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MareLuce

macrumors 65816
Original poster
Sep 26, 2010
1,156
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Just used my Revive Solar Charger 4000mAh External Battery for the first time.

Specs are here:
http://www.amazon.com/gp/product/B0083ACGCO/ref=oh_details_o00_s00_i00

First I fully charged the solar charger via USB for > 12 hours.

Then I used it to
- Charge my iPhone 4 from 35% to full
- Charge my iPad 2 from 49% to 71%. (Yes, it has a 2.1amp USB port.)

Then the solar charger was out of power.

What is the math for checking if it truly used 4000mAh that it is supposed to have for that amount for charging?
 
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Just used my Revive Solar Charger 4000mAh External Battery for the first time.

Specs are here:
http://www.amazon.com/gp/product/B0083ACGCO/ref=oh_details_o00_s00_i00

First I fully charged the solar charger via USB for > 12 hours.

Then I used it to
- Charge my iPhone 4 from 35% to full
- Charge my iPad 2 from 49% to 71%. (Yes, it has a 2.1amp USB port.)

Then the solar charger was out of power.

What is the math for checking if it truly used 4000mAh that it is supposed to have for that amount for charging?

It would be difficult due to the random charge %'s and the devices state when charging. If the devices are on then it screws everything up!
 
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I'm using the maximum battery capacity, so it may have charged even more. Go figure.

iPhone 4 - 1420 mAh
iPad 2 - 6930 mAh

iPhone 4
35% to 100% = 65%
65% * 1420 mAh = 923 mAh

iPad 2
49% to 71% = 22%
22% * 6930 mAh = 1524.6 mAh

923 mAh + 1524.6 mAh = 2447.6 mAh

2447.6/4000 mAh = 61.19% (38.81% capacity loss or 1552.4 mAh loss)

The page also states this:

On first use, charge it up 100% by USB, then drain fully so that the Lithium-polymer battery chemicals can be exercised and broken in.

So since you're using this for the first time, the performance may not be the best.
 
kokhean thank you!

How did you know how many mAh the iPhone and iPad batteries needed?
 
To test it again I think I will drain iPad 2 battery completely.

Then, the Revive should charge it to

4000mAh(Revive charger capacity) / 6930mAh(iPad2 battery capacity)
=

57% full

I guess I'd need to be nearby as it's finishing to get the charge % measurement. If not, the iPad 2 will start using the charge after the solar charger stops charging it. Then the iPad 2 might go down a couple % points in charge. Right?

Or, if the iPad 2 is completely drained and off when I start to charge it, will it stay off before I turn it on?
 
It will use some battery when on, but it's not very noticeable. The other time I tried switching it off an iDevice while it was charging and it indeed charges faster, but that was on an iPhone 3GS with the horrible battery life.
 
Second test results

iPad 2 = 6930 mAh capacity as per kokhean's resesarch above.

Today's test:

My fully-charged (via electrical outlet) Revive Solar Charger 4000mAh External Battery took my iPad2 from 5% full to 47% full.

47 - 5 = 42% charge

42% * 6930 mAh iPad2 capacity =
2911 mAh


My Revive Solar Charger is supposed to have a 4000 mAh battery when full, but it only charged my iPad 2 2911 mAh worth.


2911 / 4000 = 73% (27% capacity loss or 1089 mAh loss)

vs test #1 undercharge (difference in actual vs stated capacity):

2447.6/4000 mAh = 61.19% (38.81% capacity loss or 1552.4 mAh loss)

So I'm still not seeing over 25% of the alleged capacity of the charger.

Should I send it back or try again?
 
Today's test: iPad 2 was Off

First test, iPhone 4 was charged while on, iPad 2 was off
 
Test #3 results

Assumptions:
iPad 2 = 6930 mAh capacity as per kokhean's resesarch above.

Today's test:

My fully-charged (via electrical outlet) Revive Solar Charger 4000mAh External Battery took my iPad2 from 37% full to 78% full.

78 - 37 = 41% charge

41% * 6930 mAh iPad2 capacity =
2841 mAh


My Revive Solar Charger is supposed to have a 4000 mAh battery when full, but it only charged my iPad 2 2841 mAh worth.


2841 / 4000 = 71% (29% capacity loss)

I thought it actually would be better this time because it took a LOT longer to charge to full from an electrical outlet.

Any other solar chargers out there that have similar or better specs?
 
4'th and final test

4'th and final test

Revive Solar Charger charged my iPad2 from 42% to 82%.

40% * 6930 mAh iPad2 capacity =
2772 mAh


My Revive Solar Charger is supposed to have a 4000 mAh battery when full, but it only charged my iPad 2 2772 mAh worth.


2772 / 4000 = 69% (31% capacity loss)

I'm sending it back on Monday.
 
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