MC3000 - Why are the battery terminal thingys so hard to move ?!?!

I have a 2 month old MC3000. I also have several other chargers.

The spring loaded posts that you move in order to get the battery in place are STUPID hard to move?
It’s like the metals HATE each other and don’t want to move easily past each other?
I’m inclined to lubricate them but I’m thinking that might do more harm than good.

ALL my other chargers with this type of rails move smoothly and with minimal effort. I have to fight them on the MC3000.
Seriously. It’s like trying to grind two very rough rocks past each other.
Like the metal is VERY rusted…but it isn’t.

Anyone else have this issue and what did you do about it?

Has anyone tried Carbon Conductive Grease for this ?

You can use any type of grease , because the electrical connection is made by the spring and not by rail !

I would be careful putting grease on the rails as it could affect the resistance measurement, I would contact kreisl in the link below for advice.


I’d be worried about shorting something if using a conducting grease.

I would personally lean to using dielectric grease.

Can you maybe use thermal paste?

that is non electric afaik!!

Be careful with carbon grease. It stains like crazy and can cause mystery shorts with very tiny amounts. Sometimes the angle of the sliding contact is just a tad off and, under tension, the sharp edge slides against the strip contact. I know I had to tweak a few of my OPUS sliding contacts by bending them between two pliers to get them to slide more smoothly.

But doesn’t the spring connect the two rails?
My resistance measurements seem too high. Maybe this is why?

If you look at this video, you can see the wire attached to the other part of the rail so unless I’m mistaken, there appears to be a dependency on the rail to conduct?? (If wrong, it would be the first time…. :innocent: )

MC3000 Teardown

I had a similar problem with one of the rails. Resolved by loosening one of the case screws a bit. Remove the rubber feet and try it.
If you dont wish to dissasemble and look for tolerance errors or possible misalignements, this could be your easiest way to fix it.Unless its something else in your case.

I asked an SkyRC Rep for advice.

Thanks John. The slider slides on top of the rail. On top. So there can't be anything holding the slider back from its movement and the sliding movement should feel natural and unimpeded. I could think of 3 tings:
1) the spring gets caught somewhere inside, maybe at the edge of the PCB. This would create a scratchy sound.
2) the tip of the spring is not seated in the middle of the slit of the rail. This would create a scratchy sound too.
3) the bottom edges of the slider are not rounded off, the burr(s) scratch along the rail. This would scratch up the rail.

While the production line worker found the sliding behavior of a particular unit within the acceptable tolerance band, QC passed!, a very critical end consumer might prefer natural unimpeded sliding as on my sample.

I am a critical end consumer, so i checked 1) 2) 3) to pass my own QC. Personally i don't recommend the use of Deoxit Gold or other grease on the rails. In the end grease only catches dust/smoke/debris and things get dirtier i guess.

hope this helpz

You are out of the hook this time.., you are right ! I don't have a MC3000 so I thought that could be the same as to other chargers , where the spring is soldered to the negative side of the slot , but here is not the case , the spring is just for getting enough tension ( I've looked at the video). So ,my bad ...

On the other side , it seems that the plastic lines that are pressing the metal rails( from the underneath cover), could be filed down few teens of a millimeter , in order not to press so hard..., try with one slot , assemble and see what is happening ...If is ok , go with the other .

(hopefully it’s obvious i’m just kidding around with that claim)

The charger works well so I’m hesitant to take it apart……heard some horror stories trying to get it back together.

You do not need to take it apart , as in the video.. , just the underneath cover , where the plastic rails are..., but , is up to you !

And don't worry , maybe I'm old but, my sense of humor didn't left me...

One of my three MC3000s, the newest, also has this problem. I have to slide the posts from the bottom, otherwise they bend backwards.

ThIs is EXACTLY the problem I’m having.
If I don’t manually assist the rails by using a finger down near the bottom, the thing is so hard to move it DOES bend.

This must be a problem with the latest ones because I’ve only had mine a few months.