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Gators
06-27-2020, 05:49 PM
Time to replace the marine starting battery for my 50hp four stroke mercury outboard on my boat. Anyone have any experience using a deep cycle battery rather than a starting battery to start their outboard? Any issues using a deep cycle battery?

Johnny G1
06-27-2020, 05:52 PM
I use a Blue Top for my boat, Expensive but don't get beat up in a boat.

-JR-
06-27-2020, 06:30 PM
I got a deep cycle starting battery for mine. Does that help.
My last one I had lasted 24 years

EZM
06-27-2020, 06:43 PM
A deep cycle battery is different compared to a starting battery - two totally different purposes.

A deep cycle will deliver a steady power supply to your sonar, radio, electric trolling motor and is designed to be drawn down and recharged repeatedly. They will crank a battery over, but if your motor is hard to start or you need to crank it a few times and hold it OR expect a big push of power to start your motor it's not ideal.

A cranking battery is the opposite. It does not like to be discharged regularly, and will deliver alot of juice when cranking your engine. Ideal in that applicaion. You can run your sonar, radio and electric trolling motor on it but the life of the battery won't be very long for it, and it typically does not "hold as much juice" as a deep cycle - so it won't last as long.

There are combination batteries - which, if you only have one battery on board - then that's the one you want to have - does both duties relatively well ans splits the difference on performance.

If you are just cranking your engine and maybe running a low draw item like a sonar on it AND already have deep cycles for your trolling battery, get a cranking battery for your cranking battery.

Hope that helps.

I have had excellent results, reliability and longevity with Interstate batteries. Don't buy into the BS about all batteries that are rated equally should be equal in performance - because they are simply not the same.

There are also different types of batteries in terms of "what's inside" like AGM, Lead Acid, etc... each has it's advantages and disadvantages.

Gators
06-27-2020, 08:28 PM
Thanks for the replies. The boat has 2 separate batteries. EZM a month ago replaced my original Costco gr 27 deep cycle trolling motor battery on the boat with a gr31 Interstate deep cycle battery. Funny thing I did notice when I used the deep cycle trolling motor battery to boost my starting battery the outboard did seem to turn over slightly slower than usual but it did get the engine running. Sounds like a dual purpose battery would be a good choice the starting battery also runs my fish finder, radio and GPS. Thanks for the help