Wasted $85 on a battery analyzer that fried my old ThinkPad

Picked up a cheap battery analyzer off an auction site to revive a T430 that still runs great otherwise, and it ended up shorting the charging circuit within 20 minutes. The seller's listing said it worked with any 20V laptop, but there was no voltage regulation and it spiked my old pack right into the board. Has anyone else had a supposedly universal gadget kill a machine, and what do you actually use to safely test aging batteries without risking the laptop?

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lisa_murray21d agoTop Commenter

Did the listing mention anything about the battery having to be disconnected from the laptop first? I've seen a lot of those cheap testers rely on the pack's own protection circuit, and if it's old or faulty, it can send weird spikes back up the line. In my experience, the real safe way is to check voltage at the pack's connector with a basic multimeter before you even plug anything in, and then charge the battery outside the laptop if you really want to test capacity. Those universal gadgets are usually fine for RC hobby batteries, but laptops have a lot more going on, so your mileage may vary. Also, a T430 is worth more than $85 to me, so I'd probably just grab a genuine Lenovo charger and use the built-in battery report to watch health over time.