery and test every individual 18650 cell that I have.

DaveyDave

Half tempted with doing an ebike restoration on my hardtail. I'd like to cycle to work more but the distances are killer for a commute. 21km in and back or 15km back if I take the back road at night. A regular ebike wouldn't suit as my return journey on the R149 is done at a leisurely 30-35kph.

I see there's kits with wheels for €300 or so, my old MTB needs a new rear wheel anyway so I was thinking about going this route.

If I could get something that would assist to around 30kph and maybe have a range of 80km or so that would be ideal, genuinely have no idea what sort of range a normal kit would do.

unkel

Yeah that's no problem. You have to realise though that a non-pedelec (doing 30km/h) is officially a mechanically propelled vehicle, or in other words, illegal in the current legal framework. A range of 80km is very long. You will either have to do most of the pedaling yourself or get yourself a big ass battery.

DaveyDave

unkel wrote: »

Yeah that's no problem. You have to realise though that a non-pedelec (doing 30km/h) is officially a mechanically propelled vehicle, or in other words, illegal in the current legal framework. A range of 80km is very long. You will either have to do most of the pedaling yourself or get yourself a big ass battery.

Yeah, I'm aware of the legal issue. Are many people abiding by the 25kph limit with ebike kits? If the majority are really sticking to it, then I suppose I will too...

I must try demo an ebike and see what it's like on a commute and see how it fares. I'd be conscious of losing any time saved on hills by having to pick up the slack above 25kph on the faster sections. I could be completely wrong though.

I could do with 45km range or so, 80-90 would just be nice so I wouldn't need to charge every day.

[Deleted User]

First, a geared hub is a must if you like to actually pedal at all, direct drive hubs are great for sheer raw power but they are less efficient and a b1tch to pedal without power.

2nd, torque arms are essential, you risk the axle spinning in the dropouts and this will break the motor and hall sensor wires if this happens and you don't want that to happen crossing a busy street etc and you sure as hell don't want to open the motor to replace all the wires !

3rd. If going more than bicycle speeds , motorists will see you and think you're doing bicycle speeds and pull out right in front of you so when you see cars wanting to pull out of entrances , side roads etc slow down.

4th and absolute most important, the ability to stop, don't underestimate it. I replaced my disk brakes from the standard Bicycle size to 8 inch and the difference in stopping power was massive, if going 45-50 Kwh and above this is essential, I needed adaptors to suit the new disks.

If using a throttle get a thumb throttle, it's far more comfortable on a bicycle.

If you're out in the Country like me you can very easily get away with much higher speeds but the usual caution when in town, slow down pedal etc and you'll be grand.

In Dublin things will be very different, no proper cycle lanes lots more Cyclists , then the cycling purists , just go to the cycling section here on boards.ie and see the hatred towards ebikes , mentioning ebike kit will get you a ban too. bunch of fools.

[Deleted User]

DaveyDave wrote: »

Yeah, I'm aware of the legal issue. Are many people abiding by the 25kph limit with ebike kits? If the majority are really sticking to it, then I suppose I will too...

I must try demo an ebike and see what it's like on a commute and see how it fares. I'd be conscious of losing any time saved on hills by having to pick up the slack above 25kph on the faster sections. I could be completely wrong though.

I could do with 45km range or so, 80-90 would just be nice so I wouldn't need to charge every day.

A proper legal ebike with a Bosch/panasonic chain drive motor will be fine assisting you at up to the cut off which is a bit too low, in my opinion and at the edge it can be frustrating where the motor is cutting in and out constantly at this limit.

These bikes can be hacked to remove/increase the cut off, you can increase it an extra 5 Km/hr and it will make all the difference.

I expect a legal hub motor bike will be the same. But if you have lots of hills then the Bosch / Panasonic are much better options or a kit but most legal ebikes run far higher power than 250 watts.

Why do you need 80 Km range ? you will have to pedal a hell of a lot and restrict your speed a lot for this kind of range.

DaveyDave

I don't need the range, my commute is 42km so I can charge daily if needed, I was just hoping to get 2 days out of it if I could. I can also charge in work before going home.

I've booked a trial with GreenAer, hopefully I can go for a spin on something for the day to get a feel for an ebike. I'm on a road bike so it's light but I'm a big guy so it slows me down a bit.

The mountain bike with kit will be a lot heavier and I'm wondering if it could pick up the slack on the flats while also making the hills easier. I'm curious if an ebike conversion would be any benefit, if it would suit my commute etc.

Now when I say hills, they aren't really hills. There's a few long stretches of inclines on the second half of the commute that slow me down a good bit.