Can this actually handle 55 amps?

Papabravo

Joined Feb 24, 2006
13,724
Hi, can this connector really handle 55 amps? I need at least 30-40A. It says 12 AWG silicon so that seems a bit suspicious. Is it true because it is short?

https://www.amazon.com/gp/product/B07QM1WS2J/ref=ox_sc_act_title_1?smid=A1JTH8JAMM4IYJ&psc=1
You can answer this question for yourself by consulting a current capacity chart for AWG 12 wire.
See the calculator at the bottom of the page
https://www.powerstream.com/Wire_Size.htm

The general rule for power transmission (very conservative) is that you need 700 circular mills per Ampere. AWG 12 only gets you 9.3 by that standard. Your mileage may vary depending on conductor length and tolerable temperature rise.
 
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Hymie

Joined Mar 30, 2018
819
12AWG should be good for up to 25A, but a short length could handle more.
It does say ‘up to 55A’, that may be conditional on a maximum ambient of say 0⁰C.
 

Thread Starter

-live wire-

Joined Dec 22, 2017
911
You can answer this question for yourself by consulting a current capacity chart for AWG 12 wire.
See the calculator at the bottom of the page
https://www.powerstream.com/Wire_Size.htm

The general rule for power transmission is that you need 700 circular mills per Ampere. AWG 12 only gets you 9.3 by that standard. Your mileage may vary depending on conductor length and tolerable temperature rise.
It says 41 amps for chasis wiring so since its so short 55 amps is roughly accurate?
 

Thread Starter

-live wire-

Joined Dec 22, 2017
911
12AWG should be good for up to 25A, but a short length could handle more.
It does say ‘up to 55A’, that may be conditional on a maximum ambient of say 0⁰C.
Okay, since the motors are 14A for each, but the voltage is a bit lower, and it is shorter, I guess then it should be fine.
 

Papabravo

Joined Feb 24, 2006
13,724
In his favor, the lapse rate of the standard atmosphere is 1.98 °C/1,000 ft up to 36,000+ ft., so the higher he flies the more the air temperature will mitigate the temperature rise in the wire.
 

Reloadron

Joined Jan 15, 2015
5,454
I can tell you the problem.
"The ampere, often shortened to "amp", is the base unit of electric current in the International System of Units. It is named after André-Marie Ampère, French mathematician and physicist, considered the father of electrodynamics. Wikipedia "
That International System of Units isn't quite true. The Ampere is pretty international but not quite. China uses a smaller Ampere unit. Matter of fact I have seen some specifications where I figure a 2:1 ratio. 20 Amps becomes 10 of the rest of the world amps.

I doubt I would be comfortable running 55 amps continuous through that connector. With 30 ~ 40 amps open air I would be comfortable with the suggested Power Pole connectors. Initially I would give them a feel test in your application to see if they are getting warm.

Ron
 

nsaspook

Joined Aug 27, 2009
7,294
I can tell you the problem.
"The ampere, often shortened to "amp", is the base unit of electric current in the International System of Units. It is named after André-Marie Ampère, French mathematician and physicist, considered the father of electrodynamics. Wikipedia "
That International System of Units isn't quite true. The Ampere is pretty international but not quite. China uses a smaller Ampere unit. Matter of fact I have seen some specifications where I figure a 2:1 ratio. 20 Amps becomes 10 of the rest of the world amps.

I doubt I would be comfortable running 55 amps continuous through that connector. With 30 ~ 40 amps open air I would be comfortable with the suggested Power Pole connectors. Initially I would give them a feel test in your application to see if they are getting warm.

Ron
I really don't like high current solder connections so Deans connectors are a no-no in my shop. Power Pole connectors are usually my first choice. ZERO failures!
 

Wolframore

Joined Jan 21, 2019
1,748
The ampacity chart according to the note is a rule of thumb and conservative values based on air and not in bundle. And Ive seen them rate higher based on insulation temp rating such as silicon and kynar. I wouldn’t trust it either. I have seen silly things like this also. Even if you could why would you want the voltage drop?

1586561382505.jpeg
 

SamR

Joined Mar 19, 2019
2,125
Well, at least it is silicone rubber jacketed wire... I always wondered if china rated a wires ampacity as the point at which the wire melted open like a fuse.
 

AnalogKid

Joined Aug 1, 2013
8,464
Okay, since the motors are 14A for each, but the voltage is a bit lower, and it is shorter, I guess then it should be fine.
Nope. 0 for 2.

1. The voltage across the load is irrelevant. The issue is heating in the contact area of the mated connector parts. It is covered by Joule's law, P = I^2 x R, where R is the contact resistance. The larger the wire gauge, the more heat is conducted away; but after a couple of inches the thermal conduction caused by longer lengths is minimal.

2. There is a voltage drop associated with the wire gauge and length, covered by Ohm's Law, and a corresponding heating covered by Watt's Law. So shorter wires mean less power loss in the system, but have nothing to do with heat generation and reliability in the connectors.

Some connector companies cheat by listing the current rating for an individual pin, rather than all pins at the same time. The all-pins rating is lower because the pins heat up each other. Pins in the center of a connector pin field run hotter than the ones out at the edges. Normally the difference is trivial, but an 55 A, nothing is.

ak
 

Wolframore

Joined Jan 21, 2019
1,748
Having said that, the deans connection should survive, it dissipates about 1 watt for that 3 inch length. I use the XT variety connectors like this for my RC car, I havent done the calculations but they draw some serious current and have some decent airflow in use. These are designed to be light and small for hobby use. I have seen underrated motors burn up from too much current but the wires and connectors seem to be fine.
 
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