Vado/Como/Creo/Levo/Kenevo SL USB-C Charger Adapter Interest Check

[coffeemaker]

Hi folks, I'm working on an USB-C adapter that would allow the SL battery to be charged with a USB-C adapter, such as the one used for modern MacBooks. The original Specialized charger is $200 and is bulky. When I ride my bike to work or friend's house, there's a good chance there's already a USB-C adapter lying around so all I'd need to bring is this USB-C adapter. It'll be a thumb sized module that gets the max power the USB-C adapter can deliver, boosts it up to the battery voltage and charge it. This project started for my own Vado SL, but if anyone else is interested, I'd be happy to make some more.

• Which bikes will this be compatible with?
  • Vado/Como/Creo/Levo SL with the 54.6V 320Wh battery. A non-SL version may be available if there's enough interest.
• How long will it take to change a completely empty battery?
  • The adapter will draw as much power as the USB-C adapter will provide. Using a 96W MacBook USB-C adapter will fill up the battery in about 4.5 hours.
• Which USB-C power adapters are compatible?
  • USB-C adapters that support the Power Delivery (PD) standard. If it's rated for 20W or more, it likely supports USB-C PD.
• Can the final charge level be set?
  • A WiFi web interface is in the works to allow the user to set the charge voltage. This would be useful when you don't need to charge all the way to 100% in order to extend battery longevity. This is commonly done in electric vehicles.
• Can this charge the range extenders?
  • If there's enough interest, I can get a range extender and test it out.
• How much will this cost?
  • I'm aiming for under $100, but ultimately depends on the interest.
• When will this be available?
  • Likely a few months out.

Please let me know if you're interested and if you have any questions or feature requests.

 

[kahn]

Well, I have to express some interest and if that price is not far off, seems fair. Creo and Range Extenders (2)

Any idea about the cost of the suggested AC adapter block?

 

[coffeemaker]

Creo and Range Extenders (2)

Thanks. I may need some more interest to get a range extender and test it.

Any idea about the cost of the suggested AC adapter block?

Here's a 90W USB-C PD charger and cable that you can use:

https://www.amazon.com/Charger-Charging-Adapter-MacBook-Laptops/dp/B09PBK115P

$30 or $24 with the promo coupon.

 

[kahn]

So, what level of reality is this project? Have you actually created one you use with your Vado SL?

 

[coffeemaker]

I'm working on the PCB design. While it's sent off to a fab, I'll be working on the code for the MCU.

 

[kahn]

I will note that the Range Extender can be charged by itself using the regular charger/adapter used for the Main Battery.

The more interesting situation is that both can be charged at the same time using special Y-cable. But there's obviously "brains" in that Y-cable or somewhere in the system. Since when using the Y-cable BOTH batteries must be attached for charging. The Y-cable will not charge either battery alone. I guess the brains could be in the coupler/divider where the cable splits or in the single end.

Here's a photo

 

[Allan47.7339]

So what are the back of the envelope calculations? The Specialized charger is 54.6V at 3A, 163.8 Watts. USB C is max at 100W so does that mean this will be more of a slow charger at 1.8A or less? Isn't there some Specialized proprietary charging control logic to overcome as well?

 

[PDoz]

I'm interested in one for charging the range extender - the dream being charging 1 extender from the cars dual battery system whilst I'm out riding on the other . Finally having an ultralight lsl with the main battery removed!
Sounds like the third run would be with a half charged extender, which would give me a good excuse for a long lunch .

Why didn't you include the kenevo sl?

 

[coffeemaker]

So what are the back of the envelope calculations? The Specialized charger is 54.6V at 3A, 163.8 Watts. USB C is max at 100W so does that mean this will be more of a slow charger at 1.8A or less? Isn't there some Specialized proprietary charging control logic to overcome as well?

Slightly slower at 100W compared to the original charger's 163.8W. USB PD 3.1 allows up to 240W, but no chargers support it yet so I'm planning to stick to 100W max. If 240W USB-C adapters come out in a few years, I may update the design. For the charge control logic, I believe the charger applies a 5V signal to the battery BMS and the BMS then exposes the pack voltage. It's up to the charger to apply a CC-CV charging curve, and the balancing the handled by the BMS.

Why didn't you include the kenevo sl?

Good point, it should be compatible as well since it uses the same battery and charger.

 

[Stefan Mikes]

How comes you cannot charge two Range Extenders with the SL Y-Cable at the same time but you can charge the main battery and a single Range Extender together? Is the logic so simple?

 

[coffeemaker]

How comes you cannot charge two Range Extenders with the SL Y-Cable at the same time but you can charge the main battery and a single Range Extender together? Is the logic so simple?

I don't have a range extender or a Y-cable so I'm not sure. May be an oversight or a technical limitation, although I can't think of any off the top of my head. In your experience, what's the charging order? Main battery then the range extender, or simultaneously? Do they charge simultaneously even when they're at a different state of charge?

 

[Stefan Mikes]

simultaneously?

This.

Do they charge simultaneously even when they're at a different state of charge?

Yes, they do.
Interestingly, charging both batteries from 5 to 100% takes the same time as charging a single RE (3 h 20 min) while charging the main battery alone takes 2 h 30 min.

 

[BEC111]

This.


Yes, they do.
Interestingly, charging both batteries from 5 to 100% takes the same time as charging a single RE (3 h 20 min) while charging the main battery alone takes 2 h 30 min.

The main battery, RE battery and the charger all contain circuitry to manage charging. This include intelligence to prevent overcharging, possibly charge optimization (as on iPhones and other mobile devices) and so forth.

Lithium batteries are susceptible to damage during charging. Using non-OEM chargers and cables can be dangerous for the batteries and can be a fire risk.

I don’t know what will happen with this experiment, and expect Specialized would not approve regardless of actual efficacy and safety. I do know doing this can cause warranty issues.

Be careful out there.

 

[coffeemaker]

The main battery, RE battery and the charger all contain circuitry to manage charging. This include intelligence to prevent overcharging, possibly charge optimization (as on iPhones and other mobile devices) and so forth.

Lithium batteries are susceptible to damage during charging. Using non-OEM chargers and cables can be dangerous for the batteries and can be a fire risk.

I don’t know what will happen with this experiment, and expect Specialized would not approve regardless of actual efficacy and safety. I do know doing this can cause warranty issues.

Be careful out there.

You're correct that li-ion batteries need to be treated with respect. Operating or storing them out of spec (under or over voltage, overcurrent, over or under temperature) can cause serious issues. The USB-C adapter will have safety features that takes this into account.

 

[geeksville]

Hi @coffeemaker,
This idea sounds great and I'd love to buy one. Also if it helps: I'm an experienced firmware developer (and wrote a fair amount for the OpenSourceEbike github project) and if you want to delegate the software writing to me I could sign up for that also.

Super cool!

 

[coffeemaker]

Hi @coffeemaker,
This idea sounds great and I'd love to buy one. Also if it helps: I'm an experienced firmware developer (and wrote a fair amount for the OpenSourceEbike github project) and if you want to delegate the software writing to me I could sign up for that also.

Super cool!

That'd be amazing, thanks for the offer.
To give you a better idea of the HW, here's what I'm planning on doing:

• The MCU is an ESP8266 for info display and control over WiFi.
  • Haven't decided if we'd like the ESP to act as an WiFi AP or have the ESP connect to an existing AP.
  • Monitor pack voltage, set charge % cutoff, etc.
• USB-C PD negotiation is done through FUSB302 via I2C.
  • The max output power of the USB-C adapter is negotiated and set.
• The boost converter IC is LT3755.
  • Designed for driving LEDs, but we can use CC-CV to charge li-ion packs.
  • CV voltage of 54.6V is set using feedback resistors.
  • During CC stage, the current is set to a maximum of 1.80A via a sense resistor for ~100W max.
  • When a <100W USB-C adapter is connected, the CC current can be set by an analog voltage input 0-1.2V to the LT3755 to avoid drawing too much power.

I'm planning to get the boards made and assembled by JLCPCB. They've promised double sided PCB assembly last month, so that'll help making the PCB size much smaller. As soon as they're made, I'll send some boards your way. Thanks again for your help!

 

[geeksville]

Ok sounds great! I can sign up for that. I'll send you a PM.

 

[Borelij]

Any news on this?
Ever thinking to start Kickstarter campaign?

 

[coffeemaker]

Sorry, I've been busy for some time. I've been in touch with geeksville, who has graciously volunteered to work on the firmware side of this project. Will provide updates, and hope to see it finalize in the next few months.
No plans for Kickstarter due to lack of demand. This seems to be a niche product.

 

[rstouchet]

Sounds very interesting and I would definitely consider buying one. What charger plug are you using to interface with the Creo?