Outboard Battery size

[mxtommy]

Hi!

I recently bought an older Honda 15HP four stroke outboard motor for our dinghy to replace an a smaller 6hp.

One of the features of the 15HP is electric start, which would be awesome to take advantage of. I currently have no battery or electrical system aboard the dinghy though.

Reading the manual, they mention to use a battery with a 40AH rating (no CCA given) as minimum. Looking at batteries it seems to me maybe this is a bit overkill? 40Ah you're starting to get at the bigger (and heavier/more expensive) batteries.

I was wondering if a motorcycle type battery would do? Something like 12Ah 200CCA? I mean they start up large motorcycle engines, surely they'd work with a small 15HP?

Thanks!
Thomas

[john61ct]

Those little lithium "jumpstarter powerpacks" now come powerful enough to crank big diesel engines.

Can recharge off 12V or mains plug overnight.

[Colin A]

Small power sport/motorcycle batteries should work fine. Not sure exactly why but the ones marketed to lawn mowers with the same specs on the powersports batteries tend to be cheaper.

[a64pilot]

I’d look hard at a SLAB or sealed lead acid battery, sort of like the ones used in exit signs etc, no vent caps and you can’t spill acid etc.
Not sure if they are AGM or Gel?

[Lrak]

Is there a voltage regulator on the charging circuit of the motor? If not, the battery size could be so you don't cook the battery charging it rather than cranking power needed to start it.

[a64pilot]

At least the older outboards that I have experience with had very similar charging systems like older motorcycles. That is rectifiers.
Basically they made all the power they could and wasted the excess as heat, reason rectifiers are finned. It’s not much power either, they sort of trickle charge the battery. Of course they didn’t cook motorcycle batteries.
I’d assume even newer small outboards are similar? I know the bigger ones have automotive type alternators, but doubt the little ones do.

[ranger58sb]

Originally Posted by mxtommy

Hi!

I recently bought an older Honda 15HP four stroke outboard motor for our dinghy to replace an a smaller 6hp.

One of the features of the 15HP is electric start, which would be awesome to take advantage of. I currently have no battery or electrical system aboard the dinghy though.

Reading the manual, they mention to use a battery with a 40AH rating (no CCA given) as minimum. Looking at batteries it seems to me maybe this is a bit overkill? 40Ah you're starting to get at the bigger (and heavier/more expensive) batteries.

I was wondering if a motorcycle type battery would do? Something like 12Ah 200CCA? I mean they start up large motorcycle engines, surely they'd work with a small 15HP?

Seems odd your manual would specify an amp-hour rating but not CCA/MCA.

Our dinghy battery for a 15-hp Suzuki 4-stroke is a small Deka "Outdoorsman" model , in one of the U1 categories.

Like from here: http://www.eastpennmanufacturing.com...Flyer-0008.pdf

Probably ours is the 11U1L, 350 CCA... since our outboard wants a minimum of 330 CCA (or 450 MCA, or 70 RC) per the Suzuki manual.

I would eventually look to see if there's an Odyssey AGM equivalent (size and cranking specs) just to reduce issues with self-disharge... since we don't run our outboard very often... but haven't gotten to that point yet...

-Chris

[MV Wanderlust]

We have a 15 hp Mercury with electric start. The dinghy came with a motorcycle battery in it and has been working fine. If it ever wears out, we'll probably replace it with the same.

[flyingfin]

Or simply get a lawn tractor battery, usually under forty bucks, motorcycle batteries are more expensive