18650 x40 case

thingiverse

A module based 18650 battery pack. Print the connector to join multiple x40 packs together, as many as you want! Print the attachment board to mount stuff on the side of the pack. (Added 15-09-2019) My 40p3s pack of old mixed type 18650 cells is still working great. i had a few cells go dead on me (cant hold charge for more than a minute), but that is because some 18650 cells just charge quicker than others and so they would over charge. I'm choosing natural selection for that problem. (Update End) For one module (with up to 40 cells), you will need: 2x Lid and 2x BatteryHolder. If you don't plan on using springs inside the BatteryHolder, you probably want to design your own Ring parts to suit your needs, because the pack height will be different in height. Otherwise, print 2x Ring aswell. If you plan on more than one module, print one or two HolderConnectorWide to connect two BatteryHolders together. The Handle part will only fit like its shown on the pictures; across 3 boxes on the top. For safety reasons, add 5 amp fuse wire to connect the springs to the bussbar on atleast one side. Batteries might die by shorting out essentially becoming a big wire. If this happens, all the amps of the other batteries will rush through the fuse wire and melt it, disconnecting the shorted battery from the pack. When you assemble a module, make sure all batteries within it are within about the same voltage. Once both batteryHolders are on tightly the batteries in that module will start evening out their voltages. If the voltage difference is too grate on say one battery, the rest will charge that battery with a lot of amps. That might kill that battery one battery. I'm using the Victron SmartSolar as solar charge controller and have been playing around with the settings. The settings i've arrived at for my 12v battery pack, is selecting battery preset LiPo and changing the float voltage to 12 and the absorption voltage to 12.10. This way the charger goes from bulk charing (pushing as many amps as possible into the battery), to absorption mode for up to 4 hours, to float. On sunny days, i'm able to charge both my laptop and the battery pack at the same time, with my 100W solar panels. There are plenty of power in 100W, for my purposes (usb charged devices like phones, tablets and a few drone batteries), but you need to figure out your own dimensions of your system; what is your needs and how to achieve them. Once the solar panel voltage reaches all-most-zero (like at night), the charger will consider doing another absorption charge. For some reason, the solar charger won't let me go under 11.7 volt. In the future, i might add another module to my pack, to get the voltages up. (Added 15-09-2019) I needed to remove a jumper from the solar controller, for the software settings to take affect. Important. You will need a battery balancer to even out the packs once in a while, otherwise the solar charger will overcharge the high voltage packs and kill the batteries. You should also put up a fuse that will limit the max outtake from the battery, to protect the bussbar and the wires inside your modules. that way you make sure that a short out side your battery wont melt the wires you use. I found a fuse holder in a local car-part dealer and i'm using a 15 amp car fuse (the black box on the red wire. You should decide on a wire/plate thickness for your buss bar, that can handle the load (amps) you plan to draw out from the battery pack, and then some. if the holder you are planning for doesn't have springs in it, you might want to cut off some of the battery holder, just to save some material. Apart from some M3 screws I used the following items: https://www.aliexpress.com/item/50-Pairs-Metal-Battery-Spring-Plate-Set-for-AA-AAA-Positive-Negative-Contact-New/32870772743.html?spm=a2g0s.12269583.0.0.73621fd6ToAKLI Some twisted wires, Car fuses