Polarity

[gdjsky01]

I am looking at my junk with JST connectors. The Teeny Tiny ones, and the next size up.
Looking at the connector from above, wires to the back and the pins/slots (where the locking tab to keep them in the connector) are visible on top. ALL of mine are Positive to the LEFT




When I assembled the Eggtimer ION, nothing I had had negative on the left. I went to the Sparkfun site, and sure enough, the recommended 400mah LiPo has negative on left.
So it is NBD to wire up my own ION power wires. But is all my junk wrong?

 

[heada]

A lot of the cheap ones from ebay and Amazon are wired backwards. They're factory rejects and sold for super cheap for that reason. I toasted a EF Quark for just that reason

 

[Voyager1]

 

[Titan II]

A lot of the cheap ones from ebay and Amazon are wired backwards. They're factory rejects and sold for super cheap for that reason.

That is not exactly correct. There is no industry standard regarding the polarity. The RC industry set the original standard, but other subsequent industries did not go along with the same scheme. This issue is covered extensively and a Google search will give you plenty of info if interested. The good thing is that it is easy to change the polarity.

 

[waltr]

^^This is correct. No standard on polarity.

Even when the polarity is correct on the two mating connector it is possible to connect these red JST connector backwards as the key is small. Done that and kill the circuit.
I use these and always look to see that the red wires on each side match before connecting.

 

[gdjsky01]

Yeah I gave up and simply am labeling power cables, charging cable, batteries, as to what they are intended for.
Like two 380mah LiPo batteries have a message on them, ION only! Watch Polarity! (for charging)

 

[cerving]

And that is why in the ION instructions I have you connect the battery to the JST-PH connector before you solder it to the board, check it with a DVM, and mark the "-" side with a black Sharpie. Whichever side is marked goes on the "-" side of the board. Altus Metrum and a few others sell similar 1S batteries with the Adafruit/Sparkfun polarity rather than the R/C polarity... so if your altimeter vendor sells a battery (and charger) designed for their altimeter, it's not a bad idea to spring for it instead of rolling your own and possibly dorking your electronics.