1
\$\begingroup\$

I’m planning on building a 220v AC powerbank, using 3.7v - 4.2v 2600mah Li Ion Cells (18650 type).

My plan is to have 3 groups, each containing 6 cells in parallel. These groups are then placed in series to make 12v DC, which will then be stepped up to 220v AC. Each group is removable from the circuit and is charged independantly. Each group also has its own TP4056 soldered to the battery holder - this isn’t removable. This is so i can have 2 parts charging at the same time, since i have a few micro usb’s. This cuts down charging time significantly.

Notes: - The batteries I’m buying are capable of such high discharge rates, so this isn’t an issue. - This is also very expensive, i know - Alternative to the removable sections is using a switch, but I’d rather they be removable.

My questions are: 1. Any problems with this idea? Any improvements or changes to the type of battery recommended? 2. What happens if I didn’t remove one section when charging, i left it in the circuit, with the other packs also there (the other packs are not being charged)? 3. What if I, again, left all the packs in the circuit, but this time all three are plugged to the power simultaneously while in the circuit.

diagramThe inputs drawn are for question 3.

Edit: I have placed diodes in the circuit as shown in this picture: https://myfunwhispers.tumblr.com/post/171651819540 . Will this now allow me to have all three inputs plugged in simultaneously, or will a short circuit still occur? 2.Also, considering that the transformer has no current protection, i should add a fuse @12.5 Amps somewhere after the batteries, shouldn’t I?

\$\endgroup\$
  • 2
    \$\begingroup\$ Schematic/block diagram or it didn’t happen. \$\endgroup\$ – winny Mar 6 '18 at 9:32
  • \$\begingroup\$ Can’t find a way to do it on iPad \$\endgroup\$ – SomethinggUnique Mar 6 '18 at 9:38
  • 1
    \$\begingroup\$ Then use a computer? It's not that hard. Want a proper answer? Can't find a way to do it without proper information. \$\endgroup\$ – MrGerber Mar 6 '18 at 9:41
  • \$\begingroup\$ Draw it on paper, photograph and upload. \$\endgroup\$ – winny Mar 6 '18 at 9:59
  • \$\begingroup\$ TP4056 is an IC designed to charge a single cell. I presume you're talking about one of the cheap eBay modules that use it along with other components? And you're going to charge six cells with it and ignore balancing? \$\endgroup\$ – Finbarr Mar 6 '18 at 10:13
1
\$\begingroup\$
  1. What happens if I didn’t remove one section when charging, i left it in the circuit, with the other packs also there (the other packs are not being charged)?

  2. What if I, again, left all the packs in the circuit, but this time all three are plugged to the power simultaneously while in the circuit.

If you use separate isolated 5V supplies (like cellphone chargers) to charge each battery, then this will work fine.

If there is one 5V source, and you connect all 3 batteries to it, then the batteries will be shorted through the power & ground wires, and something will burn.

This isn't the most usual or efficient way to do it, but it should work. The usual way would be a CC/CV balancing charger. But if you always charge all the batteries (don't forget one!) they should be properly balanced.

\$\endgroup\$
  • \$\begingroup\$ How would the batteries get shorted if I only use one power input, wouldn’t the voltage just be be dispersed between the three batteries and have no impact? Just to check, so plugging all of them in at once is ok? What if it’s only 2? \$\endgroup\$ – SomethinggUnique Mar 6 '18 at 10:31
  • 1
    \$\begingroup\$ I mean if you connect several batteries wired in series to the same 5V source, a short will occur \$\endgroup\$ – peufeu Mar 6 '18 at 11:04
  • \$\begingroup\$ I’m sorry, but I forgot to mention, that when all three are charging, I will disconnect both the loads, so the circuit will open up after the transformer. Will this still create a short Circuit? \$\endgroup\$ – SomethinggUnique Mar 7 '18 at 21:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.