15PCS 18650 Battery Holder Bundle with Wire 18650 Battery Holder Case 3.7V, 1 Slot DIY Battery Storage Boxes, 1 Slot Black Plastic Batteries Case for 18650 Single Battery

Handy to have screw holes to mount this bad boy. Holds the batteries in well, and roughly medium duty.

Purchased for the 4s holder. Due to some of the other reviews stating that the included wiring wasn't sufficient enough, I attempted to soldering thicker wire to the brass brads. It worked, but be careful with how much pressure you apply to the brad. The black plastic housing was very soft when the solder finally turned shiny.I used some repurposed, Samsung flat-top 18650 batteries for this project and they fit great in the holder. Tight enough to keep from falling out, but easy to pry them out.

In general these are good 18650 battery holders as the cells fit quite well and are snug in the holder. The down side is they are assembled with 24 or 26 gauge stranded wire and on top of that the wire is simply fed under the "rivet" (crimped) that is used to hold the pos and neg terminals. I've had one of these holders waste 15 min of my time tracking down an open circuit situation and problem turned out to be poor contact between the wire and positive rivet. Fortunately I was able to force the wire under one of the rivet edges and flatten tight so I didn't have to throw that holder away.If your project only needs a few hundred millamps at most (brief surges preferably) then these holders will work ok. So far i haven't melted or broken a wire from handling/installation efforts but I'm sure that will occur with the holders I use with breadboard projects - btw, don't waste time trying to get the stripped ends into breadboards - solder a piece of resistor/diode cut off solid lead wire on first, it will save a lot of frustration.So far I haven't found a better holder with leads so maybe if sellers will pay attention they'll tell manufacturers to up the wire size and maybe solder the wire onto lugs which are then crimped on the plastic holders. Meanwhile, anticipate an occasional problem with this style holder.

While light GA wire, these worked perfect for my projects that make use of recycled laptop batteries. I only pull 1 amp current and the wiring is fine for that.

Performed as expected, I daisy chained them together to get the required voltage, great for hobbyists

They fit the button head cells.

This holder is a good cheap source of raw materials to fashion a battery bank out of. Several issues: (1) there is no side clearance for the battery to move - sides need to be heated up and bent out a little for the battery to move. The sides hold it so tight that the spring won't even push the + end against the contact. Also it is so tight you can not take the battery out without some sort of tool. (2) wires are only crimped under the end pieces when "riveted" in. (3) The wire is really small (26ga??), so its not going to handle much current. Needs a little work to be useful, but can be done easily - RAW MATERIALS

All the holders are in series with none of them in parallel. Voltages would be in the 3.7v, 7.4v, 11.1v and 14.8v range with 1, 2, 3 and 4 cells respectively. The cells are very hard to get out of the holders, spicificly the single cell holders. This might be a benefit or a draw back. The wires and then and cheap feeling and are not soldered but crimped in place. Dirt cheap, for the price what more could you ask?