Jump to content
cg

Generic OEM - Unicycle-A2

Recommended Posts

Your BMS won't cut anymore, try as hard as you can, you'll see this problem is no more and you can enjoy the wheel with confidence.

BTW, here is the update post of your mod on my blog (the thing about the heat sink may interest you) : http://hobby16.neowp.fr/2015/07/21/a2-generic-bms-shunt/

Hey hobby, I have been riding the last couple of days, and it there has not been any cutouts, I haven't really done any meassurement as to how long I can ride, I surely not done any measurement on the capacity, I might order one of you charge-doctores, but I am a bit hooked to the idea of building something into the bike that can monitor and log the voltage, current and speed while driving, I might do both, but I think I will start an new thread for that than this 'review' thread :)

About the heat sink, I think I read you said the same in the french forum... but what is the heatsink supposed to cool? I mean, isn't it voltage regulators or somethink like that it is attached to, and is cooling?

 

Lightinthebox has now also offered to let my return the bike to get the money back, not really what I wanted, and probably not going to happen when the get the 'tape assembled' wheel back... ohh well, I have asked them to either send me a new battery or to cover the expences, but to be honest I don't really care since the bike now is working :)

Share this post


Link to post
Share on other sites

Hey hobby, I have been riding the last couple of days, and it there has not been any cutouts, I haven't really done any meassurement as to how long I can ride, I surely not done any measurement on the capacity, I might order one of you charge-doctores, but I am a bit hooked to the idea of building something into the bike that can monitor and log the voltage, current and speed while driving, I might do both, but I think I will start an new thread for that than this 'review' thread :)

Monitoring the battery charging (with Charge Doctor) and monitoring the battery current draw is not the same thing indeed.

I have built an Arduino nano with sd-card to do just you are looking for and even more, with temperature, buzzer sound, current direction (for braking) recording. It is small enough to be stuck in the mainboard compartment, communication with the outside will be done by the unused pin #3 of the charging connector (bi-directionnal pin, for receiving commands and for download log data). The main goal is to make a detailed review of every possible wheels, with precise measuments following well defined protocols. I just lacked time to finalize to software, maybe I'll do it finally.

 

About the heat sink, I think I read you said the same in the french forum... but what is the heatsink supposed to cool? I mean, isn't it voltage regulators or somethink like that it is attached to, and is cooling?

The heat sink is for the mosfets of the motor power stage. Here is what you have on a Gotway, a huge aluminium plate under the mainboard and attached to the mosfet, as it should be, to maximize radiation surface and to efficiently remove heat. And not a ridiculous aluminium bloc on the X3 and clones. After a long ride, if you touch the wheel, you'll see your mainboard is heating a lot under the red pad. If no additionnal heat sink is added, it will fail sooner or later because of heat buildup and material fatigue. It's written on the wall, probably on purpose for planned obsolescence. I'll make pictures of what I've done on my X3 clone.

motherboard_side1.jpg

Edited by hobby16

Share this post


Link to post
Share on other sites

Monitoring the battery charging (with Charge Doctor) and monitoring the battery current draw is not the same thing indeed.

No, but it it possible with the same integrated device?

I have built an Arduino nano with sd-card to do just you are looking for and even more, with temperature, buzzer sound, current direction (for braking) recording. It is small enough to be stuck in the mainboard compartment, communication with the outside will be done by the unused pin #3 of the charging connector (bi-directionnal pin, for receiving commands and for download log data). The main goal is to make a detailed review of every possible wheels, with precise measuments following well defined protocols. I just lacked time to finalize to software, maybe I'll do it finally.

I also have an small arduino-pro (3.3V), that is what I want to use, I haven't really used it for anything, but I guess this is it :)

Do you have a description of the hardware, my idea was to use a magnet from a bike computer for the speed, and then find something on banggood for voltage and current measurement. If your design is open-source, then please share :)

regarding the heat build up, I do think I have felt some heat build up at some point in time... I have ordered some thermal sensors, intended for my solar heater for my allotment. But I could make some measurement on the heating plate so we can get the real temperature.

Share this post


Link to post
Share on other sites

find something on banggood for voltage and current measurement.

I ordered some (up to) 100V DC self-powering voltage displays (no need for separate power for the display, it draws directly from measured wires), and one current/voltage display (100V/50A) with separate shunt. Already got the current/voltage display today (it wasn't supposed to arrive for a week or two yet), haven't tested it yet though. It's this one: http://www.aliexpress.com/item/DC-Car-LED-Red-Blue-Dual-display-DC-0-100V-50A-Voltmeter-Ammeter-2in1-Voltage-Current/1684125289.html  Gotta try to cook up something to test & calibrate the display, I don't have a configurable power supply, but I do think I have a simple 3-12V DC transformer, with options for voltage every 1.5V between those, then compare it to basic multimeter (which probably isn't very accurate itself either, it's not a Fluke ;)). And then something for checking the current measurements...

I did know it seeing the dimensions in the page, but still that shunt is large (about 17.5 x 25 x 120mm) :wacko: I originally thought I could fit it inside the bike front, but too big... probably need to attach it inside the mainboard compartment and use lots of silicone/large heat shrink tubes/electric insulation tape/something to prevent it from shorting anything...

regarding the heat build up, I do think I have felt some heat build up at some point in time... I have ordered some thermal sensors, intended for my solar heater for my allotment. But I could make some measurement on the heating plate so we can get the real temperature.

My plan is to add thermal paste between the metal plate where the heat sink is connected to and to add small copper heatsink with fins on top of the current aluminum sink... probably not that big difference vs. the aluminum sink by itself, but at least something ;)

 

@Chriull : I separated the discussion about the voltage/current display and heat dissipation on Firewheel to here: http://forum.electricunicycle.org/topic/753-currentvoltage-measurement-and-heat-dissipation/

as we're going badly off-topic... ;)

Share this post


Link to post
Share on other sites

No, but it it possible with the same integrated device?

I also have an small arduino-pro (3.3V), that is what I want to use, I haven't really used it for anything, but I guess this is it :)

Do you have a description of the hardware, my idea was to use a magnet from a bike computer for the speed, and then find something on banggood for voltage and current measurement. If your design is open-source, then please share :)

It depends if you talk about logging data or not. If not, indeed, a bike computer (see my signature) and a simple voltamp display would be ok.

For logging, I will use directly the signal of one hall sensor, it's quite clean. The Arduino just needs to divide it by the number of poles (24 on a X3) to deduce rpm. I said "Arduino" but in fact, I use just the board hardware, not the Arduino software toolsuite, which is quite dumb as to debugging or simulation. I use AVR Studio, so making the project open source is possible but not quite straightforward as an Arduino sketch. We'll see.

 

regarding the heat build up, I do think I have felt some heat build up at some point in time... I have ordered some thermal sensors, intended for my solar heater for my allotment. But I could make some measurement on the heating plate so we can get the real temperature.

Stick an aquarium thermometer or a car thermometer if you have one, you'll see how the mosfets become hellishly hot !

Share this post


Link to post
Share on other sites

It depends if you talk about logging data or not. If not, indeed, a bike computer (see my signature) and a simple voltamp display would be ok.

For logging, I will use directly the signal of one hall sensor, it's quite clean. The Arduino just needs to divide it by the number of poles (24 on a X3) to deduce rpm. I said "Arduino" but in fact, I use just the board hardware, not the Arduino software toolsuite, which is quite dumb as to debugging or simulation. I use AVR Studio, so making the project open source is possible but not quite straightforward as an Arduino sketch. We'll see.

 

Stick an aquarium thermometer or a car thermometer if you have one, you'll see how the mosfets become hellishly hot !

HAL sensor, I have heard that before :). I am looking forward to the the poor electronics engineer from my work getting back from vacation ;). Anyway, I totally agree that the Arduino IDE is rubish, I can't even resize the window (I am using a tiling window manager (xmonad) highly recommendable, and normally it fits the window just perfectly).

Regarding the temperature, I guess I better figure something out with a  cooler then, especially since I completely sealed the compartments with silicone yesterday to prevent stones et al to enter... 

And it is for logging.

 

I ordered some (up to) 100V DC self-powering voltage displays (no need for separate power for the display...

...I did know it seeing the dimensions in the page, but still that shunt is large (about 17.5 x 25 x 120mm) :wacko: I originally thought I could fit it inside the bike front, but too big...

oh yes, that is a big one :), 

Share this post


Link to post
Share on other sites

@hobby16, here is an updated image of my shunting... I think i used 'de soldering' wire for the previous shunt :/

20151003_004.thumb.jpg.b69849621c2b3fcf9

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...