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Garrie Lim

King Song Lenovo Charging Port Question

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Hi guys, as some of you may know, I recently did a small DIY project to make a fast charger adaptor for my impending KS16X

I ride a Gotway MSX however and didnt have a chance to test the adaptor because there arent many ks18L/XL in my group. Most of us ride gotways or kingsong wheels with the usual GX16 port.

Today i had a chance to test the adaptor on a friend's KS18L. However when it was plugged in at the Lenovo end to the wheel(the other end NOT plug to any charger), there was no reading on the voltmeter. Turning on the wheel and plugging in again had no effect as well.

Now im pretty sure the polarity on my adaptor is correct as i followed the diagram on the back on the KS18XL charger, and it was also tested using a multimeter.

My question is, are kingsong wheels built such a way that i cannot get a reading just by plugging in the voltmeter even if the wheel is turned on? But if the other end is plugged to a charger and then the lenovo end is plugged to the wheel, then a current flows and i have a reading on the voltmeter.

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Just to clarify, I followed the polarity diagram on the charging brick of KS18XL and KS18L. 

Positive OUTSIDE and Negative INSIDE

Plugging my fast charger to the GX16 end (without plugging the lenovo end to a wheel) has a voltage reading ~84.0V

So now I'm wondering if my theory stands true and that everything will work once i plug one end to my fast charger and the other to my new KS16X

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Some wheels (including most newer King Song wheels) have a diode somewhere along the charging circuit for safety, so you won't be able to probe the voltage of the battery pack through the charging port unless the charger is connected. The benefit from this is that you can no longer blow out the charging port from dropping a metal object into it.

TL;DR: Yes, your theory stands true.

Edited by hyperair

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What do you need to know.  The pinnouts?    I know my 18xl intimately.

 

I installed an internal 84 volt boost circuit and a USBC trigger chipset so I can charge from 12-20 volts from laptop chargers.   I could have also done a port for car vehicle charging.

<a href="https://ibb.co/CQNYmhJ"><img src="https://i.ibb.co/6FVTrgv/20190628-045308-COLLAGE.jpg" alt="20190628-045308-COLLAGE" border="0"></a>

 

 

20190628_045308-COLLAGE.jpg

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I just need to know if there is really a diode blocking a voltage reading. 

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16 hours ago, hyperair said:

Some wheels (including most newer King Song wheels) have a diode somewhere along the charging circuit for safety, so you won't be able to probe the voltage of the battery pack through the charging port unless the charger is connected. The benefit from this is that you can no longer blow out the charging port from dropping a metal object into it.

TL;DR: Yes, your theory stands true.

But can you confirm that?

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14 minutes ago, Garrie Lim said:

I just need to know if there is really a diode blocking a voltage reading. 

Well, I don't know really, but likely there's a what's known as "ideal diode" circuit (likely in the battery BMSs) to prevent the flow of current in the wrong direction from the charging side. My Firewheel didn't have any protection, so it would allow the current to flow in the "wrong" direction, Gotways apparently still don't have the protection, but I think most current wheels do have it.

fiZ4ZFb.jpg

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8 minutes ago, esaj said:

Well, I don't know really, but likely there's a what's known as "ideal diode" circuit (likely in the battery BMSs) to prevent the flow of current in the wrong direction from the charging side. My Firewheel didn't have any protection, so it would allow the current to flow in the "wrong" direction, Gotways apparently still don't have the protection, but I think most current wheels do have it.

fiZ4ZFb.jpg

Yup I ride an MSX and I’ve got a voltmeter adaptor for it as well. 

 

I just need someone to use a multimeter against the KS18L/XL Lenovo charging port and confirm that there is no voltage reading. 

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26 minutes ago, Garrie Lim said:

Yup I ride an MSX and I’ve got a voltmeter adaptor for it as well. 

I just need someone to use a multimeter against the KS18L/XL Lenovo charging port and confirm that there is no voltage reading. 

95% sure the answer will be "no reading". ;) I don't think any KS ever had a "live" charge port. But it doesn't hurt to check.

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5 hours ago, Garrie Lim said:

I just need someone to use a multimeter against the KS18L/XL Lenovo charging port and confirm that there is no voltage reading.

I can do that for you...

5 hours ago, esaj said:

95% sure the answer will be "no reading". ;) I don't think any KS ever had a "live" charge port. But it doesn't hurt to check.

I would have said the same @esaj - But was moderately surprised to find that there is a reading...

My 18XL showed a charge of 1.2 volts across the charging port while turned off.   :huh:

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Just now, The Fat Unicyclist said:

I can do that for you...

I would have said the same @esaj - But was moderately surprised to find that there is a reading...

My 18XL showed a charge of 1.2 volts across the charging port while turned off.   :huh:

There's a very small leakage current through the mosfets used in ideal diode-circuit, the meter has high input impedance/resistance... not surprising that you see a small voltage, but nowhere near the full voltage of the actual batteries.

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9 minutes ago, esaj said:

... but nowhere near the full voltage of the actual batteries.

Definitely not!

I hope that answers your question @Garrie Lim. And while I had the meter out, I also confirmed that it is positive on the outside.

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16 minutes ago, The Fat Unicyclist said:

Definitely not!

I hope that answers your question @Garrie Lim. And while I had the meter out, I also confirmed that it is positive on the outside.

Thank you very much. That is very helpful!

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