Taming the dreaded 10s spark
 

As some of you large scale guys may know, you get one heck of a spark when you plug in an 8-12s setup. And Castle escs do not like slow charge up, so i thought why not put one of these http://www.robotmarketplace.com/prod...-SWHELLA2.html between the batteries and the esc so that you can plug your packs in and then flip the switch to let all of the voltage flow through the already connected wires to avoid the spark. Am i right on this? I mean the spark is from the caps charging up; correct?

Its going to spark no matter what. You are just moving the location of the spark to the inside of a switch rather than the battery connector. As far as i know the spark is harmless.

Triac switch.....

TRIAC stands for "Triode for Alternating Current", so can it even be used to switch a DC load?

I hate to say it but, I love the spark! There is just something absolutely wicked about the sound and look of all that power! Watch some newbies eyes bulge out when you connect and enjoy an evil chuckle.

A easy fix is to move up to 12s setup. Then the 10s spark wont seem so bad. haha

Of course it can! :smile:

It's just two SCRs connected inversely so it can conduct current in both directions. You could just use one SCR, but a Triac would allow for regenerative braking.

Seriously would it still spark just as bad if you had a switch turned to off when you connect the batts? The spark is completely harmless, it can seriously pit the connectors. Due to my limited hand strength, i usually need someone to connect them for me, which is difficult when there scared:lol:.

A triac has a ~0.7v drop so the power dissipated at ~20A would be 14w - not a small amount. Also, you would need quite a large triac to handle the 150A+ bursts without damage. If anything, a smaller triac could be used to get the caps charged up, then connect the main wires together (bypassing the triac) for running.

If you still want to go this route, I'd use a small bank of FETs to do the switching. That way, you can keep it in the circuit with minimal losses if you really want to use it while running.

Yes, the spark is still there because no matter if the ESC is on or off, the caps are the parts that cause it.

Basically the spark would just be transferred from the connectors to the switch contacts, and they would still get pitted after awhile.

Maybe use a parallel set of "sacrificial" contacts? Something easier and cheaper to replace?

Hey I didn't say it was practical... :whistle:

I am there with ya on that one. I went to the local flying club and watched this guy connect the plugs on his Trex 700 and boy what a show. Love it. I use extra caps on all my ESCs and get a decent spar too. Just change the connectors more often. No big deal, and keeping connectors fresh means lower resistance.

IIRC someone used to have a diagram of how to use a resistor on the neg side with a small bullet connector to let the caps charge slowly. I do remember pdelcast saying that was not good for a few of the cc escs...

BrianG has a calculator and wiring diagram for the spark eliminating circuit on his RC calc website, and it is noted on there that you can't do that with Castle ESCs.

I still dont see what the big deal is over the spark? Its really a non issue right?

Each time you see that spark the surface where the spark contacts gets pitted out. The higher the voltage, the bigger the spark, the worse the pitting. It hurts the continuity and life of the connectors.

I was considering using some dielectric grease on my CC 6.5mm bullets. Partly because they are so difficult to connect and disconnect but also to see if it helped any with the sparking. I also have considered using a sacrificial connector to save my 6.5's, I have some mini-deans I've been using for my servo's and BEC that could be piggy backed on my battery/motor leads.

I'll give it all a try when my MM XL shows up and I pull out the MMM.

Kind of a tangent, but I just picked up some sets of those mini-size T-plugs for my Xray M18T and they are great. The regular T-plugs are too big, and the micro ones are too small, but the mini are juuuusst right for 1/18!

They would work out well as a sacrificial spark connector. This is the only place I've seen lately that has them.

http://www.progressiverc.com/index.p...emart&Itemid=1

What i was getting at though is that the switch i had linked would be installed between the batteries and the esc switched to off essentially isolateing the batteries from the caps until everything is connected then turn it on. I dont care if a spark occurs inside the switch as long as i doesnt happen when i plug the batts in.:neutral:

You are correct, it won't happen when you plug the batts in, it will happen when you turn on the switch. You will just be transferring the spark point to the switch contacts instead of the battery connectors. IMO it doesn't make much sense to me to use a $33 switch as the "sacrificial" sparking point to protect the main connectors that cost probably no more than $5.

Ask BB16 or Mike I can't help jumping when plugging in the Baja on 8s with the size of the spark. I've worked out a trick though to just close my eyes for a split seccond when you do the first connect - No jumping!

That was hilarious..:lol:
As he is telling us about how he has gotten used to the large spark of 8s, he plugs his baja in and darn near levitated.

^ lol

Spark = good
No spark = bad

Even 6S is good to plug in at night. Only plugged 8S during the day & that's worth seeing too

At least i wouldnt witness the horror, i would just hear it.:lol: