Need help for upgrading the Chinese folder

[Hjzz]

Hi everyone,

I’ve just bought a Chinese folding e-bike (Hidoes C5) for commuting to work and grocery shopping.

Overall, the bike is OK for the price (£250), but I want to upgrade it for more range (around 20 miles) and a higher top speed (around 25 mph). Right now, the bike does around 15 mph on flat roads and gets about 10–15 miles of range.

I’ve done some research and realized I’m really getting into the e-bike world, so I decided to use this bike as my first project to learn more about motors, batteries, controllers, displays, etc. I found this forum and it seems like the best place to learn.

Long story short, I need your help to upgrade the bike.

From what I’ve found, I’ll probably need to change the battery to 48V because the current 36V setup feels underpowered. I’ll also need to change the controller and display. I think the motor will probably be fine for now, but otherwise I’ll change the motor too.

I have a few questions:

• Which controller and display should I buy?
• Why does the bike slow down downhill?
• Why does the throttle act like it’s just ON/OFF with no smooth adjustment?

 

[gromike]

I'd be careful about sinking all that much money into your bike. Finding a decent 48v battery that fits will cost more than your bike.
If you want to do something, replace the controller initially. I've had good luck with KT's 22a 36/48 volt controller. You would need a compatible display, that and soldering skills.
25mph is quite fast for that tiny bike. If you're young and unbroken--go for it! Vaya con Dios.

 

[offGridDownUnder]

Some questions/thoughts:

• Do you need a folder? Do you need that folder? <= this is a really critical question, addressing the riding you want to do
• Tell us about the routes you wish to ride - hills? roads with cars? cities? off-road?
• What do you wish to carry? What does it weigh? You? Cargo, how large? You've mentioned a bit, but the more you also want to do, the more thought is justified - I'm just checking your outer boundaries.
• Do you pedal? Do you want to?
• Are you already bicycle savvy? Can you solder? Do you have electrical test equipment? Can you weld? It's not that you need to do all of these, it's that we can gauge what to ask and how you can save vs. spend.

Capability costs money. Cleverness can save some money, so you helping us know your wishes helps us offer some cleverness (we hope).

 

[Alex12345]

• Why does the bike slow down downhill?
• Why does the throttle act like it’s just ON/OFF with no smooth adjustment?

You mean if you coast downhill it still limits you to 15mph? Perhaps a direct drive motor then.

A throttle should not behave like an ON/OFF, sorry for your experience. If you replace the controller with a KT or some other good one, it should fix the issue, unless the throttle itself is bad.

 

[docw009]

14" wheels? That's 432 rpm at 15 mph. You may be getting close to the max rpm of the motor even at 48V. I really dunno. Maybe higher voltage can get another 20% and you hit 18 mph..

What's the top speed on the display with the rear wheel lifted off the ground at 36V? This will tell you if you're speed limited by controller.

 

[Hjzz]

Some questions/thoughts:

• Do you need a folder? Do you need that folder? <= this is a really critical question, addressing the riding you want to do
• Tell us about the routes you wish to ride - hills? roads with cars? cities? off-road?
• What do you wish to carry? What does it weigh? You? Cargo, how large? You've mentioned a bit, but the more you also want to do, the more thought is justified - I'm just checking your outer boundaries.
• Do you pedal? Do you want to?
• Are you already bicycle savvy? Can you solder? Do you have electrical test equipment? Can you weld? It's not that you need to do all of these, it's that we can gauge what to ask and how you can save vs. spend.

Capability costs money. Cleverness can save some money, so you helping us know your wishes helps us offer some cleverness (we hope).

• Yes, I need a folding bike because I live in a small flat.
• I’m not sure if this specific folder is the best choice, but it’s what I currently have.
• I live in West London, so there are a lot of uphill and downhill roads, usually short but fairly steep (around 10% slopes).
• I don’t carry much weight, usually just 10–15 kg of groceries.
• I almost never pedal because my job already involves riding a cargo e-bike for around 7 hours a day, so my legs are too tired to pedal uphill on the way home.
• I’d say I’m bicycle-savvy, but I don’t know much about e-bikes yet, which is why I want to learn.
• I can solder, and I can get some electrical testing tools if needed, but I can’t weld.
• My weight is around 75 kg, and the bike weighs about 25 kg.

 

[Hjzz]

I'd be careful about sinking all that much money into your bike. Finding a decent 48v battery that fits will cost more than your bike.
If you want to do something, replace the controller initially. I've had good luck with KT's 22a 36/48 volt controller. You would need a compatible display, that and soldering skills.
25mph is quite fast for that tiny bike. If you're young and unbroken--go for it! Vaya con Dios.

It was actually my first plan to just change the controller and display, but from my online research it seems there won’t be a very noticeable improvement with the original 36V battery.

I found some 13S5P battery packs on AliExpress for around £100, and a controller + display combo for around £30–40, which seemed like a reasonable upgrade cost. My main concern is the battery quality.

Can I use a KT controller on this bike? I realized the wiring and connectors on my bike are completely different from most of the KT setups I’ve seen online.

Also, my main question is: can this bike realistically reach 25 mph just by changing the controller, or is that impossible with the current motor and battery setup?

 

[Hjzz]

14" wheels? That's 432 rpm at 15 mph. You may be getting close to the max rpm of the motor even at 48V. I really dunno. Maybe higher voltage can get another 20% and you hit 18 mph..

What's the top speed on the display with the rear wheel lifted off the ground at 36V? This will tell you if you're speed limited by controller.

Yes 14 inch wheels
The top speed is currently locked to 15.5 mph because of UK regulations, so I guess just changing the controller could probably get it close to 20 mph. With a 48V battery upgrade, I think 25 mph might be reachable, but I’m not really sure.

Honestly, I also don’t know the motor’s max RPM because there’s no brand name or specifications written on the motor, so I can’t find any technical information about it.

 

[Hjzz]

You mean if you coast downhill it still limits you to 15mph? Perhaps a direct drive motor then.

A throttle should not behave like an ON/OFF, sorry for your experience. If you replace the controller with a KT or some other good one, it should fix the issue, unless the throttle itself is bad.

Yeah, that’s exactly what shocked me. Even when I turn the bike off while going downhill, it still feels like something is limiting the speed or adding resistance.

Can I replace this controller with a KT controller? I actually don’t even know what model my current controller is because there are no labels or specifications on it.

 

[offGridDownUnder]

Even when I turn the bike off while going downhill, it still feels like something is limiting the speed or adding resistance.

I can't tell from the available information, but some general truths about ebike (or their motors):

You will feel resistance from an unpowered motor due to the magnets inducing it. The term is 'cogging'.

Also, in general, a motor is a generator. This doesn't just mean that you can use it either way by how you hook it up, it actually means that when you are using it as a motor, it's also acting as a generator. This produces resistive forces which lead to a top speed it will turn at.

This may act to provide the experience you report above, but that could be from other aspects, I can't tell. But it's about ebikes.

The small wheels you have mean high RPM for the speed you travel at, and that means the motor will be closer to it's self-induced speed limit, apart from issues due to voltage or controller or settings. I don't know if anyone else reading this has experience to say this is or can't be an issue in this case.

 

[Hjzz]

I can't tell from the available information, but some general truths about ebike (or their motors):

You will feel resistance from an unpowered motor due to the magnets inducing it. The term is 'cogging'.

Also, in general, a motor is a generator. This doesn't just mean that you can use it either way by how you hook it up, it actually means that when you are using it as a motor, it's also acting as a generator. This produces resistive forces which lead to a top speed it will turn at.

This may act to provide the experience you report above, but that could be from other aspects, I can't tell. But it's about ebikes.

The small wheels you have mean high RPM for the speed you travel at, and that means the motor will be closer to it's self-induced speed limit, apart from issues due to voltage or controller or settings. I don't know if anyone else reading this has experience to say this is or can't be an issue in this case.

I guess my first step should be changing the controller and display to better understand what’s actually limiting the bike before upgrading the battery.

Right now, I’m mostly confused about which controller would fit this bike best. Should I go with a KT controller even though the connectors and cables are completely different from mine, or should I look for a similar controller with the same type of connectors?

I’m also wondering if there are controllers that support multiple voltages and different current settings, for example something that can work with both 36V and 48V batteries and allow amp adjustments.

 

[RunForTheHills]

You can buy connectors with pigtail cables on them and splice them in with butt connectors or solder and heat shrink tubing. Grin sells a small form factor controller called the Baserrunner that can be combined with either their Superharness and color display or with a CAv3. It works with multiple voltages, torque sensors, PAS, throttles, ebrakes, etc.

Baserunner
Superharness
Cables

 

[docw009]

The RPM of brushless motor correlates directly to voltage, A 48V pack has 13 series groups, while a 36V pack has 10 series groups. That would suggest a 30% increase in speed. So if you motor can go 15mph on 36V w/o hitting the limiter, it should go 19.5 mph on 48V. The question is whether the motor has approached its max speed already spinning at 430 rpm. If so, you may not get much more. I doubt that 25 moh is possible. You're asking the motor to spin at 700 rpm.

If you look at your bundle of wires, you might see a single wire come out to a connector and go back into the controller. That's often a speed limiter circuit on many controllers, including some KT. Just open the connector. See if the bike still runs,a d iff it runs any faster,

 

[Hjzz]

The RPM of brushless motor correlates directly to voltage, A 48V pack has 13 series groups, while a 36V pack has 10 series groups. That would suggest a 30% increase in speed. So if you motor can go 15mph on 36V w/o hitting the limiter, it should go 19.5 mph on 48V. The question is whether the motor has approached its max speed already spinning at 430 rpm. If so, you may not get much more. I doubt that 25 moh is possible. You're asking the motor to spin at 700 rpm.

The current RPM is about 366 with an 11.8-inch tire.

The US version of the same bike can reach around 488 RPM.

My goal is about 600 RPM. Does that sound too high to achieve?

 

[Hjzz]

If you look at your bundle of wires, you might see a single wire come out to a connector and go back into the controller. That's often a speed limiter circuit on many controllers, including some KT. Just open the connector. See if the bike still runs,a d iff it runs any faster,

No cable like that one you said in my controller

 

[Hjzz]

You can buy connectors with pigtail cables on them and splice them in with butt connectors or solder and heat shrink tubing. Grin sells a small form factor controller called the Baserrunner that can be combined with either their Superharness and color display or with a CAv3. It works with multiple voltages, torque sensors, PAS, throttles, ebrakes, etc.

Baserunner
Superharness
Cables

The controller you suggested is out of budget
What about this one?

https://a.aliexpress.com/_EvVLtXU

 

[RunForTheHills]

The controller you suggested is out of budget
What about this one?

https://a.aliexpress.com/_EvVLtXU

A 500W controller probably won't get you to 25 mph, but you can give it a try. That's about the same as your current controller (36V X 15A = 540W). I am not sure what motor you have, but you can play with the motor simulator to see what combination might work for you:

Grin Motor Simulator

 

[Hjzz]

A 500W controller probably won't get you to 25 mph, but you can give it a try. That's about the same as your current controller (36V X 15A = 540W).

Thanks for the info. I’m new to e-bikes, so I’m just trying to understand how the motor behaves without the controller limits. I guess the best thing to do is replace the controller with one that has the same cabling type and test the speed first, then upgrade the battery to 48V.

(48V × 20A = 960W)

Does that sound like a wise decision, or am I going in the wrong direction?

 

[hillslayer@]

I bought one of these for a 150.00 came with a 48 volt battery. Put a 26 amp controller on it and goes faster than what I consider safe 25 mph is dangerous on it. Mostly gets used as a wheelbarrow hauling wood.