GreasyFingers

I have a friend with a 1996 Odyssey with 365 k miles, that is loosing battery charge. Primary symptoms are that car is jump-started, driven for an inconsistent period, transmission unexpectedly rough up shifts at approximately 40 mph, likely signalling that battery has been loosing charge, and car will then run rough and will need a jump start to drive again. She indicates her mechanic has been unable to isolate the problem. Possibly related, car has had a history of horn working properly only in cold weather. Please be patient with my replies, as I will often have delays in talking with her. Please help.