preventing sparking with high voltage
 

I found this article on MGM's site:

How to prevent sparking when connecting batteries with higher number of cells


Where do I get a metalized 0.6W, size 0207, 20Ω resistor?

I have never bought one before so have no idea which one would be ideal for this or which one to pick, all Greek to me.

Don't do this with a MMM it causes them to fail!

I thought Patrick stated in a post not to do this. I remember one of the guys here burning up his MMMs because of the installed resistor.

Yeah, I noticed BrianG also put it on his web page. To not install them on the mamba's.

http://scriptasylum.com/rc_speed/_nospark.html

This is good to know since I may own the MMM one day. Since I will be using this for my MGM, any idea what resistor I should get?

I am going to be starting another hobby in electronics this winter. I should know more about them then. You probably don't want to wait that long though. Check out the link I posted above. It has BrianG calculator that figures out what resistor to get.

I have seen that calculator but I just don't know anything about resistors, anyone have a link to one that will work with 6S or less?

Use the calculator to determine what value/rating resistor to use, then visit somewhere like radioshack, or DIGI-KEY.

the spark is the best part!!!! especially when someone unfamiliar with r/c is standing next to you!

It does not HAVE to be that exact type. The metalized will probably just be a bit smaller for a given wattage than a carbon type. And you aren't worried about high accuracy or noise (as some carbon resistors do with hi-end audio).

So a typical 1W 20Ω resistor from radioshack will be fine. Actually, any value from 10Ω to 50Ω will work, and power values 1w to 2w will be fine. You could even parallel a couple 100Ω 1/2w resistors (very common) and get the 50Ω @ 1w...

good info, I had went to radio shack just to look and did see them there. I will use this info when I go back to buy one. I had no idea they sold them, I was there for another item.

One question, is the spark harmful? When I saw how to get rid of the spark I thought it would be worth it to get rid of it. It just seems as if it could cause damage.

The spark will damage the plugs. You should see a few of mine that I used with 12S and even tried 60V once with my 40.160.

We need solid tungsten bullet connectors.... :lol:

Yeah, the spark will pit the connectors. Not only does this remove material, but the surrounding area gets sooty and does not conduct as well. Over time and enough arcing, the contact resistance will increase quite a bit - and contact resistance is a bad thing.

Some would argue it's better to just replace the connector every so often instead of using some type of resistor, but I kinda like to make my setups so that they last.

I have a question, what causes the charging resistor for spark control to kill the MMM?

The resistor itself doesn't cause the problem, it's the limited current being drawn while arming (beeping the motor). When the resistor is hooked up, the MMM attempts to arm, but when it does so, it tries to pull more current. When the current increases, the voltage drop across the spark resistor increases which reduces the voltage at the ESC.
Somehow, the MMM doesn't like the fluctuating voltage.

However, Patrick's warning was given when there was trouble with the BEC in V1. I wonder if it was just a coincidence, or if it would be ok now that the BEC issue is resolved?

so why cant you use the resistor to charge, then arm the esc?:neutral:

That might be a possibility, but you'd have to remember to have the switch shut off EVERY time.

Very true..... my MMM needs to get here faster.