Diy battery 18650 pack or buy one?

Hello guys,

Few days ago I ordered my 80100 motor and now it’s time for a strong battery!
Which would you recommend me or should I build my own
IF I should build my own:
Which spotwelder?
How big the battery and which cells?
Where can I get such a strong bms?
If I should buy one:

Thanks, Felix

Hi, I don’t know where you are from, but I can recoment the sony vtc6 batteries from nkon. I have made my own spotwelder from a microwave oven transformer and it works realy well.

My battery pack is 14s11p and I only use a bms for charging.

With this battery I can foil for more then 1 hour.


Thanks a lot for this detailed information,
I am from Austria(Salzburg) and I don’t have a spotwelder now. Can you reccomend me a spotwelder? Specs:
100amps output
18650 cells
What about 18650 30q or 25r cells? Are the ratings correct?


probably best spot welder is kweld:

second best would be:

and third:

-personally I own this one, it works great, but I am using Kweld electrodes instead of stock.

another option is to build your own spot welder, google it, there are many guides.

like @Rienk says, order cells from nkon (
vtc6 are great cells, but unnecessary overpowered for our use case. instead, get samsung 30Q (Samsung INR18650-30Q 3000mAh - 15A - 18650 - Li-ion - Rechargeable batteries | NKON)
consider vtc6 only if you gonna buy 600 pcs, only then price will be almost same as 30Q.
in 10p setup, 30Q can output almost 200 amps continuous, which is more than enough.

I can build battery for you, but it will take some time.

If you want a 1kwh pack at 14s that would be something like 14s7p. The 30q is rated for 15A max. So this pack could deliver 7x15A is 105A max. If you want 100A discharge in a small pack I would buy the sony vtc6 they are rated at 30A.

I can not recommend you a spotwelder because I have only used my diy spotwelder so far.

Ok I think I’m gonna buy the arduino spotwelder and thanks that you would build a battery for me but I want to learn how to build one and will make more batteries not only for my efoil.
Can I make lots of issues and do you have tips for me?

So what about this site and this cells:

25r is my favourite because very cheap and high discharge rate and in total it’s much cheaper then 30q

Thanks @Rienk and @tinp123 for this support

first of all, get this book:

you can get it on ebay too.

building batteries is very dangerous, because you can short it really easy and fire from lithium ion batteries is not so easy to put out. not just that, if one battery catches fire, there will be chain reaction because of high temperature and every battery next to it will do the same. you have to be absolutely sure what you are doing.

why do you specifically want 25R? they are older batteries with much higher internal resistance and voltage sag than 30Q. on page that you linked, they are much more expensive than 30Q on nkon, so why would you get them from there? shipping from nkon is like 12 eur. you will get 30Q for 2,99 eur if you order 200 pcs. if you insist on 25R, they are 2,40 eur for 200 pcs on nkon (Samsung INR18650-25R 2500mAh - 20A - 18650 - Li-ion - Rechargeable batteries | NKON)
but trust me, go with 30Q. you won’t regret it.


Ok then i will for 30Q I thought i should buy it at a local seller and I will buy the book imediatly.

And the spotlweder? I want a arduino one but does it include the electrode of the welder? I’m not sure.


Felixfoiler i want to buy cells too at nkon maybe we can do together to get better price?
Where are you located?

I will need about 120 cells. Thats cool.

arduino comes with electrodes, but tips are just copper wires, and they bend. it is a little bit irritating to work with them. but they do work, yeah. I am much more happier with kweld electrodes. I have to work with both hands, but every weld is perfect. and you will need lipo battery with each of those spot welders.

Ok great but i dont need something else then a battery and some cables

I am in Austria too. Perfect I am close to Klagenfurt and you

Super dm mich bitte😃und kannst du mir Elektroden für den arduino empfehlen?
Bin von Salzburg

I made a spot welder using a 340CCA car battery and bought the leads from The other parts I used were:

Solenoid - £6.53 6% Off | Dual Battery Start relay 4 Pin Large Current 500A 12V 24VDC Car Power Switch,Starting Relay,Auto Start Contactor,Heavy current

Digital delay timer - £2.31 23% Off | Micro USB Digital LCD Display Time Delay Relay Module DC 6-30V Control Multifunction Timer Switch Trigger Cycle Module Board

Fuse - £0.58 | 30-500 AMP ANL Fuse Holder Bolt-on Fuse Automotive Fuse Holders 50A 60A 70A 80A 100A 125A 175A 200A 225A 300A 400A 450A 500A

Foot switch - £1.48 | IMC Hot SPDT Nonslip Metal Momentary Electric Power Foot Pedal Switch

Nickel strip (best quality I could find) I got from eBay:

Just to add. If I was to buy one for personal use, it would be in this order:

  1. K-weld - great for consistent welds due to operating principle
  2. Malectrics
  3. Boss level

If money was no object, then I would get a Sunstone.

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Thanks a Lot will Go for k-weld or arduino spotwelder
One question remains:
Is the nickel strip capable to transfer 100amps?
I mean I need 5000 watts!

Thanks to all people for this great support love this forum.

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Yes. You can actually get away with smaller if you build/wire it correctly. The current should be pulled “evenly” across your parallel group. For example, if you had a 12P battery on your 5kW load, you want to try and pull 8.3A from each series string (if that makes sense!?)

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Forgot to say … Based on experience, use the ~27mm nickel strap if you’re going to build your battery with the cells standing on end. It’s loads easier to work with.

Ok thanks
What du you think about the
18650 vtc6 cells?

I know someone who offers me them for 3€