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Powering up a servo centering tool

mayan

Well-known member
#1
Hey everyone,

A few days ago I burned the balance connector on my 2S battery which I used for flying but mainly for checking things were working fine before hitting the field. Any how I used it also to power the servo balancer tool that I have because I knew how to use only one cell so not to over power the tool as it needs only one cell of power. Can I do the same with a 3S battery? If so how?

Pictures would help :).
 

CarolineTyler

Well-known member
#2
You could, just need to connect it across only the ground (black) and the second along.
rcheli-diagram-balance_jst-xh.png
what I use is a cheap USB charging lead, hacked off the micro USB connector and spliced on defunct servo lead powering just the ground and positive. That way I can power my servo checker from any USB socket (computer, powerbank, wall plug etc.)
 

Gazoo

Active member
#9
Yes, in-fact that is what I use, 4 AA batteries. Similar to what @Gazoo uses.
True. The only difference, I guess, is that the phone charger that I use is a regulated 5VDC supply. Four AA batteries would start at 6VDC and then drop until unusable. Either way, they both work great.

@CarolineTyler also has a nice method by using the powered USB port on a computer but it would not exactly be portable though.
EDIT: I see that Caroline also uses the wall wart and power pack as well.

I have also tried to use those cheaper USB rechargeable power banks/sticks but they cannot provide enough amperage and tend to brown out under a load. I do use them for a small 25mW FPV camera though.
 
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#10
Oh, related public service announcement.

If you are testing an ESC that has a BEC in it, you don't need to plug in separate power since that's what the BEC is for.

If you are going to test an ESC that doesn't have a BEC, do NOT plug a servo tester into the balance port of the same lipo. You'll short one or more of the battery cells through your ESC's ground wire. Use a second battery, or other external, 5v power supply. Ask me how I know this...
 

mayan

Well-known member
#12
Oh, related public service announcement.

If you are testing an ESC that has a BEC in it, you don't need to plug in separate power since that's what the BEC is for.

If you are going to test an ESC that doesn't have a BEC, do NOT plug a servo tester into the balance port of the same lipo. You'll short one or more of the battery cells through your ESC's ground wire. Use a second battery, or other external, 5v power supply. Ask me how I know this...
Generally I don't recommend test ESCs with a sero centering tool burned one that way, might be just bad luck though.
 

mayan

Well-known member
#13
Thank you all for the advice. Now I'll be able to connect the electronics for the Tedge tonight :). I like the idea of using a usb cable, seems like an option worth having around even if I have a battery laying around.
 

FDS

Well-known member
#16
You can move the pins to match the +/- if it’s a balance connector type JST. Or put a servo plug on, just use the right pins to match the polarity, you don’t need signal.
 

Bricks

Well-known member
#17
I am lucky enough I fly Nitro so have a bunch of NIMH 4 cell packs laying around and LIFE batteries only problem using LIFE is the starting voltage is 7.5 and some servos do not care for this much, smoke baby smoke.
 

CapnBry

Well-known member
#20
That USB charger idea is a good one, why didn't I think of that? My workbench already has a 2x 2.1A USB ports on it anyway, the USB to 3-pin is genius.

My combination battery meter / servo tester is just a pain to use that what I usually do to center a servo is just grab a conveniently located model and use one of the unused ports on the receiver for it. I also made a BEC out of a $1 "mini buck converter" from eBay, a used (broken) servo lead and an old XT30 connector that I've used before but that's not as convenient. I don't think I'll ever use that any more once I make that USB cable version. Thanks for asking this question!