Battery How Big Can I go? Can my 115HP Charge a 200Ah Battery?

[Hypalon]

I have a Suzuki DF115B on my 18' RIB, and for electronics I have Garmin UHD 72sv, Suzuki SMG4 Gauge and Icom VHF-
I want to get a battery that I know I can use my electronics all day, and know the engine will always start.
I purchased, but haven’t installed yet an AGM 105Ah dual purpose battery.
I was thinking about changing my group 32 102Ah AGM for a massive 8D 225Ah battery, but then have concerns the charging system on the Suzuki won’t properly charge such a massive battery.
Question is, I’m I being neurotic in thinking I need such a large battery, or will the AGM 105Ah power the few electronics I have and have enough charge to start my 115HP outboard after a long day on the water.

[Pikey Dave]

A 2 battery setup with house & starter with appropriate switches & split charger would be better ,& give you redundancy. The engine will charge any battery given time. Regardless of the battery capacity, the engine only has to replace the charge used, so assuming that the battery(s) are charged to start with, the engine only has to replace the relatively small amount of charge used by the electronics.

[Hypalon]

After chatting with some people I decided the best route is to add another 105Ah and add a BLUE SEA SYSTEMS has an "Add-A-Battery" Dual Circuit System and simply run two batteries, rather than 1 large battery.

[Hypalon]

Thank you- I decided on the 2 battery set up, you and other people have said that. There's a product made by BLUE SEA SYSTEMS called "Add-A-Battery" Dual Circuit System. I just purchased it and tomorrow I'll purchase another 105Ah battery and then run them both. Thanks for the help.

[Pikey Dave]

I’ve used the Add A Battery kit before. Good bit of kit

[paintman]

Originally Posted by Pikey Dave

Regardless of the battery capacity, the engine only has to replace the charge used, so assuming that the battery(s) are charged to start with, the engine only has to replace the relatively small amount of charge used by the electronics.

^^^^That.

Charging devices on cars, boats etc are only really designed to do that & run the vehicle electrics whilst the engine is running.
Alternators aren't designed to charge flat or deeply discharged batteries & you won't do them any good if you keep doing so. Not just my opinion.
http://www.optimabatteries.com/exper...dead-batteries Ignore the redtop/yellowtop etc advertising blurb.