Should I buy a non functioning ebike?

[Rousabout]

Hi, I'm new here and to the ebike scene.
So there is an auction selling factory seconds with a few generic brand ebikes and I can't inspect before the auction. But I'm a tinkerer and I was thinking about fixing one for myself if I score a bike I like and fix one or two to help pay for the first. I'm trying to figure out the risks and what the likely problems and fixes are. As I see it off the shelf controller might be worth buying online if it's possible and cheap, but motor not...
They have remarks like:
"Item turns on but does not function"
"electric not functioning"

So, is it worth it?

 

[Manbeer]

Buying even used and confirmed working e-bikes can be a bit of a crap shoot which is why many of us noobs even decide building up an existing bike ends up being the better value.

Typically the generic bikes use one of the typical generic form factor batteries that will be easy to find a replacement. Bear in mind that usually, the replacement battery with even just decent quality cells can cost 3-400 dollars for a 36v or 48v 10-12 ah pack though.

At best , the battery won't be the problem but probably will be somewhat lackluster in performance.

If it appears to be, check the voltage output of the charger if it is included before reaching a conclusion though as cheap Chinese chargers can fail fairly often

At worst , you will be in the hole 3-400 plus the cost of the bike

If it's a hub motor, a motor laced in a wheel that is compatible probably can be had for a couple hundred. I'd somewhat prefer a bad motor to a bad battery under normal circumstances, bit the reality is that a "good" battery probably isn't "great" on most of these anyway so at least if you did have to replace it, you would be upgrading

This is actually how I got started on my first build. I am a bike mechanic and a customer had a pack with cheap Chinese cells that had horrible voltage sag. I replaced it for him and used the old pack on a lower power build and it became addictive

On the lower end of things , you can find a decent kit with a battery for around 500 bucks with just about everything you need on places like aliexpress from chamrider store or other

Something with more power and a decent (still not great but acceptable) battery. Paired with something like a cheap used steel hardtail like a trek 8xx series, you will generally have a much better bike with better components than a 700 dollar generic ebike, which tend to be based on bike shaped objects with the lowest available quality components

Just food for thought as I don't know what they are charging ,what your skill level or price range is , and what is necessarily wrong with said bike. It could be something as simple as a bad connection or charger and if it's a couple hundred bucks, great. Otherwise, I would steer clear

 

[ZeroEm]

by Rousabout » Oct 13 2020 6:43pm

Hi, I'm new here and to the ebike scene.
So there is an auction selling factory seconds with a few generic brand ebikes and I can't inspect before the auction. But I'm a tinkerer and I was thinking about fixing one for myself if I score a bike I like and fix one or two to help pay for the first. I'm trying to figure out the risks and what the likely problems and fixes are. As I see it off the shelf controller might be worth buying online if it's possible and cheap, but motor not...
They have remarks like:
"Item turns on but does not function"
"electric not functioning"

So, is it worth it?

Manbeer has good advice. Most (hard time finding one) here avoid factory bikes. They like to lock you in to buying their parts and most are slow.
Nothing like building your E-bike. Figure out what you want or think you want and many here will tell you what you need to get there. Slow, flat ground, close by is cheap. Fast, Mountains, Far is not cheap.

Don't know where you live, might want to stick to the speed limit or may be not! 15-20 mph/24-32 kph is a good riding speed but have it top out at 25-30 mph/ 40-48 kph. How far 20 miles or 50.

 

[LeftCoastNurd]

indeed. I could have bought a Specialized Vado, or something, but I chose to take the hybrid 'city bike' I'd built up a few years back and e-power it with a TSDZ2 and 52V 14AH 'Shark' battery. its a ripping fast urban bike. there is no throttle, it is pure pedal-to-go, pedal harder to go faster. if you run the electric motor near full power, it can get too hot, and have to throttle the power way back, which is bad on a hill. you can adjust the power boost level with a +/- control and 10 steps. there's 8 gears, and you use them, lower gears for climbing hills, top gear for zooming the flats, and downshift before stopping.

way happy with how its turned out, and I'm not quite done with it. I think I'm $1500 into this build. the original bike I started with was a $200 Globe Vienna 02 hybrid, that I'd customized and upgraded quite a bit even before the e-build..

 

[Rousabout]

Thanks for the input guys!
Beer you're right! I'll try to get them for only a few hundred. I've also been eyeing off kits for a while and I figured if I can get one of these rejects up and going for the price of a kit, but with a generic, integrated battery I can upgrade will be a plus. I've been thinking of a tonsheng kit on my old giant anthem like the kit leftcoastnurd is using. The real problem I have with that is I can't see a drinkholder/framebag battery and bike taking my kind of punishment. I'd have build a custom carbon mount to make things as firm and secure as I'd need. Ideally in the future I want to build a duel mid/r hub drive to experiment with customizing torque curves at the rear wheel while taking the strain and wear off the drive train. (for a later ag bike project) But for now to answer you ZeroEm it's all for shits and giggles. I don't need speed for that(but I'll probably brick or break a controller or two...)

On paper I see issues possibly in:
-poor connections (easy fix)
-break lever cut out not disengaging/engaging (cheap fix)
-faulty throttle (cheap and easy)
-cadence sensor where no throttle (cheap and easy)
-speed sensor where system requires feedback (cheap and easy)
-faulty display if controller requires (a few dollars, easy)
-faulty controller (a few dollars, easy)
-motor (some more dollars, easy)
-battery (some more dollars, generic and easy PVC pack)

"Item turns on but does not function" This tells me battery is working
"electric not functioning" This is too vague, but if display is not activating, it would indicate at least one problem is not the motor...

 

[Rousabout]

I guess what i'm really trying to find from you guys with experience beyond my purely instinctive theoretical grasp is what you think the probability/or not of it being motor or battery. I know the bike above turns on, so should have a functioning battery atleast...

 

[electric_nz]

If it’s something with a geared hub motor like a Bafang, then any old controller and battery can be made to work if they have failed. If it’s an inbuilt mid drive of unknown providence then it’s a bit more risky.

 

[qwerkus]

img]https://assets.kogan.com/files/product/2020/FS27HCMEBKA/FS27HCMEBKA_Hero_V2.jpg?auto=webp&canvas=753%2C502&fit=bounds&height=502&quality=75&width=753[/img]

Not sure a tsdz2 or a bbs02 would fit on this bike. The BB has a strange geometry due to the (badly) integrated battery enclosure. For aftermarket mid drives, best get a frame with more freedom, and use a triangle battery - hailong or delta style.

 

[99t4]

But I'm a tinkerer and I was thinking about fixing one for myself if I score a bike I like and fix one or two to help pay for the first.

Depends how you quantify the value of your time. Helps if you are retired or independently wealthy. You as a self-described tinkerer probably enjoy the process and approach it as a hobby.

As much as you are trying to be careful and assessing the risks of each potential project, luck plays a big part in whether you end up with something that is a royal PIA at every turn, or an easy lucrative flip.

My first such project turned out to be a 45 MPH+ screamer worth many times what I paid for it.

Second project was not that difficult to get functional but its highly proprietary nature makes it a PIA where parts are much more expensive and harder to obtain than if it were an off-the-shelf design.

If you can get them for a few hundred $, there is not much risk, as if worst came to worst, you could probably sell the parts to recoup most of that.

My overall advices: Stay away from proprietary systems! And built-in batteries (unless you are set up for refreshing them yourself).

 

[ZeroEm]

You could find out what's wrong but fixing it would mean buying expensive parts from the company or try to adapt after market parts. Get out your tester, test the battery, motor, look for broken wires, test for shorts, bad switches. Should only have the controller and or display left. Use another controller to test with, ect.......................

While i'm riding will be thinking about you testing. You can build your own controller if you want!

 

[LeftCoastNurd]

re punishment, I've got a 9 lb "Shark" battery on my bike, 52V 14AH (14S4P, 728 Watt*hour), mounted using one frame water bottle captive nut, and one 'bottlebob',and its quite rock solid, i've been over gravel, hopped curbs, and so forth, and its been quite solid. not a single rattle, and I am running 700x40 tires with no suspension.

I can't tell what the drive system is on that bike, is it a rear hub motor ?

 

[AHicks]

For me, it would be about a call regarding if I liked the bike or not. If you've been shopping, and you have been looking at similar, then maybe go for it.

If the style bike is NOT something you would normally go for, say it's a 20" folder and you've been looking at mostly non folding 26" bikes, then I would not buy that bike.