As I spec'd out my long range 3" build, powering its flights started to come up.  Looking for the best option in LIPO's uncovered several videos regarding Lithium Ion packs, 3S and 4S...



This one really piqued my interest.  Seems simple enough...then I came across this one:



30+ km of total flight on a quad that is very similar in weight to KT-Leaf!

I have been using 18650 Li-Ion for high output torches for decades, but just beginning to "see" the potential for flight.  I do have an understanding that I will have lower potential amp draw, but as my conservative flight practice is to stay below 12 amps of draw, 20 amps should be fine.

I believe this could be a good thread for our long range discipline, so here it is.  How many of of us have used or are currently using 18650 or similar packs?

A simple wiring diagram.  I cannot take credit for this artwork...my skills in graphic arts is sorely lacking.  I borrowed this one as it essentially shows the same thing as my hand drawing, but much cleaner.




By soldering in a balance lead, it should allow for consistent charging across all 4 cells.

I know the best way to do this is build your own packs.  I would like to get some premade packs in 4s or 6s and 3000mah-5000mah and try them out.  Then if I like'em, start building my own.  Have you seen a source for factory made packs?  Or are you planing to build your own?

If you build your own packs are you going to get a spot welder or solder them?

I have made 2s and 3s packs using samsung inr18650 25r(2500mah) and Sony vtc6 (3000mah)using the diagram kaity posted above. Both Samsung and Sony packs performed almost same. 2s weighs 100gm, 3s 150gm. I just used normal soldering. Was careful not to touch the battery pads too long with heated soldering iron.

I tested hovering my 3 inch quad with AUW 230gm with above packs. Throttle was at 65% to 80%. Current draw about 12A. Not efficient at all. Got 10 to 11 min fly time. Batteries landed 45 to 50 degree Celsius. I could discharge up to 6v. Motors landed just warm.
Same setup I tried with 3s pack, but the added up weight did not really improve the situation, and also burned 1 motor.

My motors are dys 1104 7000kv. I think replacing them to a better choice like emax 1106 4500kv should give me double flight time. Less amp draw and less hover throttle percentage.

I have YouTube videos of tests, with OSD data.

Subscribing to the thread, as I am also interested in endurance flying.

(27-Dec-2019, 05:00 AM)Krohsis Wrote: If you build your own packs are you going to get a spot welder or solder them?

I plan to roughen and solder.  I guess I could spot weld them after watching a video on how to do that...but soldering seems just as easy at the moment.

Just pulled the battery out of an old Toshiba laptop that was collecting dust in the garage.  There are 6 cells in it.

Spot welding is the way to go.

(27-Dec-2019, 06:03 AM)kaitylynn Wrote: Just pulled the battery out of an old Toshiba laptop that was collecting dust in the garage.  There are 6 cells in it.

So, inside the laptop battery housing the cells are individually contained?

My newest old lap top battery is wide and flat more like a cell phone battery.

(27-Dec-2019, 01:19 PM)Krohsis Wrote: So, inside the laptop battery housing the cells are individually contained?

My newest old lap top battery is wide and flat more like a cell phone battery.

This is not my photo...yet.  I have salvaged about 20 of these over the years as a provider of cheap flashlight batteries.



This is what is inside the older LT packs.  They tend to be "unprotected" cells as the charging board of the pack takes care of that.  Have to be careful about over discharging them, but there are usually 6 to 9 18650's in one.

You are right about the new packs.  Newer batteries seem to be one big cell.

I recently created some 4S Sony VTC6 3000mah packs for my Eachine Black Wing.
It's a perfect fit and they provide a much longer flight time.
Normal 4S LiPos tend to be to high to fit nicely into the compartment.

These Sony 18650 can deliver up to 30A. So that's enough for my wing.

Some pics:

And 100 grams lighter than equivalent size lipo probably.

(30-Dec-2019, 04:22 PM)ShadowFPV Wrote: I recently created some 4S Sony VTC6 3000mah packs for my Eachine Black Wing.
It's a perfect fit and they provide a much longer flight time.
Normal 4S LiPos tend to be to high to fit nicely into the compartment.

These Sony 18650 can deliver up to 30A. So that's enough for my wing.

Are you spot welding or soldering the connections to the batteries?

(30-Dec-2019, 04:50 PM)Krohsis Wrote: Are you spot welding or soldering the connections to the batteries?

The 4th picture shows soldered connections. Bruce recently did a video on soldering to Li-ion 18650 batteries and it's pretty easy. Just de-oxidise the surface of the contacts really well and scratch them up a bit, then use a high heat for a short period. Jobs is then a good-un with no need for a spot welder.

EDIT: Here you go...

(30-Dec-2019, 04:40 PM)Sugs Wrote: And 100 grams lighter than equivalent size lipo probably.

My 1500mah lipo's weight 173 grams and this 3000mah li-ion pack weighs 208 gram.
So double the capacity for 20% more weight.

I don't have a 3000mah lipo to compare.

(30-Dec-2019, 05:27 PM)SnowLeopardFPV Wrote: The 4th picture shows soldered connections. Bruce recently did a video on soldering to Li-ion 18650 batteries and it's pretty easy. Just de-oxidise the surface of the contacts really well and scratch them up a bit, then use a high heat for a short period. Jobs is then a good-un with no need for a spot welder.

EDIT: Here you go...

Yes I first work the cells with sandpaper.
Then I put the solder on using my TS100.
Tricky part is the positive side. You don't want to much solder on there as it could flow out to the side and make contact to the negative side.

Maybe a spot welder would be better / easier. But then again maybe also more difficult to add the balance leads.
I pulled the wires after soldering and found that they are really firmly soldered onto the cells. They won't come off easily.

I bought these cells new for €4,- a piece.