I use a digital onboard charger......you need one with at least 10 amps per bank.....i have used several ....the minnkota is what i have now and yes my batterys do last longer....all three are 6 years old now. I plug my boat in and do not un plug it untill i go fishing....when i get back i plug it up as soon as i park the boat. I check water in batteries once a year.