Cameron Sino replacement batteries don't work in SL-5500?!

[ceratophyllum]

Is there something strange about the original SL-5500 battery?
I bought two replacement batteries that are supposed to be for the SL-5500 and it acts like it has no battery in it when I insert them: the battery LED just flashes forever and the battery does not charge.
I checked them with a mutimeter and they both have about 4.0V across + and - so they're not dead.I notice the voltage across the middle terminal and + is a little less? What's the middle terminal do anyway? I assume it is connected to some temperature sensor...

I booted the Zaurus into the service menu to check battery voltage and it looks like there is no battery inserted.  If I force it to try to charge the battery in the "Charge" menu, the yellow LED comes on but the battery does not charge: after leaving it in there for a few hours, I checked the battery with the meter and it still reads about 4V and it is not even slightly warm.

If I put the original Sharp-branded battery in, it is detected and charges normally. Before I send back both of these for a refund, am I doing something wrong? Is there some kind of voodoo battery detection going on involving that middle terminal? i.e. Sharp trying to prevent third party batteries from working, so they could rip people off with outrageously overpriced batteries? (I've heard of such shenanigans from Lenovo with their expensive thinkpad batteries....)

[Varti]

This might be a problem with bad battery contacts, try to follow the instructions on this thread (from post #9 onwards): https://www.oesf.org/forum/index.php?showto...=24784&st=0

Some years ago I bought a couple of Cameron Sino batteries too, and one of them had exactly the same symptoms as yours, though I never tried to fix this problem since at the end one battery was enough for me. Another possible reason is that the battery has been manufactured many years ago and might have weared out in the meanwhile... did you buy them directly from the manufacturer? Someone on #zaurus has commented a couple of months ago that he has also bought a battery from CS and that he had no issue with it, maybe they are produced on-demand to avoid aging issues.

Also, this might not be related, but the 5500 (and the 6000 too) have a secondary, backup battery which might also require to be changed. AFAIK this battery is only used for software resets: https://www.oesf.org/forum/index.php?showtopic=11337 (see post #13).

Varti

[ceratophyllum]

This might be a problem with bad battery contacts, try to follow the instructions on this thread (from post #9 onwards): https://www.oesf.org/forum/index.php?showto...=24784&st=0
...

That was it: the plastic surrounding the 3 contacts is off center so that the + and - terminals were touching plastic instead of the metal contact area. Fortunately, the metal contacts extend a few mm under the plastic so you can easily nip off the plastic that is in the way. Flush cutters work well for this.

 I never would have noticed this: you can just barely see how they miss if you take a bright flashlight and shine it in there with the battery about 1 mm away from the contacts.
Thanks Varti!!

[Varti]

Glad to have been of help. CS' quality control have always been lacking, luckily these issues can be easily fixed.
I'm curious to hear for how long do these batteries hold the charge, I'm planning to buy some new ones from them in the future for my Zauruses.

Varti