Lithium Pure Sine Wave Power Device AMAZON

42 amp hour at 12 volts is what 500 watt hours Mex you said 50 VA at 12 volt (At 12 volt DC VA = Watts by the way PF not a factor at DC). So you'd have around 10 hours run time assuming 12 volt battery. Or less. Not sure if you can run LI's to zero or not.

Two of 'em and swich when you neat the head at 1AM might.

My CPAP requires about 50VA @ 12vdc
Their specs do not address the issue at all.
Found in Craigslist Tijuana, a complete Respironics unit for sale for $113. Total hours on the unit (cannot be reset) 273.

For overnight, a 3-pound battery ain't gonns cut it.

road-runner wrote:

red31 wrote:
42ah X 5v = 210wh

This is true, but the only labeled output voltages are 12 and 120, so where does 5 come from? On the Amazon page for this device, there are 3 other "similar items" shown where the watts/Ah works out to 3.7 volts. So is this energy spec in Ah based on the voltage of the internal battery which isn't stated?

page 11 of customer questions is this

"Question: How many amp hours does the power bank have?
Answer: hello, 36AH3.7V or 12AH11.1V or 133WH

HKSY Seller · October 31, 2018"

????? a different model ?????

I used 5v since the USBs are 5v!

Powkey website shows 146wh
http://www.ledpowkey.com/content/?235.html

so yes ah is useless without a voltage! like 3.7v

road-runner wrote:
Can anybody explain to me how the mAh rating is of any use? With some digging you can find the useful storage capacity value of 210 Wh. Does the mAh value serve any purpose other than advertising a larger number, even if it doesn't mean anything at all for how much energy the device can deliver?

The mA rating is typical of small batteries.. Larger batteries (you know the ones which weign in at many pounds like 20 or more) tend to be rated in amp hours.

The "m" means 1/1000 so if you want to know what the Amp Hour rating is just divide by 1000 2500 mAH = 2.5 AH. that simple

Now for me at least it is. but I know many who claim they can never understand "Metrics"

10 pennies in a dime
10 dimes in a dollar
10 dollars in a 10 spot
10 ten spots in a C note (C stands for 100 by the way and c for 1/100)
10 C notes in a Kilobuck (Grand 10000)

If you are going down the road at 60 and pass a sign that says Speed Limit 40 and glance in you rear view and there he is .. Officer smiley. Big smile. OVerhead lights on . Pointing you to the curb. What is about to happen..... And will it be KPH or MHP?
(Hint 40 is a valid limit in both standards and.. I DID NOT SPECIFY!).

And that folks.. is all you need to know about metrics. You are not experts.

How to convert from "F" to "C" well I do that easily too but you really don't need to know that.. All you need to know is -40 is TOO DANG COLD.

An impressive device, but the numbers don't add up.

Claims 42000mAh(210Wh). 210 Wh would equal about 16 Ah.
Unit weighs a total of 3.3 pounds. A typical lithium battery that weighs 3 pounds puts out about 14 Ah.

Claims "Recharge the power bank faster than ever with the 15V/2A DC input, only need 6-7 hours to get fully recharged".

To recharge 42 Ah with 2 amp charger would take 21 hours.

Here's the same one with different brand:
https://www.amazon.com/Power-Station-FLOUREON-Generator-PowerBank/dp/B074QK75TM/ref=sr_1_5?keywords=Powkey+200Watt+Portable+Power+Bank&qid=1560686776&s=gateway&sr=8-5

red31 wrote:
42ah X 5v = 210wh

This is true, but the only labeled output voltages are 12 and 120, so where does 5 come from? On the Amazon page for this device, there are 3 other "similar items" shown where the watts/Ah works out to 3.7 volts. So is this energy spec in Ah based on the voltage of the internal battery which isn't stated?

many small items like lithium backup phone chargers and Li jump start boxes are rated MaHrs instead of ampHours

most Li batteries for electronics are rated in MaHrs, not AmpHrs or Watt Hrs

its just the standard way of doing it, look at phone batteries, tablet and laptop batteries etc.. something like 2400 MaHrs or 3000 etc..

i have a small pocket size Li phone backup 2000 MaHrs aka 2 AmpHrs
and much larger one that is 12000 MaHrs

road-runner wrote:
Can anybody explain to me how the mAh rating is of any use? With some digging you can find the useful storage capacity value of 210 Wh. Does the mAh value serve any purpose other than advertising a larger number, even if it doesn't mean anything at all for how much energy the device can deliver?

divide by 1,000

I assume it is a bit overrated.

42ah X 5v = 210wh

Can anybody explain to me how the mAh rating is of any use? With some digging you can find the useful storage capacity value of 210 Wh. Does the mAh value serve any purpose other than advertising a larger number, even if it doesn't mean anything at all for how much energy the device can deliver?