Connector advice needed

[Madman]

OK, so with most of my ESCs I am able to use Astro zero loss connectors on the battery side. BUT I have a CC 120HV ICE2, and a CC 110HV and the battery leads, especially the 120, are huge! What are you guys with big systems using between the batteries and the ESCs? I would prefer suggestions I can pick up locally but please don't limit your responses, I am looking at what works.

I installed a set of CC 5.5 mm connectors between the motor and the ESC. They had a little room left over on the ESC wires (god what size are they?) and lots of room on the AXI 5345-18 wires. On my 110 and the other 5345s I have I am using 4mm bullets between motor and ESC. Since I am mostly playing on the bench right now I took the battery leads from the 120 and ground them down to fit into a Sermos connector. They are less than 1/2 the diameter of the original wire.

All systems will probably be propped around 60A static give or take. The motors I have are rated to 90A (AXI, Scorpion). Batteries will be A123 packs between 6S and 14S and 2P or 3P. Thanks in advance for any ideas.

Stephen

[piker]

Where's your committment!?  Take a soldering iron to the field and solder the wires together.  Who needs connectors?!!

But seriously, I got nothin' for ya.  I still use Sermos.

[Ededge2002]

I would use 5.5mm bullets or so. Even at 60amps I think might be too much for 4mm ones. Running too small a connector can act the same way as long battery wires.

[bfeist]

The current is quite low. My understanding is that connector size is all about amps, not total watts. You'd be fine with 4mm which are good up to 100A. I'd use 6mm just to be safe. I use 6mm on my 200A F5B.

Ben

[Ededge2002]

I agree with Ben.  just Be sure to use the top kind of connector pictured as I just dont think the bottom style is as good of a contact.

[Madman]

I guess I was looking for a 2 pole connector like Astros, Sermos, etc. I was hoping you guys were using some common brand/style. One with connector and shell but individual insulated connectors would work as well.... Gotta remember I was the guy who caught himself reversing his Sermos to 'make them fit', too bad if it would have reversed polarity into the ESC!

The Castle connectors I have look like the top ones in the pic. Any one local carry these in these sizes?

Rob-I will have to re-visit dropping by meets this summer, at least not set up too near your 'charging' station! I liked the Sermos as well until the above incident then quickly changed to Astro zero loss ones.

Edward-How would 500 W/lb look on a 25 lb 1/4 Fokker D.VII? I would have to carry an extra 5 to 10 lbs of battery at least to get any decent run times! Hmmmm 500 x (say) 35 = 17500 watts/60V (14S A123s hot off the charger)=300A. Night flying by the glow of the wire. My buddy with the 1/6 EDF Harrier runs at these levels.

Ben-4mm would fit the AXI wires but the ESC wires are way larger. Do you think it would be safe to grind these down to fit?

Thanks for the replies and keep them coming in. I posted the same questions on RCC and RCG but only got looks, no replies. Goes to show who is out there to help. Thank you very much.

Stephen

[bfeist]

I've cut wires down before, but only if I knew that the current wasn't going to be as high as the wire rating. Go with 6mm or 8mm individual bullet connectors if you don't want to cut the wire down. I understand you wanting a housing to hold the connectors, but at 6mm and larger it takes a lot of force to disconnect each connector. Doing them one at a time is the only way I can see it working.

[Madman]

Thanks for all the help guys. One of the local fliers recommended the EC5 connectors and I have gone that way.

Stephen

[pmackenzie]

Where's your committment!?  Take a soldering iron to the field and solder the wires together.  Who needs connectors?!!

The R/C car guys used to do that, but they always did a lot of strange stuff. Like paying $100 for $5 can motors

[Ededge2002]

My trouble with the CE5 connectors is that they are like the lower ones in the picture I posted. I've seen the "spring" that is the conductor develop resistance between itself and the main post of the body. This showed up on the motor with erratic start up and occasional loss of synchronization.  Not a reason not to use them but something to be aware of.

[MarcV]

Stephen,

I spent a bit of time today measuring the resistance of the connectors that I use.
I used two 30A power supplies in parallel to do the measurements at 60A.
Note, I only used one test sample per test, so my results should only be used as a guide.

I used to use Sermos, but once I started buying my batteries with the connectors already installed (Hobby King) I got tired of cutting them off and attaching my connectors, so I've been standardizing on the XT60 and the 4mm bullet with protector Hobby King connectors.

Sermos/Anderson: 60A gives 18mV voltage drop (jumped to 30mV with pressure on the connector).
Voltage measured at far end of connectors.
Thus 0.3mR per connector, which gives a power loss of 1.1W at 60A (per conductor, so 2.2W per a two wire connector).

Standard 3.5mm bullet:  60A gives 27 to 33mV voltage drop, Tmeasured = 91C
Voltage measured 1.3cm across connector.
Thus 0.5mR per connector, which gives a power loss of 1.8W at 60A per conductor.

Hobby King Nylon XT60 Connectors
"These original Nylon XT60 plugs can handle over 60A current for extended periods without exceeding 80°C thanks to their better contact surface area."

60A ->  29mV, thus R = 0.5mR & P_loss=1.75W per conductor.
Tmeasured: 82°C (thus 60C rise above ambient).

Note: the standard 3.5mm bullet has the springy collar and the XT60 the split plug which is supposed to be superior, but from my measurements, there's no significant difference.

Hobby King  HXT 4mm Gold Connector w/ Protector:
Rated to around 93A
60A -> 23mV, Tmeasured: 80°C
thus R= 0.38mR and P_loss=1.4W (per connector, thus 2.8W total)

Note: At 60A the power loss is 1.4W and the connector is heating up to 80°C - I wouldn't trust these at the rated 93A as they'd get well over 100C.  The fact that Hobby King is using these connectors on a 5Ah 45C (or more) battery (i.e. 225A) is a bit of a joke.  But they are starting to use 5.5mm bullets on some packs.

Castle Creations 5.5mm bullet.  Has a tight fit.
60A -> 7mV, thus R = 0.12mR. (2cm measure delta)

Hobby King 6mm bullet, has tight fit.
60A -> 5.5mV, thus R = 0.09mR. (2cm measure delta)

Marc

[Ededge2002]

Wow that is some terrific data!  Thank you for taking the time to research AND post your results!

I wonder where genuine Deans fits into that chart?  It would also be interesting to see the numbers as the connector has more and more cycles. My experience with the spring barrel type of 4mm bullet developed over about 30 flights @60 amps on 6S.  It seemed the barrel had damaged its contact to the pole because of arcing. 

[Madman]

Wow Marc. Thanks for all the effort. Who do we ask to make this a sticky? If I supply a set of Astro Zero loss and an EC5 set would you like to test them as well? Or is this asking too much. I assume you were testing what you had at hand.

Stephen

[MarcV]

I have an EC5 that I can test (it's from Hobby King), some Deans (not sure if genuine), but no zero loss.  I don't mind doing some more testing.  I'm a bit embarrassed to admit that my most recent project used 4mm bullets with a 160A ESC (but the average current draw is just 20A so I'm not changing the connectors just yet).

A quick internet search has found others who have done testing:

This person used a 5A current and cleaned the contacts before testing:
http://www.rcgroups.com/forums/showthread.php?t=1234717

If your test equipment is good, then a 5A test current can give you decent results.  But with my test current of 60A I was able to stress the connectors during the test.

Stefan did some testing here, but his methodology of including the resistance of the soldering in his results adds some variability to the results.
http://www.stefanv.com/rcstuff/qf200001.html

More info here with dead links:
http://www.rcgroups.com/forums/showthread.php?t=665240&highlight=connector+resistance

Marc