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

[dp106]

One of these packs would be good in my Ranger. It will cruise on 4 amps or if I want to go faster 50% throttle is 9ish amps  :)

I just don't trust myself to solder them and certainly wouldn't be brave enough to try making a spot welder!  I did see some once that came with tabs on, I think they were supposedly to make soldering them easier?

I also saw someone selling plastic blocks that you could use to make up packs, wish I could find the link again! I suspect they would add a lot of extra weight and bulk though which would negate the two main benefits of using the 18650's..

[BigT]

I am going to have a go at making a spot welder with the momentary switch. Really just for something to do and because I have most of the parts in various storage boxes, symptomatic of being a "sort of"retired builder/plumber/engineer/property developer. I have ordered some cells to try out. If it works, which I am sure it will, and I can work it, I'll weld a pack up for you. Plenty of members have helped me over the years with 3D printing, repairs etc.


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[dp106]

I am going to have a go at making a spot welder with the momentary switch. Really just for something to do and because I have most of the parts in various storage boxes, symptomatic of being a "sort of"retired builder/plumber/engineer/property developer. I have ordered some cells to try out. If it works, which I am sure it will, and I can work it, I'll weld a pack up for you. Plenty of members have helped me over the years with 3D printing, repairs etc.


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That would be cool, thanks!

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[English Turbines]

  Soldering was easier than I thought it would be TBH...:

1) Use a large Iron.

2) Abrade the surface with fine emery or similar and then wipe clean with alcohol.

3) Apply a little flux to the surface.

4) Apply the iron (briefly) to the flux to melt it.

5) Tin the surface of the cell with LMP Solder, ensure you use Leaded Solder!!!!! Don't overheat.

6) Apply pre-tinned wires to the joint and apply heat to the end of the tinned cell, (not the main wires) until it forms a joint.

7) The wire conductors in the photo are copper, which solders more readily than steel braided, it's also more conductive.

8) Lastly, solder on the balance wires, to the copper conductors / cell ends, do not overheat the thin balance wires.


   Flux and Solder :

                             I think the Flux came from B and Q and the Solder came from RS Supplies, note, the solder is 60 / 40 type with 40% being Lead.  Clean off the Flux residue with alcohol when you get finished, its acidic.



                                                                                               :vulture:

[Billy_boy_2010]

hi guys

would love some advice on these little things

I bought 6 of these with the aim of wiring in series and parallel to give 6000 of 3s

however- the motor and prop setup I have is such that I would much rather run 4s.

However- this seems it's likely to be a far harder wiring issue. Is this possible ? and is it possible to balance the cells effectively like this ?

If not i will have to cope with 3s- it's not the end of the world.

Thanks :)

[Dillwhacker]

No, not possible with 6 cells.
You can have 3P2S or 2P3S.
If you want 4S, you need 4 or 8 cells, 4S1P or 4S2P.
:)

[Billy_boy_2010]

Ah bugger- ok thanks

Think I will have to go for 3s- the airframe won't cope with the extra 2 batteries I fear.

Any hints on how I can wire this up?

Two lots of 3 in series then wires in parallel should be easy enough- but the balance leads are confusing me?

Cheers

[Schalonsus]

Better imagine you build three packs of two in parallel and wire these in series. Now the balance leads go between these in series wired packs

[Jake Bullit]

I found this guide quite useful.I built a 4S2P that`s 6000mAh 60a from an old laptop battery
I AIN`T FLOWN IT YET THOUGH   :+

https://blog.seidel-philipp.de/diy-build-a-longrange-lithium-ion-battery/

[Billy_boy_2010]

Hmmmm ok thanks guys

Should I wire 3 pairs of parallel, of 2 triplets of series?

The latter seems best to me?

[Dillwhacker]

It depends on if you want 3S (12.6Volts) or 2S (8.4Volts).
If you put them in series, you add the voltage and keep the mAh the same.
If you wire them in parallel, you add the mAh and keep the voltage the same.

[Billy_boy_2010]

Ok so I got this built. It's quite time consuming really. in the end I made two 3s packs in series- and then paralleled them up to make 6500 of 3s. Pack weighs around 300g. For reference a turnigy 4000 3s weighs around 250g- so it's around 100g saving for the same capacity.

On the other hand- it cost me £35 to build. I could have had 3 multistars for that price.

Time will tell if it's worth it. One big advantage is the customised form factor.

[gowen]

For those who don't fancy soldering or spot welding this system could be the answer.

https://electrek.co/2018/04/17/diy-li-ion-battery/

[Drone 5]

Interesting. Will give it some thought.

Thanks

[dp106]

Has anyone tried the vruzend kit?  This could be the perfect solution my only concern would be how much weight it would add. The main benefit of 18650 cells is the weight saving so this could impact that quite a bit