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Old Feb 11, 2013, 07:39 PM
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Chris Nicastro's Avatar
Post Falls, ID United States
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Latest Opinions - Spark Arrestors

Im just wondering what the latest opinion is on the subject of Spark Arrestors built in-line compared to none at all.
I have run 12S with and without the spark arrestor and there is a huge difference in the condition of the plug after a few cycles due to the spark obliterating the tabs or barrel on a bullet plug.

Recently a friend asked me about how to make one for his new project, a converted large Ultimate Bipe to brushless power. He didn't like the spark he got and from plugging it in and was slightly burned once.
He called both Castle and BVM for advice and both said to him NOT to use a spark arrestor.
This puzzled me, Ive run a spark arrestor for a long time with no issues, why would they say not to run one? They claim it causes problems when arming with the ESC but no specifics were given.

Ive researched, designed and tested high current plugs which are currently in production. What I know of high current plugs is the surface area of the plug contact is what carries the current. Material and plating will also effect performance, goes without saying. The surface area should be as close as possible to the surface area of the wire strands that come in contact with the plug. By obliterating the surface of the plug with each connection made the plugs surface area is eroded. The blown out area causes less contact and arching which increases resistance and operating temps. I have seen plugs with poor contact or cold solder joints over heat and melt their solder joints. This becomes a point of failure, the weak link, in the system.

Basically the secondary spark arresting circuit doesn't add any significant resistance and even less if the plug is disconnected after the system is armed.

Ive run 12S on large racing catamaran boats, 4-6Kw, and have not had any problems when using a spark arrestor. I have had more issues and even ruined an ESC when not using one just arming it. If you know these boats they are high stress systems similar to EDF, they don't rest much.

So can anyone weigh in on this topic and explain why they do not use spark arrestors or what the effect is on the ESC, if any?
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Old Feb 11, 2013, 08:11 PM
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stoneenforcer's Avatar
United States, FL, Mt Dora
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i think it depends on the resistor load, which could possibly effect arming... just a guess.
maybe just call castle up and ask them why..?
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Old Feb 11, 2013, 08:39 PM
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WhalleyB0Y's Avatar
Canada, BC, Surrey
Joined Jul 2011
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I have thought about other ways of eliminating the spark and thought about using electrolyte grease on the connectors.
This is the grease used to protect trailer plugs and battery terminals from arcing on contact. Available everywhere where autoparts are sold.
Any thoughts on that?
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Old Feb 11, 2013, 08:46 PM
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I think this was posted some years back, but it may still be relavent See figure 1 for ohms.
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Old Feb 11, 2013, 10:20 PM
Life begins at transition
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From my understanding, the concern is the micro turns on at around 7V (assuming a 5V micro and a non-LDO voltage regulator). During the startup, it does two things that "can" cause issues:

a) measures the startup voltage to determine the number of cells connected. Simple solution: Don't use auto-LiPo. I think most using HV setups avoid this anyway.

b) make the beeping noises. When the coil in the motor is energised, it creates a magnetic field. The creation does two things - moves the motor slightly, which is where the noise comes from, and stores energy. The coil is then turned off, and the energy in the coil goes back into the ESC. That's entirely normal, and is where active freewheeling earns it's money.

Where this can cause issues though is the current flow during these on/off cycles can cause large voltage fluctuations on the supply line because the battery itself isn't connected yet (through a 1ohm resistor means a large voltage drop when we're talking tens of amps!). The supply line may drop below the minimum to keep the FETs open or closed properly, and potentially allow shoot-through. That means both the upper and lower FETs are on(or in this case, not fully off...) Basically, puts a wire between + and -. Not good!

A way around this, and how YGE works, is to put a FET between the capacitor bank's -VE and the battery's -VE. During startup, all the battery needs to charge are the small capacitors around the circuit. Thousands times less than the main caps, so no big spark.
Once the circuit is up and running, but before it tries to use the motor, the cap FET is turned on. This can be done slowly (microseconds), so as to be kind to the CAPs. Once the FET is fully on, the ESC is good to go.

A similar thing can be achieved by modifying the hardware of any ESC - cut the old caps off altogether, add new ones with a FET on the low side, and a small resistor/cap pair to slowly turn the FET on. Warranty? We don't need no stinkin' warranty!
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Old Feb 12, 2013, 07:30 AM
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if im reading this one correctly, i believe these are used as the main, not a jumper. thus eliminating a jumper

http://www.espritmodel.com/search.aspx?find=anti+spark
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Old Feb 12, 2013, 07:50 AM
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Quote:
Originally Posted by stoneenforcer View Post
if im reading this one correctly, i believe these are used as the main, not a jumper. thus eliminating a jumper

http://www.espritmodel.com/search.aspx?find=anti+spark
These Jetti Spark arrestors are the BEST IMO.
Honestly I don't understand why all the good manufacturers don't have spark arrestor circuits built into the ESC like some of the higher end ESC's from Europe.

Terry
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Old Feb 12, 2013, 11:29 AM
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Quote:
Originally Posted by Chuchuf View Post
These Jetti Spark arrestors are the BEST IMO.
Honestly I don't understand why all the good manufacturers don't have spark arrestor circuits built into the ESC like some of the higher end ESC's from Europe.

Terry
Money. It's extra components. Those Jeti connectors are electrically identical to the jumper solution, just a lot more convenient. I tried making my own, but the outer contact (the ring) kept breaking my resistors. Maybe I should just buy theirs!
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Old Feb 12, 2013, 12:49 PM
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i buy my resistors at radio wack. they're about a buck for 10. i just make my own jumpers. never had an issue.
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Old Feb 12, 2013, 01:18 PM
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Robert Belluomini's Avatar
United States, KY, Crestview Hills
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Here's an alternate solution for those controllers that may NOT arm properly with a spark arrester circuit.
Create and secondary connection as shown in post 4 above with expendable plugs and just leave out the resistor.
Always connect the secondary circuit first then the Primary circuit and you can leave both connected. As the connectors of the secondary circuit burn replace them
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Old Feb 12, 2013, 01:38 PM
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ive never had an arming issue. but i have seen caps blow from plugging 12s in with no pre charge.
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Old Feb 12, 2013, 02:48 PM
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The earlier Schulze ESC's were a perfect example
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Old Feb 12, 2013, 08:52 PM
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Chris Nicastro's Avatar
Post Falls, ID United States
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Quote:
Originally Posted by Robert Belluomini View Post
Here's an alternate solution for those controllers that may NOT arm properly with a spark arrester circuit.
Create and secondary connection as shown in post 4 above with expendable plugs and just leave out the resistor.
Always connect the secondary circuit first then the Primary circuit and you can leave both connected. As the connectors of the secondary circuit burn replace them
Thats a good idea as well. Some set of plugs would last for a while just for this use. As you say, unplugging and securing them afterwards would not be a big deal.
You can make a simple junction to the primary circuit thats not meant to take high current.
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Old Feb 13, 2013, 07:45 AM
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We ran the Schultze on a 14S 6500mA setup and they were the best. Plug in the batteries and the esc has spark arrestor circuit built in so no spark. I'm thinking they have a current limiting circuit initially there that allows the caps to charge and then they switch from that to full capacity.
IMO all the HV should be looking at this way of doing it.
Castle says that the spark is good, it lets you know the caps are working.
I say there is a better way.

Terry
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Old Feb 13, 2013, 09:34 AM
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Robert Belluomini's Avatar
United States, KY, Crestview Hills
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The Schulze ESC's have always worked flawlessly for me. The built in Spark Supression on the newer ESC's is so nice.
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