Hey What About A 6000Mah Battery


borgqueenx said:
External batteries are always overrated. My duracell energizer battery says 8000mah, but can charge my iphone 3gs about 3 and a half times. (3gs=1220mah)
and that 8000mah is at 5v.
The numbers aren't supposed to work out like that. Your battery requires significantly more energy to charge than it is able to provide to your phone. The charging circuit is not 100% efficient either. Whenever heat is being given off, that's wasted energy. You will always get less out than you put in, that's the rules. :)
 
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that doesn't make sense! if it's claimed to be 8Ah then it has to be, likewise, it should charge your crapplephone 6.5 times (actually nearer 6 times), either the big pack isn't getting a full charge, or the current limiting for the Iphone is done with some cheap resistor circuit thing, wasting most of the charge current as heat, does the phone get hot when charging? or the charger?

failing that, run the Duracell pack as low as you can then give it a full initialising charge (ignore any "pack full" or "charge complete" lights), give it the full eight hours or whatever they say it needs for first charge, that might cure it, with many high capacity packs you MUST give them the full initial charge in order to reset the charge/discharge controller and switch it from the factory "pack storage" mode to "charge cycle" mode, if you don't do that the pack manager gets confused and misreports the main pack state, shutting it down to prevent over-discharge when it still has plenty of juice left because it thinks it's almost empty due to not being reset properly when first charged.

edit @Gruso

yeah! thats true, but 50% efficiency is way out, he should be able to squeeze 5 charges out of it imo, when running and cycling flight packs I find the chargers report a close correlation between what they put in and the capacity of the cell (better than 5%), my chargers are pretty fancy programmable things mind you, they may be more efficient than some freebie supplied with the pack/phone

edit:edit: hah!, probably sussed it!, for a guess the pack is a single cell 8000mah LiPo, that gets pumped up to 5 volts to charge USB devices, the extra voltage = reduced capacity (ie double volts=1/2 capacity, 3.2 volts > 5v = capacity divided by 1.5625, 8000/1.5625=5120mah (at 5v assuming 100% efficient conversion), that's 4.19 charges, if you assume the converters in the phone and the charger/pack eat up the differential, not being 100% efficient, as you say, you can't really get a charge when the pack is discharged to the same level as the Phone, so subtract 0.6/0.7 = 3.5 charges, so 3.5 recharges sounds about right (imo), if he could charge the Iphone cell directly off the Duracell cell then he would get his 5 charges, the voltage pumping/dropping between the pack and the Iphones electronics is eating the difference (I think), pumping up to 5v and then dropping it back to 3.2 is losing a whole chunk of power.
 
@borgqueenx: Also, was the iPhone running while you were charging it? That power doesn't come out of nowhere. :D

Also, why nobody has suggested the obvious solution: buy the pandora spare battery. I doubt you'll get any replacement battery that will fit as perfectly and be as cheap as the ones provided by OpenPandora themselves. Come on, it's only $30 for it. You even get a nice case for the battery too. :D

But buy it only if you really need it. Not a very good idea to buy a LiPo battery and not use it for long periods, it would self discharge and die on its own. Even if kept at optimum storage conditions (~40% charge, low temperature), it would still degrade over time.
 
I wonder if the battery cases will be included in the selection of spares that they'll be selling?
 
rabidpoobear said:
atomicthumbs, I know you're kidding

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I have the same size, but they're Werkers and only 7.5 AH. I don't have a voltage converter, though, unless I use my inverter and a 120VAC -> 5VDC power supply.
 
lulzfish said:
I don't have a voltage converter, though, unless I use my inverter and a 120VAC -> 5VDC power supply.

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atomicthumbs said:
lulzfish said:
I don't have a voltage converter, though, unless I use my inverter and a 120VAC -> 5VDC power supply.
Voltage convertors
Well, yes, I've got one or two of those, but mine are linear. I mean I don't have a voltage converter that could take 12 V down to 5 V without burning off more than half the power I put into it.
Wonder if Jameco sells magical PWM ones.
 
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lulzfish said:
Well, yes, I've got one or two of those, but mine are linear. I mean I don't have a voltage converter that could take 12 V down to 5 V without burning off more than half the power I put into it.
Wonder if Jameco sells magical PWM ones.

pretty much any electronics place'll sell you a voltage regulator
 
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MWeston said:
If you even need it...this thing runs all week for me with random testing and listening to music with the lid down. Maybe for a long flight or something but it's quite impressive as is, in my opinion.

Even then, the last three long-haul flights I have been on have in-seat usb port for charging personal media players and the like - and yes, that was in economy class!
 
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atomicthumbs said:
lulzfish said:
Well, yes, I've got one or two of those, but mine are linear. I mean I don't have a voltage converter that could take 12 V down to 5 V without burning off more than half the power I put into it.
Wonder if Jameco sells magical PWM ones.

pretty much any electronics place'll sell you a voltage regulator
They probably sell both, normal voltage regulators and PWM control integrated circuits. You probably want a PWM power supply though, there's no comparison efficiency-wise (specially with such a large voltage drop).

The basic PWM ICs do take a more complex circuit design to work, not to mention an elusive inductor (well, the inductor core that is, since its not very hard to wind some wire around). Don't know if there are PWM ICs that work with simpler circuits, though.

Or you could get a ready made PWM based power supply. Pandora uses a charger similar to PSP, right? Isn't there PSP power supplies that can run of 12v from car battery? That could probably work.
 
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Yoyobuae said:
Pandora uses a charger similar to PSP, right? Isn't there PSP power supplies that can run of 12v from car battery? That could probably work.
Brilliant!
http://www.amazon.com/PSP-Car-Charger-Sony/dp/B000ASGFLU
I'd just have to crack that open, slap some quick-connects on the 12V terminals, and hook up the 2nd3rd biggest portable external Pandora battery ever.
 
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I've got 4 of these sitting on the floor next to me at the office. I doubt anyone would miss them:
battery.jpg

Each one is 12v/12Ah
 
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