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| Curious warning printed on a power bank |
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| atmfjstc:
My 10,000mAh powerbank has a warning printed both on the case and in the manual: "Do not use with wall chargers that exceed 1A output" by which it is referring to when we need to recharge the powerbank itself via its USB-like input port. My question is, isn't the charging controller inside this thing supposed to limit the charging current? Surely they didn't wire up the lithium battery directly to the input port? Obeying the directive would be quite inconvenient, as pretty much all of my chargers have 2.1A max output ports. |
| jeroen79:
That sounds odd. Could the instruction be mistranslated? Usually powerbanks are made to be charged from USB where the supply provides a fixed 5V. The powerbank then should not draw more than 500mA unless the supply signals that it can provide more current. What is the brand and type of your powerbank? Does it have a USB input or it's own supply? What does the powerbank draw if you give it 5V? |
| edpalmer42:
I've seen one cheap speaker/media player that charges from USB and has a small Lithium internal battery. A label says (translated from Chinglish) to limit the charging time to 3 - 5 hours. When I looked inside, all they did was put a single diode from +5V to the battery. This gives about 4V3 which is close enough for them. :-- If your unit is similar, a discharged battery will suck huge amounts of current and burn out the diode. Ed |
| janoc:
--- Quote from: edpalmer42 on March 24, 2019, 05:43:09 pm ---I've seen one cheap speaker/media player that charges from USB and has a small Lithium internal battery. A label says (translated from Chinglish) to limit the charging time to 3 - 5 hours. When I looked inside, all they did was put a single diode from +5V to the battery. This gives about 4V3 which is close enough for them. :-- If your unit is similar, a discharged battery will suck huge amounts of current and burn out the diode. Ed --- End quote --- In that case that 10Ah capacity is likely completely fake as well. |
| edpalmer42:
--- Quote from: janoc on March 24, 2019, 06:02:38 pm --- --- Quote from: edpalmer42 on March 24, 2019, 05:43:09 pm ---I've seen one cheap speaker/media player that charges from USB and has a small Lithium internal battery. A label says (translated from Chinglish) to limit the charging time to 3 - 5 hours. When I looked inside, all they did was put a single diode from +5V to the battery. This gives about 4V3 which is close enough for them. :-- If your unit is similar, a discharged battery will suck huge amounts of current and burn out the diode. Ed --- End quote --- In that case that 10Ah capacity is likely completely fake as well. --- End quote --- I thought that all battery capacity figures that come from China are to be considered fake until proven otherwise. :-// I bought a battery bank kit where you provide your own batteries. I used 4 18650 cells in parallel. I tested each cell and confirmed that they were in the range of 2500 mah each. In the bank, it takes ~10Ah to charge them, but I only get ~6 Ah out of the bank. So part of the discrepency can be attributed to differences in charge and discharge limits while part is due to inefficiencies in the circuitry. Add in battery capacity ratings that are often wildly exaggerated and there's no way to know what you're going to get. Ed |
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