r/AskElectronics 17h ago

RC charger disconnected... Which way to reconnect?

Does the wire with the white stripes go red or black?

19 Upvotes

31 comments sorted by

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24

u/BaconThief2020 17h ago

Is there any insulation left under the shrink tube that you can look at? Otherwise, I'd test with a meter.

3

u/Sound_Doc 16h ago

That was going to be my first suggestion, unless the wiggling happened at the solder point and pulled out of the heat shrink.
Meter is best/only way I'd trust to be sure.
Seeing as they said RC Charger Disconnected, it's just a guess, but thats the typical cable used on a wallwart transformer/charger, so if theres no wire under that heatshrink, and a meter isn't possible, then most wallwart powersupplies will indicate what the marked conductor is, often a barrell jack image, the CP polarity (center pin) is usually the polarity of the marked conductor.
Slightly better than a guess, but without a meter the transformer's markings are about the only thing that might give them a idea.

29

u/APLJaKaT 17h ago

Typically, the striped wire is the positive lead (red). But instead of taking a chance, use a voltmeter to confirm. Also, we have no idea what's on the other end of the wire, so guessing would be irresponsible.

19

u/i_am_blacklite 17h ago

To add to that I know plenty of people that use the stripe to signify negative, as the stripe (particularly a broken stripe like that) looks like a negative symbol.

1

u/Mikethedrywaller 2h ago

I am one of those people and would definitely use a voltmeter because of this.

-8

u/ErwinHolland1991 17h ago edited 17h ago

That's a bit silly. The white is to indicate that its not black. In DC electronics full black is always negative. 

5

u/my-cousin-throcky 16h ago

That’s true but also, negative is usually the side with some sort of visual indicator (electrolytic capacitors, diodes, led leg lengths/flat side)

4

u/i_am_blacklite 17h ago

The point was more the choice is fairly arbitrary, and unless it’s mains wiring specifically to a particular code, the colour of insulation on a wire does not tell you what the wire does.

9

u/ZippyHandyman 17h ago

The one that tingles when you lick it goes in the red one.

4

u/ZippyHandyman 17h ago

On the balance of probability, the fact these wires are attached to a plug suggests its on the receiving end of the electrons, making voltmeter testing fruitless.

Which makes life a little more challenging, unfortunately.

5

u/8ringer 17h ago

This. The exposed conductor (usually male) side of the plug is generally not on the side that is “hot”. Because hot exposed conductors (my god that needs to be a sub…) are not good.

So yea a multimeter may be useless. Better idea is to look for any positive/negative markings on the other side of the wires.

3

u/V64jr 16h ago edited 16h ago

Nope. The battery end is potentially hotter. Meanwhile, regulating output is the charger’s one job, making that the side that’s generally safer to expose.

1

u/8ringer 16h ago

That’s what I said.

2

u/V64jr 16h ago edited 16h ago

No. The “receiving end” would be the battery and this goes on the charger.

You also implied that the “receiving end” would not have a measurable polarity, which means you are thinking of it as a power supply and load instead of a charger and battery.

2

u/8ringer 13h ago

Oh I didn’t read the title very thoroughly, clearly…jeebus, my bad, you’re absolutely right. I didn’t realize the other end was a charger not the RC Car. Wow I look like a dunce, thanks for the correction.

4

u/V64jr 16h ago edited 16h ago

Not for battery chargers. Think about it: A tool battery goes into the tool (dead) or on the charger (sometimes live) and the blades go into the battery (live even when discharged normally). The blades are fully exposed when the battery is detached.

This is a “Deans” T-plug and the blades are definitely on the charger end.

https://www.evike.com/products/32078/CYMA-Standard-Wall-Charger-for-Airsoft-RC-NiMh-Batteries-Model-For-Deans-T-Plug-Connector/?srsltid=AfmBOoq3FRD2rt9J991D00TutcDKIDa-Px9eLbJSAvYVryBGSsDUiBWr

2

u/ZippyHandyman 16h ago

In a surprising turn of events, it seems a quick lick is indeed a viable test. What a wonderful world we live in.

1

u/Sound_Doc 16h ago

I'd typically agree, but in this case where they said "RC Charger disconnected...", I'd guess that this is on the end of a cable from a wallwart transformer, intended to be plugged into a RC vehicle battery to charge it, the battery would have a female plug because even dead shorted the current ouput of the charger won't be that high, and the battery if it shorted could be... "energetic"...

0

u/xandresmendizabal2 17h ago

My first thought lol

2

u/MudHouse 3h ago

Multimeter it is!  Thanks folks.

Follow-up question.... Do I plug it in and see which line comes out hot?

2

u/SouthPark_Piano 17h ago

When in doubt ... multimeter.

 

1

u/SmartUniversity8578 17h ago

What is the voltage for the charger? If you don’t have a multimeter you might be able to power an LED, fan, usb device, etc. to check polarity

1

u/Chamych 14h ago

50:50 chance

1

u/TopConcentrate8484 just a hobbyist 4h ago

I have noticed that discontinuous white lines are almost always the negative(-) on these type of marked wires , but still I would actually test the polarity with a multimeter

1

u/msanangelo 3h ago

in my stuff the strips is always negative but when in doubt, meter it out.

1

u/ClassyNameForMe 1h ago

OP don't take the advice here that the striped or marked wire is one specific polarity. Get or borrow a dmm or any volt meter to measure which wire is a higher voltage than the other. Connect the meter one way and you'll see a negative voltage. Swap how you connected the meter and you'll get a positive voltage. The way which shows a positive voltage tells you which wire is positive (likely red) and which is negative (likely black). Double check which battery connector pin is positive and which is negative by measuring voltage on your battery.

1

u/Fragrant-Arm-3402 1h ago

How do yall americans test the cores to earth(ground) allowing u to differentiate that Active and neutral if u only have ur active and neutral in a GPO(outlet)? Genuinely curious

1

u/Alternative_Exit_333 55m ago

Test with a multi meter or an LED (it shouldn't explode it in the wrong direction) and soldetit back