I'm planning to use lithium ion batteries to power GPS trackers PCB that I've designed. I'm struggling with how to connect it to my PCB both as a final product and for prototyping? Also are there special precautions I should take care of when it comes to those batteries? shall it be protected? mercury or explosions precautions? Also sometimes they specify that a certain battery is mainly designed for flashlights, does that mean it wouldn't work well with my trackers?


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    \$\begingroup\$ What is the current demand of flashlights? What is the use time? How does this conpare to your tracker current demand and projected use time? Do you see any use difference? \$\endgroup\$ – Solar Mike Jan 21 at 6:40
  • \$\begingroup\$ Question is way too wide, to know what you are asking. So I had to roll big overview about how batteries are made in production, in a hope you will find a way. \$\endgroup\$ – xakepp35 Jan 21 at 7:41
  • \$\begingroup\$ Please reword your question, to make the topic narrow and clear. Please, ask just one specific question, and show what effort and research on that topic you've done by yourself before asking. Or rather "big brother" will delete your question.. ;-) \$\endgroup\$ – xakepp35 Jan 21 at 9:03
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    \$\begingroup\$ "shall it be protected?" - YES!!! \$\endgroup\$ – JimmyB Jan 21 at 12:54
  • \$\begingroup\$ @JimmyB Sure thing! :-) \$\endgroup\$ – xakepp35 Jan 21 at 19:09

How batteries are made? Here is a step-by-step description of a process, that is typically used in making production-level assembly.

Spot-Welding cell terminals with nickel strip

Single cell gives low voltage, so you may want to stack some cells in series. But dont ever try to solder directly to battery (even something like a copper wire)!!! Each battery terminal must be welded to a nickel strip, with spot welder. A welder's primary goal is to give short pulse of high current, to make a couple of connection spots. Metal surfaces are connected by shortly melting metal to alloy, at the spots where arc hits their surfaces. Doing that several times in adjastent spots could reliably connect terminal and battery together. Also it allows to avoid terminal oxidation and danger to overheat battery with soldering iron. After you know safety of operation and theory of welding process, you may buy yourself special welder. Or order ready-to use pre-packed battery assembly, welded by professionals:

enter image description here

"Protecting + Chagring + Balancing" circuitry

Then, your battery needs to be charged, not to die. Its very dangerous, so you MUST hide it from user interference. So there is a good practice, to embed controlling circuitry with battery - that will save from overcharge(fire danger: lithium is not exploding, it is burning VERY intensily when overheated), overdischarge(significant irreversible cell damage and capacity loss, if discharged below 3.2V) and, if you have some cells in series - circuitry could balance them to same voltage. In my country we successively used these PCBs HCX-D119, maybe they have another name:

enter image description here

They could be soldered to nickel strip either directly or with wires: enter image description here

3. Wisely choose output connector, according to your power needs

  • Contact terminals' have to be insulated, to provide user's safety - he cant be able to short circuit something with metal terminals hidden in plastic.
  • Think about polarity reverse - DC polarity forced connection to be kept in strict right order, connector must be "connectable only in one way".
  • Think about power demands: Actually, I meant "current that your contact can survive, without excess heating and oxidating"

For powerful output we had successively used "molex minifit" connector (as in motherboard "CPU power" connector). It can easily provide 50-100 watts of power, and is sitting in your hand very conveniently, what is good for prototyping and developement: That allows to connect and disconnect battery easily, safely, and very many times: enter image description here

Several others variants exists, both for power and low cost variants. B2, B6 and B14 are not recommended to use, now you understand. They are poorly insulated and dangerous:

enter image description here

And even some "wire-less" stuff, with metal terlimals in rigid cases, sometimes with charge-monitoring microcontroller:

enter image description here enter image description here

Insulate everything:

Wrap assemled thing to insulation: gurantee maximum operation and maintenance safety!

enter image description here

Or put it in a rigid case, if battery does not have its own:

enter image description here

And that's almost ready to deploy!

Satisfy ambient conditions for safe and healthy operation.

Read about batteies, better kept at 3.8V and 5-10 degrees celsium. Most cycles and battery life you will get at 20-50% DoD, charging it to 4.0V and discharging not less than 3.7V. Dont discharge less than 3.3-3.6V (capacity loss), dont overcharge over (4.2-4.3V) will overheat and catch fire. Its danger to use in high humidity areas; Also when over +40 degrees Celsium, and less than -10 degrees for long time.

Be careful, read manuals and specifications.

Think, read, research, design, discuss before doing. Avoid dangerous things. Lithium is extremely flammable, could easily produce directed high-temperature flame jets. That can burn skin or eyes out, if was threated without care.

enter image description here

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    \$\begingroup\$ Are you proposing the OP make a spot welder based on a microwave transformer - are you sure the OP has the skills and knowledge to do that safely? \$\endgroup\$ – Solar Mike Jan 21 at 7:25
  • \$\begingroup\$ @SolarMike Just told him about "how this could be easily done". Should I also add a note like "dont lick the terminals"? :p "If you have the desire to make that safely, the skills and knowledge are obtainable things!" I did that manual home-made "unsafe" welder, and after a couple days of practicing I've started doing good spots. (Short press time/low force = not welded, Long time/excessive force = burned contact") \$\endgroup\$ – xakepp35 Jan 21 at 7:38
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    \$\begingroup\$ @SolarMike, However, I've added a warn notice, like "dont do that if you dont know" \$\endgroup\$ – xakepp35 Jan 21 at 7:43
  • \$\begingroup\$ That notice is not very prominent - and you should consider proof-reading your post for errors... \$\endgroup\$ – Solar Mike Jan 21 at 8:32
  • \$\begingroup\$ @SolarMike ok i would better remove remark about welder \$\endgroup\$ – xakepp35 Jan 21 at 8:35

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