Maker Pro
Maker Pro

How come these alligator clips only transfer electricity when swapped at the battery terminals?

juntjoo

Jun 8, 2015
82
Joined
Jun 8, 2015
Messages
82
If input the clips on their respective terminals it won't work. And the positive part of this configuration on the barrel connector is on the outside. Not sure what they usually are. I don't recall doing anything with these clips. I can tell you they came with a solar trickle charger product and connects to the solar charger to charge a battery. So I'm guessing they are designed to go the opposite direction maybe? Does that mean there's a "diode" in there restricting electricity flow to one direction? This stuff is still new to me.

Either way, I won't be able to use these to charge to the barrel connector as I'm intending to do will I? If I swap them to get current flow I'll have to rig something up with female barrel connector and an sae one to connect to my motorcycle to charge the battery

IMG_20210213_234621311 (1).jpg

[Mod Note: resized image and put inline].
 
Last edited by a moderator:

Bluejets

Oct 5, 2014
6,073
Joined
Oct 5, 2014
Messages
6,073
Given it is solar related, guessing there will be a diode in there somewhere.
All I can see is a barrel plug and jumper clips, no idea what goes where from your photo.
Normally would expect negative on the outer sleeve of the barrel plug.
 

Martaine2005

May 12, 2015
4,404
Joined
May 12, 2015
Messages
4,404
Again, your explanation and photo doesn’t tell us much.
Is this cable terminated with a DC barrel jack and crocodile clips only?.
No other ‘box’ in between?.
Use your multimeter to check each wire for continuity then swap the probes and check again.

Martin
 

juntjoo

Jun 8, 2015
82
Joined
Jun 8, 2015
Messages
82
Given it is solar related, guessing there will be a diode in there somewhere.
All I can see is a barrel plug and jumper clips, no idea what goes where from your photo.
Normally would expect negative on the outer sleeve of the barrel plug.

There's nothing else to see. And I guess the plug polarity is switched because I have the alligator clips switched. I think I'll just splice together a polarity switch/adapter
 

Audioguru

Sep 24, 2016
3,650
Joined
Sep 24, 2016
Messages
3,650
Barrel connectors like you showed are connected with both polarities but usually show a sketch of the polarity used.
The protection diode is called an "idiot diode" because only an idiot will connect the polarity backwards.
 

juntjoo

Jun 8, 2015
82
Joined
Jun 8, 2015
Messages
82
Barrel connectors like you showed are connected with both polarities but usually show a sketch of the polarity used.
The protection diode is called an "idiot diode" because only an idiot will connect the polarity backwards.

I see what you did there.

It's a pair of wires with alligator clips on one end and a barrel connector on the other. Why can't I repurpose this thing for my specific needs? That little solar charger pad that it came with proved to be useless and I want to connect my regular battery charger (with alligator clips) to my SAE pigtail on my motorcycle

Is there really a diode in there somewhere? In the barrel connector itself? There's nothing else to it other than what is in the pic. Just more wire. Nothing along the wires.
 

bertus

Moderator
Nov 8, 2019
2,793
Joined
Nov 8, 2019
Messages
2,793
Hello,

To check if there is a diode in the plug, you could measure from the plug to the connector both ways on the inner contect and the outer contact using the diode check of the DMM.\

The protection diode is called an "idiot diode" because only an idiot will connect the polarity backwards.
Perhaps the diode is in there to make the circuit "fool" prove.

Bertus
 

juntjoo

Jun 8, 2015
82
Joined
Jun 8, 2015
Messages
82
Again, your explanation and photo doesn’t tell us much.
Is this cable terminated with a DC barrel jack and crocodile clips only?.
No other ‘box’ in between?.
Use your multimeter to check each wire for continuity then swap the probes and check again.

Martin
I think I did that. I'll do it again later then edit this.
Hello,

To check if there is a diode in the plug, you could measure from the plug to the connector both ways on the inner contect and the outer contact using the diode check of the DMM.\


Perhaps the diode is in there to make the circuit "fool" prove.

Bertus

Yes, I think that is what Martin was getting at. I'll try that and report back later. Thanks...

Haha you guys are funny. Maybe the diode is in there to make the circuit "the biggest moron in the world" proof
 

Audioguru

Sep 24, 2016
3,650
Joined
Sep 24, 2016
Messages
3,650
Years ago I was a technician on the car radio production line. The radios had a huge reversed diode directly across the supply to blow the car's fuse if the radio power polarity was connected backwards by an idiot. A series diode was not used because it would reduce the radio's maximum output power.
 

Martaine2005

May 12, 2015
4,404
Joined
May 12, 2015
Messages
4,404
The idiot diode/fool proof thing is very real.
If your cable has a diode, it will probably be in series with one of the wires. Probing the wires both ways will find it.

Edit: you say reversing the leads polarity gets voltage to the jack. This suggests a reverse biased diode in the positive feed (conventional current). It is there so the solar panel charges the battery but the battery can’t feed back to the panel. IMO.

Martin
 
Last edited:
Top