Turns on the instrument panel lights, cuts off the radio?

Hello I have a '98 Accord V6 with 127k miles - sometimes while I'm driving the electrical system does a pause and turns on the instrument panel lights, cuts off the radio and heat for about a second and then comes back on. My father checked and filled my battery with water over a week ago and it stopped for a few days but did the same thing again today. What should I check to correct this? Thank you.