Draining battery with heated grips

[Fifteen15]

I fitted some heated grips to the SV a few weeks ago but now everytime I leave my bike running and heated grips on I always think the battery will run flat. The grips use up to 4 amps, so how long would it take to drain an SV battery?

Thanks :)

Edit:

How long would they take to drain the battery if just the ignition was on?

[SV Mad]

If you're riding the battery is charging. Regardless of the grips being on the battery should be fine surely?

[SVMAT]

just dont leave them on with engine off. bumping the sv for the first time is a right kunt so i got em wired into ignition with relay. As for drain on battery it depends on how good nick your battery is in and how well its being charged. I always made sure i turned the heated grips off a couple mins before end of ride. HTH