I can highly recommend the Malectrics spot welder. It works well. Far better than a lot of the Chinese rubbish available.
https://malectrics.eu/product-category/arduino-spot-welder-bundles/
Cheers, gents.
Any Alibaba or Aliexpress suggestions for 30qs? Am from Aus
Cheers, Dan
Dan be very careful buying batteries from AliExpress or Alibaba. There are many fake batteries out there. I’m currently looking for a new supplier in Australia too. A few suppliers are having difficulty getting stock at the moment. The cheapest supplier I can currently find at the moment is in Perth.
$7 20 per cell
https://www.lanplus.com.au/index.php?route=product/search&search=Samsung
You will need to email them to get a bulk order price.
Where in Aus are you?
Thanks for the info, I am in Perth. I will explore them further.
Thanks heaps, cheers, Dan
1 Like
I decided to go NOT with the 12C LiPo batteries but actually I would like to buy a pre-built battery pack, rather than welding my own one. I have read some descriptions and I respect the process to much.
What is your opinion with `this pre-built battery pack?
I am just concerned about the 48V. If a battery has 3.6 x12S should be 43,2 V right? It is also possible to ask them for a customization. Has anyone experience with pre-built battery from AliExpress or even did buy customized one?
Best regards,
Umut
Hi Umut,
it’s 13S - maybe your ESC can handle it.
Very hard to say anything about quality - with this the chinese are “individual” 
Mike
Most of the time classic cell like 18650 nominal voltage is 3,6-3,7v , but charged is 4,2v so no problem with 12s you will have 48v
Ok, maybe I will build my own batteries. I have found this gem on Youtube! I think this is a must see for every DIY battery builder and I want to share it with you. The guy is explaining it very reasonable for a newcomer like me.: Don’t use BMS!
Would you agree with him?
Best regards,
Umut
I have designed a 12s6p battery pack based on 14s14p pictures of @Flightjunkie. I will use two 12s6p.
Here are the wiring diagram. Could please someone double check it?
Also I am a little confused regarding the BMS. Shouln’t it be 13 cables? 12 for the cells and 1 negative (1 battery pack). @Flightjunkie is using 8. 7 for the cells + 1 negative. Can a BMS with 7 cables in my case handle that?
Best regards,
Umut
Attachment:
- top and bottom 14s14p of @Flightjunkie 's battery
- 12s6p wiring diagram for a 12s12p pack
2 Likes
ISTR @Flightjunkie was not using a BMS, but much like i do, uses a balance charger.
You get more control and better balancing with one of these. BMS on the discharge is expensive for the AMPs we use. As long as you trust your ESC fail safes. You can eliminate the BMS entirely.
This allows me to charge only to 4.1v using my ISDT T8 charger. (many more charge cycles due to being much better for the batteries)
Hi.
Looks like a good start on your battery build!
I suggest not using a BMS. I don’t use a BMS.
But, the types of BMS I am familiar with all required the extra wire. Number of cells plus one.
Sorry actually I meant balance charger instead of BMS. Im thinking to get an iCharger X6.
On the wiring diagram the “BMS” stands for the connector which will be plugged into the iCharger X6.
What confuses me though is, that the balance charger will recognize the 6 cells.
Best,
Umut
I’d love to know exactly what it is about the chemistry that makes them so much less reliable. I’ve got four of these large lipo’s. Two have inflated and just don’t feel safe, the other two are doing pretty good. With a charge cycle or two nearly every day for a little while now. Haven’t yet built 18650 packs with this kind of current drain application.
My internal measurements for the bad packs is up to about 3ohm compared to the healthier packs hovering around 1ohm. Not sure where the safe margin is or what caused it. Could be over stressing during early build stages or simply not having been stored well for an extended period by the previous owner on those packs. They don’t get excessively hot but it still scares me enough to not use them.
Or is it that the package of 18650 simply hides these types of things?!? And that they see similar internal increases. Anyhow, curious as to the causes and why’s 
Finally, I received the batteries 
Which type of soldering do you use for soldering @Flightjunkie? And how many watts / heat do you use?
I would like to prevent galvanic corrosion and brittle joints.
Currently I am trying to understand this wiki page
Hello.
Based on your question it sounds like you are new to soldering?
Watch some YouTube videos on soldering Li ion cells.
Practice on some old cells until you get the technique down. Read my thread on soldering battery with individual fuse wires. You must learn to solder each cell quickly with the soldering iron on the cell for only 1 to 2 seconds. If you are doing it right the solder will flow out and create a solid connection. And a second later you can hold your finger on the battery terminal you just soldered because minimal heat was transferred to the battery. Too much heat and you can damage the cell.
Suggestions:
- Clean the battery terminals before soldering. A light sanding, or rubbing alcohol. They will solder much better clean.
- use a paste type soldering flux
- use high quality lead free solid core solder
- use a soldering iron that is at least 100 watts
- have a damp sponge to quickly cool the solder joint.
Don’t buy cheap solder or flux. This is the stuff I use.
As far as galvanic corrosion…as long as the battery doesn’t get wet, you won’t have any corrosion issues. I spray my complete battery assembly with several coats of Conformal coating so it has some water and corrosion protection.
https://www.amazon.com/gp/aw/d/B0070XZM2G?psc=1&ref=ppx_pop_mob_b_asin_title
https://www.amazon.com/gp/aw/d/B0182L4KG8?psc=1&ref=ppx_pop_mob_b_asin_image
2 Likes
Hi @Flightjunkie,
exactly I am new to this topic. Thank you very much for all the information. I have seen youtuber who are using some special acid for the lithium ion cells. The soldering part looks perfect afterwards. But I will go with the lead free solder and a powerful soldering device as you told me.
One last question regarding the fusewires. I have seen that you used in some of the pictures thicker fuse wire for the front cells and thinner for the remaining. Then I have read you had started with 30 AWG wired but switched to 20 AWG because the 30 AWG was too thin?
Can you make me a suggestions please which AWG to use and maybe also give me a an amazon link?
Thank you very much for your support.
Best regards,
Umut
Hi.
I use 30awg for the fuse wire.
The 20awg is not a fuse wire, and will not blow under load. Every cell in my pack is fused with the 30awg. One terminal on the ends of the pack have 20awg where the bus bar is attached, securing the 6awg battery leads. Because the fuse wires have a tendency to break on this bus bar when handling the battery. But these cells are still fused because of the 30AWG on the other terminal.
If you read my thread on all the testing I did to decide on the wire type, you will see how I determined 30awg was correct. At 10-15 amp the 1/2" long fuse wire doesn’t get hot. At 20 amps the fuse wire gets hot. And at 25 amp it blows. Perfect for the 30Q cells.
I can draw 280 Amps continuous out of my battery with these fuse wires. But, it’s fused at 250A. And over 140A (10A per cell) the 30Q cells get hot (130°F). I prefer to keep my cells cool.
1 Like
Aaaah, now I understood!
Thank you!!