Large Scale Central

Reverse Polarity

Electronics
#1

I created charging cable for my Lithium Ion batteries using JST connectors. When I plugged the charge cable in to my Tennergy charger I immediately got a Reverse Polarity warning. Upon investigation it was obvious the male side did not equal the battery side. The barrel jack was wired correctly (red to the short side and black to the long side.) Batteries were purchased through either RLD or Reindeer Pass. I don’t remember where I ordered the JSTs…I think it was Amazon but I couldn’t find any reference. So, when I plug in the JSTs in the red battery side is against the black barrel side and visa versa.

What are my options?? I just want to create few charge cable that I can charge batteries outside the engines or tail cars.

Thanks,
Richard

#2

Not sure what to tell you, but I’m sure someone will have your answer. I do know that working with lithium-ion batteries that the correct battery charger and battery match-up is very important. I’ve always purchased my batteries and chargers from RCS of New England and have always got the correct results that work with my Rail Pro system. The wife and I have ebikes and their batteries are something not to be messed with, that is, using the correct battery charger with the battery that it is recommended for. All being said, these lithium-ion battery can be dangerous if missed used in many ways, I would think and incorrect polarity hookup would led to a disaster. I too am waiting for the answer on this question.

#3

Last time I ordered connectors they were wired reverse for what my packs are. It’s annoying, but you can remove the pins from the connector and swap them.

#4

Right on Bob. I’ve had to do this many times as I ordered a large amount of connectors that were reversed from what I needed. Just use a multimeter and wire them as needed. The electrons flowing through the wires are color blind! :laughing:

#5

Hey Bob,

Can you clarify removing the pins from the connector? I’ve never done this before. Is there a special tool that I would need to take care of this?

Thanks,
Richard

#6

I have received JST’s that were “backwards” from Ebay.
And I have tried “Other brand” batteries that arrived “backwards”
(Cordless Renovations comes to mind).
I have been using Tenergy’s for years now. If I get a package of JST’s that are backwards, I just toss them and order from a different supplier. They are cheap.

#7

Thanks for the advice John…can you recall whom you have ordered from to replace?

#8

There is a special tool, but you can use a thin shim of metal to do it. I found this video which explains what to do. https://www.youtube.com/watch?v=kRvDgiX4Sk4

#9

Looks like RLD Hobbies sells them. Just confirming with them that they are wired the same as the batteries. I’ll trash the others

#10

I am thoroughly confused. JSTs are plugs, and have whatever polarity they are wired with. There’s no such thing as a ‘backwards’ JST.

But there are battery packs wired whichever way the owner desires, so I have seen battery packs wired the opposite way from what I expected.
My charger has a big Tamiya (?) plug and I have a variety of plug-in cables for whichever battery pack I am charging. Not all my batteries have JSTs - some have 5.5mmx2.1mm power plugs.

If I was you, I’d just rewire the battery pack or make up a reversing cable.

#11

Honestly , depending on the style of JST connector it would narrow it down to a few less selections to choose from. However swapping the pins would be the cleanest way to go in my opinion. Didn’t you just announce your retirement Richard? So for under $15 you now have the time to save yourself some money cause you retired guys are on a budget!

Just saying
:rooster:

#12

Way too much work in my opinion :smiley: