lazy wipers, faint horn ect

My indicators freeze if I trun on somehthing else like heater fan. They go faster and slower. The horn makes the faintest of noises, the wipers work just. If I put more than 1 thing on everthing stops?!
Would a new alternator help or is this a wiring fault?
cheers
CC

Is the Battery Flat? Check with a volt meter should be around 13.5v

Check the earth strap (off the battery) to the bodywork etc… Unscrew, clean and re-connect then let me know if it makes any difference.

Hi, I agree with madferret, My campaign would stall when I put the wipers on and refuse to run again, not good when in the outside lane of the M25.
I managed to fix the fault an improve the speed of my wipers by running a seperate earth from the wipers and replacing the earth connection at the battery.
Alex

the battery is OK.
It does run down after a week or so.
I'll check strap and clean.
cheers

I cleaned the earth strap and battery terminals but no change really.
I'll try a separate earth