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HomeRC & PowerAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › 3-Pin Deans Micro back in stock
03-24-2017 03:01 PM  18 months agoPost 1
Four Stroker

rrElite Veteran

Atlanta

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If you charge through the balance lead on a 2S A123 or other pack, I recommend putting a Deans Micro 3-pin balance lead on the battery.

REASON: Ohm's Law. If you charge at 10 Amps and either the + or - has 100 milliohms resistance through a bad crimp, the charger sees a 1 volt imbalance and tries to correct it. Won't work. Other scenarios are more realistic but there is still a problem. One of three of my A123 RX PACKS had this problem using original Futaba servo leads as the balance tap. Crimps aren't what they used to be.

Tower now has the 3-pin Deans Micro connectors back in stock.

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03-24-2017 06:16 PM  18 months agoPost 2
EEngineer

rrProfessor

TX

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"Other scenarios are more realistic but there is still a problem."

Good point on the contact resistance of the balance connector pins.

Also, what if with each pin, there is such contact resistance?

Seems like it is cumulative...not a good situation, regardless of what type of connector is used.

Contact resistance is bad....minimize it wherever possible.

Logo 600SXs, 800XX, TDR IIs

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03-24-2017 08:18 PM  18 months agoPost 3
Four Stroker

rrElite Veteran

Atlanta

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In the remote past I tested Deans Micro connectors to have about 1 milliohm per contact pair. A GOOD servo connector tested at about 3 milliohms. I found some crimps that had a 1 volt drop at 2.5 Amps! Ancient Kraft and ITT Centilock connectors (Bonner, RS, EK, etc.) with 40 year old crimps also tested in the 1 milliohm range (barrel crimps over tinned wire). A good knife action switch is about 1 milliohm - Futaba HD, JR Gold.

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03-24-2017 09:42 PM  18 months agoPost 4
EEngineer

rrProfessor

TX

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A crude test for a bad contact/crimp/solder joint at the ESC connectors....after a flight...is to see if these connectors are warm/hot to the touch....

Like you said, a few tens of millohms at 100 A or so, causes a lot of power to be dissipated by the connector.

P(in watts) = I(amps) * I(amps) * R(contact resistance)...

100 * 100 * .01 ohms = 100W

Logo 600SXs, 800XX, TDR IIs

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