Looking for the most efficient 18650 powered powerbank. How many iphones should i expect to charge on 1x3400mah battery?
Thanks
I have the cager b030 15000mAh
This one has 5 18650 batteries in it and is really close to 15000mAh measured on the batteries with my hobby charger (accucel-6)
Since it has to crank the voltage up to 5V, and charging is not 100% efficient there are losses.
I also performed a real life test with my samsung galaxy s4 (2600mAh battery)
I used the phone until it shut itself off due to low battery. Then charged it overnight.
When I woke up the charger was off so it stops when the device no longer needs power.
This way I could get 3 full charges and 1 charge to 88. This translates to 10088mAh real world usage with my phone. That would translate to 67 efficiency.
But I’m not entirely sure if the powerbank stopped immediatly after reaching 100% on the phone or still had some extra losses.
And I think charging from 0-100 is less efficient as 10-90 for example, and different phones might have different charging efficiency.
None!, you might just get 3/4s of a charge from a flat phone battery (if you turn it off to charge), but if you start to charge with it still on you might just get over half to maybe 3/4s of a charge.
I bought this
QIDIAN 1A/1.5A/2A/4A, 6 - 18650 Mobile Power Bank
because of this
Review of USB battery box 6x18650 Qidian
I’ve charged my S4 at least 4 times before having to recharge, and i’ve used it for other things inbetween also.
I use one of the RAVPower 14000mAh external battery charger. 5 * 2800mAh 18650 samsung sell. It charges my iPhone up to 8 times.
Can you open it up and look at the cells?
power bank efficiency is higher as phone converts 5v back to 3.7-4.3 for battery so have losses on both sides
True, if you have something that runs directly from 5V (For example an usb powered bikelight) and do the math you’ll get a better number.
This was merely a calculation to show how much real world use I got out of it. Maybe efficiency wasn’t the correct term.
I have been thinking about efficiency of powerbanks. There is always losses when we step up 4v voltage of lithium battery to 5v and phone circuit does step down back to 3-4v. Quality chips, slow charge current and usb output to 4.3v could reduce these.
Circuit which does step up voltage incrementally until phone is charging could be the most efficient one.
On some older phones circuity heats phone noticeably while charging low battery. So you might also want charge before battery is low.
iPhones have relatively small batteries. The iPhone 6 has an 1810 mAh battery and all older models have smaller batteries. The charging process would have to be less than 53% efficient to be unable to fully charge an iPhone 6 battery from a 3400 mAh 18650. Only the 6 Plus has a large enough (2915 mAh) battery that a power bank with a 3400 mAh 18650 would be unlikely to fully charge it.
I wouldn’t expect more than one full charge from an 18650 on any recent iPhone. Modern Android phones tend to have larger batteries, and many higher-end models won’t get a full charge out of any 18650.
People here really seem to like the Miller ML-102. It doesn’t look like much, but it appears the latest V7 model can deliver 1.8A over USB, which will charge many devices faster than the stock wall charger as well as charging larger devices that may not charge from most power banks. It’s under $6 on Fasttech. I haven’t seen a test of its efficiency.
Hi, just wanted to ask what is the current most efficient powerbank that is powered by 18650?
Thanks