A Very Reasonable 18650 Battery Source

[Boyntonstu]

This YouTube guy has done it.

He show why soldering is better than the module design.

I am going to contact him about solar charging.

Check out his interesting and comprehensive links.

[video=youtube]

 

[jonyjoe303]

soldering is good but if you can get a tab welder that is even better. I find soldering works best in the positive side of the 18650 cell, the negative side can be more problematic. It can be done but its not easy work.

Not mention in the video is the hard work of scuffing up every cell to make the solder stick. Some use sandpaper I use a file to scuff up the ends of the battery and even then sometime the solder has problem sticking. Prepping the cells can take hours if you have hundreds of cells to do.

For the larger lifepo4 cells, you need a tab welder, solder just doesnt stick to them.
With the tab welder I don't even need to scuff up the cells. But even with a tab welder you still need to solder the wires and fuses to the battery pack.

The module design is good for those that don't want to solder or tab weld. 100 cells, would make at least a 60 ah 3s 11.1 volt battery pack. A very decent battery pack if you use those 1 dollar 18650 cells.  

This is the tab welder I bought, paid 95 dollars for it, runs off any 12 volt lead acid battery. Does quick work of building battery packs.

 

[Wabbit]

Just an FYI, lithium-ion batteries can be dangerous. Remember all those hoverboard fires? Lithium-ion batteries. I would strongly suggest anyone working with these to look into safety issues\precautions first. Don't take anyone else's word that these are "safe" batteries. Safe is a relative term. Read up on them yourself. Period. Stay informed and stay safe. Best of luck on any projects, and tutorials\write ups are appreciated. Include safety warnings if they are needed.

 

[John61CT]

Lithium-ion is a useless catch-all that covers dozens of chemistries.

The batteries that have thermal runaway problems in screen gadgets have nothing to do with

LiFePO4

chemistry batts, or LFP, which are now widely in use on expensive yachts, and some land vehicles now as well.

These are perfectly safe wrt fire risk.

However these DIY 18650 projects are not how things are usually done, would never be allowed by insurance inspections on boats and may be IMO fine for hobbyists with plenty of skills and time on their hands, but not the way I would go for my energy storage.

That would be factory-made "prismatic" cells, each being 3.2V nominal x4 gives 12V, for example
http://www.electriccarpartscompany.com/100Ah-CALB-UL-Certified-Batteries

There have been several threads already about their very high cost compared to lead, specialized care requirements and the need (or not) for BMS electronics.

Carry on in this thread with the 18650 DIY approach, just wanted to point out the more conventional approach for House banks in multiple 100AH capacities, and correct the common misperception that this specific chemistry is prone to fire risk, it is not.

 

[Wabbit]

...Lithium-ion is a useless catch-all that covers dozens of chemistries...

I stand corrected. Will have to look into the 18650's that are without the exploding\fire risks. I use them in my e-cigs. Be a lil worry off my mind if I didn't have to babysit them so much. Thnx for the info, any idea of a link for them or terms used to find them? Thnx again.

 

[ZoNiE]

Never solder the batteries. Spot weld only. Soldering puts too much heat into the cell and permanently damages it...

 

[John61CT]

> Will have to look into the 18650
...
> any idea of a link for them or terms used to find them?

Yes, LiFePO4 for the chemistry

18650 for that cell type

 

[Wabbit]

Didn't even think of that. Why? Because I'm an idiot.

 

[Boyntonstu]

soldering is good but if you can get a tab welder that is even better. I find soldering works best in the positive side of the 18650 cell, the negative side can be more problematic. It can be done but its not easy work.

Not mention in the video is the hard work of scuffing up every cell to make the solder stick. Some use sandpaper I use a file to scuff up the ends of the battery and even then sometime the solder has problem sticking. Prepping the cells can take hours if you have hundreds of cells to do.

It took me about 6 months to learn the trick on how to solder the negative terminal as well as the positive.
I used a vintage wooden handle 150 Watt soldering iron with a huge copper angled tip.
Using a 1,000 watt light dimmer connected to an AC receptacle, I controlled the iron until it tinned well.

Overheating or under-heating is the problem.  It has to be right.
Sanding became less important as my skill level was raised.

I hope that this tip helps.