Latest Firmware Current Consumption


foft

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Squidge posted on Dec 31 2005 at 05:20 PM said:
Hmmm, a saving of over 300mA by just increasing the battery voltage. Nice :)
Think Power, not Current. P=VI... Seems it takes a fairly constant amount of power, which makes sense.

Mark

(edit: When I say constant, I mean when just varying the voltage and the current changes...)

(edit2: Doh, Reaper already said this)
 
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nubie

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I posted this on the 22nd in the gp2x.com forum.

I think that lithium batteries die if you don't take care to keep them between 30% and 80% charge all the time, IE don't overcharge, don't run dead, don't overheat.

We would need to find a good Lithium battery controller.

I checked into it and here's what there is:

this is the page to put a CRV3 lithium camera battery in a GP32:

http://www.gp32games.com/modules.php?name=...showpage&pid=26

This came from candlepowerforums where people were discussing powering their flashlights:

"The CRV3 is two AA sized 3 volt lithiums side by side in a shrink wrapped package. If you disassemble it you end up with two AA sized cells that are 3 volts each. They appear to use the same chemistry as the Duracell 123A battery."

Each cell appears to be 1500mAh, they are both 3 volts, so they are aligned in parallel and deliver 3000mAh together, they also will not just drop in.

The only real difference is that NiMH will discharge themselves fully sitting on the shelf in about one or two months, whereas Lithium-Ion should hold it longer, not really a concern in a regularly used and charged device.
 

Hanz™

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reaper79 posted on Dec 31 2005 at 06:44 PM said:
Well, I think the hard part will be finding rechargeable lith-ions with enough amp/hours in the proper AA size package.

If we have (2) 1.2v AA Ansmanns @ 2600mah, as an example, then we have: 6.24 watt/hours.

So we need a lith-ion pack around 1750mah @ 3.6v just to equal current nimh capacity.

Still searching... only found 3.6v 1300mah lith-ions so far...

EDIT: typos

EDIT: Oooh, found Tekcell 2400mah 3.6v = 8.64 watt/hours, not bad, don't know if they are rechargeable.
I searched for a couple of hours last night - was really really bored. Before.
And after. :lol:

Points I would like to make is that lithium ion CRV3 batteries need a different charger depending on the batteries.

The best rechargeable I have found is this one: http://www.radioshack.com/product/index.js...oductId=2110935

But I am not sure whether that information is correct (3.7v 1440mAh) as I cannot find the same spec on their website here.

Apparently this is true.

I actually wonder whether a 7.2v battery could be used (would the voltage be regulated?)
As this battery would fit - sticking out of the GP2X - we would have to fiddle around with some cabling at such though.

Most of my research was posted here - but nobody else really seemed interested at the time (of night): http://www.gp32x.de/board/index.php?showtopic=23965&st=0#
 
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Squidge

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foft posted on Dec 31 2005 at 07:17 PM said:
Think Power, not Current. P=VI... Seems it takes a fairly constant amount of power, which makes sense.
Yes, but the less current draw from the batteries, the cooler they shall become, and the longer they should last, as you are not running them at silly amperages all the time :) Drawing an amp off any rechargable AA battery is going to make it seem flat pretty quickly even if it was a 3000mAh battery, as it simply can't sustain such a current draw.

Even the 12V batteries I have here say that you should should draw the current over a period of 8 hours to get the maximum performance from the batteries. I'd love to see the recommended usage table for the rechargable AA's. It's probably 250mA over 10 hours or something and we are drawing 800mA, so a higher voltage battery should be a lot more efficient.

EDIT: Or am I talking out of my arse? If I am, someone please correct :)
 
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Hanz™

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Is this actually useful at all:
How can a 1200mAh Li-ion CR-V3R out-perform 2100mAh AA NiMh batteries?
The energy content of NiMH batteries such as the 2100mAh rechargeable AA batteries are measured by draining the battery from its 1.2V 'notional' voltage right down to 0.9V. Unfortunately, long before that point, the voltage becomes insufficient to power a high drain device. Digital cameras will shut themselves down. Flash guns take so long to recycle that the photographer gives up.

Lithium-ion has a notional voltage of 3.6 volts and the voltage remains high right until the end of its battery life. It will keep powering high drain devices until the bitter end.

Another way of looking at it is that milli-amp hours (mAh) is only useful for comparing batteries of the same chemistry where the voltage produced over time is similar.

mAh is not useful when comparing differing chemistries such a a pair of NiMH batteries producing 2.4 volts with a Lithium-Ion battery producing 3.7 volts.

To compare dissimilar batteries it is better to consider the energy content in watt hours (Wh). Watts are calculated by multiplying current with the voltage and it takes account of different voltage patterns.

so for NiMH batteries: 2300mAh x 2.4 volts => 5.53 Wh

for a CRV3R battery: 1200mAh x 3.7 volts => 4.44 Wh

In fact this is still not as flattering as the Li-ion chemistry deserves. NiMH cells spend most of their time producing less than their 'notional' voltage. An average voltage of 2.1 volts would be more appropriate for the calculation. And Li-ion drops to 3.7 towards the end of its charge cycle. An average voltage of 4.1 volts would be more appropriate.

These voltages suggest an energy content of 4.83 Wh for the NiMH eclipsed by 4.98Wh from the Li-ion CRV3R.

These figures are very similar and, given that much equipment ceases to operate at the low voltage at the tail end of the NiMH charge cycle, it is easy to see how many users report that 1200mAh CRV3R comfortably out- perform a pair id 2300mAh NiMH batteries.
 

abigsmurf

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does anyone have the dimentions of the battery case?
I've found what looks to be a suitable Lithium ion Polymer cell which is 3.7V and 1100mah but should be thin enough to fit two in the case with enough space left over to include a "please god don't explode on me" board.

the cells are 5.0x37x59 (square) each
 

Pixman

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A very interesting thread.
lorgy77: Could you upload it to imageshack.us to make it public? Tnx. It's nice that you can look at it, but we want too ;)

Did you also did a long time battery test, Squidge? How long are you going with the movie player running with 2500/2800mAh batteries?
 

Squidge

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I can't do a battery test as I don't have any rechargable batteries. The only AA's I have are the "4 for £1" batteries from the local market (which seem to keep the 2x going for a few hours, although I've never tried the movie player with them).
 

DaveC

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does anyone have the dimentions of the battery case?
I've found what looks to be a suitable Lithium ion Polymer cell which is 3.7V and 1100mah but should be thin enough to fit two in the case with enough space left over to include a "please god don't explode on me" board.

the cells are 5.0x37x59 (square) each

Yeah but what is the point? 1100 MAh is less than half the capacity of 2500 MAh NiMH AAs. You would be getting half the playtime and for what? Just so you can say that you have Li-ion?
 
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Ravnos

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does anyone have the dimentions of the battery case?
I've found what looks to be a suitable Lithium ion Polymer cell which is 3.7V and 1100mah but should be thin enough to fit two in the case with enough space left over to include a "please god don't explode on me" board.

the cells are 5.0x37x59 (square) each

Yeah but what is the point? 1100 MAh is less than half the capacity of 2500 MAh NiMH AAs. You would be getting half the playtime and for what? Just so you can say that you have Li-ion?
I don't know shit about this sort of thing, but I read a site that said that the mAh of NiMH and Li-ion weren't directly comparable because the voltages were different.
 
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Series-8

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Remeber because the GP2X is voltage/current regulated the VCM will boost/buck the voltage/current as needed. (Actually is anyone shure that the GP2X is BOTH current and voltage regulated..? usually its one or the other)

A 4V 1000mAh cell has the same energy density as a 1V 4000mAh cell. (mostly, depends on the current draw limits, ect...)

Converting Amperage to Voltage/ Vice Versa is not 100% efficient. (usually about 70-90% depending on quality of parts/design/temperature)

I have seen drop in replacement Lithium rechargeable cells for 2xAA Digital cameras.
They are simply shaped like 2 AA cells stuck together.
 

reallynotnick

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At Dave: First what series-8 said up ahead, and then also a Li-ion batteries stay stronger longer, while a NiMH will slowly dwindle down losing a Li-ion will out put higher for longer and drop dead faster.

But I still don't think that is very cost effective and I am going to stick with my NiMH.
 

Squidge

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Yeah but what is the point? 1100 MAh is less than half the capacity of 2500 MAh NiMH AAs. You would be getting half the playtime and for what? Just so you can say that you have Li-ion?
Someone hasn't been reading the thread :)

If you increase the battery voltage, you increase the efficiency as the vreg in the 2x isn't wasting energy boosting the voltage for you. Also, li-ion's don't loose there charge over time as the AA's do (therefore needing further voltage boosting, and therefore even higher current drain...)

So a pair of 2500mAh AA will probably last 2 hours in mplayer
A single 1100mAh li-ion could last the same time period.
 
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abigsmurf

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Yeah but what is the point?  1100 MAh is less than half the capacity of 2500 MAh NiMH AAs.  You would be getting half the playtime and for what?  Just so you can say that you have Li-ion?
Someone hasn't been reading the thread :)

If you increase the battery voltage, you increase the efficiency as the vreg in the 2x isn't wasting energy boosting the voltage for you. Also, li-ion's don't loose there charge over time as the AA's do (therefore needing further voltage boosting, and therefore even higher current drain...)

So a pair of 2500mAh AA will probably last 2 hours in mplayer
A single 1100mAh li-ion could last the same time period.

Not to mention I said I'd try to fit two in the space:p. With the increased voltage, you'd have a pretty uber battery
 
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