commercial solar sipper .
this bowl will keep the water warm in winter but it is not for large dogs.
this bowl was made for small dogs and medium size dogs, i bought it for my german shepherd about 4 months ago and it keeps the water cool even in cold weather without electricity .
since there are no battery-operated water bowls than the commercial solar sipper is really your only option.
the commercial solar sipper is not perfect but i would highly advise you to give it a try and see if it works for you, good luck.
no company makes a battery operated water bowl, right now you can try the commercial solar 