Warning: Do not put 21700 cells in chargers not made for that cell! (pics in post #4)

[sarge12]

@tatasal

@Zappaman

This is one of those “learn from somebody else’s mistake” moments. :+1:

Careful with chargers for sure, but ALSO good to check the surface of whatever you are inserting the battery into.

That solder blob took some time to work through that battery and is a dangerous manufacturer error. Glad you light didn’t go thermal in your hand!

I mentioned to Niwalker the dangerous design fault and pointed them to the thread.
They sent me a “new” re-designed carrier but because the springs are very stiff and with that solder blob still there albeit a little farther away, virtually very little allowance for space available, look at what it does to the wrappers:

Just a suggestion of something that might prevent future damage. Roughen the solder there with sandpaper and then coat the solder with clear nail polish. You would only roughen the solder to provide better adhesion of the polish. Allow to dry completely and may even want to put a second coat of polish on it. Just a thought.

[Pete7874]

@raccoon city

@Pete7874

@raccoon city

I think I’ll get a Nitecore UM4.

They will accept really long cells (up to 79.8 mm) and they’re pretty cheap.

How much are you getting the UM4 for? Seems like Miboxer C4(v4) would be another good choice at a very reasonable price.

I paid $21.71 (total price) on Banggood.

Good deal. The C4 is currently $23.75 with free 2-day prime shipping on Amazon. I just don’t know which specific version it is…

[d_t_a]

@LoPan12

my guess is that in putting the long cell in, you tore the wrap on the battery, and the positive contact terminal on your charger shorted the negative body to the positive terminal.

This appears to be the most plausible explanation. Putting the Molicell P42A in the SC4 slot, may not have torn the wrapper, but could have “pulled” the wrapper enough as to make a short happen.

borrowing tatasal’s picture:
(probably something like this happened to the wrapper, except with the P42A, there is no insulator beneath the wrapper.

But appreciate the OP mentioning this, I’ll have to be more careful when I’m checking and testing various chargers.
I noticed that the Molicell P42A is one of the shortest 21700 battery I’ve checked (it’s a bit shorter than the Samsung 30T or 40T).

For instance, I can slide the P42A onto a Liitokala Lii-100 charger, where other unprotected 21700 batteries do not fit at all.
(however, I need to be more careful when I do such test of trying to check “which charger can fit which batteries”, since the wrapper could accidentally be “pulled” exposing the + and - sides and causing an unexpected short)