Stupid battery question


#1

Maybe I’m blind and it’s right there in the documentation I’ve been looking through, maybe it’s an industry standard I’m not aware of. What is the polarity of the battery connector? The left side of the connector has a notch in it; does that indicate positive or negative?

I ask because I moved the jumper and plugged in a new battery and it won’t boot. Pull the battery, switch the jumper back and now it works.


#2

Hi there! Definitely not a stupid question. I can’t speak to if this is an industry standard, but it’s pretty standard from what I’ve seen. The connector type is JST, and most batteries you will find on Adafruit or Sparkfun have this head built in. Looking at it head-on with the notch facing up ground is on the left and positive is on the right. I typically buy these headers/cables when I’m plugging in from some other source: https://www.amazon.com/gp/product/B01DUC1O68

Hope that helps!

Best,
Kevin


#3

If the battery polarity is reversed, will it damage the Dash, or is there some reverse-voltage protection like a diode?


#4

It will damage it! I learned the hard way.


#5

Sorry to hear that, but good to know. Thanks!


#6

just to be sure, is this image represent the correct polarity?
https://www.espruino.com/Battery

also there is a + sign on the dash1.2 board near the connector, it’s a bit far away but does it represent le + side for the connector?

the more I watch the batteries on sparkfun, the more I notice a difference in polarity so I’m very confuse.


#7

a quick answer would be appreciated. is the plus on the right or left side of version 1.2?


#8

The pin closest to the + is positive. The pin closest to the USB connector is negative.

If you don’t trust the documentation of a board or a battery (or in cases where there isn’t any, or it is in a language you don’t know), it is useful to verify yourself using a multimeter.
https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter/continuity
Checking for continuity between GND and the battery connector will tell you which is positive and which is negative.


#9

Thanks for the reply, my english isn’t perfect so I had some doubt about some stuff written above. I’ve put the voltmeter on thoses poles but was sceptical with the result.


#10

The quickest way to test would be to check for continuity on the negative or positive I don’t know what side the Dash breaks for charging circuit but it would be quick to test. Put a multimeter on continuity then place one probe on the negative and the other in the JST connector if you have connected you are on the right pin. I would test by doing the opposite as well put one pin on the positive and the other in the JST and see what you get. Some battery controls break negative some break positive.