hi i’m not sure if you fully understand how lithium ion charging should be done. it’s not just a simple cc/cv. the charge controllers also SHUT DOWN the current once the current drops to a certain threshold in the CV phase. typically 10% of the CC value
ever noticed how the current gets smaller and smaller as you approach the 4.30v mark? the problem is right there: the current (albeit small) keeps flowing for a long long time. that’s why a proper charge controller cuts off before that happens e.g. if CC is 500ma then once the current drops below 50ma then charging is terminated
Yes, and a charger that does the CV phase correctly also outputs a voltage higher than the cell's fully charged voltage, otherwise the current is so small it takes forever. See HKJ's charger review graphs. A charger that outputs .05v higher than the cell's final voltage MUST shut off when current drops below 10%, otherwise the cell would be overcharged if not removed. If the charger's voltage is equal to the cell's voltage when fully charged the charger IS essentially 'shut off'.
If you can live with the longer than normal charge times due to setting charger voltage no higher than cell final voltage, then it's a cheap option for a 4.30/4.35v charger, and is probably better than a cheap pre-built charger for those same higher voltage cells. Many of them are junk, too. But at least this one is adjustable, the limitations can be worked around.
I have been using a different board for charging anyway, one of the 10A buck regulators. It has to be done manually, not a problem as I can have it right beside me and monitor the DVOM. With the cells at 4.20v off the hobby charger I move them to the DIY setup to finish. Doing 4 at a time in parallel I set the initial current limit to 2A (starting from 4.20v, on their own they won't take that much current anyway with the voltage limited to 4.32v, 4 in parallel will draw a little over 1A) and voltage to 4.31-4.32. As the cells get full the voltage will blip up to 4.33, I then turn it back down to 4.31-4.32 and keep doing that until the voltage stops rising above the set point. When finished they settle in right dead on at 4.30v.
I am also not sure if it harms the cell in any way, I have a pair of the LG 3000mAh cells which can be charged to 4.35V and I have charged them only 5 times with a normal charger to 4.2 and then used a bench power supply with voltage adjusted to 4.35V and current regulation set to 1A so it is a CC/CV charger.
I unplugged them after hours the current displayed was small(i dont trust the power supply display to say how many mA were still flowing) …. after resting they show 4.3V
I also thought about using smaller constant voltage as a work around, but i guess some tolerances are okay so i dont care.
Finally got my board thrown together. I am using a 12 volt switching power supply that I had sitting in the closet, with magnet leads on the battery. Using Chinese banana plugs for the connections (I already had a bunch). I had an E09 tin sitting around that I wasn’t going to use for anything else that I decided would be a good candidate for a case.
Is it a flashlight?
Nope! Charger . I used some Fujik under the chip to secure it to the tin. It seems to be transferring some heat because the tin gets warm around the board. I put a little Kapton tape over the exposed metal on the board, just in case.
I soldered mine only on top and it works fine. I tested for continuity and they're the same node.
Also, in other news.
The charge indicator light is really quite simple and is absolutely no measure of voltage.
It states pretty specifically that the default is to switch off the LED after the current drops below to a multiple of the CC value.
I set mine to 0.01 of the CC value (I set my CC value to 1.499A - because I couldn't get exactly 1.5A)
My CV is set to 4.35V and my UR18650ZTAs as-is from FT settle above 4.34V.
Here is a pic of mine.
I power it using my modded PSU for my hobby charger.
I use XT-60s for connections and the battery holder is about to get replaced with a gutted charger with a slide that can fit protecteds and 26650s.
I like these cradles, I can solder everywhere so resistance is no issue. Just glued the circuit with a bit of hot glue on top.
The voltage pot seems indeed a bit touchy, or maybe my multimeter isn’t good enough for measuring hundredth of volt.
I accidentally connected a flat-top battery the wrong way because it was too dark and I was careless.
Lots of smoke and bad smells ensued. I saved the battery (only dropped down to 3.64V from 3.98V) and the next day I tested that the internal resistance was barely a few mOhms higher than the rest, so I charged it back up and it was fine.
I figured that a battery protection PCB wouldn't work properly if the battery itself polarity was reversed. Looked into some diodes, including shottkies and non-synchronous rectifying circuits, but they all were designed for the battery to be the only source and the protection only hand in mind the power coming from the battery.
So only circuit would be set at 4.29V, the other at 4.19V, the toggle switch would be on the input side of the charging circuit, and the circuit breaker on the battery side of the charger. Pics when done.
I can't take a picture of mine, because I fried the first one, but when it was functional, all I did was connect the in and out using the screw junctions and everything worked fine.
I'll get out my multimeter and check when I get the next one.
I Use these for my pink LG,s works very well I quick charge with my hobby charger first then finish with this little module.I parallel 4 batts at a time .
. I used some Fujik under the chip to secure it to the tin. It seems to be transferring some heat because the tin gets warm around the board. I put a little Kapton tape over the exposed metal on the board, just in case.
