Charge doctor

[hobby16]

Hobby Wheel Gadget Factory is proud to present the "Charge Doctor", specifically designed to survey the monowheels' batteries.
It's in fact an off-the-shelf USB charge monitor I have hacked and reprogrammed for our use.

Specifications
Voltage 40.0V - 80.0V
Current 0.00 - 3.00A
mAh-meter 0-19999 mAh
Energy meter 0-999.9 Wh
Serial data output for logging at 9600 bauds TTL levels
With 3-pin GX16 connectors compatible with Airwheel & clones, TG, iezWay, Gotway, Firewheel... (not on Ninebot One with a different charge plug)
Plug & play

Price
15€ + 4€ international shipping = 19€, Paypal payment to

User instructions
First line: voltage and current. Second line: total charge in mAh or Wh, click pushbutton (PB) to alternate between mAh and Wh.
Hold PB for 2 s to reset the total charge.
PB also enables calibration of the Charge Doctor (see below).

Data logger
Charge Doctor sends out data every 10s in ascii line format with ',' separator, at 9600 bauds, TTL level
Line format:
Time (seconds), voltage (0.1V), current (10mA), Wh (0.1Wh)
Example:
590,596,193,183 <=> 590seconds, 59.6V, 1.93A, 18.3Wh

Data are sent to a PC, MAC or Linux using TTL serial-USB converter dongle (cost < 2 $) and a terminal emulator for disk storage or graphic display (see below for a setup example). Look up  "CP2102 USB converter" or "CH340G USB converter" on eBay (avoid PL2303HX chip based dongles which work fine but rather pricky when installing driver).

Calibration
Voltage is factory (ie by me) calibrated at +-20mV and current at +-2mA.
Recalibrate when necessary only if you have an accurate multimeter.
Press & hold the pushbutton (PB) for more than 6 s when the second counter is at the corresponding number :
1: decrease voltage gain (about 0,02V per PB click, so you must click 5x to see the number change)
2: increase voltage gain
3: decrease current gain (about 2mA per click)
4: increase current gain
5: reset current offset = 0 (no load)

The variable to be calibrated flashes and the change direction is indicated by the display's up or down arrows.
The calibration mode ends after 10s of no PB click.

 

Lastest batch of Charge Doctors. Thank you Ironfox for being the first international buyer and for ordering 4 (four !) of them.
Zoom image : http://googledrive.com/host/0BxMfsstZ1EMcfkYzSzFmTVRHZGg5UzUwQjlqbk1wTzJTNjJiMG9wRWRKdVZlMnlEbGVqZkE/chargedr/DSCN1676.jpg

Charge Doctor display, charging a 260Wh empty battery.
1) beginning: V=60.2V, I=2.11A, Charge=29.1Wh
2) near end: V=67.1V, I=0.4A, Charge=230.8Wh
3) end of charge: V=67.1V, I=0.0A, Charge=243.4Wh
Notice that it's a generic wheel (TG) battery with Chinese cells, so total charge is only  only 243.4Wh, the nameplate "260 Wh capacity" cannot be reached. On the Firewheel 260Wh, with Panasonic cells, I can charge up to 285 Wh.

Charge Doctor - PC link using a Serial-USB converter dongle, data logging by terminal emulator puTTY. Only two connexions of the dongle are used: 0V and RxD
Zoom image : http://googledrive.com/host/0BxMfsstZ1EMcfkYzSzFmTVRHZGg5UzUwQjlqbk1wTzJTNjJiMG9wRWRKdVZlMnlEbGVqZkE/chargedr/DSCN1580.jpg

Serial link : blue=0V, orange=Transmit (connect to dongle's RxD)
Zoom image : http://googledrive.com/host/0BxMfsstZ1EMcfkYzSzFmTVRHZGg5UzUwQjlqbk1wTzJTNjJiMG9wRWRKdVZlMnlEbGVqZkE/chargedr/DSCN1582.jpg

More images on the French forum : http://trottinetteselectriques.heberg-forum.fr/ftopic1000-0.html

Edited June 1, 2015 by hobby16

[Lorents]

Looks fantastic! Cant wait to get mine

[Lorents]

Woohoo, I received the Charge doctor yesterday!
Very fast shipping and a very cool product!

Tried it on two of my three chargers and this is what I found:

Airwheel X8 charger (without fan):
- Charges to 67,5V before reducing the current
- Rated for 1.75A, charges @ 2.00A

GotWay charger (with fan)
- Charges to 67,9V before reducing the current
- Rated for 2A, Charges @ 1.9A 

It seems like both chargers are charging with too high voltage, especially the GW charger. Is this a problemt for the battery or do the BMS protect the cells from overcharging?

Will try the last charger too as soon as I have a battery to charge

Edited June 4, 2015 by Lorents

[Lorents]

And my last charger:

TG-T3 charger (with fan)
- Charges to 67,3V before reducing the current
- Rated for 2A, Charges @ 2.04A 
- Light on charger turns green when charging @ 0.28A

Seems like the cheapest wheel came with the most accurate charger

Do anyone know if the BMS built into the battery packs will protect it from chargers with too high voltage?

Edited June 4, 2015 by Lorents

[EUC Extreme]

Did I understand correctly that, this can be put in after the original charger?
Gotway the faster charger to recharge 4A. Are there plans to do also like that speeds sturdy?

[Lorents]

Hello Vee,

Yes just plug this between the charger cable and your EU and it will show all kinds of neat stuff

Edited June 4, 2015 by Lorents

[hobby16]

 

Do anyone know if the BMS built into the battery packs will protect it from chargers with too high voltage?

​Hi Lorents,

It's nice to know you like the Charge Doctor.

All the BMS I know have a protection mosfet that cuts the current when the constant voltage phase ends to prevent overvoltage (see the schematics in my thread about BMS on the French forum).

You can let the charger connected for a long time, even with a open-loop 68V voltage (that what I have on one of my chargers). The Charge Doctor will show that the current always drop to zero, meaning that the BMS has cut the current. If not, it means that the BMS is in trouble.

[hobby16]

Did I understand correctly that, this can be put in after the original charger?
Gotway the faster charger to recharge 4A. Are there plans to do also like that speeds sturdy?

The Charge Doctor is rated for 3A maximum. 4A would be too much, especially for the wires.

I must verify the firmware conversion routine but I am sure I didn't program it for 4A.

[Lorents]

​Hi Lorents,

It's nice to know you like the Charge Doctor.

All the BMS I know have a protection mosfet that cuts the current when the constant voltage phase ends to prevent overvoltage (see the schematics in my thread about BMS on the French forum).

You can let the charger connected for a long time, even with a open-loop 68V voltage (that what I have on one of my chargers). The Charge Doctor will show that the current always drop to zero, meaning that the BMS has cut the current. If not, it means that the BMS is in trouble.

Exactly what I was hoping! If not I would have to ditch at least one of the chargers
So these chargers are more or less stupid power supplies that feed the BMS which again charge the cells, is that right?

[hobby16]

Exactly what I was hoping! If not I would have to ditch at least one of the chargers
So these chargers are more or less stupid power supplies that feed the BMS which again charge the cells, is that right?

Not exactly stupid but quite basic indeed since there is protection redundancy with the BMS.

[dranreb]

HI Hobby16, How do I order this? 

[hobby16]

HI Hobby16, How do I order this? 

​Hi, thank you for your request. It's like in the first post, prices haven't changed :

Price
15€ + 4€ international shipping = 19€, Paypal payment to

 

[Gimlet]

It's a great piece of kit with very useful information but it could do with a 4 pin converter so that it can be used on IPS wheels as well.

[dranreb]

Money is sent using Paypal.

Can't wait to check what battery capacity I have on my Gotway.

[esaj]

Just a heads up for anyone using the USB-dongle & PuttyTray: Newer PuttyTray-builds have broken the serial (and telnet?) connections, see  https://github.com/FauxFaux/PuTTYTray/issues/174

At first I thought that the dongle might be broken or send something that screws with PuttyTray (It exits with error message "(null)" when connecting), but after checking with Device Monitoring Studio that it was indeed sending datapackets, I searched and found the bug report. There's a link to unofficial build with fix in the bug-report, checked with Avast, no viruses found, and reading the data from Charge Doctor works with it: 

https://www.dropbox.com/s/399wk33z5p86pxg/putty_unofficial_GH-174_fix.zip?dl=0

 It's a stand-alone Windows exe-file, no installation needed.

 

Instructions for capturing Charge Doctor -data with Windows & Putty

When you plug in the USB-dongle for the very first time, Windows will detect it, look for suitable driver and install it. Before it reports the device is ready to use, don't try to do anything with it.

To find the COM-port and settings for the dongle, open Device Manager (Start -> Control Panel -> Device Manager) or directly Start- > Devices and Printers.

If using Device Manager, the device should be listed under Ports (COM & LPT), double-clicking it will bring out the Properties-view, from which you can select the Port Settings -tab. The COM-port is listed in the device name, on my computer it was using COM3.

If using Devices and Printers, scroll down until you find the device (your view might look different depending whether it's displayed with icons, details, tiles...), double-click it to open Properties, select Hardware-tab and click Properties -button, then select the Port Settings-tab.

The settings can be different on different dongles, just open up Putty and set same settings:

In the Session-view, you want to select Serial -type of connection, and enter COM<X> in the Serial line -field (<X> will be the number from device name, in my case COM3). Under Connection -> Serial -view, enter the COM<X> again in Serial line to connect to -field, and put same settings in Configure the serial line -part that were shown in the Port settings-tab (Speed, Data bits, Stop bits, Parity, Flow control). Finally you can go to Terminal -view and check the Implicit CR in every LF -check box, so it lines up nice (this has to do with how line endings are handled in different terminals). Finally, in the Session-view, you can save the settings by writing some name for the settings in the Saved Sessions -field and clicking Save. You can then reload the settings later on for another session without having to enter them again. If you want to save the session output to a file, for example to draw graphs in Excel or something, the data output is valid  CSV (Comma Separated Values) -file, you will find options for it under the Session -> Logging -view.

Either double-click the saved settings name in the list (The list is where the  "Default Settings" is shown in my screenshot) or click the Open -button. You're greeted by a black screen. The Charge Doctor will send a line of data every 10 seconds. Here's an example where I've first opened the Putty-session to the COM-port and then power on the Charge Doctor (it isn't connected to a wheel, as my battery is full, so all it shows is the voltage, other values are 0's):

The very first line is just some garbage from the line(?), then comes the greeting the Charge Doctor sends when powered up, the rest is the data it sends. Here's the data format from hobby16's first post:

Data logger
Charge Doctor sends out data every 10s in ascii line format with ',' separator, at 9600 bauds, TTL level
Line format:
Time (seconds), voltage (0.1V), current (10mA), Wh (0.1Wh)
Example:
590,596,193,183 <=> 590seconds, 59.6V, 1.93A, 18.3Wh

So in my case, it shows first sends 00,676,0,0 meaning 0 seconds passed, 67.6V, 0A, 0Wh (as there's no charging really occurring, it's just Charge Doctor connected to charger without a wheel to charge). Then the voltage goes up by 0.1V for the next 20 seconds (10,677,0,0 & 20,677,0,0), then I unplug the charger, and the Charge Doctor still manages to send one last message at 30 seconds mark with voltage 53.2V (30, 532, 0, 0), before the voltage drops enough to not be able to keep it powered up.

Haven't tried with Linux yet, but connecting to com-port should be easier on that anyway (if there are drivers for the USB-serial -dongle), as I'd expect I should be able to just pipe out from something like /dev/ttyS<X>.

Edited July 17, 2015 by esaj
Images lost... fixed

[hobby16]

Thank you @esaj

Putty is indeed tedious to configure. Its parameters are stored in Windows' registry so I can't add them to the exec.

To make things easier, I use a putty version accepting a config file. I have bunddled everything (putty & graphic plotter) in a zip file so all is needed is to extract, change the serial comport and launch, voilà. The tutorial is here : http://hobby16e.neowp.fr/charge-doctor-graphic-display/

Some examples of battery charge logging :

Firewheel 260Wh. Good Panasonic batteries, I can charge more than 280Wh

 

Gotway 340Wh. In fact, I can’t charge more than 300Wh. cheating from GW ?

Generic X3 Clone 130Wh. In fact, I can’t charge more than 125Wh, not bad.

[cg]

I have looked at the Doctor

It Is looking nice, bit is it possible to program it via the serial interface so it can limit charging to 80% capacity? perhaps by disconnecting after a set current or voltage?

[esaj]

I have looked at the Doctor

It Is looking nice, bit is it possible to program it via the serial interface so it can limit charging to 80% capacity? perhaps by disconnecting after a set current or voltage?

Maybe a DC voltage monitor -relay with configurable disconnect values could be used in series for such: http://www.bender.org/products/voltage-relays.aspx#Features

Features, emphasis mine

Key Features: VME421H

Digital voltage and frequency relay for single-phase AC and DC system

• Overvoltage, undervoltage, overfrequency, and underfrequency monitoring for single-phase AC and DC systems
• True RMS readings
• Digital display with values shown in real-time
• Separately adjustable alarms for each alarm type
• Onboard menu for settings; explicit trip values can be entered in
• Two SPDT contact outputs, independently configurable to any combination of alarm types

• Separately adjustable time delays for response delay, startup delay, and delay on release
• Built-in test and reset buttons
• Latching or non-latching operation, selectable
• Normally energized or normally de-energized operation, selectable
• Last tripped alarm value stored in memory
• Powers itself from monitored lines

 

 

 

 

 

 

That's just some random configurable AC/DC -relay that's meant to be connected to a DIN-rail (electric cabinets), so it may be a bit over the top & expensive in comparison to the need... I just found it via Google, probably best to ask from some electrics store.

[Tilmann]

Hi @hobby16,

I received your Charge Doctor a few weeks ago and loved using it ever since when charging my Gotway Msuper. Then I got an additional GW Mten and used Charge Doctor twice when charging it without problems. When connecting it for the third charge, I heard the typical "pew" sound of a short circuit and saw a spark flash from the Charge Doctor. I immediately disconnected the Charge Doctor and disassembled it for inspection. Here is what I found (pictures photoshopped for clarity of the details and I blurred part of the pcb, which does not show burn marks, to protect your IP):

Here is a more detailed view around R33, which appears to be blown:

Everything else does not show any visible signs of damage or shorts:

What upsets me, is that my Mten is not charging anymore after this incident. The charger (actually two chargers, both original GW, max. 2A) is still ok and works with the Msuper, but it stays on green when connected to the Mten, although its battery is empty.

 I did not open the Mten yet. Can anybody help with ideas?

[esaj]

 

hat upsets me, is that my Mten is not charging anymore after this incident. The charger (actually two chargers, both original GW, max. 2A) is still ok and works with the Msuper, but it stays on green when connected to the Mten, although its battery is empty.

 I did not open the Mten yet. Can anybody help with ideas?

At least on my Firewheel original charger, the light stays green when the charger is unplugged or the charging current is below 250mA. I also have a 4A Gotway-charger I bought off from vee during the summer for faster charging, which seems to behave similarly (don't know the current where the light turns green, as 4A is too much for Charge Doctor, but it's also green when disconnected from wheel), so based on this I'd claim there's no connection between the charge port and the battery BMS. With any luck, it's just a connection that's gotten loose or the plastic charge port has melted inside so that there's no connection, but in the worse case it's something that's blown from the BMS charging-side (overcharge protection mosfet? Just guessing really...).

As the wheel is pretty much brand new, I'd expect you'd get a replacement battery from Gotway under warranty?

[Tilmann]

Posting this on behalf of hobby16. He immediately responded to my troubles. As he can't afford to dive into the forum right now (I sure know how time consuming that can be ), here's his very plausible view, that Charge Doctor is an unlikely suspect in this incident:

 

Hi Tilmann

I am nearly sure it's the GW Mten which has a problem and causing the Charge Doctor to fail because of over-current and not the other way round. The Charge Doctor is a passive device, I can't see how its failure can grill the GW.

You have a battery or BMS problem over-current problem, probably a wire short which ends up fusing and giving an open circuit, hence no further charge possible, I've already seen it. Or (I hope not) worse, a faulty BMS, then you must ask GW for a warranty replacement. Sorry but you have to open the beast to see what's in there.

Give me your address, I'll send you asap a new charge doctor for replacement. Please, if you don't mind, once you receive the new CD,  send me back the dead CD, it's the first time such mishaps happens to it, I would like to make an autopsy.

BTW, you can show pictures of the internals of the Charge Doctor, I have no IP problem, lol !

BTW, you can post my followup and infos in the forum, no problem too. I avoid for the moment to go over there because I will be tempted to stay hours, you know what it is beeing sucked in a time consuming machine. You can announce I am on some nice projects for the wheel so I want to stay concentrated and finish them before getting back to the community.

Best regards,

Fred.

[Tilmann]

@hobby16    Updates:

1. Charge Doctor clearly had nothing to do with the charging problem of my Mten. When 1RadWerkstatt opened the battery pack, they found strong corrosion leading to shorts on several cells. The problem has been fixed under GotWay warranty and I am happy with the solution. There is no conceivable way, how Charge Doctor could have caused instant corrosion inside the battery pack.
2. Observations by @SlowMo lead me to a theory, what killed my Charge Doctor: his Charge Doctor blew when he connected the Charger to the EUC with Charge Doctor in between, but without the charger being plugged into mains. My speculation: I guess, there is a larger capacitor on the DC output side of the Charger. When the Charger is connected to the EUC's battery while this capacitor is unloaded, a momentary strong current from the battery loads the capacitor. This current in opposite direction may over-stress something in Charge Doctor and cause it to burn up (by the looks of it, a resistor). 
   Advice to Charge Doctor users to be on the safe side: always plug in the charger to the wall outlet first and connect the cable to the EUC charge port second.

[SlowMo]

5 hours ago, Tilmann said:

@hobby16    Updates:

1. Charge Doctor clearly had nothing to do with the charging problem of my Mten. When 1RadWerkstatt opened the battery pack, they found strong corrosion leading to shorts on several cells. The problem has been fixed under GotWay warranty and I am happy with the solution. There is no conceivable way, how Charge Doctor could have caused instant corrosion inside the battery pack.
2. Observations by @SlowMo lead me to a theory, what killed my Charge Doctor: his Charge Doctor blew when he connected the Charger to the EUC with Charge Doctor in between, but without the charger being plugged into mains. My speculation: I guess, there is a larger capacitor on the DC output side of the Charger. When the Charger is connected to the EUC's battery while this capacitor is unloaded, a momentary strong current from the battery loads the capacitor. This current in opposite direction may over-stress something in Charge Doctor and cause it to burn up (by the looks of it, a resistor). 
   Advice to Charge Doctor users to be on the safe side: always plug in the charger to the wall outlet first and connect the cable to the EUC charge port second.

Thanks for the valuable info @Tilmann. I already ordered a new charge doctor since my old one now gives false readings. I am happy to report that my MCM2s was not damaged. I was initially afraid since I saw the red charge lights blink around 4 times then stayed fully charged. Now it has gone to 3 bars at 62volts and my generic EUC charger works.

[mokwichi]

just ordered one of these. Cant wait to get it ad try it out...

[OneWheel]

Is there a way to power on the charge doctor display to check battery status while not connected to the wall outlet (while outside riding). Thanks.

Edited January 30, 2016 by OneWheel