Lithium Ion Flight Packs....Making your own packs.

[English Turbines]

My Sanyo NCR18659GA cells have arrived...All three measured 3.55 volts, amazing.

  They look nice quality and the postage was reasonable too...I also got a few other small accessories from this UK supplier.

  I may have a go at soldering them up tomorrow...Im guessing draining them to 3 volts per cell is acceptable?

                                                                                              :vulture:

[English Turbines]

  So, yesterday I soldered these cells together.

Using a large iron and some flux paste, it was pretty easy to get a fast clean join, although if I do it again, it will be easier for sure.  Not sure about their capacity yet and when I charged them they took about 2300mah. There is no text printed on these cells, so not so sure about them being genuine SANYO TBH.

Oh yes, and in case you ever wondered about why they are called 18650 cells...?

                     18mm diameter x 65.0mm long.

  My charger has a 4.10 volt cutoff point for these cells, does that sound about right because Im sure the spec says 4.20volts?

               Photos to follow...

                                                                                              :vulture:

[Coyote]

4.2v is the max voltage fully charged.

Glad to hear it went well, I am a bit dubious how well it will work, because of why they insist on spot welding them together if soldering is perfectly fine ?

[English Turbines]

4.2v is the max voltage fully charged.

Glad to hear it went well, I am a bit dubious how well it will work, because of why they insist on spot welding them together if soldering is perfectly fine ?

Hi Ian,

  So,I can set my charger as a Lipo then and take them to 4.20 volts per cell?

  Yes, the answer is easy, speed...the spot welding is a lot faster and cheaper than soldering ever will be, plus it eliminates the heat damage possibility.

Im going to run them down to 3v per cell and see how much capacity they will absorb afterwards.

  Is 3v per cell ok do you think?

                                                                                               :vulture:

[Schalonsus]

Try 3.2V first and look what your charger put in after flight

[English Turbines]

Try 3.2V first and look what your charger put in after flight

  Oh, ok...3.20v it is then....and charging, is 4.20 v ok as well..?....My LiIon setting in my charger cuts off at 4.10 volts per cell.?


  Some photos of my first attempt showing soldering, the joints look a bit dirty / sticky due to the flux residue, but they are good despite what they look like.

               




                                                                                                :vulture:

[Schalonsus]

old Li-Ion batteries were charged to 4.1V but the new generation is chargeable to 4.2V

soldering joints looking good and solid!

[English Turbines]

old Li-Ion batteries were charged to 4.1V but the new generation is chargeable to 4.2V

soldering joints looking good and solid!

  Cheers m8,....sooo...does this mean I can set my charger as if these were Lipos?...ie use the Lipo setting which cuts off at 4.20vdc?

                                                                                               :vulture:

[Schalonsus]

Absolutely!
I also use LiPo program for my Li-Ions.

[BigT]

Most of the mid range chargers have an "auto" setting. Usually found by selecting LiPo and scrolling through the  capacity setting. It's usually at the top end of the capacity setting   On my HK supplied iMax  for example. What I do is leave the charge on auto, select the capacity, 3s for example, connect and press start. The charger software checks and then if it is a LiFe cell it sort of knows and charges to the correct capacity with the cell count flashing. I have 2 chargers that do this. My guess is that the algorithms are generic. Maybe I will do a video to show this.


Sent from my iPad using Tapatalk

[Coyote]

Lithium-ion
Nominal Volts  End-of-discharge  Max Volts
   3.6V                      2.8–3.0V        4.2V
   3.7V                      2.8–3.0V        4.2V
   3.8V                      2.8–3.0V      4.35V
   3.85V                    2.8–3.0V        4.4V

[English Turbines]

Lithium-ion
Nominal Volts  End-of-discharge  Max Volts
   3.6V                      2.8–3.0V        4.2V
   3.7V                      2.8–3.0V        4.2V
   3.8V                      2.8–3.0V      4.35V
   3.85V                    2.8–3.0V        4.4V

  Thanks Ian,
                      Yesterday, I used a largish slave motor and a 10 x 6 Prop and gently discharged the new cells over a period of 90 minutes. Individual cells stayed within 0.2v of each other.

On reflection, I dont think I discharged them low enough, because I only ran them down to 3.50v per cell.
  A re-charge indicated only 2,100mah absorbed.
I need to do this test again as I think the true capacity is nearer 2,500mah, perhaps a little more.
   I was a little worried about them being new cells and if they need some sort of break in period..?

                                                                                               :vulture:
 
 

[Coyote]

No they discharge much lower that lipos do, 2.8v is fine.

[Schalonsus]

Dont go too low with the Sanyo 18650GA's...
Look at my Skyfun video how much capacity i used at what cell voltage ;)

[English Turbines]

Dont go too low with the Sanyo 18650GA's...
Look at my Skyfun video how much capacity i used at what cell voltage ;)

   Ok, what is the safe lower voltage limit on the Sanyos do you think..?

  If Im not mistaken, your 8 cell flight pack in the Skyfun is rated at 5200mah capacity..?

This seems a little on the low side to me, as that's only 650mah per cell..?  which makes my 3 cell at 2100mah seem ok..?
What is the actual capacity of that 8 cell pack do you think..?

                                                                                               :vulture: