I have a latitude C800 and use it with 2 batteries. Recently it refused to boot up at all, so I removed the batteries and dismantled the machine, suspecting a mis-seated internal connector. The problem turned out to be that the HDD was not properlly pushed 'home'. The laptop appeared to work fine after re-assembly, but when I next came to use it from batteries, I found that they were virtually fully discharged, despite having been on charge for a long time. Up to the time of the crash the batteries were holding charge well, despite being a couple of years old.

I have tried many things to try to cure the problem, including re-installing the OS (WinXPpro) and replacing the battery charger board within the laptop....The bios is fully up to date (vers A21) and I have reset all Bios settings to default values. Dell diagnostics reports no faults. I am not sure whether the problem lies with the laptop or with the 'smart' batteries....I have read that they can get completely confused if the data held in them becomes corrupted....is there any way to 're-set' them?

I am about out of ideas of how to fix this.....does anyone have any suggestions?