I just got a Q8 and after using it I noticed that the tops of the cells looked a bit weird, as you can see in the picture. They are Samsung 30q’s that I got from nkon. Is this normal or should I stop using them?
I would send a message to Nkon.nl.
These aren’t dangerous mind you. You can still continue using them.
That means the spot welds haven’t been done well, and the high current of the Q8(5A+) are testing the weld to the limit.
Nice photo
Robert
Thank you, I’m glad it isn’t anything dangerous.
Thank you
Really?
I have bought a couple of these Samsung 30Q batteries. Unfortunately, these spot-welded button tops won't last very long and tend to break off easily. Some of these buttons had contact to one joint, only. Moreover, these batteries had significant more indicated internal resistance, caused by additional contact resistance due to bad joints. These cells run much better since they got solder blobs.
Yep, it’s problematic. As I mentioned before, I would just contact Nkon.nl for some replacement cells with better spot welds.
Is that the insulation ring being burned through? If that ring is at all in bad shape, the cells are not safe to use. That ring is there to keep the anode and cathode from shorting out.
Is that ‘rust’ on the cell tops??
Nah, that’s burned steel/nickel.
Small badly done spot welds tend to do this at high currents.
High currents? How small would the spot weld have to be before the current of a battery would tax the weld?
Small spotwelds are not the problem here.
The problem is very bad contact, which causes high resistance, and therefore, the spotwelds will get very hot.
OK… thanks Blue. :+1:
That still doesn’t sound very good, to me. How is it still safe, if it’s burning the nickel or steel strips or welds? I’m not doubting you, I’m just wondering how that is safe.
If it was me, I’d take off the outer wrapping, pull off the button tab, and sand down any rough spots. Then just use it as a regular flat top. Or, (safety) put some solder blobs on it, after I made it into a flat-top. Or, if I didn’t solder, perhaps just put a small magnet on the top, then hold it in place with some glue around its edges.
You’ve got it.
That’s a slow burn if I’ve seen one. Slow burns mostly affect the outer surfaces of the conductor. When they will completely burn off, the spot welds will be easily removable.
A rapid burn would be very dangerous. Rapid burns will completely deteriorate and may be a safety risk.
IMO, I would actually just remove the spot weld and leave the weld marks. These actually have good contact resistance, and using my good old VTC4s inside of the Q8, I haven’t had any problem with the button welds yet.
[quote=WalkIntoTheLight]
Not a good idea! Using magnets in the Q8 might end up with a short as magnets can shear off when turning/tightening the battery tube against the head of the Q8.
I thought the same thing, rust.
[quote=Lux-Perpetua]
That’s why they need to be held in place with superglue or something. An electrically conductive glue on their surface would be even better. But, yeah, there’s always a risk they might come loose.
I know it looks like rust in the picture, but it’s definitely not.
I got these cells less than a week ago, and they haven’t been in contact with water.
They also looked perfectly fine before using them in my Q8.
I wouldn't say that is a nice photo. It's blurry.
Aaaah button tops! I find no reason to design a device which forces the usage of button top cells, yet I can understand the $aving$ reason. What the manufacturer saved is now costing you money. 
^:)