Battery sparks when connecting to controller

[BikeD]

I recently purchased a battery in a bag to go with a 350w 36v kit from Drift Maniac. I first connected the 2-pin waterproof end of the battery cable to the controller, then the XT60 end to the battery's XT60 connector. I had already connected the LCD display, but could not get it to light up, so I disconnected the battery at the XT60s to check the voltage. The battery voltage (39v) seemed reasonable, as I had not yet charged the battery. When I went to reconnect it, there was a strong spark, which melted the metal part on the negative sides of each XT60. Afterwards, the battery was still at 39v.

Why did this occur? How can I prevent this from happening again?

 

[harryS]

That kind of stuff happens when one of the connectors is miswired. I suppose you checked polarity of the new battery..The flat side of the XT connector is positive.

 

[BikeD]

The red pin of the cable I was provided is connected to the flat side of the male XT60. However, I cannot determine if this is the correct polarity for the controller. Neither of the male pins on the 2-pin battery pigtail from the controller have continuity to the chassis.

In the attached photo, the female connector at the other end is oriented so that it match the continuity of the XT60 pin adjacent to it, i.e. positive on the left when the notch is "down". Is this the typical convention?

 

[scrambler]

You need to check the controller manual or contact whoever sold it to you...
Hopefully you did not fry the controller

 

[BikeD]

The polarity of the battery is correct : Red is +, Black is -. However, the battery cable does not follow the usual convention. The red lead of the battery has continuity to the center jack of the 9-pin battery pigtail, which should be ground (black). Documentation said only "black male 2 pins plug - battery"

Hopefully the melting of the between the XT60s connectors during momentary contact was enough of a fuse, and I just need to them both. I am also considering making a XT60 jumper cable with a lamp inline rocker switch to be able to depower the controller gently.

 

[m@Robertson]

You need to check the controller manual or contact whoever sold it to you...
Hopefully you did not fry the controller

Or the battery. You can fry both with a short like that. I had one happen once and only once, and I got lucky with only a fried plug. But I have heard of others who were not so lucky and roasted components within their battery or controller, both.

The reason I had no damage to either my battery or controller was partly because I ALWAYS use a very short extension at the end of the controller cable and the battery cable. Usually with two pigtails I joined together to make a short cable. So when I am connecting live power, I am not doing so with a cable wired into the battery, or into the controller. When the connection fried, it ruined the XT60's that were involved. I just unplugged my short extensions, threw them away and plugged new ones in. Its a safety valve I only had to take advantage of that one time but it worked.

 

[postalstephen]

I recently purchased a battery in a bag to go with a 350w 36v kit from Drift Maniac. I first connected the 2-pin waterproof end of the battery cable to the controller, then the XT60 end to the battery's XT60 connector. I had already connected the LCD display, but could not get it to light up, so I disconnected the battery at the XT60s to check the voltage. The battery voltage (39v) seemed reasonable, as I had not yet charged the battery. When I went to reconnect it, there was a strong spark, which melted the metal part on the negative sides of each XT60. Afterwards, the battery was still at 39v.

Why did this occur? How can I prevent this from happening again?View attachment 159256

When batteries are connected to discharged capacitors there is usually a spark. In order to prevent sparks you can use a resistor between the ++ or the - - connectors with a wire connecting the other side. This will allow the voltage to charge the capacitors in your controller more slowly and without spark . After 10 seconds remove the resistor and plug the cable together.
50w 3RJ resistor (aprox.2" long)