Fried XT-60's

[t_tberg]

I was overvolting a generic 1000W hub motor using a Lyen controller and 20s of 5000 mAh of lipo. Four 5s batteries wired in series, I no problems. I acquired two more of the same 5s batteries and made a 15s2p harness - two sets of three in series and the two series connections were paralleled. I used a new XT-60 and plugged it into the old one that was on my bike. BIG sparks, this seems to happen when I use a new connector, however, this time the XT-60s were completely blacked and the connections were visibly melted and wouldn't fit into each other. Why does this problem occur? I've heard of using pre-charge resistors but I didn't think it would be necessary for 55.5v when 74v seemed to hold up without. Any thoughts on how to avoid melting my connectors again?

 

[spinningmagnets]

It looks like you have a short from the harness being mis-wired. If that's true, then the XT60 's acted like a fuse.

 

[Ykick]

Any thoughts on how to avoid melting my connectors again?

Use correct polarity.

 

[t_tberg]

Thanks,

After a quick review you're both right. Using 4mm bullet connectors for the parallel connection I didn't consider that they would plug into each other opposite.

 

[ecycler]

I would call that a narrow miss of some KFF!

 

[galvatron1]

I just tried plugging in my new battery pack I bought from Backfire, and I saw a big brown spark through the yellow plastic as the connectors touched, then quickly pulled them apart. Is my XT-60 connectors about to get fried too? I didn’t expect that from a prebuilt board like the Backfire G2, using the recommended battery from the same company. Is there an anti-spark attachment I can just fit over the plug, or is this a more serious issue? Thanks!

 

[DogDipstick]

I just tried plugging in my new battery pack I bought from Backfire, and I saw a big brown spark through the yellow plastic as the connectors touched, then quickly pulled them apart. Is my XT-60 connectors about to get fried too? I didn’t expect that from a prebuilt board like the Backfire G2, using the recommended battery from the same company. Is there an anti-spark attachment I can just fit over the plug, or is this a more serious issue? Thanks!

If you co not have an "antispark" or " precharge circuit" you can use a simple resister to bring the bikes power rail voltage up to the batt voltage slowly.... a jumper with a resistor ( 100-100Ohms) and a jumper for the negitive.. wait a few seconds, and then fully connect the poles. No/less spark.