This one is for Sim and anyone else who wants to prevent heated grips accidentally being left on. I purchased an automotive relay. You can get them at any car shop or Maplins etc for around a fiver or less.
Place under the seat/near the battery. Connect:
87 to the + terminal on the battery
86 to the – terminal on the battery
30 to the live on the heated grips
85 to an ignition switched live (eg. horn, brake light switch, number plate light etc)
When you turn off the ignition the circuit is broken and the grips go off even if they are still in the on position! This is the professional method of installing grips. I have not done it on the VL because I don’t ride far in the cold weather. However I installed mine on the DL and it works fine – the method is the same on any bike. Wiring/routing the wires might be a bit fiddly but well worth the effort for peace of mind. The heavy current comes direct from the battery and the relay live is just to switch the circuit on and off. If you have grips wired directly to the battery already, you can still insert this cheap mod any time. If you have other appliances ( GPS, heated gloves etc) you can wire these into the same relay using a simple distribution block.