[pimmis]

[QUOTE=eBookLuke;1922127]Hi,

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3) now you can check the batteries glued on the back. The battery kit is composed by two battery pack and one board. Thera ere two kind of these assemblies: the older has the batteries soldered directly to the board, the newest has the batteries connected to the board with a red/black detachable cable.
4) Check the battery integrity: both battery must look as flat, rectangular, silver pack. If one or both are swollen or broken, then the battery is gone.
5) test the battery efficiency: with a digital tester, check the voltage of both batteries. The voltage of each battery should be between 2.7 volts and 4.1 volts. Another very important thing is that the voltage MUST be equal in both batteries.
The batteries are good IF the voltage is >= 3V AND both voltages are identical.
A battery is damaged IF their voltage is < 2V.
The batteries are damaged IF the voltage are not identical.

Now:
As I stated, in the Museum we have some batteries for you. Anyway, the battery must be replaced both, to ensure a correct balance in the voltage.
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A few remarks: I didn't know that this particular model had two identical batteries, but don't doubt that this is the case. My main remarks are in the details - how to determine that the batteries indeed are the culprits and if it may be so that only one of them makes most of the trouble. To charge LiIon batteries properly is a real science in itself. There is statistically a slim chance that both batteries have aged in the exact same way, however from practice I would not bet my head on it.

To proper compare two batteries of the same model I would first start to charge them. Measure the voltage over the batteries during charging. There are certainly some electronics controlling the charging of the batteries. If it's a common system for both or a separate system for each I do not know. But if you measure the charging voltage and the voltage is slowly and smoothly rising on both batteries this is a good sign.

If you are able to rather quickly notice that the voltage during charging starts to differ substantially (in the order of ~0.5 Volts or so), then you can be sure that the performance characteristics of the separate batteries are not the same. At least one of them is bad. With a little basic common sense you may be able to pinpoint which is bad.

If you only can get hold of one "better used" battery, then you can exchange the bad ones to this and your reader will at least work better. The prefered way is though to exchange both batteries to a matched pair (whenever they happen to be brand new or used but to the same extent both of them and having the same characteristics/performance).

So in short: If you can find the faulty battery and only get hold of one other - exchange it. If you can get a matched set of (used or new) batteries - exchange both.

Then comes the tricky part: Assume that you did not notice any eye-lifting difference between the voltages of either battery during charging. Then you can charge the batteries to known-full status and load them with for example a resistor or a small incadescent lamp. The capacity of the battery is perhaps printed on the battery packs, but if not you can calculate by yourself if having the estimated known-good running time of the reader.

The unit for battery capacity is mAh or Ah (milli Ampere Hours or Ampere Hours). You can then easily calculate what current is drawn from each of the batteries. So then charge them fully and load them with a resistor or an incadecent bulb (a regular small glow lamp that you can find in old-fashioned torches (flashligths).

Load the batteries one at a time with a current which is ~5 times the normal current for some time (perhaps 5, maybe 20 or 40 mins). The time as such is not important as long as you load each battery individually and with the same load and during the same time. Measure the voltage over the batteries during loading (you should have disconnected the charging before all this is done).

If you monitor the voltage drop with time for the two batteries it will be evident for you which is the bad one. If you load them individually and can't notice any striking differences then it may be the case that both your batteries are bad, and not only bad but that they still are matched while loosing most of their capacity. In that case there only exist one solution: exchange both of the batteries to a matched (used or new) set.

There may also exist the possibility of that the charging electronics of one of the batteries is malfunctioning (if the case is that each battery has its own charging regulator). If suspecting this, then just exchange your old batteries against each other and it will be evident if it is the charging circuit or the battery itself which is the culprit.

Often the charging electronics is built-in within the battery pack and then you have to think of the battery + charge regulator as one unit. The voltage figures given in the refered posting are in a rather wide span. My experience is that in reality these spans are not that large. Only if the battery is very bad or about fully non-functional.

So to start with: open your reader. Check the voltages and write all down. Charge the batteries and discharge them and note your observations. If it will not be obvious to you wherein the error is you can always write your findings in a posting on this site and there sure are people around here who knows a lot more about LiIon batteries than me who can give you even better advises regarding what is considered normal or not regarding this type of batteries.

By the way: if you can't get a suitable resistor or a bulb as loading for each battery, then connect only one of the batteries and if they are parallell connected you can startup the reader using only one battery pack. You can then set up your reader so that it consumes power in a controlled way and just notice how long it works on each of the batteries. In case the battery packs are serially connected this "poor mans method" of testing will not work though.

/Pimmis