Was looking for a cheap external battery…
5600mAh PowerBank Dual USB External Battery - AU $7.94 Delivered
http://www.buyincoins.com/item/43831.html#.U3w40PmSzL0
16800mAh PowerBank Dual USB External Battery - AU $13.75 Delivered (Cheaper via eBay)
http://www.ebay.com.au/itm/16800mAh-Dual-USB-Power-Bank-Exte…
http://www.buyincoins.com/item/44802.html#.U3w4NfmSzL1
20000mAh PowerBank Dual USB External Battery - AU $14.67 Delivered
http://www.buyincoins.com/item/44807.html#.U3w4NfmSzL1
those are all dodgy. theres no way any of them will be even close to there rated mAh claims and unless you get a money back guarantee from these places they are worthless as you cant even send them back for a refund once you realise how pitiful they are
Inclined to agree. Read some interesting stories about power banks from BIC.
Had a disappointing transaction with them not long ago for unusable LED spotlights where the lens melted within weeks. They actually tried to get away with a partial refund because of shipping cost.
I would not buy this type of equipment from them. They are not the least bit bothered about whether what they sell might be dangerous.
last one is pretty terrible
20000mA? I'm saving up for a 20,000,000 microAmp one.
This is very misleading, I remember buying a 11,000 one and it wouldn't even charge my phone up once. I have a sony one now that I got from another ozbargain deal that actually is the figure it quotes.
check out their negative feedback and look for "power bank": http://feedback.ebay.com.au/ws/eBayISAPI.dll?ViewFeedback2&u…
It would need to be nuclear-powered to generate the specified capacity :)
Funny nobody gets that mAh is a meaningless spec for capacity. Mans nothing without @Volts. 20Ah at 1.2V (if it were using NiCd batteries for instance) would be 5AH (5000mAh) at 5V, even before conversion losses. These things never say if they are rating battery output capacity or system output capacity or even battery charge capacity.
It is a bit hard to sy an utterly meaningless spec is wrong lol
The proper units would be WattHours or Joules (WattSeconds) (Watts = Volts x Amps)
my banggood bank has 4000mAh @ 3.7v written quite clearly on the back of it, this is part of the reason for the refund they gave me and others (in fact it ended up being only [email protected] and they guaranteed 4000)
These things never say if they are rating battery output capacity or system output capacity or even battery charge capacity.
as far as im aware they use battery storage capacity not there 5v output capacity or anything else. to use anything else would be quite stupid because efficiencies vary wo wildly as anyone who knows anything about these things would already know. while it may not be perfect it gives you a fairly reasonable ballpark in which to compare and gauge your needs.
efficiencies vary wo wildly as anyone who knows anything about these things would already know.
Yes, as this electronic technician of 2+ decades knows
Which is exactly why it is idiotic to rate them as anything other than total unit output in watts, otherwise there is no basis for comparison. What is the point of rating the battery when DC-DC converter efficiency varies wildly between designs and makes it meaningless.
Yes, as this electronic technician of 2+ decades knows
wow, apparently a tech for 20 years? surely you would know how much discharge rates effect cells then? what about thermal effects both on the cells and associated circuitry? surely even you should realise that all these are going to be compounded if you measured anything other than mAh battery capacity? like i said it may not be perfect but its by far batter than what your suggesting.
its no wonder the countries going down the toilet with the level of "expertise" shown by so many trades people.
Comparing mAh with databanks is like comparing megapixels with cameras. Says nothing about the quality whatsoever.
Hope you know what you are really getting, otherwise better to steer clear and go with a reputable brand.
And judging from the numbers and the price, it's more than likely crud. You get what you pay for most of the time.