Thank you HKJ for your test of this charger board.
I have been using my four charger boards very successfully , powered by my 5V 4A switch-mode PSU … I have set the PSU voltage to a few mV below 5V and am very happy with the performance … My PSU has four USB sockets attatched and I have 50cm interconnect cables (USB to mini-USB) … I personally have no problem in using mini-USB connectors … For me it was just a simple matter of buying the right 50cm cables which are now kept in a box along with the charger boards , the PSU and the magnets.
Will you be testing these boards in parallel to give a higher charge current ? … Some users might prefer a higher charge current when charging 3100mAh Li-Ions … On the other hand , two boards in parallel with each set to a lower charging current than one amp would also reduce the temperature of the chip … That would only increase the charger cost by another £1 or so.
Can you suggest a better method of attatching a heatsink to the module or indeed to the chip itself ? … … I did try cooling with a small fan , but although it did cool the chip it didn’t seem to reduce the charging time significantly … I understand that these chips will tolerate a fairly high temperature so perhaps just a simple heatsink would be the way to go … My boards are used in a near vertical position with the USB at the top , so maybe there is a slightly better cooling airflow.
Thanks again for your great charger board tests (including the destructive test !).
s. Does the Cottonpickers charger use the same chip ?
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For four charger boards it would be easier to just solder a cable between them.
Micro usb connectors are much stronger than mini usb connectors and with many phones using them also much more common.
I do not plan on testing any more on them.
As you can see on my curves, there is no reduction in current at 5 volt input, but electronic always last longer at lower temperature. The easiest heatsink is just a piece of aluminium, where you place the board against (Remember some isolation between), as you can see on the temperature curve, the temperature was reduced significantly.
At one time it was TP4054, I do not know if he is still using that chip.
What insulation material do you suggest to go between the back of the board and the alluminium heat sink ? … Presumeably it would have to transfer the heat through to the alluminium.
Would it be better to glue (somehow) a small (finned) heatsink directly to the top of the chip instead ? … This would not need any insulation material.
On the other hand , copper shims might glue on the back of the board OK.
Or maybe just leave the charger boards as they are , without heatsinks … I have not had any trouble so far … If they do get too hot , the chip will apparently automatically reduce the current as necessary … It’s only for the first part of the charge that the chip heats up anyway and mine were less than 65C at worst … Even holding my finger on the chip for a while reduced the temperature according to my infra-red thermometer.
I will use the double-sided tape to hold the aluminium heatsinks to the underside of the charger board … I hope this will give some reduction in chip temperature during the first part of the charge cycle … It certainly can’t do any harm.
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Ordered three of these for 1.60 each inc shipping on eBay. I already have 18650 sockets but they don’t give much space for protected cells. I guess I can make my own emergency packs with these.
Still, for standalone chargers, does anybody know a place for strong 18650 holders those can accept even an XTAR 18700 cell?
I found that the normally available battery holders won’t accept protected 18650’s (which are actually 18700’s) … The easiest way is to use short leads (4”) fitted with croc-clips … The croc-clips will easily clip onto magnets … The magnets will “stick” to the battery … Easy !
That’s the way I’m using my hobby charger. Magnets don’t stick to copper PCB’s at the bottom of protected batteries, I’m afraid. But still, you’re right. Attaching crocodiles to the output seems to be the best option for now. You can even charge cell phone batteries this way, through a clipper, a pin or another mating socket.