Lenovo S340 wont run off battery after RAM upgrade

[AJ847.63e]

Hi All,

Bit of a strange one. I upgraded the RAM in my laptop yesterday. Removed the battery before removing/installing the new RAM. Reinstalled the battery booted the machine up on battery only and ran a few tests everything seemed fine. All the new installed ram was detected and available to Windows. Windows said it was on 64% battery so I left it for a few minutes on idle to see how quick the battery would drain. Roughly 4 minutes into that the machine shut off and now it refuses to turn on unless I have the charger connected. With the charger the battery is recognized and is now charged to 100% but as soon as you disconnect the battery it shuts off.

Apart from a bad battery, which seems a bit too coincidental because it's been fine up until now, what else could be causing this? I've had a look through the schematic on this forum and haven't been able to see any battery fuse or something that could of been blown while reconnecting the battery. Not to mention that seems implausible since it was working first time boot after installing the new RAM. I haven't been able to find the board view for it so finding where the battery connects and tracing it back to the charge circuit hasn't been possible.

Thanks for your assistance!

[mon2]

Re: Lenovo S340 wont run off battery after RAM upgrade

Is this the board view for your board?

https://www.badcaps.net/forum/showth...light=LA-H131P

Near your battery connector should be the battery mosfet. This mosfet enables to power the logic board if the external power adapter is absent.

Locate the mosfet. Check the voltage to ground of each pin on the mosfet with the battery only connected.

[AJ847.63e]

Re: Lenovo S340 wont run off battery after RAM upgrade

Thanks for that. That's the post where I got the schematic from there's only that in the zip folder no boardview, unless I'm missing something?

Extremely weird. I closed up the chassis today to put it away while I wait for the new battery to arrive and now it's working fine. Charging fine. Disconnecting the charger it stays on, you reboot it without the charger its fine. You shut it down and turn it on without the charger everything seems fine. Very weird. Thanks for the help it's working now so I'm going to see how it goes, hopefully it was just some gremlins it had to get out...