These are rated at 75A (each), so they should be fine switching a pack like this. On one end, a pair of IRF1404Z MOSFETs handles switching duty for the pack. I’d be surprised if the fusing current was consistent within 50% across a bunch of packs, but it should blow if the whole pack shorts, and that’s the goal. It’s a perfectly good “Aw, this has all gone very wrong…” sort of failsafe. The thin strips on the edge will melt if the current gets too high. Look at the weird little circle in the nickel strip on the lower right - that’s a basic fuse. Like most modern tool packs, it’s a 5S lithium battery built out of 18650 cells. With a bit more fiddling (pull the side latch buttons out first), the whole pack comes clear of the base. The pack comes apart easily enough (with some broken screw tabs on one end), and… yup! There’s a complex battery management system in there! If someone is going to have the proper sized small Torx bits to open the pack, the “security bits” don’t really add much of a hurdle. This pack uses some T10 security bits (they have a little pin in the center). I do not understand why companies bother with security Torx bits on tool batteries. If you want to replace a NiCd pack with lithium, you need something to manage the pack, because the tool won’t do it (draining a NiCd pack all the way down is fine, but doing the same to lithium damages the cells - you need a low voltage cutout far above 0V for a lithium pack, and you have to balance the cells during charging). Given that this looks like the pinout for a pre-lithium pack (there aren’t enough pins for the charger to see the per-cell voltage), there’s almost certainly a BMS down in there. Either the pack is dead, or there’s a BMS shutting things down until it receives the proper initialization signal. Probing around the pins with a voltmeter doesn’t give me anything more than a few dozen mV, so there’s no obvious voltage on them. Presumably, one is positive, one is negative, one is related to temperature in some way, and… I have no idea what the other is. On the top of the pack, there are 4 pins. If we use a more reasonable 18.5V rating, that’s 1297mAh per cell (call it 1300). If we use the nameplate 19.2V, 24Wh is 1250mAh per cell. The DeWalt 6.0Ah pack claims 120Wh (I’d rate it a bit less, but then I’ll probably disagree with this pack rating as well). We can see a rated capacity of 24Wh, which isn’t very impressive. Right… it’s in my shop as a battery pack, it’s getting opened. The bottom contains the usual warnings I’m about to partially ignore. That’s a 16S NiCd voltage rating - for a 5S lithium battery, you might call it 18.5V (3.7V * 5), you might call it 21V (4.2V * 5), or… you might call it whatever you want, because marketing decides what to use, and battery powered tools are incredibly tolerant of a wide range of input voltages. In any case, we’ve got a “19.2V” battery. They used to have the perk of “If you break a simple tool or socket, take it to Sears and they’ll replace it,” but where’s your closest Sears? Can you answer that without pulling up a map application and checking? I didn’t think so. I can’t say I’m a huge fan of Craftsman anymore. The “stalk” style connection and the larger base are common with the NiCd packs. This battery looks to me like a lithium replacement for the old NiCd batteries common in the early battery powered tools. You can find the OEM packs for about $40 on eBay, with various aftermarket clones for a bit less (including some with a nice capacity bump - buy the 4.0Ah packs if you need one of these and don’t mind some extra weight). Craftsman 19.2V DieHard 315.PP2011 Lithium-Ion Battery It’s always interesting to see how different companies approach much the same problem. If you’re bored of tool battery teardowns, you could always send me more interesting things to mess with! I enjoy poking around tool batteries, and a lot of the ones I pull apart are “new to the internet” in that they haven’t had a detailed teardown before. They’re both lithium, and I’m going to dig into both of them, because that’s what I do with old batteries I pick up out of junk bins. It’s time for more tool battery teardowns! This week, I’ve got a Craftsman 19.2V DieHard battery, and a cute little Ridgid 12V battery.
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