Why don’t we pass around ideas for battery charging stations for those of us that have enough cells that a standard 4 cell charger doesn’t hack it.
Here is my battery station as it sits right now:
I have been using a hobby charger to charge my batteries since day one, partly because I already knew how to use them and partly because they are more powerful then the dedicated 18650 chargers for anything close to the same price point.
Well for some time I used the old classic Imax B6 charger but the calibration was always off a bit and they stupidly won’t let you recalibrate it after the first power on.
I then upgraded to a Turingy Accucell-6 charger, it has 6A of charger current for 5A for the B6 but mostly the calibration was closer (only about .01-.02 off instead of .05). It served me well but there were still little things about it that annoyed me.
Recently I was reading something about chargers and heard about some custom firmware for the Imax B6. Turns out it uses an ATmega MCU and can be flashed just like with do with the Attiny’s, same programmer ect. Just make sure you read the hardware section to ensure you have an ATmega version of the B6.
You can find the firmware here: GitHub - stawel/cheali-charger: cheap lipo charger
So I decided to give it a try, well I wish I had found it sooner! I am now using the Imax B6 as my primary charger once again, the features on this firmware are great, you can set everything exactly how you want it to be and it is DEAD ON accurate, like down to the .001 level vs my UT139C.
The single best feature though is that you can use the balance ports for voltage detection when charging. Usually you lose a fair amount of voltage in the wires and this means the charger thinks it is imputing a higher voltage to the batteries then it actually is. Thus it will think it needs to reduce current before it actually does, extending charge times.
By taking the voltage reading with the balance port it sees the actual voltage and thus sends the full current the battery can accept. This greatly reduces charge time and accuracy! It also allows for much better internal resistance and even wire resistance tests along with a ton of other features.
So if you are looking for a cheap charger that will handle lots of current/batteries, look into a $15 imax B6 with custom firmware
Now for the rest of my charging station setup.
You will notices the charging banks for 14x 18650’s at a time, 4x 26650’s, 2x 18350 and 4x 14500. I have a 2 wire voltmemter from RMM mounted on the 18650 and 26650 to allow for quick voltage checks of batteries and to see the exact voltage while charging. If you calibrate those little meters they are surprisingly accurate.
I love having the large charging banks because as you can see I have lots of backup batteries. I simply swap out batteries in lights until I have a full “load” and charge them all at once. It takes awhile but frankly I am in no hurry, I figure I abuse them enough during discharge, so a slow charge is a good thing.
Naturally you can load up as few batteries as you want and charge them at up to 5A.
This is a great way to charge a lot of batteries easily.
Next you will notice the 3D printed battery holders, these are great for keeping the batteries organized and ready for use.
Each 18650 tray holds 60 batteries in this case but can be made to any size you want basically if your printer is large enough. I like having them in sets of 6 per row as for laptop pulls you generally get 6 cells. I then use a few from a set in a light and the fully charged ones stay on the left hand side, the discharged ones stay on the right hand side. When they are all on the right side it is time to recharge the batch.
Thats it for my basic charging station. Although when I am in a real hurry to charge something I bring the battery bank over to this 12A power supply where I can charge it fully loaded with 14 cells with almost 1A per cell (they have a 15A power supply now that could do more).
I reviewed these here: Review of DP50V5A & DPS3012 bench top power supply modules, best bang for the buck around!
I also have a simple nitecore USB charger that I keep around for times when I just want to charge a single battery for some reason.