I've seen quite a few customized chargers that folks have made, which are all awesome, and I thought I'd share mine too.
I had trouble converting PC power supplies into power stations. Not sure why, but they work fine until I cut and solder the wires together, at which point it starts behaving weird. Voltages are wrong, or wildly fluctuating, and other strange things. I mean, its not hard right? Green goes to a black. All the blacks go together, Orange gos together, red, yellow, ignore the rest. Put a small load on it to stabilize it and you get 12V, 5V, 3.3V, and ground.
I went through all my old power supplies (I'm a bit of a computer parts hoarder) and finally had to buy one. This time, I decided that no modification would be made to the power supply. Instead I made a little power distribution box and plugged the power supply directly into that. The green to black, small load, and the colored wires all happen inside the box. At any point I could take this PS and put it in an actual computer and it would still work.
For reasons I still can't figure out, doing it this way actually works. Though, I did have to add some 12V inputs on the back since the two yellow wires on the motherboard cable didn't seem to be enough.
The next part was building charging panels. I like how the TP4056s charge cells better than the iMax or the Opus. Especially if they're under voltage. They're also super cheap, and easy to use, so they free up the more complicated chargers for doing testing on cells that have already been charged.
Anyway, The one thing I don't like about the TPs is that there's no indication of where in the charge cycle the cells are. Or if they're even making any progress at all. (Sometimes they don't.) So I wanted something with a Voltmeter, Ammeter, cell holder, and switch to give me all the info. This is what I came up with:
I used a Voltmeter with an independent power in, so that it could run off the 5V supply regardless of whether the cells had charge or not. The Ammeter is analogue because I didn't want to be restricted as to where I could put it in the circuit. The switch is only for the TP4056. With that off, I can continue to monitor the cell voltage as long as the panel is plugged in. I chose the oversized knife switch style just because I thought it looked cool.
The cell holder sockets are in parallel, so any from 1-4 cells can be charged on one TP.
The next part is putting it all together in some kind of thing so as to hide the cables and get some of my desk space back. I ended up making a table which rather than designing, I just made it up as I went. All made of scrap wood I had laying around the basement. I even found a nice piece of stair step which made a perfect table-top. Didn't have to cut it or anything.
The power supply is secured inside, with the power cable and switch facing out. The distribution box is mounted to the top so I can get at it easy to add more wires. The panels are held in place by a notch on the bottom and magnets on the top. They are on long-ish cables and can be pulled out of the table-thing easily for whatever reason that might arise. Three 12V cables feed the Opus and the two iMaxs. I even found a little chest of drawers to store the cells in.
So if any of this looks familiar, I have posted some of these pictures before in my
cell harvesting thread. But here is a part that's brand-new: Thermometer-things! Well, its brand-new to me. I totally stole the idea from other folks here on the forum. :angel: The idea is, to put a sensor in between the sockets 1,2 and 3,4 of the 4-cell holder so each sensor can monitor up to two cells. I don't have the room or desire for 4 readouts on each panelso two will have to do.
Added more wires to the mess behind the panel, and hot glued the sensors in place. Also, I discovered I didn't need the fancy square holes for the wire plugs to fit in. I thought they'd protrude into the panel more, but they don't.
First one done. Seems to read ambient temperature ok.
Got em all done. I went through my pile of rejected cells looking for heaters.
Found a couple. Although, the temperature seems a bit off. Maybe because the sensors are not quite in physical contact with the cells?
I've done a few tests after this picture, and it seems pretty consistent that ambient temperature is accurate, but when the displays read 30C the cells are more like 40C, and when the displays are 35C, the cells are more like 50C. Fortunately, accuracy is not as important to me as consistency. I can now look from across the room and see if a cell is above ambient temp, and keep a closer eye on it. Plus, more gadgets makes it look cooler, yeah?