Stefan Wagner

@4e131906  Hi, it shouldn't be like that. At what output current does the voltage collapse? Which battery (internal resistance) and which inductor (resistance and maximum current) have you installed? How is the battery connected to the board (cable length, thickness and connector type). Which switch have you installed (please measure the resistance)? As you may have noticed in my questions, every small resistance up to the boost converter leads to significant efficiency losses.

4e131906

Hello @wagiminator! I received my pcb/ components and did my first soldering!
I discovered a few design issues of my own, which are fine. Nonetheless, I am facing a more serious issue: When I connect a load, the voltage drops significantly on the boost end. Making it unusable. Do you have any idea how to narrow the issue?

All the best!

Stefan Wagner

@4e131906  I don't know the CN61CN33, but as far as I can see from the data sheet, your circuit should work. A toggle switch always guarantees the safest shutdown. Please note that the switch must be able to withstand 4.5A! Soft switches mostly use a MOSFET and some more components. I haven't used something like this myself, but you will definitely find a few examples on the internet. If you still have enough space on the board, nothing speaks against a soft switch. I think the power loss on the MOSFET is acceptable.

4e131906

Oh, and btw, do you think it make sense to add a soft latch power switch on the second board? Or is it best to keep on using a standard toggle switch? Any downside I might not have considered? If you have a good recommendation for such circuit, I'll take it :)

Have a great evening!

4e131906

I think I'm gonna keep the fp6298 then, but add a low 3.3v battery led with a CN61CN33.
Is my logic ok? See https://i.imgur.com/JBZ63vV.png or https://oshwlab.com/4e131906/tp4056-6v-2a-fp6298-boost-converter :)

Stefan Wagner

@4e131906  You are welcome!

4e131906

I can't thank you enough for your detailed comment!!
I wish you a very happy New Year too!! Thank you so much :)

Stefan Wagner

@4e131906  The law of conservation of energy applies. In simplified terms it can be said: U_in * I_in = U_out * I_out. Of course\, the efficiency of the boost converter has to be taken into account (with 2A output this is about 75%\, i.e. Eff = 0.75). After changing the formula: I_in = U_out * I_out / (U_in * Eff). Let's take a battery that is almost empty with U_in = 3V (not including the losses at the MOSFETs). Then I_in = 6V * 2A / (3V * 0.75) = 5.3 A. With a full battery (U_in = 4.2V) it would be: I_in = 6V * 2A / (4.2V * 0.75) = 3.8 A. As you can see\, 2A at 6V will probably only be achieved with a full battery\, as the maximum switching current (I_in) is 4.5A. I hope that was halfway understandable.
I WISH YOU A HAPPY NEW YEAR!

4e131906

@wagiminator, any idea on how to calculate the required switching current for 6V/2A ?I found tons of calculators and docs, but they require a lot of data I don't fully understand. And from what I tried to do with the values I have, none of them give me relevant results.

You said it depends "on the ratio between input voltage and output voltage".Do you have the equation on hand?
Have a great end of year! :)
Cheers

Stefan Wagner

@4e131906  I soldered everything by hand. The only difficulty is the bottom of the two SOP8 ICs. A heat gun is helpful here. As far as I can tell, your design looks functional. I wish you good luck with it!

4e131906

Okay, I think I'm done with it! :)
Do you think you could have a look? I changed the design quite a bit, especially because I need it to be compact, so I split the board in half.
https://oshwlab.com/4e131906/tp4056-6v-2a-fp6298-boost-converter

If you have any suggestion, I'll be really glad to exchange a bit with you!
Cheers!

4e131906

@wagiminator  Thank you very much!

Did you hand-soldered or is it too hard?
I'm very new to this and never soldered a pcb before!
Thank you for doing those open-hardware boards! Those are very valuable to the community I think!! 🌟 ✌️

Stefan Wagner

@4e131906  Hi and thank you. R6 limits the switching current, which is NOT the output current. With a boost converter, the output current is always smaller than the switching current, depending on the ratio between input voltage and output voltage.
Since there is always some voltage drop on the transmission lines, it is advisable to set the output voltage slightly higher. With an R7 of 91k you are around 6.06V.
Greetings

4e131906

Hey Stefan! Awesome work!
You used a 27k for R6, so I guess the board is set for the max current: 4.5A ?
Because the project mentions 2A, so I'm a bit confused, shouldn't this be 55k ? :)

I'm trying to edit it for 6V output for a camera, I changed R7 to 85k, is that correct?

Have a great day! 🤗
Cheers @wagiminator

Stefan Wagner

@mpranjali05 You're welcome!

ANJALI MOTGHARE

@wagiminator Thank you for your support.

Stefan Wagner

@mpranjali05 Hi Anjali, the input voltage of the TP4056 is in the range 4V - 8V. As long as the output of the solar cell is in this range it should work. However, it's not very efficient if you connect the solar cell directly to board. You can use solar cells with an integrated DC/DC converter or you can take a look at the CN3801 LiFePO4 Solar Charger SMD which has an integrated MPPT and can be modified to work with LiPo batteries.

ANJALI MOTGHARE

Hi Stefan,

Thank you for superior imagination.
I want to use this for my solar powered light. Is it feasible to use?