Hey, could not find dedicated sub forum for power banks and cells so decided to post it here, hope you don't mind. I decided to update my outdoor electricity pack to unify the battery cell standard between different devices like flashlight, headlamp, e-cig and power bank. Decided to go for 18560 cell "DIY" power bank, so I was looking for a long time for PB case that support Q3, 18560 cell and USB-C type of input/output and certified by CE or FCC. I found XTAR PB2S charger/PB (I'm aware of XTAR sub forum, but the problem of this topic is not related strictly to XTAR) that more or less cover my requirements. I've read some revives of XTART PB2S and was aware of problems like inaccurate measurement of voltage/amps and not fully supporting even Quick Charge 2, regardless manufacturer advertising. So I bought XTAR PB2S and confirmed product's originality on the XTAR webpage. Also I bought few 18560 cells from trusted source and decided to do some testing while charging my phone. I don't have any good equipment like multimeter nor professional charger to do proper testing of cells and PB, neither I'm not an expert in the matter so I'm asking you for opinion if I do something wrong or I'm cheated.
For the test I used, XTAR PB2S and original USB to USB-C cable, one and two 18560 cells (LGEBMJ11865) and my phone Redmi Note 7. As for the phone batter is 4000mAh and its voltage is 3.7V I guess. As I understand, for battery capacity comparison I need to convert it watt hours. So for the single 18560 cell its 3.6v x 3500 mAh / 1000 = 12.6 Wh and for phone battery its 3.7v x 4000 mAh / 1000 = 14.8 Wh. So while charging my phone from a single cell I should be able to charge it at least to 85% without including power waste on a transfer and PB/phone electricity consumption during the process? In both tests I started to charge my phone as soon as battery level reached to 0% and system turned off and in both tests the 18560 cells from which I charged my phone were 100% charged.
So in first test I was charging my phone from a single 18560 cell. It took me 58 minutes to charge my phone to 58% before 18560 cell dried. The battery at finish was unpleasant hot in my hand, but I could hold it tight without worrying about skin damage. I left the cell to cool down for a moment and then putted it back to PB, the display has showed me 20% more of power in battery but I was only able to charge my phone for 2% more. I expected to charge my phone to at least 70% including power loss on transfer. From the PB display at the peak I was able to charge my phone with 8W top so I was a little disappointment as my USB charger that came with phone has 10W (5V/2A).
In second test I used two cells to charge my phone. I was able to get the phone fully charged in 2h and 11m. The phone at peak was charged with 10W from the V/A readings and my phone had indicator of Quick Charging, which is weird as while I charge my phone from 10W USB plug its only "normal" charging mode. After finish, both cells were insignificant warm and the charge level was around 20% on each cell.
Does such huge loss of power, during power transfer is normal or I'm wrong on some point? Thanks for the answers and opinions.
For the test I used, XTAR PB2S and original USB to USB-C cable, one and two 18560 cells (LGEBMJ11865) and my phone Redmi Note 7. As for the phone batter is 4000mAh and its voltage is 3.7V I guess. As I understand, for battery capacity comparison I need to convert it watt hours. So for the single 18560 cell its 3.6v x 3500 mAh / 1000 = 12.6 Wh and for phone battery its 3.7v x 4000 mAh / 1000 = 14.8 Wh. So while charging my phone from a single cell I should be able to charge it at least to 85% without including power waste on a transfer and PB/phone electricity consumption during the process? In both tests I started to charge my phone as soon as battery level reached to 0% and system turned off and in both tests the 18560 cells from which I charged my phone were 100% charged.
So in first test I was charging my phone from a single 18560 cell. It took me 58 minutes to charge my phone to 58% before 18560 cell dried. The battery at finish was unpleasant hot in my hand, but I could hold it tight without worrying about skin damage. I left the cell to cool down for a moment and then putted it back to PB, the display has showed me 20% more of power in battery but I was only able to charge my phone for 2% more. I expected to charge my phone to at least 70% including power loss on transfer. From the PB display at the peak I was able to charge my phone with 8W top so I was a little disappointment as my USB charger that came with phone has 10W (5V/2A).
In second test I used two cells to charge my phone. I was able to get the phone fully charged in 2h and 11m. The phone at peak was charged with 10W from the V/A readings and my phone had indicator of Quick Charging, which is weird as while I charge my phone from 10W USB plug its only "normal" charging mode. After finish, both cells were insignificant warm and the charge level was around 20% on each cell.
Does such huge loss of power, during power transfer is normal or I'm wrong on some point? Thanks for the answers and opinions.