Portable chargers

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Mark
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Re: Portable chargers

Postby Mark » Thu Oct 23, 2014 5:12 pm

Scubadoo wrote:Dimensions and weight are often a fair guide unless they have substituted some battery cells with stones. :?
If the details are correct they weigh the same as my power banks.


Summer is coming and I'm back on the case.
Seems to me that there are several options that look the same, are the same dimensions, and the same weight.
All that appears different are the claimed capacities: 5600mAH - 30,000mAH and the prices: like US$13 - US$25 (or so, from memory)

Am I correct in assuming that these are in fact identical products and the higher prices merely reflect the higher claimed capacity rather than any real differences?

Pity there is no Consumer Guarantees Act to keep these Chinese outfits honest :(
Mark
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Re: Portable chargers

Postby scubadoo » Thu Oct 23, 2014 5:58 pm

All my power banks contain 4 or 5 18650 lithium manganese dioxide cells in parallel. Typical output from these cells is 3.7VDC and the associated internal case circuitry up converts this to 5VDC.
Claimed capacities of the supplies range from " 5000mAh" way up to "60000mAh". TUI definitely comes to mind.
Casual testing here suggests real figures are much closer to the lower value.
These 18650 cells can have actual capacities (assuming new ones are fitted) :shock: from perhaps 800 to 3400mAh.
I'll take a guess that most (all?) of these power banks from Chinese eBay sellers contain the cheapest available cells - i.e. c1000mAh.

eBay 18650 Battery Buying Guide
Neville
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Re: Portable chargers

Postby Neddy » Thu Oct 23, 2014 6:54 pm

With most all of these units looking and weighing the same, it is hard to evaluate the accuracy/honesty of the claimed capacities.
My "30,000" mAh unit arrived just yesterday so I am still evaluating it. I can tell you that...

It will recharge our 5 volt cellphones.
It will charge/run our 19 volt/3.5 Amp laptop.
It will charge/run our 16 volt/3.5 Amp laptop.
It will charge/run our 12 volt/1 amp GPS.
It will charge/run our 5 volt/1 amp tablet.
It will charge/run any USB powered device.
It includes an LED "torch". With its high-capacity battery, in the event of a power cut this unit should give many hours of emergency lighting.
It will start a car. A Start current of 300 Amps is claimed, with a 3 second Peak of 600 Amps.

The power unit itself can be charged from mains or any 12 volt/1 amp source, taking 3 hours or so. This suggests that its capacity is about 3000 mAh - a far cry from the claimed 30,000. I have begun a capacity test running a 12 volt/6 watt bulb. I will let you know how long this runs before flattening the battery. At 0.5 Amps, it should last about 60 hours but I reckon that is very unlikely. I'll keep you posted.

Regardless of the results of this test, I would still recommend these units. Mine does all that I want and I am a very satisfied customer.

Neville.

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Re: Portable chargers

Postby Mark » Thu Oct 23, 2014 7:34 pm

Thanks again, Nevilles :)

I'll be very interested to hear of the results of your test, Neddy.

Can you say which model you bought? I'm guessing it is a flasher one than I am looking at since you mention starting a car. Not an anticipated use for mine.

But I would like to get 3 full charges for my phone out of one, if possible - 4 would be even better. I just don't want to pay a premium for a claimed 30,000 mAh if all I am getting is the same as I would achieve by buying a cheaper one that claims 5600 mAh.
I'm mean that way :-T
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Re: Portable chargers

Postby Neddy » Fri Oct 24, 2014 8:09 am

Hi Mark,
I got a JX-R02, as shown here :-
http://www.aliexpress.com/item/30000mAh ... 41764.html
This model is widely available and can be bought elsewhere for a LOT less than US$258! I paid US$84 all up.

The 12 volt/0.5 amp test ran for 4 hours. That's just 2000 mAh at that rate and voltage. This test will not give you much idea as to the units 5 volt charging capacity at the USB socket - which is what you would be using to charge your phone. I am now running a 5 volt/0.5 amp test discharge via the USB socket. It will be interesting to see what the units capacity is at this voltage and current. If it was, say, 6000 mAh this would allow 6 charges of our little cellphone (1000mAh battery) and nearly 3 charges of our Galaxie S3 (2100mAh battery) but we will see.

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Chinese Portable chargers

Postby Neddy » Fri Oct 24, 2014 2:48 pm

A 0.5 amp load powered from the 5 volt USB charging socket flattened the battery in just over 6 hours.
This equates to a battery capacity of 3000 mAh - exactly one tenth of the batteries claimed nominal capacity.
That's 3 charges for our little cell phone and just one for our Samsung Galaxie S3.
Good luck with your search, Mark. I don't know how you can hope to make intelligent comparisons amidst so much misinformation.
Falsely inflated specifications are the norm.

You get similar dishonesty with Chinese LED torches where, for example, light outputs of 2000 Lumens are commonly claimed from 7 watt torches running Cree Q5 LEDs. (Which Cree rate as 100 lumens per watt). That's if they really are Cree LEDs, of course.

I have been doing a bit of research on batteries and have come to the conclusion that the 3000 mAh UltraFire 18650 Lithium batteries that I recently bought are very likely to be fakes with only a fraction of their claimed capacity.

Neville.

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Re: Portable chargers

Postby Mark » Fri Oct 24, 2014 4:27 pm

Neville. Thanks very much for conducting and posting the results of your testing.

Bummer.

What is it with these people? I guess, until there is competition from another country (who? India?) there will be no need for them to tidy up their practices. (or maybe that will just give them another reason to further inflate their claims).

The problem is that, now that it is so easy for anyone to buy online, they are no longer protected by domestic consumer law: unless we all revert to buying locally and claiming our money back when (the same) products don't meet their claimed specs.

You next task is to buy another, much cheaper, unit that claims only 3600 mAh capacity and see if that, in fact, is accurately spec'd of whether it provides really only 360 mAh :shock: :-T

Not sure where to go now. I guess one charge is better than none - but I'm not sure I would pay $80 for it. Maybe one with small solar panels would be the "go" so that at least (if you could find a way to attach it to the top of your pack) it would recover a little more power during the day, giving the opportunity for a further small charge. Hmm.

But, if you are going that way, maybe a stand-alone (larger) flexible solar panel plugged into the device during the day, might end up being a better solution.
Mark
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Re: Portable chargers

Postby scubadoo » Fri Oct 24, 2014 5:13 pm

Mark wrote:... Maybe one with small solar panels would be the "go" ...

Be aware Mark that the "solar panel" may or may not be operative or attached internally and then expect perhaps 10% of the claimed charge rate or 10x the charging time. ;)
I have a bluetooth GPS device that the "solar panel" contributes about 20mA to the internal 1800mAh Li-ion cell on a good sunny day!
Neville
Mitsi Fuso CI Ultimate 6.8m 3.9 T/D. 180l fresh/grey. Single 300Ah LiFePO4 for truck/house.
500W solar. Victron 50A MPPT. 6kW Webasto diesel water/air heater.
255l Samsung 230VAC digital inverter fridge/freezer.Gas cooking/oven.


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