I get tired of charging my Fatshark Packs. I actually made some out of 18650. Before my diversity module, I get plenty life. But now, I get probably 1.5hr. So, I decided to use 25650. 5000mah. I thought they would be too heavy for the head strap, but I don't even notice it.

Here are the parts:
Nickel solder tabs
22 awg wire. Red, black and one more color.
2.1mm x 5.5mm barrel connector
2 25650 li-ion
85mm wide shrink wrap clear
Lipo meter board (optional)
3 pins JST 2.54mm connector



You will of course need basic tools.  Solder, soldering iron, wire clippers, you get the point.

I don't like soldering to batteries, but you can.  You will need a big tip and a powerful soldering iron. You want to be quick when you solder to batteries.  If you have a spot welder, it is the best way. I build my out of a microwave transformer. I use an adruino with a foot pedal switch to control the pulse duration. A potentiometer adjust the pulse duration and the foot pedal to start the weld.


This is the schematic.


Cut one white wire about 7-8 inches
Two black and two reds to 4 inches
Only strip the end that you are going to solder to the tab. Don't strip the both ends. Because once you connect the tabs to the pack, the stripped end becomes live.

Strap the barrel connector as shown in photo below. You can make the connector wire as long as you want.

Measure and cut one tab to span the 25650.  Two tabs about half the diameter of a single 25650.

You want to solder all the wire to the nickle tabs first. White wire to the center of the long tab. Solder the two black wires and the black wire from connector to the short tab at one end. Don't solder to the middle if the short tab, otherwise you will not have space to spot weld or solder to the pack. If you plan to solder, I still like to use tabs, because you only have one solder to make and not multiple on the battery.



I like to tape my two batteries together. Make sure you have one negative and one positive face the same direction. Spot weld the negative of one to the positive of the other battery using the long tab. 



Now flip pack over and spot weld the red wires tab to the positive end and black wires tab to the negative end.



I like to zip tie all the wires together. 


Now you will run one black and one red for the meter board. Solder the wires as indicated. I just use form tape to keep the board in-place.



Now run the remaining red, black and white wire for the balance connector. Cut all the wire to the same length. Tip: don't cut them together. You will cause a short. Cut them individually.  Now strap one of the wire, crimp on the pin, and insert into the JST. Important that you follow the order in the photo. Connect the balance port to your charger or battery meter to make sure you see all the cells.





I usually put a piece of electrical tape on the long tab.


Cut the shrink wrap as shown. When I shrink wrap, you want to create the end tabs. This makes it stay in the head strap without falling out.

Nice, voodoo! Would love to see a detailed "Howto" on your spot welder!!

(04-Feb-2018, 03:22 AM)sloscotty Wrote: Nice, voodoo! Would love to see a detailed "Howto" on your spot welder!!

I should post a "how to" for the welder.

(04-Feb-2018, 03:39 AM)voodoo614 Wrote: I should post a "how to"  for the welder.

Thanks for the EXCELLENT tutorial on building a battery pack!  A "how to" on the spot welder would also be greatly appreciated!!!

(13-Jun-2018, 06:41 AM)Schutes Wrote: Thanks for the EXCELLENT tutorial on building a battery pack!  A "how to" on the spot welder would also be greatly appreciated!!!

http://intofpv.com/t-mot-spot-weld-with-...er-control

(13-Jun-2018, 07:09 AM)voodoo614 Wrote: http://intofpv.com/t-mot-spot-weld-with-...er-control

Thanks!  I forgot to search first....