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18650 beginners guide/introduction

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nemail2:
Hi

is there any beginners guide or introduction in 18650 cells you can recommend?
I have salvaged some of them (Sanyo) and would like to use them for my projects but I also don't want them to catch fire or explode in my hand. I'm very aware of the danger those batteries carry within them, that's why I'm asking for advice here.

I know that shorting them and charging them with too much current is not good.
Do I always need a charging controller or can I charge them using constant current with my Lab PSU as well? How much current, are they all the same or does it depend on the manufacturer/part number of the 18650?

Also I heard of balancers which I need if I want to charge two or more cells, are they connected in series or in parallel then, does that even matter?

Are there basic circuits or ICs which practically everyone uses (general purpose parts) which I should take a look at?

Thanks!

spec:
Hi nemail2,


--- Quote from: nemail2 on November 20, 2018, 07:35:35 am ---is there any beginners guide or introduction in 18650 cells you can recommend?
--- End quote ---
Look up 'Battery University' on the net: https://batteryuniversity.com/learn/article/types_of_lithium_ion


--- Quote from: nemail2 on November 20, 2018, 07:35:35 am ---I have salvaged some of them (Sanyo) and would like to use them for my projects.
--- End quote ---
Sanyo, now Panasonic, are one of the best manufacturers of batteries, so you are off to a good start. :)


--- Quote from: nemail2 on November 20, 2018, 07:35:35 am ---I also don't want them to catch fire or explode in my hand. I'm very aware of the danger those batteries carry within them, that's why I'm asking for advice here.
--- End quote ---
The dangers of LiIon batteries are often greatly exaggerated, especially on some forums.

Your batteries are almost certain to be lithium/cobalt chemistry (LiCoO2), which presently has the highest capacity/weight ratio on the market. LiCoO2 is also the cheapest.

But, one downside of LiCoO2 is that if it overheats it can get into a thermal runaway situation where the more heat it generates, the more heat it generates. But the manufacturers are aware of this and house the battery in a substantial case with blow off vents to allow any excessive gas pressure to escape.

The other thing to bear in mind is that we are surrounded by LiCoO2 batteries. They are in mobile phones, laptops, battery power tools, electric cars, E-cigarettes, and so on. And in many of these devices the batteries have a hard time. That is why they don't last very long.


--- Quote from: nemail2 on November 20, 2018, 07:35:35 am ---I know that shorting them and charging them with too much current is not good.
--- End quote ---
Just like any battery ;D


--- Quote from: nemail2 on November 20, 2018, 07:35:35 am ---Do I always need a charging controller or can I charge them using constant current with my Lab PSU as well?
--- End quote ---
It is far better to use a dedicated charge controller, but you can charge your batteries with a lab power supply set to no more than 4V, and no more current limit than capacity/10. 200mA would be safe for all 18650s.

(UPDATE 2018_11_21) Depending on your lab PSU design, there is a danger of back flow if the power supply is turned off while the battery is still connected. So best to put a switch between the battery and the power supply to cater for this. Then ensure the switch is off, turn the PSU on and connect the battery to be charged. Once charging is complete, turn the switch off first.


--- Quote from: nemail2 on November 20, 2018, 07:35:35 am ---How much current, are they all the same or does it depend on the manufacturer/part number of the 18650?
--- End quote ---
18650 only refers to the case size: 18mm diameter, 65mm long. There could literally be anything in the case, but generally it is LiIon of some flavor.

The earlier LiIon 18650s had a maximum capacity of around 1AH, but in 2018 the maximum capacity is around 3.5A, that is from first tear manufacturers like Panasonic (Sanyo), LG, Sony, Varta. Makes, other than first tier, should be avoided.

Like most electronic devices, the manufacturer will have a part number for their batteries and related specification sheets. If you don’t have the manufacturer's part number, the only way to determine battery capacity is to test it at 200mA constant current load. I would guess though, that your batteries would have a capacity of around 1.5AH.


--- Quote from: nemail2 on November 20, 2018, 07:35:35 am ---Also I heard of balancers which I need if I want to charge two or more cells, are they connected in series or in parallel then, does that even matter?
--- End quote ---
Yes, in series

--- Quote from: nemail2 on November 20, 2018, 07:35:35 am ---
Are there basic circuits or ICs which practically everyone uses (general purpose parts) which I should take a look at?
--- End quote ---
There are common charger chips, but they are not basic. They are readily available, and dirt cheap though

Sudo_apt-get_install_yum:
Get some cheap Chinese 18650 batteries that are filled with sand and you won’t need to worry about any explosions   ;D

spec:

--- Quote from: Sudo_apt-get_install_yum on November 20, 2018, 09:55:21 am ---Get some cheap Chinese 18650 batteries that are filled with sand and you won’t need to worry about any explosions   ;D

--- End quote ---
:-DD

Whales:

--- Quote from: spec on November 20, 2018, 09:13:48 am ---... but you can charge your batteries with a lab power supply set to no more than 4V6 and no more current limit than ...

--- End quote ---

Make that 4.2V, not 4.6V!

There are enthusiast forums dedicated to batteries -- checkout candlepowerforums for all sorts of guides, horror stories and the likes.

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