Car has 3/4 tank of gas in it and as you drive you here a chime and look at the dash and it says "low fuel". Started doing this last week and then the battery died. I put a new battery in and it actually stopped doing it for a few days and now its doing it again. After the low fuel display comes on it goes back to normal and then does it again minutes later then back to normal, and so forth. Any idea what the problem is? Thanks.

Clean the battery cables. If you find any corrsion under the insulation, replace it.