starter battery also used for occasional house needs?

[calden]

Greetings: Question about battery needs...


I have a Neptune 24' that is used for daysailing. I have an older Yamaha 4-stroke outboard that uses electric start.


Right now I have a West Marine Dual Purpose grp 24 battery, MCA 675. I use it almost exclusively for starting the engine. I will be putting in a bilge pump, and possibly a depth finder. I rarely if ever use nav lights or cabin lights or other accessories.


It's been three years now that I've had this setup and the battery is reading something like 13.6 v after not being used for a couple of weeks. THis is lower than it used to be. I would like a battery to last and be there for starting, and that's about it.



Would I be better off with a starter battery (for life span of battery) seeing as how that's what I almost exclusively use it for? Also, Starting batteries are a lot cheaper.



Also, I have a 5 or 10 watt solar panel that (hopefully) keeps the battery topped up. Also the engine charges the battery when running, but this being sailing, that's not a lot of charge time.


Any thoughts? Thanks in advance,


calden

[ltd]

13.6V actually seems a little high. A little degradation can be expected over time, even if you meant 12.6V that's not unexpected. You're probably fine to keep the same setup for a while. The main thing with outboard charging and small solar panel charging, is those are both situations in which a flooded cell battery works best (because there isn't "smart" regulation of the charging sources). Best you can do is top off the battery with distilled water every once in a while.
But yes, a start battery would do just fine for your purposes.

[HankOnthewater]

I agree with above resting voltage of a lead acid battery (and AGM is a lead acid type of battery as well), is around 12.6 to 12.8 Volt. Maybe you read 13.6 Volt due to the connected solarpanel?

For your purpose, one battery should be plenty and no need to go for complex and therefore expensive solutions. Just be mindful that the connected accessories can drain your single battery. Can you hand/pull start the outboard?
But really, a bilgepump should be rarely operating, a few lights use only a little if they are LED, same with navigation lights. Even a depth sounder does not use much.

Now to your question to buy a starting battery vs a dual purpose one. A genuine starter battery does not like it when drained or drained flat, particularly for the latter, it shortens its liefespan dramatically. Therefore a dual-purpose battery would be better..... but often the labelling does not reflect how batteries are made, it seems often a marketing affair
Try to find a knowledgeable retailer, or stick to very well known reputable brands. But those brands generally are more expensive.

[OldManMirage]

It doesn't hurt a deep cycle battery to use it as a starter battery, especially in your case since your just starting a small outboard. If you had a big 4 cylinder diesel maybe you might need the extra cranking amps of a starter battery.

You mention the starter battery are cheaper, and that's because there is less material in them. The deep cycle battery will start your outboard and give you long term power for things like your depth finder and other accessories.

The alternator will charge it when running of course, but you probably don't run it for long so the small solar panel is good idea to keep it topped up. Make sure you keep up with checking the fluid level in the battery.