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Posted: 8/31/2015 11:18:07 PM EDT
Should a 16,800 mAh battery be able to charge a 9,000 mAh battery 1.86 times?

I have a 9,000 mAh battery on my phone (yeah, it's big).......and a 16,800 mAh rechargeable battery.

The 16,800 barely charges the 9,000 with just a little to spare....but certainly not 1.8 times.

Did I get fucked on the 16,800 (got it on ebay) ?
Link Posted: 8/31/2015 11:26:54 PM EDT
Quoted:
Should a 16800 mAh battery be able to charge a 9000 mAh battery 1.86 times?

I have a 9000 mAh battery on my phone (yeah, it's big).......and a 16800 mAh rechargeable battery.

The 16800 barely charges the 9000 with just a little to spare....but certainly not 1.8 times.

Did I get fucked on the 16800 (got it on ebay) ?
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What brands of battery (packs) are you using?

Lithium-ion, probably.  You don't want to deplete a 3.6v/3.7v li-ion down much below 3.0v, which is probably down to 10-20%.  

Also, don't forget that there's a certain percentage of 'inefficiency' built into chargers, maybe 15%-20%, so it's not a 1:1 ratio.

I'll assume that your phone isn't completely discharged, so if you're at that 3.0v on it, you'd need 8100mAh, or 7200mAh to make it full.

Your 16800mAh battery pack should be able to do that, even at a 50% depth of discharge, if it's in fact a 16800mAh battery.

Remember, these guys are fudging the numbers, which is why I asked you about the brands.

Chris
Link Posted: 8/31/2015 11:40:04 PM EDT
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Quoted:


What brands of battery (packs) are you using?

Lithium-ion, probably.  You don't want to deplete a 3.6v/3.7v li-ion down much below 3.0v, which is probably down to 10-20%.  

Also, don't forget that there's a certain percentage of 'inefficiency' built into chargers, maybe 15%-20%, so it's not a 1:1 ratio.


I'll assume that your phone isn't completely discharged, so if you're at that 3.0v on it, you'd need 8100mAh, or 7200mAh to make it full.

Your 16800mAh battery pack should be able to do that, even at a 50% depth of discharge, if it's in fact a 16800mAh battery.

Remember, these guys are fudging the numbers, which is why I asked you about the brands.

Chris
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Quoted:
Quoted:
Should a 16800 mAh battery be able to charge a 9000 mAh battery 1.86 times?

I have a 9000 mAh battery on my phone (yeah, it's big).......and a 16800 mAh rechargeable battery.

The 16800 barely charges the 9000 with just a little to spare....but certainly not 1.8 times.

Did I get fucked on the 16800 (got it on ebay) ?


What brands of battery (packs) are you using?

Lithium-ion, probably.  You don't want to deplete a 3.6v/3.7v li-ion down much below 3.0v, which is probably down to 10-20%.  

Also, don't forget that there's a certain percentage of 'inefficiency' built into chargers, maybe 15%-20%, so it's not a 1:1 ratio.


I'll assume that your phone isn't completely discharged, so if you're at that 3.0v on it, you'd need 8100mAh, or 7200mAh to make it full.

Your 16800mAh battery pack should be able to do that, even at a 50% depth of discharge, if it's in fact a 16800mAh battery.

Remember, these guys are fudging the numbers, which is why I asked you about the brands.

Chris

The 9,000 on the phone is from ZeroLemmon, and I'm pretty sure it's Li-ion.   It's actually decent....keeps my LG G3 running to about 5.5 days on a charge.

The 16,800 rechargeable batt is the one I'm suspicious about...it was purchased on ebay, came with barely intelligible instructions in broken English, and while it didn't ship from China, I'm sure it was manufactured there...and it certainly was priced as if it were.  The 'brand' on the box said "HIGH POWER", as if that helps...

The ad and the packaging both said 16,800 mAh.....Ironically, while looking over the battery's case for more info, and to make matters worse, it's labeled as a 38,000 mah battery.  It's DEFINITELY not that.  I guess they must use the same case for more than one battery.

You can see the 16,800 here on ebay: http://www.ebay.com/itm/231509197852?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Link Posted: 8/31/2015 11:57:22 PM EDT
How do you know it just barely charges the phone battery?
Is there a display on the battery pack that shows its current capacity?

Nevermind, I see the part about the 5 segment capacity display.
Link Posted: 9/1/2015 12:02:13 AM EDT
That 16.8 amps may be 12 volt capacity.    I also see it does 19 volts so who the hell knows.
It probably has a shitty DC-DC convertor to step up to 19 volts and also a shitty voltage regulator to drop to 5 volts.  
It will probably be most effecient at the batteries rated voltage.

If it is using a linear voltage regulator you may be losing 50% or more as heat.
Link Posted: 9/1/2015 12:05:55 AM EDT
Quoted:
Should a 16,800 mAh battery be able to charge a 9,000 mAh battery 1.86 times?

I have a 9,000 mAh battery on my phone (yeah, it's big).......and a 16,800 mAh rechargeable battery.

The 16,800 barely charges the 9,000 with just a little to spare....but certainly not 1.8 times.

Did I get fucked on the 16,800 (got it on ebay) ?
View Quote


Remember, you're not completely depleting one into the other, you're creating an equilibrium between the two devices.  You're probably damn lucky you're getting a full charge on the smaller battery.
Link Posted: 9/1/2015 12:06:55 AM EDT
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Quoted:


Remember, you're not completely depleting one into the other, you're creating an equilibrium between the two devices.  You're probably damn lucky you're getting a full charge on the smaller battery.
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Quoted:
Quoted:
Should a 16,800 mAh battery be able to charge a 9,000 mAh battery 1.86 times?

I have a 9,000 mAh battery on my phone (yeah, it's big).......and a 16,800 mAh rechargeable battery.

The 16,800 barely charges the 9,000 with just a little to spare....but certainly not 1.8 times.

Did I get fucked on the 16,800 (got it on ebay) ?


Remember, you're not completely depleting one into the other, you're creating an equilibrium between the two devices.  You're probably damn lucky you're getting a full charge on the smaller battery.


It looks like a 12 volt battery regulated to 5 volts.
Link Posted: 9/1/2015 12:07:30 AM EDT
Since it can jump start a car and since it's a smallish box at 6.5"x3.5"x1.5", it's most probably a lithium-polymer pouch, or prismatic cell, as opposed to a bunch of 18650 cylindrical cells.

It needs high current to start the car, but who knows what the capacity is and I doubt that you're getting 3000 cycles out of it, regardless of what's inside.

16,800mAh and even the larger number you cite, can be possible, but I don't know about that formfactor--how big is a 16,800mAh pouch cell going to need to be?

If you're only charging up a 9000mAh cell once with it, it may have a cutoff voltage built in and therefore, you're not able to access all of the power stored in that pack.

I guess what I'm trying to say is that if you know your phone is a 9000mAh battery and you can charge it just over one time when it's completely discharged, then that is your answer, minus any efficiencies inherent in your booster pack.

Chris
Link Posted: 9/1/2015 12:43:43 AM EDT
thanks for the input (that was a pun, no homo)
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