[NTLK] Components needed to rebuild eMate300 batteries

[Andrei Chichak]

Good evening all,

I took a look at the instructions to rebuild the emate battery pack that is on www.pda-soft.de and it has a lovely picture of the current limiting component.

That component is known as a PolySwitch, originally made by Raychem. They act like a resettable fuse. If you put too much power through them, they heat up and massively restrict the power. Disconnect them and they cool off, becoming a conductor again.
There are a bunch of polyswitches, depending on the voltage and current being used, temperature, now long they take to work, etc. So which one did Apple use?

The trick is that there is a marking in the picture, “L19”. This is the important bit.

https://datasheet.octopart.com/BBR550-Tyco-Electronics-datasheet-23326.pdf

Says that L19 is printed on Raychem part number LTP190, which is obsolete and no longer produced.

Raychem PolySwitch got bought by Littelfuse, who produce a line called - PolySwitch  - (so far, so good). But Digikey, an electronic component supply house in Minnesota says that the LTP190 is a “Polymeric PTC Resettable Fuse 24V 1.9 A”, obsolete.

Digikey also says that the substitute part is a Bourns MF-LS190.

Arrow, another electronic component supply company that also sponsors McLaren F1 (thank you Arrow), says that they have 1650 pieces of MF-LS190 in stock, for $0.0838 each, but I really doubt that. The normal price is about $0.84.

Enough for now.

Happy rebuilding,

Andrei in the Great White North