RC Heli spark suppressor?

[DerekB]

Yes I got my mag.
Does any one know the formula to calculate the resistance ohms for the spark suppression circuit?
A great idea, good article except leaving out this important part.
And what does the other little bit do, the round orange thing?

[mkoutnik]

The round orange thing is resettable fuse, it's optional.

I agree, the article was OK, but lacked on the details.

[FatRat]

See this post:

https://www.helifreak.com/showthread.php?t=289341

[AnTi Taco]

http://www.xtremepowersystems.net/pr...ISPARK1&cat=34

[TheBum]

It's really dependent on the minimum voltage rise time the ESC logic circuit can tolerate. On my HobbyWing 70HV, it's 10 ohms.

[AnTi Taco]

Originally Posted by TheBum

It's really dependent on the minimum voltage rise time the ESC logic circuit can tolerate. On my HobbyWing 70HV, it's 10 ohms.

you got a pic on how yours looks?

[TheBum]

Originally Posted by AnTi Taco

you got a pic on how yours looks?

Here's a diagram.



The larger rectangles represent EC5s, the smaller ones represent JST connectors (not the same as JST-XH). The resistor was built into the negative power lead on the ESC from the factory.

[AnTi Taco]

can the SS be built into the series harness that way you don't gotta wire anything up on the esc wires?

[TheBum]

Originally Posted by AnTi Taco

can the SS be built into the series harness that way you don't gotta wire anything up on the esc wires?

You could, but it requires a slightly different approach. You'd have to put an inline bullet connection in one of the adapter wires with the resistor jumping between the two ends of the connection. The bullet connection would have to be completed last.

[s0laris]

So what size resistor for this setup

6cell 5000mah packs
Ice 100 esc

[Rick Dizzle]

Originally Posted by AnTi Taco

http://www.xtremepowersystems.net/pr...ISPARK1&cat=34

Will that work on a 12s power system to a castle 120HV?

[SkinWalk3r]

the Castle guys say that the spark is your "friend"...the guys that make that do hicky at xtremepower say that its not !

[Rick Dizzle]

The spark is good from what I understand as it shows the ESC capacitors are working. The spark is the immediate charge up of the capacitors. However, it arcs on your connectors just the same as a welder does (not nearly as dramatic of course) and over time can deform connectors. My buddy has one on his 600 and it is nice. No spark, no issue. His is different than the one pictured just wanted to see if this would work for my application.

[TheBum]

Originally Posted by Rick Dizzle

The spark is good from what I understand as it shows the ESC capacitors are working. The spark is the immediate charge up of the capacitors. However, it arcs on your connectors just the same as a welder does (not nearly as dramatic of course) and over time can deform connectors. My buddy has one on his 600 and it is nice. No spark, no issue. His is different than the one pictured just wanted to see if this would work for my application.

It also sends a high-current surge through the capacitors. I can't believe that the repeated surges don't gradually degrade the capacitors.

[gbidwell]

Originally Posted by FatRat

See this post:

https://www.helifreak.com/showthread.php?t=289341

I checked out this link and the calculations on this link http://scriptasylum.com/rc_speed/nospark.html differ from what was used in the March edition of rc heli mag.

For a 12s setup (like that in the mag) the above calculator recommends a 50ohm resistor with a rating greater than 8w in order to obtain a 0.25 second charge up period.

In RC heli mag the author used two 5w 4.7ohm resistors in parallel (equalling 2.35ohms with a 10w rating).
This setup would pull 21amps. Which is strange since the fuse selected was rated to trip at 3.2amps, meaning it would trip as soon as the spark suppressor was connected, increasing the resistance and reducing the current. So why not just use a resistor with a greater value in the first place?

article lacks too much info. I want to build one for my ice 100, but im not sure which method is correct

[Rick Dizzle]

Yeah I want to build one for my Ice HV120 but I can not figure out what I am suppose to use to be correct?! Any electrical engineers want to throw us a bone here? PLEASE!

[SkinWalk3r]

From where to where does one connect that thing anyway?

[hornet dave]

Radio shack carries a 1/2 W 5 or 10 ohm resistor (two to a package). One of these works fine for 12S and a castle HV esc.

[gbidwell]

different opinion again ...
"Lucien Miller, owner of Innov8tive Designs and US importer of Scorpion Power Systems, wrote me this email regarding how to make a spark arrestor for an ESC. With his permission, I am printing it here:

Yes, you can retrofit any ESC to add a spark arrester. All you need is a set of bullet connectors, a short piece of wire and a resistor. You want to choose a resistor that gives you an RC time constant of about 1 second. It takes 5 time constants for a capacitor to charge up through a resistor, so if you pick a 1 second time constant, it takes 5 seconds for the system to charge up, and this is the right amount of time to allow to minimize the spark and not take too long to charge up.

Here is what you do:

Step 1. Determine the resistor value.

Since capacitors are normally rated in Micro Farads (1 millionth of a Farad) if you take 1,000,000 (one million) and divide that by the size of the capacitor, it will give you the resistor value required, in ohms, to get a 1 second time constant. For example, if your ESC has 2 capacitors on it, and each one is a 330 uF value, the two of them together is 660 uF. If you take 1,000,000 and divide it by 660, you get a result of 1515 ohms. Resistors come in standard values like 1000, 1200, 1500, 1800, 2200, 2700, 3300, 3900 and so on, so you will need to select the closest standard value to what you calculate. In this case, we calculated 1515 ohms, and the nearest standard value would be 1500 Ohms, so that is what you would use.

The resistors also come in a variety of wattage ratings such as 1/8 watt, ¼ watt, ½ watt, 1 watt and so on. This is the maximum amount of power that the resistor can handle safely, and also determines the physical size of the part. Also, the larger the wattage rating of a resistor, the larger the lead wires it has, so that comes into play as well. The most power the resistor will see is when you first plug it in. Initially, you will have the full battery voltage across the part, and this will decrease as the capacitors charge up. To calculate the power in a resistor as a function of voltage, it is equal to Voltage squared divided by Resistance. In this case, lets assume a 6-cell Li-Po battery, which will have about 25 volts when fully charged. If we square 25 or take 25 x 25 we get 625. Now if we take 625 and divide that by the size of our resistor, which is 1500 ohms, we get 625/1500 which is 0.417 watts. We always go the next size larger on the resistor, so we would go up to a ½ watt resistor for this case.

Now we have determined that if the ESC has a pair of 330 uF capacitors, and we have a 6-cell Li-Po battery, then we need a 1500 ohm, ½ watt resistor. Pretty easy calculation if you know the math.

Step 2: Modify the ESC power lead.

Normally we cut the red lead somewhere in the middle and remove enough wire to allow for the body of the bullet connector. The size bullet connector used depends on the amp rating of the ESC. For ESC’s in the 20 to 55 amp range, a 3.5mm bullet connector is fine. For 60 to 100 amp ESC’s a 4mm bullet connector is adequate, for 100 to 150 amp ESC’s a 6mm bullet connector should be used.

After you cut the read lead and get the ends of the wires prepped for soldering, you also need to add the jumper wire. This wire can be much smaller than the power lead, since it only needs to handle the charge current of the capacitors. Normally something around a 20 ga or 18 ga wire is used. This wire is usually cut about 5 or 6 inches long, to allow it to loop back around to connect to the bullet connectors.

Strip one end of this wire and twist it around the end of the power lead that goes to the Deans connector. Then solder both of these wires into the male end of the bullet connector you are going to use in the middle of the wire. After you are done soldering, put some red heat shrink over the bullet connector.

Step 3. Add the resistor

No you can take the resistor and cut the leads so you only have about ½ inch sticking out each end. Solder the red lead that comes from the ESC into the female end of the bullet connector. After that is done, heat up the side of the bullet connector and put a dab of solder on it. Bend the lead on one end of the resistor so it angles down to go into the little solder blob you put on the side of the bullet connector and solder the resistor in place. Then take the other end of the small wire and solder it to the remaining wire on the resistor. You can put a small piece of heat shrink on the wire before you solder, big enough to fit over the resistor to help reinforce this solder joint. After you are done soldering, put a large piece of heat shrink over the bullet connector and resistor to finish the job. When finished, everything should look like this. You can see the resistor under the heat shrink on the female connector.



This set-up is for a very large 12-cell 130 amp ESC that has double power leads and a 6mm bullet connector, but it shows how everything fits together.

To use the anti-spark feature, unplug the bullet connector before you plug in the battery to the deans connector. Then plug in the battery. You will get a spark, but it will be very tiny, and almost not noticeable. After about 3-5 seconds, your ESC should give out its normal beep tones. Once you hear these tones, plug the bullet connector together and fly. When plugged together, the anti-spark device looks like this. Now it acts like a solid piece of wire and full current is allowed to flow.



Hopefully that answers your question, and gives you the steps needed to calculate the parts values to fit your ESC.

Lucien



Avant Aurora
Scorpion Power Systems
ThunderPowerRC
AMA #L315"

[cvcarl149]

instead of making a spark supressor how about a toggle switch on the battery power lead--would that work to suppress the spark? seems too simple!