Gotway charging ritual

[thwil]

The manual makes a point about a specific order of connections when charging a wheel. I have MCM4 HS but I suppose most Gotways should be nearly the same in this regard. The order is:

To charge:

    * Connect the three-prong connector to the wheel
    * Plug the charger to the wall socket

After having finished charging:

    * Disconnect the three prong from the wheel
    * Unplug the charger from the wall socket

Is this the ritual other Gotway shamans observe? I ask because even though I'm ready to accept this nonsense for the sake of preservation of an expensive piece of equipment, I don't like how too much seems to be dependent on a completely arbitrary order that's very easy to mess up.

What makes me especially worried:

    * When I start charging and connect the three-prong connector, there are sparks flying. I'm having a hard time accepting this as normal.
    * Until I plug the charger in the wall, its LED shows up as green. It's not a problem per se, but I think it's an indicator of a bad electric design.

So, should I worry more than usual about this or is this just how those things are?

[Jimi00]

I think all Gotway users do the exact opposite ! 

Charge:
1) plugin in the charger
2) plug in the GX16-4/3 in the wheel

Charge Finished :
1) unplug the GX16 charge connector
2) unplug the charger

No more sparks... The Gotways charge port are always under voltage (between 54 and 67V depending your wheel charge level). 

 

Edited June 12, 2017 by Jimi00

[Keith]

@thwil, this has been discussed on a number of occasions before. Whether the correct sequence is to plug into the wheel or the power socket first depends upon whether the charge socket has a protection diode included within it. Most do not.

If the charger is plugged into the  wheel first and it is without a protection diode then the smoothing capacitors in the charger will be in a discharged state. They will suddenly be presented with 60 or so volts from the battery and a short, but very, very high current will flow out of the battery into the charger causing a massive, and eventually damaging, spark. That confirms there is no protection diode in your charge circuit by the way.

If the charger is powered up first then it will sit at full charge voltage either 67.2V or 84V for the high voltage wheels. Even at a very low state of charge the battery is never going to be more than 12 volts lower as @Jimi00 has said above, also the smoothing capacitors are already charged up. Any spark (if there is any) will be insignificant.

If there is a protection diode then it will prevent current flowing from wheel to charger, thus resulting in it being preferable to connect to the wheel first as no current will  flow at all until the charger is turned on so there will be no spark at all providing the wheel is connected first. In practice it matters little what order they are connected if there is protection. Therefore when in doubt alsways power the charger up first.

The green/red charging light is also often misunderstood, it absolutely does not tell you charging has finished when it goes green. It is a VERY simple device, if more than somewhere around 200mA (depending on charger - but a low value of current) is flowing from the charger to the wheel then it turns red, if it is less than 200mA or so it turns green. Hence, the wheel is still taking a charge even when the LED has turned green - it is just that it is now less than 200mA. That charge will be helping to balance the cells so it is a good idea to leave it on for an hour or two (at most) after the LED turns green. However, if for any reason, due to a fault etc, no current can flow it will also turn green suggesting the battery is fully charged when it most certainly is not. 

Current flowing from the wheel into the charger, when the charger is not powered can be enough to power the LED's, since it is less than 200mA it will light the green one. 

[thwil]

Interesting. The manual that I was able to find says this, verbatim:

STEPS TO FOLLOW TO CHARGE YOUR BATTERY MONOCYCLE:

Caution: Do not handle plug dedicated to the load of the unicycle, battery or battery charger with wet hands or conductive objects.

To load your unicycle:

• Place the unicycle in a dry place at room temperature, a solid plan.
• To access the dedicated outlet to charge the battery, remove the silicone protection charging interface on the upper side of the hull of the unicycle
• The wheel charging should be done only when the machine is off.
• Insert the charger connector into the socket provided for this purpose.
• Check the correct insertion of the charger plug into the socket of the unicycle by placing the key slot opposite the slot provided.
• Next, plug the charger into your 240v electrical outlet.
• A red light will appear on the LED on the charger. It will turn green when charging is complete.

It's a funny dialect of English, but I read it as "wheel first, wall last". The finishing part matches in both cases though.

[esaj]

To further clarify what Jimi00 said above (and I think is exactly right), the issue with sparking is due to voltage difference. If there is no reverse polarity protection (with diodes or mosfets or whatever) in the BMS, the charge port will have the same voltage as the battery pack. If you now plug an unpowered charger (0V) in the port, the capacitors inside the charger will draw a sudden large current spike from the battery to charge themselves to the same voltage level when the connector is touching the pins in the port, and if the pins are at that point making a bit of a poor contact, sparks will fly. As the highest resistance is at the poor contact, that point will also waste most power as heat, and in worst case it might melt the pins or melt/deform the plastic parts, so in case of such BMSs, it's better to first power up the charger and then connect the GX16. For most other wheels, it's the opposite, first connect the unpowered charger (as the wheel charge port pins are unpowered too) and then plugin in the charger.

Having the charge-port powered at all times is both a risk (if you drop something metallic into the pins, it might short-circuit) and an opportunity for modders, as it would make it possible to power devices through the charge-port (of course take into account the voltage, if you plug a 5V device there, it will fry as the voltage can be anything between around 50V and 84V, depending on the battery configuration and charge state). If my KS's didn't have reverse polarity protection, it'd be easy to add voltage monitoring and riding lights powered directly from the wheel battery.

Quick simulation of attaching an unpowered charger (0V) with 2200uF capacitor to wheel with 55V voltage at batteries. The total parallel resistance of the packs is assumed to be 100 milliohms (a value I pulled out of thin air) over a 50 milliohm resistance at the connecting point. The current in this situation spikes up to about 350+A (the green line) and the power dissipation at charge port will momentarily go above 6kW:

 

[thwil]

I see, that's enlightening. Thanks everybody for such detailed replies! BTW, did anyone try to reverse engineer the charging circuits? Or would it be too damaging for Gotway's reputation to have them published?

In this case, I interpret my situation as such:

Sparks + Green Led when charger is off equals No Protection Diode (¿¿wtf Gotway??). Therefore, first charger to the wall, next three-prong to the wheel. 

 

[Keith]

41 minutes ago, thwil said:

BTW, did anyone try to reverse engineer the charging circuits?

To be honest there isn't a whole lot to reverse engineer, the charger is a pretty standard constant current -> constant voltage charger and in the wheel is just a BMS (Battery Managment System) that looks after the battery including charging. It was discussed extensively in the below post where I added a couple of simple schematics for how the BMS works: 

 

[meepmeepmayer]

If it sparks, you're doing it wrong. Also GW fixed that (I believe) but usually it was - plug into wall first, then plug into wheel to charge; end charging by removing plug from wheel (and possibly disconnecting the charger from the outlet for safety purposes).

There's a speedyfeet video about that, if you can find it (or maybe it was just part of some other video).

Edited June 13, 2017 by meepmeepmayer

[thwil]

The only problem with Speedyfeet videos is that there are too many of them. I think I remember seeing something about this before having bought the wheel, but finding it now doesn't seem possible. Anyway, I think the procedure is established and that's fine. The only thing that I don't agree upon is that "I'm doing it wrong". It's entirely a manufacturer's responsibility to make such essential things foolproof.

[meepmeepmayer]

It's a ridiculous noob mistake by Gotway and they fixed it. "You're doing it wrong" meant there are two ways of doing it (plug into wall first or plug into wheel first) and one of them does not produce sparks, even with the older wheels where sparks can happen.

[thwil]

Okay I thought my wheel is relatively recent, but I guess it's not recent enough.

[MaxLinux]

On 6/12/2017 at 5:30 AM, thwil said:

To charge:

    * Connect the three-prong connector to the wheel
    * Plug the charger to the wall socket

This procedure works fine for my IPS wheels, but for my Gotway, no good. I have to plug the charger into the wall socket first to avoid spark when connecting to the wheel.

Edited June 14, 2017 by MaxLinux

[man-on(e)-wheel]

Again: READ!THE!MANUAL!

[steve454]

Wall first or wheel first, if it sparks do it the other way.

[WARPed1701D]

If I may make a suggestion (for US owners anyway)...

Hailing from a country that had enough sense to put switches on their wall sockets I found it very hard to accept any kind of sparking while plugging stuff in once I moved to the US. Scared the living daylights out of me. Now on every socket in my apartment I have one of these:

https://www.amazon.com/Belkin-Conserve-Energy-Saving-F7C016q/dp/B005MYN3OO/ref=sr_1_1?ie=UTF8&qid=1499822994&sr=8-1

A pass-through wall socket with a switch on the side.

Plug into the wheel. Plug into the wall. (or vice-versa) THEN flick the switch. No sparks anywhere. Hooray!

[Marty Backe]

I'm late to the game on this subject, but since nobody has stated this yet, then here goes.

When Gotway introduced their 84 volt series of wheels (ACM, MSuper, and Monster) the issue of avoiding sparks went away. You can connect the charger to the wheel first or connect the charger to the outlet first.

[Acturbo]

On 6/13/2017 at 5:14 PM, thwil said:

Okay I thought my wheel is relatively recent, but I guess it's not recent enough.

I can confirm this is normal as an owner of an MCM4 HS myself.  Spark will occur when 3 prong is plugged in prior to plugging into the wall first.  Don't think your wheel is old or outdated.  I have a blast on mine and am going to stick with it for the foreseeable future.

[Mike Onewheel]

On 7/11/2017 at 10:38 PM, Marty Backe said:

I'm late to the game on this subject, but since nobody has stated this yet, then here goes.

When Gotway introduced their 84 volt series of wheels (ACM, MSuper, and Monster) the issue of avoiding sparks went away. You can connect the charger to the wheel first or connect the charger to the outlet first.

Hi Marty, its Mike in Tampa.  Do you know what would cause 1 out of 4 smoked pin on the charging port of a Tesla v2?

[Marty Backe]

13 hours ago, Mike Onewheel said:

Hi Marty, its Mike in Tampa.  Do you know what would cause 1 out of 4 smoked pin on the charging port of a Tesla v2?

Unfortunately, no 

[AtlasP]

 

On 7/11/2017 at 8:38 PM, Marty Backe said:

I'm late to the game on this subject, but since nobody has stated this yet, then here goes.

When Gotway introduced their 84 volt series of wheels (ACM, MSuper, and Monster) the issue of avoiding sparks went away. You can connect the charger to the wheel first or connect the charger to the outlet first.

 

 

My 100v Nikola+ purchased in ~Nov of last year still sparks loudly if I plug the charger into the wheel before plugging the charger into the wall, you have to do it the other way around. Never had an InMotion or King Song wheel do it, but my less-than-a-year-old Gotway that I paid $2450 for still does it every single time.

 

Edited July 21, 2020 by AtlasP

[Marty Backe]

2 hours ago, AtlasP said:

 

My 100v Nikola+ purchased in ~Nov of last year still sparks loudly if I plug the charger into the wheel before plugging the charger into the wall, you have to do it the other way around. Never had an InMotion or King Song wheel do it, but my less-than-a-year-old Gotway that I paid $2450 for still does it every single time.

I agree. Something seems to have changed semi-recently. I too generally always plug the charger into the wall first 

[Boogieman]

12 minutes ago, Marty Backe said:

I agree. Something seems to have changed semi-recently. I too generally always plug the charger into the wall first 

I thought everyone was well aware that plug goes into outlet first - then into wheel. Been like that for me since my nonebot mini plus 2018 and then Tesla 2018.
On my ninebot mini plus with and adaptor - i get sparks when plugging in the charger - not that strange due to adaptor being slightly smaller than std, but its AC voltage and I would rather have sparks there and fry charger, than have sparks and fry the connected wheel if charger fries upon connection.

Never had sparks when plugging connector to wheel after first powering up charger. I guess charger only activates output when there is a load (makes sense, otherwise it would never stop charging)

But putting wheel on tap before plugging charger should activate max charge as soon as those pesky metal pegs get close to the outlet. 

Edited July 22, 2020 by Boogieman

[Marty Backe]

3 hours ago, Boogieman said:

I thought everyone was well aware that plug goes into outlet first - then into wheel. Been like that for me since my nonebot mini plus 2018 and then Tesla 2018.
On my ninebot mini plus with and adaptor - i get sparks when plugging in the charger - not that strange due to adaptor being slightly smaller than std, but its AC voltage and I would rather have sparks there and fry charger, than have sparks and fry the connected wheel if charger fries upon connection.

Never had sparks when plugging connector to wheel after first powering up charger. I guess charger only activates output when there is a load (makes sense, otherwise it would never stop charging)

But putting wheel on tap before plugging charger should activate max charge as soon as those pesky metal pegs get close to the outlet. 

It's not a given. I know I had some Gotway wheels in 2017 that didn't exhibit the spark feature   It's been a long time though so the details are fuzzy.

[Rywokast]

i have always plugged the charger into the wall first, and waited about 10 seconds before plugging it into the euc... same for all brands.. if you have a charger with a display like the ewheels fast chargers you can see that the display does not show the desired voltage immediately, it takes a few seconds to get around where you want, and then a few more to stabilise, usually overshooting by .1-.2 volts... whether this makes any difference whatsoever or not, i cant say.. but it makes me more comfortable to see the numbers stabilise and to know the caps in the charger are full before plugging it into the wheel... as for gotway wheels sparking, well the charge port is live lol... dont stick your fingers in it, dont quote me but im pretty sure that it was actually ewheels that got them to put in some sort of diode or spark arrestor for the charging port so it doesnt do that, however its still live.... i believe that even to this day, if you bought from somewhere that isnt ewheels you will get this sparking (i may be wrong, they may have changed it so all wheels have this now).. whats really weird though is my nikola never sparked, and that wheel was from aliexpress, so im not sure if that wheel in particular or even that exact model of nikola doesnt spark, or that was when they started doing it for all wheels?

edit: this should only apply to gotway wheels, i believe it shouldnt make any difference in what order you do it on other wheels... but i still think this order is good practice for anything

Edited July 22, 2020 by Rywokast

[yourtoys7]

For me it sparks either way, wall first than to the wheel and wheel fist than to the wall. I usually plug wall first than to the wheel.