I have had 2 heated jackets, dual heated seat and heated grips on my two ST1300s No problem. Original battery on my A9 after 7 years and 50k+ miles is fine.
Having the Honda heated grips helps - they cut themselves off when the charge isn't keeping up with the demand. No good for the other heated gear - but the grips flash a warning, which is a good invite to turn other things off until the revs pick up again.
My heated sleeveless jacket draws around 4 amps. It just maintains a warm temperature without getting over hot. I wear it next to a thin shirt, underneath a fleece. I did have a sleeved jacket, but could never feel the heat on my arms - arms are in the draught off the screen and the jacket sleevs do not fit as closely as the body. The heat just blows away! Keeping the body warm was enough for me. If that is warm, My arms do not feel cold.
