Looking for motor wire plug testers

[DPeterson]

Now that we have a little traction under the motor testing adventure, I am looking for volunteers to do some motor wire plug testing.

I am looking for a person(s) to test various plug sizes, styles and solder types under various amp draws to determine which combination may de-solder at around a 100 amp draw. The 100 amp draw is a target for now.

My hypothesis: Amp draw through a particular size-style-soldertype wire plug will create a resistance that creates heat, which then de-solders the joint. This may be a 3.5, 4.0, or 4.5 size. There may be a couple different styles. There may be a couple different solder types.

With a race class that opens up the field for a few different motor Manufactures to participate, I am looking for this to possibly be our "parity fuse". Simple, cheap and fairly easy to tech. (not sure on the solder type?)

Depending on what may be needed I can fund the research. I for sure can provide a box full of 2030's.

Might be nice to have 3 or more persons researching this, as this would help to validate the results.

Let me know how we could proceed. Or give me good reasons this may not be a viable option.

Doug

[Mike Caruso]

Doug,

Is there such a thing as a slow blow circuit breaker? I am old so I do remember Glass slow to blow house fuses. Ha

Mike

[Whitey]

This is bad on so many levels.

Intentionally creating a failed solder joint and molten solder, at temps >370 F, in close proximity to LiPo batteries (which are protected by several thousandths of an inch of plastic wrap). Not a risk I would intentionally take.

Also, too many variables (solder joint quality, wire diameter, wire length, condition of connector surfaces, tension of connector prongs, likely more) to be an accurate gauge of the current level.

[DPeterson]

Hey there Kevin. Been awhile.

As for the molten solder and other things burning - it's already happening. I thought maybe the plugs de-soldering would be the least riskiest. They are usually under shrink wrap and inside the plug.

Yup - lots of variables as usual. I don't know if we need total accruacty but a ball park.

Don't know - thats why I put it out there for research.

Doug

[Whitey]

Doug,

For size reference, here are a couple of photos of a mockup the same size as the high amp fuses that I mentioned in the P-Ltd thread:
Fuse_Mockup_!.JPGFuse_Mockup_#.JPG

The fuse assemblies are not very large. The resistance added to the total resistance should be negligible if properly assembled.

The lugs soldered into the bullet conns would have to be heavy gauge, quality copper instead of cheap automotive or Rat Shack lugs. The bolts would need to be close fitting and capable of being torqued down good to minimize resistance. And, a piece of flexible silicone tubing can be used to slide over the assembly and insulate it.

And, the fuses can be bought for less than a buck apiece.

Far safer than melting solder joints. Cheating on fuse values can be controlled by the race officials passing out marked fuses. The correct current value fuse to put into use can be determined by multiple testers experimenting with 2 or more values of fuses.

KW

[DPeterson]

Hey Kevin
Everything I read and was told is that fuses just don't work. I am not smart enough to really know why. This is what got me thinking about the de-soldering route.

When the 2030's came out they came with the 3.5 bullits. We all started to de-solder them when we pushed the motor. We then all decided to run bigger bullits. Probably should not have allowed this. And I do not remember anything too dangerous taking place when they de-soldered. It was actually kind of nice. No motor damage. Easy fix.

Do you have any run time or test data to validate this concept? Maybe if we can get someone to step up to analyize the de-solder fuse we could also get them to do data testing on your fuse idea.

Later - Doug

[keithbradley]

The typical explanation for why fuses aren't used is because of the high resistance they add to the circuit. The bullet connector idea you have is really no different, you're just trying to design a fuse from my understanding (you WANT it to melt solder at 100A, right?). Any type of fuse is inherently going to add resistance to the circuit...if something is designed to heat to failure at 100A, by nature it's quite resistive at 90A.

A couple other things to think about:

1) A high degree of inconsistency in soldering quality. Some people have de-soldering problems with 5.5 bullets on semi-mild race setups, some people pull 300A without issue. I have to imagine the same would be realized here.

2) Ambient temperature. If your soldered connector fails at 100A on a 60 degree day, what's going to happen when it's 95 degrees? I have no idea how significant the difference would be, but there would definitely be a difference.

I don't mean to be negative and if I think of something that will work I will surely share it. It's standard for me to find what's wrong with my ideas and then try to see if those obstacles can be overcome, or if I need to scrap the idea and come up with something different. So, if it seems like I'm just finding what's "wrong" with it, please don't take it personally.

With that said, I suppose the fact that it adds resistance doesn't mean it can't be done. I'm not sure that people will welcome the idea though.

[DPeterson]

Keithbradley - thanks for the info. Also thanks to the couple PM's I got.

So - the resistance is there already because the plugs are already part of the circuit. So if the plug size and configeration was designed so that at normal or reasonable amp draw there were acceptable resistance levels and then if someone pushed this set up, to say maybe 20% above normal or reasonable amp draw, then it would de-solder. I wonder if this would be succesful?

I can see the variablitiy in acceptable solder jobs. Maybe this would teach those that have difficulty to improve their technic. :)

Not sure I could buy into the ambient temperature variability.

I am by no means trying to push this idea onto the rc boating community. I am just curious as heck.

I have access to a couple engineering colleges. I could maybe present this to them as a student project. What would be the opinions as to proper operating amp draw and then the assumed de-solder point if it was indeed feasable? I have no clue as I have only used the temperature gun on my set ups.

Doug

[photohoward1]

Was that really a Kevin whitehead sighting?

[photohoward1]

Explain to me why we can't have a restrictor type device that *!***!***!***!**s down at a specified amp draw? We should be able to design a device that monitors amps daw and opens a circuit at the specified draw.

[photohoward1]

Sorry for the spelling errors. Using my phone.

[PatrickM]

Howard-
Check out the power limiting devices that the airplane guys are required to use on Neu's website. The major problems with these devices are that a p-limited setup will exceed the limits of the largest device and the current sensor used is limited to 200 amps max. There's no reason why a similar device cant be designed and built for our needs, all we need to do is find someone willing to go to the effort for maybe 100 total units..... probably not enough profit in it to break even on the project.

[photohoward1]

http://www.neumotors.com/store/page19/page19.html

Doug, so why wouldn't something like this work. Set the limit to 800 or 1000 watts. If you go over it all shuts down. This way we could use any motor we wanted. Cheap throw aways or quality Nue or lehner that would run forever. Actually if you put a limiter on a 2030 it would run a Long time. What's $50 if we can use our motors season after season. I don't want to hear that guys can't afford the money. It's cheaper than a motor. Back in the 90s when guys ran 05 can motors I ran pletts.. I ran them for years and guys tell me it was money racing. In watched them go through 3 or 4 motors a season. Who was the fool?

[Peter A]

I've been reading (sometimes skimming) through all the P-ltd stuff that has been discussed lately. At the end of the day there will always be those who will push every rule and limit to gain whatever advantage they can to win. That is just human nature. I really question the sanity of creating rule after rule to try and contain it all. In the bigger picture will these things improve the quality of the racing and growth in our hobby? These classes are, it would seem at the mercy of a handful of manufacturers. I do get the point of the limited classes and personally like the concept, but will they last anyway? Technology changes things as most are well aware, and the rule books effectively must be 'living documents' so that things do not stagnate, die or become nothing but arguements. Keeping things as simple as possible is always better. I know that there is a whole lot of knowledge and experience out there that by and far surpasses the little that I have, and it has little to no impact where I am, but I think that some of this is heading off the reservation a bit. JMO. No offense intended though.