Large spark from XT90 connectors

[jes1111]

Ok an update on that, I have just watched another on installing on 10 AWG and it doesn't look as straight forward, requires another expensive tool and seems quite bulky.
http://youtu.be/5l31i571S6Q

That's the 75A version - a MUCH bigger beast (and capable of WAY more than 75A, btw).

A good tool for the 15/30/45A Powerpole crimping is this one. Since that's about one tenth of the cost of my soldering station, I'd say it's pretty cheap

Connectors from here (but note the cost of the "official" Anderson crimpers they sell!). Ring them and ask for the Superflex versions - they fit the multistrand wire better.

 

[Bartman]

they've been used thousands and thousands of times in the RC world, why is that not proof enough that they work fine? soldering into the adjacent wire is poor technique, not a problem with the connector. regarding hackles, the connectors weren't being discussed, arcing was. your compulsion to discuss connectors was the first of the hackles to rise. fwiw, the connectors mentioned all use the sides of the terminals for contact but that hasn't been acknowledged yet.

fun stuff.

 

[PeterLester]

Apparently even batteries have, in addition to internal resistance, some internal capacitance (not to be confused with capacity) especially those batteries that are constructed in a manner similar to a foil wrapped capacitor such as the LiPo.

Using a commercial capacitance meters one could place the battery in series with a capacitor (C1) of known value.
C = 1 / C1 + 1 / Cb
where Cb = battery capacitance, C1 is the known capacitor, and C is the measured capacitance of the two in series.
Cb = C1 / ( C*C1 - 1)
But personally I would avoid putting a good, fully charged LiPo battery thru this kind of testing.

Quinton, the sparking is normal. THe motor controllers have large capacitors which act as reservoirs for electricity. WHen there is a large and sudden demand for electricity, the batteries get a little help from the charge stored in the capacitors and when the batteries get caught up the capacitors get recharged.

When you first plug in the batteries the charge in the capacitors is zero and so there is a rush of electricity as they quickly go to full charge. The spark is from this virtually unlimited flow of electricity. One way to minimize the spark is to lean the positive side of the connectors together before pushing the connectors together. BY doing this the spark happens on the negative poles of the connectors and the spark will be lessened as the current has to flow through the capacitors and the rest of the circuitry before getting to where the contact is being made.

Hope that helps,
Bart

 

[Quinton]

That's the 75A version - a MUCH bigger beast (and capable of WAY more than 75A, btw).

A good tool for the 15/30/45A Powerpole crimping is this one. Since that's about one tenth of the cost of my soldering station, I'd say it's pretty cheap

Connectors from here (but note the cost of the "official" Anderson crimpers they sell!). Ring them and ask for the Superflex versions - they fit the multistrand wire better.

Thanks for the links, I might actually buy a few to compare to the XT60/90 connectors, just wondering if they are actually as good as you say why isn't everyone using them?

 

[jes1111]

they've been used thousands and thousands of times in the RC world, why is that not proof enough that they work fine? soldering into the adjacent wire is poor technique, not a problem with the connector. regarding hackles, the connectors weren't being discussed, arcing was. your compulsion to discuss connectors was the first of the hackles to rise. fwiw, the connectors mentioned all use the sides of the terminals for contact but that hasn't been acknowledged yet.

fun stuff.

"Working fine" is good enough for some - I choose a higher standard, because I want to reduce the chance of an in-flight problem to as low as I can manage it - for the sake of nearby property and people and, not the least, my investment. That's sensible, isn't it? What I can't understand is your intense need to defend RC-specific connectors (Deans in particular IIRC). Their prevalence in the RC world is not an endorsement of their merit but rather an illustration of the widely-held misconception that "most popular" is, by definition, "best". Like I said, I only started out to highlight the designed-in tolerance of Powerpoles to arcing. Really, it's you widening the issue, not me

 

[Bartman]

designed-in tolerance of Powerpoles is shared by other side-contacting connectors.

no need to defend, just to balance your obsession with electrical connectors. this thread wasn't about connectors and the point you're making about the anderson connector is shared with the others mentioned. you questioned his choice of the XT-90 (not my first choice but i don't go around questioning everyone's every decision) which is fine and I questioned your insistence that other connectors aren't suitable when they definitely are as evidenced by the gazillions in use many by me personally over years of success. it's common sense really.

 

[jes1111]

Thanks for the links, I might actually buy a few to compare to the XT60/90 connectors, just wondering if they are actually as good as you say why isn't everyone using them?

Good question - as already mentioned, many balk at the price of the crimp tool. But I believe the major reason is being illustrated right here (again ) - the peculiarly fierce allegiance some people have to their particular choice and the instant cries of "Heresy!" if one dares even suggest there are better alternatives from outside the RC world. Those people can get so vociferous that the "undecided" may mistake "zeal" for "sound engineering judgement"

Side note: some years ago, in the early days of electric RC when brushed motors were used it was also common practice to use an aerosol "motor cleaner" to shift the dust build-up from the brushes wearing. That solvent was discovered to attack and soften the plastic housing of Anderson connectors - they lost some ground because of that. Brushless motors have absolutely no need for that gunk, so no worries - I only mention it in case someone else knows that history and jumps on me some more.

 

[jes1111]

http://en.wikipedia.org/wiki/Xenophobia

 

[jes1111]

designed-in tolerance of Powerpoles is shared by other side-contacting connectors.

no need to defend, just to balance your obsession with electrical connectors. this thread wasn't about connectors and the point you're making about the anderson connector is shared with the others mentioned. you questioned his choice of the XT-90 (not my first choice but i don't go around questioning everyone's every decision) which is fine and I questioned your insistence that other connectors aren't suitable when they definitely are as evidenced by the gazillions in use many by me personally over years of success. it's common sense really.

If it makes you feel better, bart - I'm "obsessed" with every flight-critical component, not just connectors.

I didn't question his choice of connector - I was enquiring as to why he would need any connector rated at "90+ amps" on a multirotor. The implication was that the wiring would be deliberately routing the entire "pull" through a single wire/connector path - not good practice for a heavy-lifter.

this thread wasn't about connectors

My mistake - we were discussing recipes for Banoffi Pie and I went off topic. Apologies.

your insistence that other connectors aren't suitable

I defer to your obvious skills in reading the written word. Just so I don't slip up again, could you possibly quote where I said that? Thanks.

 

[Quinton]

I didn't question his choice of connector - I was enquiring as to why he would need any connector rated at "90+ amps" on a multirotor. The implication was that the wiring would be deliberately routing the entire "pull" through a single wire/connector path - not good practice for a heavy-lifter.

Sorry for interrupting, but this is where I get really confused.

You said the following..
The "45A" label is misleading - it's there because that's the official NEC/CEC rating of 10AWG wire (which is for domestic installation in an unventilated conduit, etc. etc.). The reality (for our application) is that the connector can take whatever the wire can take and 10AWG is the largest wire that will fit inside the Powerpole, i.e. a "45A" Powerpole matches the ampacity of 10AWG wire, which is more than 45A (in our application). User reports of "45A" Powerpoles easily handling 100A are easy to find in RCG, etc.

What is the difference between that and the 90A rated XT90? You will only be needing the amperage that your ESCs/Motors require will you not.
One of the biggest reasons the XT90 is used is because the lipo wire is 5.5mm and xt60 plugs are only 5mm?

 

[jes1111]

Yeah - sorry about the distraction, Quinton. We're all in a muddle now because somebody diverted the thread somewhat.

I asked originally about the need for a 90A-rated connector because of the implication that your rig was actually expecting to pass 90A through it, which will easily occur if, for example, you use one humongous big battery pack to supply the whole rig. Asking a 10AWG/6sq.mm. wire to carry that much is IMO inappropriate. Let's say you have an octo with 400W motors fed with 6S, i.e. 22.2V nominal. At full chat, that's (potentially) 18A each, so 144A for the whole rig. My suggested strategy is to spread that load across 3 or even 4 battery packs. Instead of, say, one 8000mAh pack, use 4 2000mAh packs or 3 2800mAh packs. With 4 packs, each only has to supply one quarter of the total current demand - 36A. Each of the 4 packs would be plugged directly to a "bus bar" - usually a power distribution board of some sort. This "bus bar" is the only component in the rig that's carrying the entire current, so make sure it's up to the job (without being excessively heavy). Now your battery connectors and the wires have a relatively easy task - no stress, no strain, no chance of excessive heat leading to failure. The small weight penalty (of 4 packs instead of one) is more than compensated for by the reliability gain (and, ideally, less voltage drop between battery and ESC). There's no need for any single connector or wire to carry 90A. Added advantage - one pack out of the four could have a ****y fit during the flight and you'd probably still make it to the ground in one piece.

As you say, most packs come with 10AWG wires, so you need a connector that's able to attach to that. An XT90 pair weighs 13g (apparently) and we need to add a couple more grams for solder and heatshrink - let's call it 15g. Four pairs weighs 60g - I'd say that was excessive since they only have to carry 36A max each. On that basis alone, I'd disqualify XT90s for the job, but as you say, XT60s have trouble with 10AWG. Four Powerpole connections would be (@6g each) 24g total. And they can be locked together for absolute peace of mind. And they're more or less impervious to arcing damage. And there's no solder so less chance of an internal breakage. And they're cheap... etc. etc. (oops! now I am pushing the Powerpoles )

 

[Quinton]

Hi Jes1111

Honestly you put up a very good reason for using the APP, I am crap at soldering, but getting there.
I appreciate your feedback, at the moment its 6 of 1 half dozen of other as I haven't invested too much money yet in connectors so I am open to suggestions.

At the moment I am making the following Skyjib 6 Ti and the Droidworx Power Distro Board which holds the ESCS very neatly under the crash cage.

Tiger Motors 3515-15 along with 15x5 props and Hobbywing Flyfun 40A opto 3.5mm banana bullet connectors connecting the motors to the ESCs
The motors came with the bullet connectors, and EC3 bullet parts were used for the ESCs without the outside plastic part.
XT60 would be hard to use as the diameter of the hole is a very tight squeeze for the 10 AWG, so I would have to make the diameter of the wire smaller to fit probably.
At the moment I only have 2x 6200 MAh Desire 6S 22.2V lipos.

 

[jes1111]

Hi Jes1111

Honestly you put up a very good reason for using the APP, I am crap at soldering, but getting there.
I appreciate your feedback, at the moment its 6 of 1 half dozen of other as I haven't invested too much money yet in connectors so I am open to suggestions.

At the moment I am making the following Skyjib 6 Ti and the Droidworx Power Distro Board which holds the ESCS very neatly under the crash cage.

Tiger Motors 3515-15 along with 15x5 props and Hobbywing Flyfun 40A opto 3.5mm banana bullet connectors connecting the motors to the ESCs
The motors came with the bullet connectors, and EC3 bullet parts were used for the ESCs without the outside plastic part.
XT60 would be hard to use as the diameter of the hole is a very tight squeeze for the 10 AWG, so I would have to make the diameter of the wire smaller to fit probably.
At the moment I only have 2x 6200 MAh Desire 6S 22.2V lipos.

Nice machine

Nothing wrong with bullets for the ESC to motor connections as long as you heat shrink over them (i.e. you have to cut the outer heatshrink off to separate the connection) - simple insurance.

So you want to fly with about 12000mAh? That rig is going to run about 25A per motor at full throttle, 150A total. Two 6S 6200mAh packs means the battery connectors/wires will need to handle 75A each - not terrible, but right at the top end of what I'd call safe. I'd still personally opt for 4 x 3000mAh with the connectors/wires at ~37.5A each max - a walk in the park for just about any of the higher-rated connectors and 10AWG wire. Makes sense, doesn't it?

Easy to solder four wires to each of the battery pads on the Droidworx PDB so you can run four packs. For absolute reliability I'd recommend hot-gluing the wires (battery feeds and ESC connections) onto the adjacent board area after soldering. The big issue with soldering wires is that the solder will wick up inside the insulation and stiffen the first part of the wire leading away from the connector. That's a weak spot now - vibration will work on that point so it can eventually start breaking conductors inside the insulation at the point where the solder stops. The solution is to provide mechanical support for the wire beyond the point where the solder reaches, so that the now-vulnerable part of the wire is held rigid and not allowed to move with vibration. A big blob of hot glue to secure each wire to the PDB surface is cheap insurance (See the pic on page 2 of the PDB manual - blob the hot-glue from the start of the insulation right to the edge of the board. Similar arrangement for the battery wires.)

Also of interest - look at the pic on page 8 of that manual - the right hand ESC of the three facing you - the red wire is certainly exceeding the minimum bend radius for the wire and will be vulnerable to breaking strands internally. On the left, underneath the ESC, they've got a wire passing down through a hole in the carbon fibre plate - that should be protected with a grommet or sleeve so the insulation can't chafe against the sharp edge. And the left-most capacitor - the top looks like it's already swelling - it should be replaced! Anal little details like these keep you in the air

 

[Bartman]

this thread got "in a muddle" because you inquired about his choice of connectors and now you're suggesting he use four batteries! i really don't know if you're serious or just trying to troll the site.

 

[jes1111]

Give it a rest, bart!

 

[dazzab]

Like you I find the sparking on connection objectionable. So I just make the connection quickly and move on. Nothing I can do about it and apparently it's normal.

Just for some feedback from a fellow Droidworx flyer. I have a coax octo SkyJib. I use the Droidworx PDB being fed from two 6S 8Amp batteries. I've been using XT60 connectors for some time. They are tricky to solder to the larger wire but it's entirely possible and I am extremely careful to make sure these connections are solid. I believe that XT60 connectors can actually handle 80Amps but I don't remember where I read that. Nonetheless, I keep a careful eye on them and they never get warm and have never caused an issue.

Anderson was recommended to me by another Droidworx flyer after I had been flying for some time. If I had it to do all over again I certainly would use them instead as all this soldering is a pain in the butt and you have to be soooooo careful. But for now I have many batteries and devices all wired up solid with XT-60s so I won't be changing any time soon.

 

[jetbootz]

this thread got "in a muddle" because you inquired about his choice of connectors and now you're suggesting he use four batteries! i really don't know if you're serious or just trying to troll the site.

I actually really enjoy reading and learning from Jes1111, he makes perfect sense to me. please carry on Jes... good stuff. Iv'e jsut changed my wiring plans based on your above advice. ... makes sense !!

 

[jes1111]

If I had it to do all over again I certainly would use them instead

I've heard exactly this sentiment a number of times. Changing after you've got dozens/hundreds of another type is painful to contemplate

 

[crcr]

Very interesting. Sorry for going off topic here a little but, @Jes, what is the minimum bend radius for silicone wire? I have seen photos in the past of wires bent with virtually no radius at all.

Thanks

 

[jes1111]

Very interesting. Sorry for going off topic here a little but, @Jes, what is the minimum bend radius for silicone wire? I have seen photos in the past of wires bent with virtually no radius at all.
Thanks

It will vary depending on the construction and the insulation material/thickness. It should be quoted by the manufacturer but I've never seen any such specs for the noddy noodles stuff from China. It's most usually quoted as a multiple of the outer diameter, e.g. "10 x dia", so 6mm diameter would mean 60mm radius of bend. "Cheap" silicone multistrand would (as a guess) be safe down to about 5 or 6 times its diameter. Folding it over double like they have in that picture is asking for trouble.

EDIT: this is the document I was referring to for those pictures. http://droidworx.co.nz/assets/PDB_mounting-021.pdf