Time for a quick teardown as I haven't done one for a while.
I noticed that my local Lidl UK store had packs of spare 20V 2AH power tool Lithium batteries, complete with chargers for £17.99. This is a bit unusual as normally the charger comes with the tool and you can only buy the spare battery packs.
I didn't give too much thought to whether I could do any better from ebay, Amazon etc. but this looked like a good opportunity to get a portable supply for my TS100 Iron and maybe a few other things. Also they're of known quality, TUV/GS etc. There is a 3 years warranty on the charger and 6 months on the battery (reasonable I suppose given the potential for abuse). At least the rated capacity of the 16550 18650 cells looks plausible for their size and not inflated like many you see.
The charger is a 65W 1 hour fast charger with 2.4A output capability.
Everything is easy to disassemble, with Hex socket head screws. The little three level battery gauge PCB (see photo) is clipped to the top molding, but everything else, including the connector, remains with the base. The contacts are +Ve, -Ve and Thermistor (seen in the underside shot). There is a fourth contact on the battery pack but it appears unused, the charger only brings out the 3 pins.
As can be seen from the battery pack PCB, it includes cell balancing and charge protection. There is also a chunky sheet metal fuse (F1). I don't know if this might be used as an overload current shunt too, probably not. As previously mentioned, there is a thermistor glued to one of the cells on the underside.
Initially I was intending to fabricate a connector to slide into the normal housing slots and contacts but, having opened it up, it looks like there is plenty of space for me to add a small DC connector (and additional lower current fuse!) which will make connection a lot easier. F1 looks rated for very high motor current.
I also opened up the charger, again four socket head screws and one screw holding the centre of the PCB down. It looks to be of decent quality, with good layout and proper safety approvals on critical components, including the fuse. The underside view shows very generous PCB safety clearances, both on the primary side and primary - secondary. The only minor criticism is that the mains lead inner wire insulation could possibly catch on the underside of the PCB, if not routed correctly. There's no danger of secondary side contact anyway. I won't be doing any further inside, this was purely a safety check.
I hope this will be of use to somebody. Of course, you need to be very careful when playing with Lithium battery packs and modifying it in any way will violate the terms of use. You have been warned!
Photos attached...
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