Help with electric problem

Hello
I’m hoping someone can point me in the right direction regarding diagnosing a problem. I just bought a 2008 WR250R with 6k miles. My first long ride (150 miles) bike ran great but then engine light came on. I stopped for gas and when I tried to start bike battery was dead. I suspected battery was old so I installed new battery. Bike ran great for a few short rides but today I took it for about 150 miles and same thing happened. Engine light came on and when I stopped for gas, battery was dead. I got somebody to give me a jump and bike ran great for about 50 miles but as soon as I turned it off, battery was dead again.
I got another jump and managed to get bike home and hooked up volt meter. Battery registered 11.5 with bike turned off. When I started bike and increased RPMs volts did not increase. I don’t know much about electrical systems but it seems to me that battery is not charging. Can anybody tell me where to start to find problem?
Thanks. Lou

Check with the previous owner whether the stator recall was done; if not, arrange to have it done by a Yamaha dealer.

If you got a CEL, there should be a Fault Code posted; find out what that is and report back.

From what you describe, it's probably a regulator/rectifier issue; go to page 8-76 of the service manual and follow the instructions for checking the stator and the regulator/rectifier.

Will do. Didn’t know there was a recall. Thanks!

P.O. Didn’t know ( he was second owner). I called Yamaha USA and gave them VIN and they were able to tell me that the recall had been done when bike had 4K miles. I’m going to go through diagnostics this weekend. I’ll keep you posted. Thanks.