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My adventures
right, modern PSUs need a 12V load to supply stable 5 and 3.3V. I connected 4 of my OPUS chargers to 12V, when they're testing, there's no problem with 16 x TP4056s charging other cells:

Have sun!

Cells tested: 6.072 (overall: 12.021 Ah, average: 1.980 mAh)
Cells in production: 2.940 (overall: 6.174 Ah, average: 2.100 mAh)
Wall bank: 7s420p, 882 Ah, 21 kWh
Project page
Live solar/powerwall values
Daily graph
Usually it is the other way round. Modern PSUs are basically 12V units and put out 5V and 3.3V via DC-DC conversion. Older ones often had issues with asynchronous loads.
(09-28-2017, 07:33 PM)Korishan Wrote: Only 1 problem I see with that picture.  There are no cells in those thar holders!  Tongue

Looks pretty clean. At first I didn't notice the redone wires coming out of the psu. Then noticed there were only 2 colors. And then was like, NICE!  But a little heavy for each TP, eh?  Wink  Afterall, each one will only pull 1A max. So you could of doubled or trippled the wire count by going with 18 awg and you'd have more chargers available to you.  But, that's just my view point. I'm sure you had a reasoning for yours  Smile  

Nice progress, though. I gotta get my capacity testers done so I can start getting some mAH ratings for mine.

Hi, thanks for the positive feedback Smile

I'm limited in cell holders by the 20A max on the 5V power rails (shows on the PSU itself). So by taking 16 cells I thought I'd have some safety there.

The reason using one pair of wires per TP is both cosmetic and practical. I thought It'd be looking nice if I have a bundle of wires coming together in a box and then going from that box to the PSU. And the practical reason is that (for me) it's easier to solder bundles of wire together in a connection box, than working with a bus bar system, soldering a wire from a bus bar to a TP. I know it's overkill, but the wires I scored for free at work, they were gonna throw away five packs of 100m brown and blue wire!!!!! I asked nicely and they were mine Smile
Korishan likes this post
It's sad when a company just "throws" that kind of stuff away. Well, sad in the sense that that is the kind of things that makes stuff so expensive to the end consumer (not sure what your company does, but just imagine how much good stuff is thrown away from an Auto' Parts store, or Electrical, etc).
But, at least you scored some decent wires. Can't go wrong with free!

The other good thing about individual wires is that you don't get voltage drop after each TP connection. Some have used 16awg and by the time they got to the 5th or so TP, the voltage was below 5V and it started having troubles charging. You won't have those issues Smile
Wattsup and Ivo Staelens like this post
Proceed with caution. Knowledge is Power! Literally! Cool 
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Good evening all.

While I'm harvesting cells, I'm also thinking ahead on the wiring of everything.

I've been drawing up a schematic with some free software I downloaded. I attach the pdf in attachment. 

At the moment not all components have been defined in detail, I'm first thinking on the main picture.

What I'm doubting on at the moment is where I'll input the generator electricity.

At the moment I intend to have a choice switch, switching between electricity from battery bank and electricity from generator when battery bank is empty. But this means that generator has to be active all the time while the battery bank is not charged by solar. And I think in winter this can take a couple of days.

Another alternative would be to have the electricity from generator injected on the "grid" side of the PIP. 

First priority is to use electricity from battery bank. If battery bank is too low, generator needs to be started and depending from load needed, part of the electricity generated can be used to charge battery bank if solar isn't enough to charge the battery bank.

I think in the end the second alternative would be better, this'll surely be better in diesel usage I think.

What's your advice guys?


Ivo Staelens
shonalex likes this post

Attached Files
.pdf   Off grid setup.pdf (Size: 219.28 KB / Downloads: 51)
The story continues. All materials for my first project (ie the portable powerbox to charge drone lipo's) are in, so construction can start.

I chose my cells with my cell database and the configuration will be 4s10p.

For the four cells I have following capacities:

I also have a question. The fourth cell I have following cell choice:

Is it a problem that there's a 600mAh difference between top cell and lowest capacity cell?

In my opinion at a certain time the higher capacity cells will be pumping energy in the lower capacity cells, generating a cell with total capacity more a less sum of capacities of individual cells. Is this correct?
It is correct in a mathmatical way. In reality it may also be that the cell with the higher capacity just puts out more current. But you will have uneven current flow across the cells anyway. The effect gets worse with higher total current draw obviously and because you have only 10P it will not even out as it would with 100P for instance. You just don't have the statistical benefit.

If you can then you should avoid it. But you have to work with what you got, it will certainly work. Maybe you can get a better result by sacrificing some capacity and settling for 22 instead of 25Ah or by adding more cells like 4S15P.
Ok, I'll rework it a bit Smile

I can arrange it!

Thx for the advice.


I redesigned the cell distribution for my mobile powerpack.

Per 10p pack the max difference between highest capacity and lowest capacity cell is now more a less 200mA.

I have following pack capacities now:

Pack 1: 21252 mAh
Pack 2: 21228 mAh
Pack 3: 21178 mAh
Pack 4: 21230 mAh

I would call that reasonably balanced. Future will tell how it'll work Smile

I keep you informed!
It's good way to start.

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