Electronics > Projects, Designs, and Technical Stuff
DIY cheap powerbank (technical suggestions R welcome !)
ym58:
My bottom-line was to build a cheap but yet fully functional and powerful power bank using :
- a PCB salvaged from a Chinese 2euro-powerbank
- two LiPos (8.2Wh each) salvaged from a defective Sony Vaio battery pack
Kind of suspicious association ... but let's try it :-/O :
The final boxed prototype looks a bit like a trendy NYC designer's techno thingy O0 ...
It works of course but there are two flaws breaking my initial rules :
#1 it takes >12hrs to recharge its two LiPos (from a regular 2A wall charger)
#2 the output current is limited to 1A or so (making it less ***powerful*** that I had expected)
The reason being (well, I suppose) that the FM9833E the salvaged PCB is based on is limited to 0.6A for the battery charging current and to 1A for the output current.
I tried to lower the R3 resistor (down to 1K) in the hope that this could increase the battery charging current but to no avail.
If anyone has any suggestion how to increase the battery charging current, please come back to me in this thread !
If I can't improve this PCB "as it is", my next option will be to try another PCB like this one that I have just ordered on eBay :
Any suggestion is welcome !
qnh:
Nice (and cheap) work ... sustainable economy :-+ !
I just can't find info concerning the chip that you mentioned (FM9833E).
Do you have any datasheet on your side. ?
JacquesBBB:
The problem with these boards is that usually you cannot charge the battery while you use it.
I prefer a different setting with
two very cheap boards
- one for charging/ discharging the battery with protection
http://www.ebay.com/itm/5pcs-5V-1A-USB-18650-Lithium-Battery-Charging-Board-Charger-Module-Protection-/322045031371?hash=item4afb6133cb:g:RDUAAOSwRgJXigY4
- a second one for providing the proper voltage as requested.
It can be USB
http://www.ebay.fr/itm/401089512266?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
- or a boost converter for higher voltage .
they can be connected together in a very small package.
total cost < 1$
ym58:
--- Quote from: qnh on August 03, 2016, 11:51:58 am ---Nice (and cheap) work ... sustainable economy :-+ !
I just can't find info concerning the chip that you mentioned (FM9833E).
Do you have any datasheet on your side. ?
--- End quote ---
Actually, the link was embedded in my previous post !
Here again >>> FM9833E <<<
Any technische Klärung ;) will be much appreciated.
ym58:
--- Quote from: JacquesBBB on August 03, 2016, 01:36:32 pm ---The problem with these boards is that usually you cannot charge the battery while you use it.
--- End quote ---
Hello Jacques,
But that was none of my intentions !
These so-called powerbanks are made to store energy from a wall charger and then to be able to transfer it back to charge any mobile device that might have run short of battery "on the road" ...
In a powerbank, those two different functions (store then give-back) are mandatoty but yet not concurrent (concomitant) !
---
The PCB I have salvaged does the job but does not really fullfill the charging requirement for two (2) parallel 8.2Wh-LiPos , i.e. a CC (constant current) around 1C, that is about 2A per battery = 4A total !
The IC used on this board (FM9833E) can only deliver a mere 0.6A charging current to the 2 batteries, hence the extended duration of the charging process (>12hrs, instead of 3 to 4hrs at 1C !)
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