Max current for 9-pin motor connectors

[liontail]

What is the maximum current (and voltage) that the standard moulded 9-pin motor connector can tolerate?

I'm talking about this connector:



I searched around on the forum, and got unsubstantiated answers between 12 amps and 30 amps. I didn't find any reports of a failure of this connector.

I believe the connector is made by Julet, and rebranded by 8FUN. I could be wrong - 8FUN might be making their own version.

I build ebikes for a living, and have used this cable at 52V 20A and 36V 25A regularly and without issue. I had one failure of the female end, but I believe that was from one of the pins becoming displaced and not from overheating.

Please report on your experience (and current/volts) with this connector, and any failures you have encountered. I am particularly curious if it can reliably operate at 52V 30A.

 

[mr.electric]

I would guess 30 or 40 amps at 48v
Only the 3 larger pins actually see high current, maybe split them off.
I have used various plugs from the rc world to make better high current connections. For my own personal bikes I crimp connect everything with no connectors just to eliminate that issue. Need to disconnect, cut the wires. It sounds stupid but it is really hard to get all your plugs positioned right on a custom build, they can pull apart, melt, corrode etc. if I were doing more custom builds I would invest in a crimp on plug system like Anderson power pole or similar. I find soldering is time consuming and excessively smokey for large gauge connectors.

 

[dogman dan]

I would not push one past 25 amps. Of course, a loose contact can cause failure much lower current that. This is a plug defect, if it happens with a fairly new plug. It can happen, but it's not common.

When I push that type plug to the limit, like in a motor test to destruction, the whole wire gets nice and warm. It's clearly not ideal for 1000w continuous for a half hour. But the motor fails before the wire, if the motor fails at all. My "test" is a 5 mile ride of gradually increasing grade, in 100F weather. The last three miles are 5-8 %. Not much of a test, till you factor in the trailer full of water jugs. So the total weight is 400-450 pounds.

The wire gets very warm, but passes. Very few riders will put that much continuous current through the plug. They don't have that long a hill non stop, they don't weigh that much usually. It's fine for 1000w briefly, including the very short 1200w spike when using a 22 amps controller.

The only big problem with this plug, is people plug it in wrong. The arrows are a bit hard to see, and it's not keyed.

 

[liontail]

Hey Dogman Dan -

That's awesome feedback. In your test, are you saying you're running 14S and 22A max current?

1000W seems like a reasonable max.

Thanks!

 

[spinningmagnets]

The five hall sensor pins run 5V at very low amps...this connector is more than adequate for that at any motor power level.

The only issue is when you want to run more than 20A through the three large motor phase pins. if the pins are getting hot enough that you are uncomfortable holding your hand on them, then you need fatter and longer pins and sockets...for those three.

 

[amberwolf]

Just a question to clarify things for others reading this thread:

For those stating the current and voltage they're using these at, are you referring to your actual phase currents you've measured, or are you reporting the *battery* current and voltage?

If the latter, that says nothing about the current actually passing thru this connector, which would be for just the motor phase (and hall/etc) wires.


To determine the currents actually being used with these connectors, you would need to measure them, and since they are 3-phase AC not DC, and generally non-sinewave AC at that, it's more complicated than just putting a meter in series with one or more of the phases to measure it. :/


However, if anyone wishes to look at various other connector types with similar pin styles and sizes, like some of the Canon "military / aircraft / test equipment" types, it would be simple enough to look at their ratings per pin to make a good estimate of what the type under discussion in this thread might take.


Alternately, a destructive test on an actual connector of this type could be performed, using DC current and a meter, and simply increase the current until significant heating begins, and then until failure of housing (melting plastic) occurs from the heat, and then call the "limit" something below that.

 

[motomech]

The Bafang BPM's come w/ that connector and lot's of folks rum them on 48 Volts and 30, 35 and even 40 Amps.

 

[amberwolf]

Battery current, or phase current?

 

[motomech]

I should have been more specific; Rated controllers.

 

[jase1979]

Sorry a bit off topic, but can anyone provide a link to where I can get one of these cables please?

 

[motomech]

Where are you?
Profile please.
Luna Cycles for the cable, assuming you are in the US.

 

[Bullfrog]

Grin Tech says 30-40A but I am fairly positive that is phase amperage and like others have said, the phase amperage is constantly fluctuating so not really something you can use. This is a link to the Grin Tech info:

https://ebikes.ca/learn/connectors.html#:~:text=The%20Z910%20plug%20is%20a,as%20a%20motor%20temperature%20sensor.

I did read a report on Amazon of somebody running a 35A (battery amperage) controller and they melted the Z910 connector.

Based on the info above and everything I can find, I wouldn't use the Z910 connector for a kit rated over about 1,000A.

A simple rule of thumb check is if you can't hold it in your hand without letting go, you are over stressing it...sort of the same rational as others have stated .

One really nice thing about the Z910 connector is they are usually the same diameter or smaller than the axle diameter so you can slip a torque arm over the connector when installing the motor. That is very nice because it can be a real pain to remove and replace connectors.

 

[Bullfrog]

What is the maximum current (and voltage) that the standard moulded 9-pin motor connector can tolerate?

I'm talking about this connector:

View attachment 205687

I searched around on the forum, and got unsubstantiated answers between 12 amps and 30 amps. I didn't find any reports of a failure of this connector.

I believe the connector is made by Julet, and rebranded by 8FUN. I could be wrong - 8FUN might be making their own version.

I build ebikes for a living, and have used this cable at 52V 20A and 36V 25A regularly and without issue. I had one failure of the female end, but I believe that was from one of the pins becoming displaced and not from overheating.

Please report on your experience (and current/volts) with this connector, and any failures you have encountered. I am particularly curious if it can reliably operate at 52V 30A.

Just a data point...I have been running my DD Hub Motor with a 52v battery and a controller that has a 30A maximum rating with no problems. If anybody has exceed my specs, please let us know and the results.

I previously mentioned failure of the connector with 35A but I did not personally verify the info...it was 2nd hand.

 

[999zip999]

I live in a place where it doesn't rain much and that's the first thing I cut off

 

[amberwolf]

Just a note: the controller current limit and the current seen at the phase connector is different; a decent rule of thumb is 1.5x the battery / controller current at the phase wires. (programmable controllers may be able to set a specific ratio or specific phase current; some like Kelly may set a phase current and then the battery current is determined from that).