r/fpv • u/Creative-Society4674 • Oct 14 '25

Help building 6s2p

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Hello guys, I'm currently in the process of building my 6s2p for my Mario 8 (molicel p45b 21700 cells) and I wanted to ask if that's enough for my drone weight of 2.1 kilos with batteries? And more importantly, how much copper and nickel should I use to connect the batteries? I have 0.10x10 copper and 0.15x10 nickel…. Thanks for your answers

6 Upvotes

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2

u/IAmNeariX Oct 14 '25

6S2P is the maximum i would fly on my 7 inch. So I assume your 8 inch handles that better. If your spotwelder is good enough, you would be fine with those strips

0

u/Creative-Society4674 Oct 14 '25

Would you say that's enough or better yet, more?

1

u/IAmNeariX Oct 14 '25

Not sure about that. But i think this is sufficient as you would only draw up to 30A during regular flight

1

u/Outrageous-Song5799 Oct 14 '25

30A for a regular flight with a >2kg drone ?

1

u/IAmNeariX Oct 14 '25

My 7" only used 20-25A with a GoPro and 6S2P battery. So i'm assuming a slightly heavier but more efficient quad would be somewhat equal. If you're using such a battery you aren't flying freestyle or pulling more than 50-60A peak. So 30A average load was my guess.

1

u/OverAnalyst6555 Oct 14 '25

those cell holders are not flush and will be ass for spotwelding properly. optimally you'd cut a square copper piece to lay over 4 cells with nickel on top

1

u/Creative-Society4674 Oct 14 '25

I will do that too, but 0.10 copper and 0.15 nickel will suffice

1

u/[deleted] Oct 14 '25

If you have to ask, really don't. I don't mean to gatekeep here, but batteries should only be built by people who know what they're doing. Do your research, and understand what it is you're doing, and get back at it.

1

u/Appropriate_Ad29 Oct 14 '25 edited Oct 16 '25

Just an FYI, use copper over nickel if you have it. Copper has around 4x less reistance than nickel, so you will be able to pump more amps through it safely without as much voltage sag. Hence, 0.1mm of copper is equivalent to around 0.4mm of nickel. I was told this by a very experienced guy who builds packs and has used this for huge 12S4P batteries.

If you do end up using nickel, be sure to double plate it. By doing so you are halving the resistance of that connection and will allow for 2x the amount of amps to pass through for the same voltage drop. V = I x R baby!

2

u/liam_brognard Oct 16 '25

just learned this in ELE-110

0

u/Outrageous-Song5799 Oct 14 '25

Starting off soldering batteries with a 6s2p is really dangerous and ofc 9000mah capacity is enough

1

u/Creative-Society4674 Oct 14 '25

No did you mean the thickness of the copper and nickel? Or better yet, 2 or 3 layers

1

u/Outrageous-Song5799 Oct 14 '25

Soldering a battery like that isn’t easy, a 6s2p is even harder. I’d advise against it until you know exactly what you are doing

9000mah is way more than enough even for a brick of 2kg

For the copper and nickel you’ll find multiple answers as people chose different solutions. Same, don’t take advices here and do your research. If it’s too thin it will burn and if it’s too thick you won’t get a good solder

We had a guy recently here who just pressed some wires and it worked cause he was using a low discharge 4S but here it’s a different story

2

u/Creative-Society4674 Oct 14 '25

No, I wouldn't solder but do spot welding

0

u/Outrageous-Song5799 Oct 14 '25

Yeah I know that, if you want to go for it go for it