Do you have a question about replacing your laptop's battery?
Do you have a question about replacing your laptop's battery?
I am trying to fix an old Dell C400 laptop (from 2002) that has 6 prismatic 3.7v batteries, making up about 12v when they are full. I took out the old ones and measured them at 9.4v right after, without a battery management system (BMS). The whole thing was dead and wouldn't charge at all. There is a button on the back of the pack that lights up five LEDs when you press it to show how much power there is. Before, the old battery had zero LEDs lit. I put in new batteries using the same kind as the original ones. When I press the button now, some lights are blinking, but they don't light up one after another like a normal sequence since all six cells were at 4.02v when I inserted them—so they should be full. Putting this whole battery pack into my laptop gives it no charge. Even when I plug in the charging cable, the charger light on the laptop turns green first, then after about 15 seconds goes to a blinking amber light, which probably means something is wrong. It's possible that the BMS isn't working correctly, but could you give me any other ideas why it won't work and what I can try? Would it be possible to swipe a BMS from a different battery and connect my cells to it? The battery connector looks like a similar or even identical one could be found.
There are lots of battery packs with special connections that cut off power if something goes wrong like being opened. That safety feature is better than just stopping the theft. I never tried fixing this myself and thought it wasn't really worth my time, but you should look into it because there might be a way to reset it or you'll have to get a new one.