Adding "Reverse Diodes" to the Charger Port

[The Fat Unicyclist]

So here's a question for the more electrically inclined among us... 

Some wheels have what I have heard called a "reverse diode" (to protect from shorting across the charging port) and some don't.

Short of shorting the charging port out, is there a way to determine whether a wheel has a reverse diode? And if it doesn't, is there a "standard" mod that could be used to add one to any wheel (after all, the charging part is fairly generic)?

[Scott Henley]

17 minutes ago, The Fat Unicyclist said:

So here's a question for the more electrically inclined among us... 

Some wheels have what I have heard called a "reverse diode" (to protect from shorting across the charging port) and some don't.

Short of shorting the charging port out, is there a way to determine whether a wheel has a reverse diode? And if it doesn't, is there a "standard" mod that could be used to add one to any wheel (after all, the charging part is fairly generic)?

All the new KS wheels have the reverse diode . As far as I understand , GW wheels do not . Maybe the newer ones do...but im not positive. The 67v varieties of all the GW wheels I know for a fact do not though . There is a French company that sells “safe“  charging port replacements for these Wheels . It looks like a simple swap but since it’s in French I can’t understand anything they are saying about it . 

I believe that using a voltage meter at the charge port will tell you what you need to know . If it registers then no reverse diode. 

This is what I believe I know . Lol I may be wrong about some of this . 

[The Fat Unicyclist]

2 minutes ago, Scott Henley said:

All the new KS wheels have the reverse diode . As far as I understand , GW wheels do not . Maybe the newer ones do...but im not positive. The 67v varieties of all the GW wheels I know for a fact do not though . There is a French company that sells “safe“  charging port replacements for these Wheels . It looks like a simple swap but since it’s in French I can’t understand anything they are saying about it . 

I believe that using a voltage meter at the charge port will tell you what you need to know . If it registers then no reverse diode. 

This is what I believe I know . Lol I may be wrong about some of this . 

Do you have a link to that company?

And, are you saying that if I put a voltage meter across the charging terminals that I shouldn't get any reading if there is a reverse diode? Or, if I use a coin I will only get a loud bang if there isn't one?

[dmethvin]

21 minutes ago, The Fat Unicyclist said:

Short of shorting the charging port out, is there a way to determine whether a wheel has a reverse diode? And if it doesn't, is there a "standard" mod that could be used to add one to any wheel (after all, the charging part is fairly generic)?

Don't short out the connector on the wheel, you can easily ruin the connector. You could try measuring with a voltmeter but be REALLY careful because it's pretty easy to accidentally touch the outer metal ring and short the connector through that. 

Here is one that I have experienced with a wheel that doesn't have reverse protection. If you haven't plugged in  your charger for a while and plug it into the wheel before you plug the charger into the wall, you will usually hear a "pop". That's the voltage from the batteries in the wheel quickly charging the output capacitor in the charger. It's better to plug the charger into the wall first so that the output cap is close to the battery voltage. 

You could put your own diode after the charge port connector inside the wheel, but it will need to be beefy enough for the max current (say 10 amps or so assuming it's got some air around it to cool). The diode will cause a voltage drop of about half a volt but you should look up the exact number for the diode you choose. As a result of that extra drop, you won't charge the pack fully and it probably won't reach the voltage to do balancing although that may depend on the BMS.

[The Fat Unicyclist]

1 minute ago, dmethvin said:

You could put your own diode after the charge port connector inside the wheel, but it will need to be beefy enough for the max current (say 10 amps or so assuming it's got some air around it to cool). The diode will cause a voltage drop of about half a volt but you should look up the exact number for the diode you choose. As a result of that extra drop, you won't charge the pack fully and it probably won't reach the voltage to do balancing although that may depend on the BMS.

So you're saying that it really needs to come from the factory that way, and it isn't that practical to add to my wheel as a mod? 

[Scott Henley]

27 minutes ago, The Fat Unicyclist said:

Do you have a link to that company?

And, are you saying that if I put a voltage meter across the charging terminals that I shouldn't get any reading if there is a reverse diode? Or, if I use a coin I will only get a loud bang if there isn't one?

Wouldn’t try to use a coin . But voltage meter. Yes . I tagged you in the thread I saw the video on.

 

[Cranium]

Multi-meter will work well for testing.  If your's doesn't have one, it's easy to add.   Get a pin diode with a current and voltage rating above what you need.  Cut one of the charging port wires and solder the diode inline with the stripe on the diode away from the charging port.

[The Fat Unicyclist]

52 minutes ago, Cranium said:

Multi-meter will work well for testing.  If your's doesn't have one, it's easy to add.   Get a pin diode with a current and voltage rating above what you need.  Cut one of the charging port wires and solder the diode inline with the stripe on the diode away from the charging port.

And not that I have opened it up yet, but I assume it would be on the red wire?

[Cranium]

37 minutes ago, The Fat Unicyclist said:

And not that I have opened it up yet, but I assume it would be on the red wire?

I don't know if every EUC would be obviously colored red and black.  But since you have your multi-meter and if you determine there is no diode, you also know which pin is the positive side and can look for the wire attached to it.  Or just check polarity where it attaches to the circuit board.