Battery Life On Gp2x

[LineOf7s]

The system isn't unstable; but very early software is imperfect. Even more so than how .. well, all software is imperfect.

NiMH batteries develop a 'memory', they are famous for it. If you have a 100% charged NiMH cell and you use it with the GP2X and drain it to say, 30% when the GP2X stops being usable (voltage level drops too much) then recharge it .. it will only last as long as 70% of its capacity! Discharge it again and it will next time, charge to about 40% capacity .. then 10% .. so forth. Eventually the batteries will appear useless! This is why you must discharge FULLY and recharge FULLY to restore full life of the batteries-- if you don't charge fully ASAP you will only see how much capacity you charged to, and a new memory will be established .. annoying, huh?

This is why I am so adamant about it. I averaged 5-6 hours of life on my Energizer 2500MAh AAs. After 5 cycles of letting the GP2X drain them til it crashed then recharging them immediately (Due to time constraints) .. they now last 1 hour! Sometimes less! I need to completely empty them in my CD player when I get back home, this reminds me.

Also, I'd use an 8-hour plus charger like mine. The ones that do a full charge in about 15 minutes reportedly charge the cells only to ~70%. This compounded with the NiMH "Memory Effect" will result in some pretty abysmal performance.

I don't think this is accurate at all. NIMH's don't have nearly the 'memory' of the other type battery (who's name escapes me). I'm not saying there is no memory or need to discharge them, but it's not nearly as drastic as you describe. In fact NIMH are 'famous' for NOT having this memory (it's the other types that's 'famous' whose name escapes me again) .

Most people recommend draining NIMH batteries fully about every 10 or so uses. I'm able to use NIMH batteries repeatedly without full discharge and get similar usage each time. But after about 8-10 useages I do start to notice a loss of performance.

The name that keeps escaping you, bigdaddy, is nickel cadmium (NiCd). Or it should be, anyway.

Here's a nice little article explaining things: http://www.dansdata.com/gz011.htm

 

[DBH]

Has anyone ever considered trying to make their own Lithium Ion AA battery pack ?? I know you can buy near AA size (look like AA but dont have the little bump at the top) for use to make your own packs... maybe someone could figure out how it would go together to make a pack for the GP2X?

 

[kidcapricorn]

Shouldn't a decent charger empty the batteries before beginning recharging then...?

I mean, it's all very well taking the batteries out of the GP2X, putting them into a walkman/torch/rampant rabbit and running it til it's dead, but in real life that just a bit of a pain in the arse isn't it...

It's not that i'm lazy, it's just that the idea of adding another stage to the battery charging procedure, however small, is rather annoying and self-defeating...

 

[nubie]

Shouldn't a decent charger empty the batteries before beginning recharging then...?

I mean, it's all very well taking the batteries out of the GP2X, putting them into a walkman/torch/rampant rabbit and running it til it's dead, but in real life that just a bit of a pain in the arse isn't it...

It's not that i'm lazy, it's just that the idea of adding another stage to the battery charging procedure, however small, is rather annoying and self-defeating...

Good points.

Question, is it that the current has run out, or that the voltage is nut up to levels.

If you could run 3 AA the voltage regulator would be much happier, as evidenced by Squidge's tests and the fact that our regulator is claimed to take up to 5 volts input.

Since it is making 3.3volts out of what we put in Squidge found it to take the least current right around the voltage that 3 AA NiMH put out , making more voltage out of less is an in-efficient process.

I think that the batteries would drain fully with 3 cells because there is less current drain on them and the voltage regulator will continue working because the voltage as the batteries approach fully discharged the voltage does not drop below the point where the voltage regulator wll no longer function.

I realize that 3-cells is weird, but if they last an appreciable time it might be worth it to buy a charger that will do individual cells.

Assuming only 50% longer it yields a run-time of over 6 hours, but it might be longer considering that with increased voltage regulation efficiency the power draw is less, also the batteries will be able to drain more fully because the GP2X will continue working as they fall below the regular voltage per cell.

@DBH Use the tutorial for putting that crv-3(or whatever) battery pack into the GP32, it should be pretty much the same because the battery holder is still the same. Someone made a really nice tutorial, use google. I do know you can get a nice kit of the crv-3 with a charger and a battery pack from Target, very expensive mind you, think Sony PSP mega pack (in mAh, regular size physically) and charger, ouch. 3 NiMH might be cheaper and provide you with the same run-time.

In which case I would sooner use the PSP battery packs, or source the cells myself and make my own pack, the real trouble with the Li-Ion is the electronics. 3 NiMH on the other hand should work as-is, just put an extra cell holder on the back and wire in series with existing batteries.

 

[Epicenter]

Yeah, my explanation is not dead on but it does give you the idea-- it won't actually happen in one cycle necessarily; and it may vary based on the age of the batteries. Very old ones may experience this more often. I do greatly see the impact after 3 or 4 cycles though-- my life after a full charge will be cut in half or to a third, or worse.

 

[zektor]

I wonder why the current chargers do not have some sort of complete discharge feature...or are there any out there that do this that I am not aware of?

 

[iignotus]

I wonder why the current chargers do not have some sort of complete discharge feature...or are there any out there that do this that I am not aware of?

There are lots out there, but they're usually very expensive as they come with a bunch of other features.

 

[BradN]

I think more important than self discharging (although it can be good in conjunction with capacity measurement) is that it charges the batteries individually - similar to fully discharging 2 or more in series, charging 2 or more in series can overcharge some of the batteries.

 

[Shikaku]

I wonder why the current chargers do not have some sort of complete discharge feature...or are there any out there that do this that I am not aware of?

There are lots out there, but they're usually very expensive as they come with a bunch of other features.

O RLY?

http://www.thomas-distributing.com/mh-gtcharger.htm

$20 + shipping, international too...

I'm buying this later..

 

[iignotus]

I wonder why the current chargers do not have some sort of complete discharge feature...or are there any out there that do this that I am not aware of?

There are lots out there, but they're usually very expensive as they come with a bunch of other features.

O RLY?

http://www.thomas-distributing.com/mh-gtcharger.htm

$20 + shipping, international too...

I'm buying this later..

Thanks for showing me the charger I have sitting here right next to me (check the first page). I'm not sure why you did, though, since it doesn't enhance your point. It doesn't discharge batteries before it charges them.

 

[Shikaku]

http://www.thomas-distributing.com/maha-mh-c204f.htm

Here you go, slightly cheaper too...

Also:

Q: How often should I condition my batteries?

For Nickel Metal Hydride (NiMH) batteries, conditioning is recommended once for every ten charges. For Nickel Cadmium (NiCD) batteries, conditioning is recommended every time you charge your batteries.

 

[Shikaku]

One more thing:

Question / Issue:
Does the C401FS charger have the "recondition" feature like the C204F charger that I own.

Answer / Solution:
The C401FS charger is so advanced that the internal charging circuit makes manual conditioning unnecessary. Since each battery is charged independently using the Flex Negative pulse charging algorithm, not only is each battery charged to its optimum capacity, but battery life is also enhanced. In fact, FLEX NEGATIVE pulse charging removes the crystal structure formed on battery electrodes (which is the source of "memory effect") and conditions your batteries as they are being charged. Full automatic charging on either Fast or Slow setting.

 

[Epicenter]

I have to wonder if 15 minute chargers like that Energizer one with the fan DO discharge the batteries; and that fan is to get rid of all the waste heat produced from removing all power from the batteries. They don't seem to charge the battery as much in the end, but memory effect doesn't seem to take hold so quickly.

 

[jdwrrzmm]

I also did my own test. 2500Mah Batteries.
DrMDx at 200MHZ with sound from speakers.

It lasted 3 hours and 55 minutes.

Note that I didn't deplete the batteries before hand.