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04-22-2009 04:33 PM  9 years agoPost 1
Texmech

rrApprentice

Camden, N.C.

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Hey did a quick search on this and didin't find much so a newby to Big electric Q comin at ya.

When I connect my 2 piggybacked 5s 3750's to my bird I get a loud pop on connection. Is this normal for this amount of juice? I don't get this sort of connection pop with my 450, so it concerned me, but I realize I'm talking about a considerable difference in voltage going on here.

Good judgment comes from experience. Unfortunately, experience usually comes from bad judgment.

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04-22-2009 06:03 PM  9 years agoPost 2
TJinGuy

rrProfessor

Socorro, NM - USA

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Anytime you connect lots cells to an esc it arcs upon contact(my 6s packs pop pretty good). The more cells and the more severe the arc. It is normal and I have never heard of it hurting anything except pitting the connectors. Some people don't like using Deans because it pits them. I have seen some guys use big bullet plugs and that works pretty well. It is easier to connect them one at a time so there is less chance of multiple arcs when connecting.

- Chris

Team New Mexico
TJinTech

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04-22-2009 10:39 PM  9 years agoPost 3
Rob_T

rrElite Veteran

..

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The "pop" is caused by the inrush current of the capacitors on the ESC charging, it's quite normal on higher cell count setups.

There are ways to use a 2 stage connection to avoid the high current. You put 3 connections on the ESC - one is the -ve connection, just the same as usual, one is the +ve connection via a small resistor (in the region of 100 ohms), and the final one is the usual +ve connection. You then connect the battery by first connecting the -ve and the resistor connection to +ve, wait a second or 2 for the capacitors to charge via the resistor and then connect the +ve that doesn't have the resistor.

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04-23-2009 12:34 PM  9 years agoPost 4
Texmech

rrApprentice

Camden, N.C.

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OK ,Thanks just wanted to make sure I wasn't doing something wrong.

Good judgment comes from experience. Unfortunately, experience usually comes from bad judgment.

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04-28-2009 02:38 PM  9 years agoPost 5
Melnic

rrElite Veteran

Columbia, MD,USA

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We were discussing this on another forum.
Does it have anything to do with using a BEC on the flightpack battery? Does using a smaller battery for the BEC only help eliminate this spark at all?

It looks like the area that any carbon buildup might be on the deans connector is NOT whre the main current flows on the curve of the metal. Am I correct?

Has anyone experianced the need to replace their Deans connector after a period of time?

Rob_T:
I understand what you are explaining. How popular is this method?

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04-28-2009 08:07 PM  9 years agoPost 6
Rob_T

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I'd say that for 6S and under most people don't use the 2 stage hookup. It gets more popular as the cell count goes up from there, but to be honest it's probably more of a perfectionist's thing than something everyone does.

A BEC is probably going to add to the issue by having it's own inrush current added to that of the ESC. I vaguely remember reading that one high voltage ESC has inrush current limiting built into it. Sorry I don't remember which brand. (I'll post it if I remember).

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