Help! What is this Component?

Thread Starter

cudawantd

Joined Nov 28, 2021
9
Help, What is this called, and what does it do? it is on the negative side of a battery for a 6v ride-on train (like a power-wheels). Only got 1 recharge out of the battery, now it won't recharge so I ordered a new battery, and the new one doesn't have this on it. What is it? Do I need it?
 

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dl324

Joined Mar 30, 2015
14,313
Welcome to AAC!

PTC fuse.

I am not a mechanical person, I barely know what is positive and negative on a battery, what is MOV?
Can you use a search engine?
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They're used as an over voltage suppressor. It would be wired in parallel to the battery in that case.

If it's in series, it's more likely a PTC (Positive Temperature Coefficient) fuse. The fuse resets itself when it cools off.
 

Thread Starter

cudawantd

Joined Nov 28, 2021
9
How do you think I found this forum? I looked up MOV, once it was mentioned, and watched the foreign guy on video talking about a blue round one on a circuit board. Mine is yellow and square and is on the battery terminal not on a board-still a MOV?? Do i need it??
 

dl324

Joined Mar 30, 2015
14,313
watched the foreign guy on video talking about a blue round one on a circuit board. Mine is yellow and square and is on the battery terminal not on a board-still a MOV??
It's the function that's important, not the color of the component.
Do i need it??
Manufacturers aren't in the habit of including unnecessary components.

How is the component connected? If it's in parallel with the battery, it could be a MOV (though unlikely). If it's in series, it's more likely to be a fuse.
 

dl324

Joined Mar 30, 2015
14,313
looked up PTC fuse on GOOGLE, and found the same thing!!
There is more than one type of component that can be in that form factor. It could also be a NTC surge limiter. We have to know how it's connected to determine it's function.

In series, it won't be a MOV; but it could be a surge limiter or fuse. I think fuse would be more likely. Fuses are usually put on the plus side. A PTC fuse doesn't open the circuit, but it will limit the current from the source.
 

Thread Starter

cudawantd

Joined Nov 28, 2021
9
There is more than one type of component that can be in that form factor. It could also be a NTC surge limiter. We have to know how it's connected to determine it's function.

In series, it won't be a MOV; but it could be a surge limiter or fuse. I think fuse would be more likely. Fuses are usually put on the plus side. A PTC fuse doesn't open the circuit, but it will limit the current from the source.
I have no idea if it's in series or parallel. It was on the negative side of the battery. I believe one leg of the yellow square was on the battery tab and the other was on the wire that goes to the electric motor? and it says A700 A9 on it
 

Thread Starter

cudawantd

Joined Nov 28, 2021
9
Well if you have already pulled it off, then can you solder the wire from the other side back in the battery terminal?
Since I don't have a tester and don't know how to short it out, I found some wire connectors that slip on the terminals, so I hooked up the new battery using the wire connections and plugged it into the wire connection on the train and plugged in the charger, and NOTHING (99% of new batteries are already charged, but I wanted to see if the red light would come on that says its charging). I pushed the gas pedal and NOTHING, I readjusted the connections and NOTHING. Now I'm beginning to wonder if the first battery was really dead (not just run down) or if the train has a loose connection under the plastic body somewhere.
 

MrChips

Joined Oct 2, 2009
25,924
I would think that the fuse blew because there was a fault somewhere. The fuse blew after the damage was already done.
So now you have to find what else is broken.
 

MisterBill2

Joined Jan 23, 2018
11,583
A device like that on the terminal battery is for overload protection. It is a nonlinear positive cefficient thermistor, meaning that when some current level is exceeded the reistance will rise and limit the power. With the ride-on train there is probably a failed connection, which may be a broken switch or a broken wire or a terminal fell off. A visual inspection might reveal something obvious, but "obvious" depends on your level of experience. Good Luck.
 
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