Seeing I use my start battery to power my graphs. I am thinking of replacing my start battery with a 29 series big ole deep cycle battery. What's your thoughts?

Failed to mention I am running a 225 EFI Merc.

I'm only running a 40 Yamaha. I use a 24 series starting battery and only run one graph, live well pump, bilg pump and running lights on it. The date on the battery is 03/10 and haven't had any power problems. About time to replace it though. Curious to see what others have to say about your battery question.

My thoughts are that the alternator on your Merc is enough to handle your power needs from just any good cranking battery and don't think I'd go to any extra expense than needed for a decent cranking battery.
WalMart now has a two year warranty NOT prorated and for a little more money you can get a 3 year. With any maintenance at all the battery should outlive the warranty and over time I think it's a cheaper alternative.

1000 cranking amps. you need alot of power on your start battery, because your sonar is going straight to that battery. if the volts drop too much, you sonar will shut off. Also most bilge pumps go to the cranking battery, so if youve got a leaker, the battery will drag down.
Marine charging systems were never designed to be a power plant to charge batteries. They were designed to replenish into the battery abt the same amount it was taking out,. Thse new outboards with fuel injection, computer, ect, use alot of juice. They have better cherging systems, but still use most of the power they produce. When it comes to cranking battery go big, or go home.,

225 is around 3 liters of motor your starting, and with outboards, you are also spinning the driveshaft, all the time, so that takes alot of juice, more than most cars nowdays. also theres a difference in deep cycle trolling batterys and starting batteries. wallmart make a good combo troll/start battery.,

A few years ago Yamaha found out that the battery they originally installed for the HPDI was not large enough and reommended a 29 series. the cause was something to do with oxygen monitoring that required power when the motor was not running. I check the manufacturer remendation then go up one size and keep my charger on the battery 24/7 when not in the water. my 2cents

I CHANGED TO OptiMA-Red tops...and forget whatever questions/problems I USED to have....

I got 7 years out of the AC Delco Marine that came in my boat. When it did go bad, I decided to try a Wal Mart battery just to see what kind of service I'd get. So far, so good.

Pepop;
I ,m with you. i ran the deco voyager maintenance free batteries for many many years , until they quit making them. I have tried several brands since. the latest is a Walmart marine battery, but have not had it long enough to know if it is the one i want.

I run the walmart ever start deep cycles group 29 one for cranking and two on the trolling motor, my buddy told me to get these because if you think about it when you are on a fishing trip out of town and you have a battery problem theres a walmart close by and so far i have not had a problem out of them and I'm on my second set, my first set lasted almost three years and i think thats pretty good when you fish all the time.

Bite the bullet and get an Optima. Add a good charger with a constant monitoring system, and you'll never have to worry or wonder again!