Some people prefer to solder their motors directly to the ESC, and avoid using bullet connectors. This help reduce additional weights, and possible electrical resistance. However by using gold bullet connectors, things get more flexible as you can swap motors, ESC without any more soldering.
I personally prefer using gold bullet connectors on my bigger builds (450+), because I like “plug and play” style and I can carry the little extra weight. If ESC or motor goes faulty, I can just swap it out easily, or if I want to change the spinning direction of the motor, I can just swap two of the motor cables without the need of soldering.
There are many different sizes of bullet connectors, depends on the current rating and size of the motor/ESC wires. When choosing the kind of gold bullet connector for your copter, make sure the connector meets your electrical rating. I follow these rules.
2mm connectors - up to 20 Amps 3.5mm connectors - up to 40Amps XT60 connectors - up to 60Amps 4mm connectors - up to 70 Amps 6mm connectors - up to 120 Amps 8mm connectors - up to 200 Amps
2mm and 3.5mm bullet connectors are the most common and cheapest, and they are suitable for most of the hobbyist level quadcopters and planes. Apart from the current rating, I always look at the size of the wires too. Always choose the ones that fit your wires nicely. If you have to remove some of the strand in the wire your using to small of a connector.
11 comments
The current at the motor side of an esc is divided over three wires. That’s the reason why those wires are usually thinner than the two at the battery side?
Hi, I have a question for you and the community. I’ve recently begun a “low-KV” quadcopter build and want to know your thoughts on using 2mm bullet connectors from the 4-in-1 ESC to the motors. I primarily fly High-KV, motors 2450 and 2600 on 30amp ESCs (on 4S lipos) and have a pretty easy time mitigating current draw with that limitation. My thoughts are that I should be okay using the 2mm bullets (which you indicate have a 20/40amp continuous/burst current rating) with my new 2306-1800KV motors. I realize the props and lipo cell count could greatly change this scenario, and I’m very interested in any thoughts regarding this. The main reason I want to use these is for their size and form factor (plus the motors have 20AWG wires with fit the 2mm bullets like a glove (or vice versa).
but why there is no data on amps for 2.5 and 3mm?
I just completed a build of 450 with 3.5 connectors I like that can swap motors esc;s and direction without resoldering .
Would you recommend using XT30 connectors on quad motors?
depends, on Mini Quad? No. Just direct solder.
Direct soldering needs 1 blob of solder.
Connector needs 2 blobs of solder + weight of the connector !.
Thanks.. I was confused among these sizes. I’m buying all things online. I have no idea about the diameter of the wire connected with motor. i think 3.5 is better.
3.5mm bullet connectors are heavier than 2mm. That’s very important when you want to save on weight of racing quadcopter. I can’t say numbers, but I’ve ordered a pack of 20pcs. 2mm and one 20pcs. of 3.5… So… difference in weight you can feel very well =)) . IMHO… I will use 3.5 on a big frame where weight is not critical. (ex. QAV400)
True, but if you really care about weight, avoid gold connectors at all cost :D
this is very minor negligible weight.. or else.. just bind the wires and don’t even put solder on it.. :p because solder has it’s won weight too. :)