Battery Mod

[EvilDragon]

Be careful when messing around with Lithium Ion batteries though.
They are explosive.

 

[abigsmurf]

lithium polymers are safe though.

 

[Goity]

Actually, 3.7v is what the core is running at iirc, there's a voltage regulator inside which converts it.

 

[BradN]

I don't think you'll run into safety issues putting cells in parallel - at most what it will do is allow the more charged ones to charge up the other cells until they're at the same voltage. Once they're at the same voltage, no energy's going to exchange between them since you need a voltage difference by definition for this to happen. You wouldn't want to, say, put a AA in parallel with a 12 volt car battery though, since the voltage will only be equalized once the AA hits 12 volts, and by the time that happens, it'll probably be burned beyond all recognition.

If you've got cells in serial though, that forces all the cells to charge or discharge at the same time, and you can end up discharging one or more cells beyond empty, causing them to reverse polarity (it actually gets a negative voltage) and likely damaging those cells.

Lithium ion cells have a whole host of other safety requirements, basically you don't want to completely discharge a cell, or overcharge it, or let the temperature exceed a safe limit, or call it and/or its mother names... etc - this is why there's almost always a supervisor chip in the pack to disconnect the output if one of those things happens.

 

[___]

Hmm... I shouldn't have called my laptop battery "dirty douchebag"...
But seriously: wouldn't it be more convenient to plug a DIY battery pack into the AC input rather then cutting out the battery compartment? Can that be done?
Cause then it would be way easier to create a kind of mod... maybe there is some kind of high ampere rechargeble battery for some other portable device that runs a 3V current... i will look into that.

 

[donny662]

Ouch, they aren't rechargable? I thought they are. Sorry, shame on me...
Yes, there it is http://www.abcde.de/data/cr17450se.pdf

It was too good to be true.

​

Is it just me, or do those batteries have a max discharge current of 9mA (150mA pulse)?

I don't think that would be adequate if the GP2X draws 500mA when it is idle and up to 800mA or more when you are actually doing something.

 

[Eso Rimmer]

To donny662:
Yes, it's true. It's some kind of special long-life battery for small discharge current and it's not rechargable. I didn't know that when I found this battery...

 

[abigsmurf]

Hmm... I shouldn't have called my laptop battery "dirty douchebag"...
But seriously: wouldn't it be more convenient to plug a DIY battery pack into the AC input rather then cutting out the battery compartment? Can that be done?
Cause then it would be way easier to create a kind of mod... maybe there is some kind of high ampere rechargeble battery for some other portable device that runs a 3V current... i will look into that.

​

But you've then got to carry around a battery pack

I've only cut out the internal part of the battery compartment and the cover still slides on (it's not perfect, there's a small gap still where I got a bit too eager with a file) but other than that it looks like a regular console.

The batteries I used were actually designed for 4th gen ipods, they just happened to be the best size for the space available (although it's still extrememly snug, even with the battery compartment cut out)

 

[Muncher666]

Actually, 3.7v is what the core is running at iirc, there's a voltage regulator inside which converts it.

​

How effective is the voltage regulator? I'm just a little worried about using an unregulated power supply with it.

Allan.

 

[Fishbong]

You should not use rechargeable batteries parallel, there are current flows between them that will dramatically decrease the lifetime of the weakest battery. (even batteries of the same type have often different capacities)
It may work, but its not a long-lasting solution!

 

[trooper]

Hmm... I shouldn't have called my laptop battery "dirty douchebag"...
But seriously: wouldn't it be more convenient to plug a DIY battery pack into the AC input rather then cutting out the battery compartment? Can that be done?
Cause then it would be way easier to create a kind of mod... maybe there is some kind of high ampere rechargeble battery for some other portable device that runs a 3V current... i will look into that.

​

But you've then got to carry around a battery pack

I can`t see that as a problem as most people carry atleast one extra set of batteries anyway.

Trooper

 

[Gaijin]

lithium polymers are safe though.

If only, I mess around with RC electric boats and during my research for cells saw a video of lithium polymer packs being overcharged, lets just say that they they're fairly incendiary.

In fact the same thing applies to cuts letting in air and discharging too far, still they do pack ONE Hell of a punch!!!

Protection circuitry can prevent this

Li-Po Fire

 

[luteijn]

Protection circuitry can prevent this

From what I understand, abigsmurf considers the protection circuitry part of the lipo-battery. They usually do come with protection circuitry anyway. Most of the sites I've seen tell you not to put more than two in parallel or the protection circuits might 'fail'... so his 3 stacked ipod replacement battery thingies might still go instable and balloon on him, although it will probably be okay.


P.

 

[GpDogg]

yes yes! I agree with person who says whats wrong with aa chargables??
I recommend going to ebay and get a uniross sprint charger and some 2500mah batteries. I got the charger for £20 and 2 packs of 2500mahs for £12! in all £32 for charger (with 4 2300mah batteries included) and 8 2500s! And it takes an hour to charge 2500s! its very fast charging and you can also get another uniross charger which charges in 15 minutes! astounding!

I just charge them up and put them in and carry them round with me the spares in a pouch for my 2x. Im happy with my 2x now also i know scummvm is coming out for it!! AAAYAYY!!!

Go and on ebay and things. look for uniross sprint charger and batteries. there are battery shops on ebay which are very VERY good!

 

[peter.stegemann]

You should not use rechargeable batteries parallel, there are current flows between them that will dramatically decrease the lifetime of the weakest battery. (even batteries of the same type have often different capacities)

Repetition does not make a wrong argument right. What happens with parellel cells in a pack has been explained several times in this thread. It's no problem if done right.

 

[Fishbong]

Bullshit. First off, that does only apply to lithium-polymer batteries.

I was talking about rechargeables in general, and i wasn´t talking about the problem of voltage reversal.

Its just that the weaker battery will wear out quicker after a few recharging cycles, because there are current flows between the batteries that can (even if both are charged), for very short times, exceed the normal levels by far.

 

[lucoxade]

I remember the GBA having third party rechargable battery packs that would sit in the battery compartment which also had a DC in to charge it. Its likely you could use one of these with a bit of dremelling?

Also what about using a DS battery? with two screens to power along with an ARM9 surely they will have enough juice, you just need a way to recharge it.

EDIT: Just realised that the DS batteries are only 850mAh and are 3.7v so I doubt they would last long in a GP2X. What eats all the juice in the GP2X? did the TV-out circuit get fixed? is it likely to get better with newer firmware?

 

[nubie]

Use 3 2500mAh AA Ansmann or Energizer.

I think we could make our own Battery cover and put another battery in it.

Just make some contacts for the end of the compartment that connects the positive of one battery to the negative of the other battery with a strip of metal.

Make Them into 2 contacts that will connect with the lid, make a new lid with a spare AA cell wired in Series with the other 2.

Bam 3.6 volts, the regulator can take it easy, and the batteries will last longer.

Plus you are still using AA based batteries so anybody can do the mod, a kit would come with the new battery cover and the replacement contacts, couldn't be simpler.

Well, it could, just get a single AA cell holder and epoxy or screw it to the outside of the cover we already have, or just above the battery compartment and let it hang out in the air.

 

[Shikaku]

Use 3 2500mAh AA Ansmann or Energizer.

I think we could make our own Battery cover and put another battery in it.

Just make some contacts for the end of the compartment that connects the positive of one battery to the negative of the other battery with a strip of metal.

Make Them into 2 contacts that will connect with the lid, make a new lid with a spare AA cell wired in Series with the other 2.

Bam 3.6 volts, the regulator can take it easy, and the batteries will last longer.

Plus you are still using AA based batteries so anybody can do the mod, a kit would come with the new battery cover and the replacement contacts, couldn't be simpler.

Well, it could, just get a single AA cell holder and epoxy or screw it to the outside of the cover we already have, or just above the battery compartment and let it hang out in the air.

​

The volts start at 1.4-1.5V then go down to 1.2V. That means 4.2-4.5V!!! NOT GOOD.... We will need a voltage converter to 3.6V so that the voltage converter in the GP2X won't die.....

We need a voltage converter for the voltage converter.... weird....

 

[BradN]

It's not known if you need another voltage converter, because nobody that actually has a gp2x has bothered to look up the datasheet for the converter in it. I'd do it myself but I don't have one.