PRS-300 Charging seems totally random. Unable to get full charge at all

[reader8317028]

What is crazy is I have been using sony readers probably well over a decade now and still have no clue how the charging works!

I have just muddled through and somehow gotten a small bit of charge most times.

I started with one of the touchscreen ones which I broke after only a couple of years.

Then got a 2nd hand prs 505 which lasted me the best part of a decade of faithful service. It was falling to pieces by the end after several fixes through it's life, with much of the plastic casing round the edges gone (!) and finally I bricked it by attempting to change the battery with one too fat and forcing it in and breaking the screen in the process.

Wanting to stick to what I know and being very happy with the design of sony readers I managed to find a used prs 300. Great condition and only ten pounds or so. It seems I have inadvertently gone simpler and simpler with each sony reader model I buy .

When I got it and tried to charge it it wouldn't hold charge. Thinking that it just had a duff battery I tried putting the larger 1000ma battery in it since I already had it from my previouls attempt to change the 505 battery. With quite a bit of struggle, but being more careful given I broke the 505, I manage to get it in with a very tight squeeze.

I used the provided usb lead which is a double usb connector to single to the device. It charged for a good while and that first time it seemed to charge almost full - to maybe 3 bars which is much better than usual on my other readers!

After that one time though it will not hold charge and behaves just like my old prs505 battery which would barely hold any charge. Worse even as with the previous one I could at least get a few reads out of it usually. Not so with this one. I would have to charge it after nearly every reading and nearly always in the triangle ! territory. Would get a few days out of it and then the hexagon ! indicating no charge at all.

I don't understand how this can suddenly be happening with what should be a new battery? It is possible the 'new' battery is also dud but don't have any way to test that theory right now as no other ones.

With all of them though, except maybe the first one which I broke before such issues became apparent (!), I have never understood how charging works and found it very hit and miss. I have read various threads regarding the readers and charging on this very forum over the years, which is what prompted me to sign up to ask this question. I recall often people comment that you can only charge via mains to get proper charge.

I never had this issue when my 505 was newer and would charge by computer usb port.

I am living in my van now so mains is not an option. I have a high powered usb port thought which is capable of 5a so I don't see that being a problem?

What the issue is is that it won't seem to charge at all until fully depleted with the hexagon ! sign and I guess shut down. If I plug it in for a 'top up' before fully depleted it refuses to charge (no red charge light) and just shows the usb connected graphic.

This would be fine if it actually charged once depleted but when I plug in after a shutdown it will show charge (red light) and charge for a good while and then turn on again after about an hour or so indicating it is booting up. I unplug the connector then most times it will just show no charge and shut down again!

Thing is though occasionally it will absorb some juice but only a little, like 1 bar's worth, or 2 then straight to 1/0, so that charge state at best will be on one bar and usually goes straight to triangle !. This will give a couple of hour's reading before the whole process must be done again.

More times than not though it will not charge at all and so am just stuck in a cycle of charge and immediate shutdown - try charging again, shutdown, and so on.

Advice please!

[Sirtel]

My advice is to buy a newer ereader. Sony readers are ancient. You may never get them to work and charge properly.

[Quoth]

Tho only worthwhile S/H Sony readers, if cheap, are the PRSx50 family and the PRS-T2

But even they are so old now they will need a new battery and the plastic is disintegrating.

[rcentros]

Originally Posted by reader8317028

Advice please!

The battery may not be good, or not suitable for the charging circuitry of your PRS-300. In the U.S. (I don't know about Britain) you can buy a battery specifically made for the PRS-300 relatively cheaply.

I should add, there could also be a short on the motherboard that drains the battery.

[reader8317028]

Originally Posted by rcentros

The battery may not be good, or not suitable for the charging circuitry of your PRS-300. In the U.S. (I don't know about Britain) you can buy a battery specifically made for the PRS-300 relatively cheaply.

I should add, there could also be a short on the motherboard that drains the battery.

Hmmm had not thought of short circuit being a possibility.

How do you mean specifically made for the prs-300? I didn't just use any random shaped battery .

Can anyone tell me what the normal charging behavior should be?

Is it normal to not charge if there is still partial charge on the battery?

[rcentros]

Originally Posted by reader8317028

Is it normal to not charge if there is still partial charge on the battery?

No, that's not the case with my PRS-300, but I have a Sony charger that uses the round charging port. It probably has a little more "juice" than a standard USB port.

When I say a battery specifically made for the PRS-300 I mean there might be some kind of circuitry built into the battery that's not present in the battery you're using.

[Quoth]

Originally Posted by reader8317028

Is it normal to not charge if there is still partial charge on the battery?

It is for LiPoly.
There is a minimum voltage at which it's safe to charge. Electronics is supposed to disconnect at about 3.7V
Charger is supposed to disconnect at about 4.2V, so you could measure 2.5V on a cell and it will never try to charge.

Many cells have a PCB with a controller built in. If the original had that, then the replacement needs one. If there was no built in controller then a cell should be identical.

They are the most tricky rechargeable technology.

Unless it's strange, the only absolute requirement of a charger is the voltage. 5V now and 5.2V on really old things. Even a 20A charger will still only charge at 500mA maximum if that's what the gadget takes. Only newer things take more than 500mA (1/2A). Also charge will be less at the start and end in most cases.
There is no ongoing trickle charge with LiPoly, that would set them on fire.

[Frogm4n]

Also, old Sony devices with mini-usb don't like to charge over USB unless it's a port on a computer, and they already have enough charge to power on and be recognized by it. That's why Sony put the barrel jack on them. Try using the barrel jack and see if you get a full charge, or plug into a powered on computer.

I have an in-line USB power meter that is super handy to see if something is drawing power and how much.

EDIT: Here's the manual as PDF. Jump to the Charging the Reader section.

[reader8317028]

Originally Posted by Quoth

It is for LiPoly.
There is a minimum voltage at which it's safe to charge. Electronics is supposed to disconnect at about 3.7V
Charger is supposed to disconnect at about 4.2V, so you could measure 2.5V on a cell and it will never try to charge.

Many cells have a PCB with a controller built in. If the original had that, then the replacement needs one. If there was no built in controller then a cell should be identical.

They are the most tricky rechargeable technology.

Unless it's strange, the only absolute requirement of a charger is the voltage. 5V now and 5.2V on really old things. Even a 20A charger will still only charge at 500mA maximum if that's what the gadget takes. Only newer things take more than 500mA (1/2A). Also charge will be less at the start and end in most cases.
There is no ongoing trickle charge with LiPoly, that would set them on fire.

Interesting, thanks for the additional details. That is useful to know so then I know what to focus my efforts on. If this is just how they charge I can concentrate on how to work within those parameters rather than thinking it some problem with the individual battery.

The battery was specified as compatible with prs-300 and identical voltage of 3.7. Chinese cheapo we must take at their word but that is what they were listed as.

[reader8317028]

Originally Posted by Frogm4n

Also, old Sony devices with mini-usb don't like to charge over USB unless it's a port on a computer, and they already have enough charge to power on and be recognized by it. That's why Sony put the barrel jack on them. Try using the barrel jack and see if you get a full charge, or plug into a powered on computer.

I have an in-line USB power meter that is super handy to see if something is drawing power and how much.

EDIT: Here's the manual as PDF. Jump to the Charging the Reader section.

As I mentioned I don't have AC in my van so no barrel.

It charges on usb just haphazardly. What special magic would make it recognize a computer usb port rather than a non computer one?

I always used the computer one to charge the 505 and the behavior with the non computer one in my van seems to act the same as that to charge it.

If it is just how the device/battery works then I will just work with it.

It was ok to read even on 0 bars these past couple of days. If I manage to get a few days out of each charge cycle it will be inconsequential to just plug it in and charge after it runs out if I manage to consistently get a few days juice out of it each time!

I managed for years like that with my 505 just want to get back to that same baseline!

[rkomar]

I am not an expert on USB, but I learned a bit from the many discussions on this site that took place years ago. USB devices can communicate with each other, passing information on the capabilities of each other before moving data or charging. For safety, the default charging mode is to use a very low current that all devices can handle. The devices can negotiate a higher charging current if they both can handle it and are capable of communicating that to each other. That last bit is what is probably holding your device back when it comes to charging if you are using something that cannot negotiate.

My old 505 would occasionally completely drain its battery. When plugging into USB, the charging would start off really slowly, taking hours before the device could successfully boot up. Once it did, it could negotiate a higher charging current, and filling the battery went much faster. The whole process was more complicated than you might think.

[reader8317028]

Originally Posted by rkomar

I am not an expert on USB, but I learned a bit from the many discussions on this site that took place years ago. USB devices can communicate with each other, passing information on the capabilities of each other before moving data or charging. For safety, the default charging mode is to use a very low current that all devices can handle. The devices can negotiate a higher charging current if they both can handle it and are capable of communicating that to each other. That last bit is what is probably holding your device back when it comes to charging if you are using something that cannot negotiate.

My old 505 would occasionally completely drain its battery. When plugging into USB, the charging would start off really slowly, taking hours before the device could successfully boot up. Once it did, it could negotiate a higher charging current, and filling the battery went much faster. The whole process was more complicated than you might think.

Thanks for the info.

Does anyone know if there is a way to test the integrity of the battery without buying another battery to swap it out with? They only cost a few quid but would be a shame to waste it if it is perfectly fine and something else is the issue.

Not like AA/AAAs (sorry if you are not in the UK you may not understand that form factor! Just think a common household battery!) where you could just put it in another device as these batteries are very niche.

I know a lot more about general DC electronics now, having done my own electrics for my van build, so wondering if I could cobble something together to test it somehow.

[reader8317028]

Originally Posted by Quoth

It is for LiPoly.
There is a minimum voltage at which it's safe to charge. Electronics is supposed to disconnect at about 3.7V
Charger is supposed to disconnect at about 4.2V, so you could measure 2.5V on a cell and it will never try to charge.

Many cells have a PCB with a controller built in. If the original had that, then the replacement needs one. If there was no built in controller then a cell should be identical.

They are the most tricky rechargeable technology.

Unless it's strange, the only absolute requirement of a charger is the voltage. 5V now and 5.2V on really old things. Even a 20A charger will still only charge at 500mA maximum if that's what the gadget takes. Only newer things take more than 500mA (1/2A). Also charge will be less at the start and end in most cases.
There is no ongoing trickle charge with LiPoly, that would set them on fire.

Hi, just reading through this thread again for more clues.

Here is the type of battery I got. Here is the datasheet. Perhaps you could indicate as to its suitability.

I was wondering maybe it is an overvoltage issue and your above post seems to indicate it may be? Does the battery require less than 5v to charge then would you say from what the datasheet says?

I know a little about the technical stuff but not too much.

I notice on the barrell connection on the sony reader it says 5.2v so I presume it is also the same for the usb connection I am using.

Could that be the issue? Any workaround if so? I have done some trickery with voltage step downs on my van's electrics in order to charge my laptop (which wants constant 12 whereas my lifepo4 leisure battery is 13+/-) and also connected phone charger right to the blade fuse holder with another step down to 1v or so.

Wondering if some similar trick could be done here? Perhaps if no solution could be found with the battery I could just take it out completely and try another step down and solder a connection right to the reader . I have wondered if that would work to do away with the battery part on other battery dependent devices.

[reader8317028]

Originally Posted by Frogm4n

Also, old Sony devices with mini-usb don't like to charge over USB unless it's a port on a computer, and they already have enough charge to power on and be recognized by it. That's why Sony put the barrel jack on them. Try using the barrel jack and see if you get a full charge, or plug into a powered on computer.

I have an in-line USB power meter that is super handy to see if something is drawing power and how much.

EDIT: Here's the manual as PDF. Jump to the Charging the Reader section.

Oh ya, some quite specific instructions. I will have a play around.

[reader8317028]

Originally Posted by Frogm4n

Also, old Sony devices with mini-usb don't like to charge over USB unless it's a port on a computer, and they already have enough charge to power on and be recognized by it. That's why Sony put the barrel jack on them. Try using the barrel jack and see if you get a full charge, or plug into a powered on computer.

I have an in-line USB power meter that is super handy to see if something is drawing power and how much.

EDIT: Here's the manual as PDF. Jump to the Charging the Reader section.

I think you might be on the money with the pc usb charge comment.

Looking in the section on charging in the manual I noticed it mention that you should have it switched on, not just in sleep mode, before connecting the usb cable. I had not been doing that.

I tried both with the pc (laptop) and the red light came on after a few seconds. I then tried with the non pc ports and no usb charge light.

So leaving it on the laptop charge now. Let's see what happens...