Battery for 17-foot Boat with Older 90-HP engine

Electrical and electronic topics for small boats
MOCON4TN
Posts: 4
Joined: Sun Aug 05, 2018 7:46 pm
Location: Middle Tennessee

Battery for 17-foot Boat with Older 90-HP engine

Postby MOCON4TN » Sun Aug 05, 2018 10:54 pm

I read the thread, The Ultimate Battery Charger, with interest. It's a bit beyond my current understanding. Please forgive my ignorance and I think this may be the best resource for me.

I have a 1998 Montauk 17. I added a second battery and Perko selector. The batteries are lead acid. I checked my Mercury (original 90 hp) owners manual and there is no battery specification. I admit I've been buying Walmart batteries because they are inexpensive but don't last. Thinking "good/better/best" If i want to upgrade my batteries what is a "better" selection (brand /specs)?

Also, I would like to maintain these batteries while the boat is stored in my garage. I looked at the Blue Sea Systems BatteryLink charger mentioned in the other discussion. Is that excessive for my application?

Again, looking for a recommendation.

Thank you
1989 Montauk 17
Old Hickory Lake, TN

jimh
Posts: 5103
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: The Ultimate Battery Charger

Postby jimh » Mon Aug 06, 2018 7:23 am

MOCO’—I have separated your request for advice on a recommendation for a specific battery for your 17-foot outboard engine boat into a new thread thread.

For your application, the most suitable battery will depend on the nature of the outboard engine battery charging circuitry.

Older outboard engines may not have carefully regulated output voltage from their battery charging circuit. If the outboard engine supplies too much voltage, batteries with sealed cases may become over-charged and may vent out electrolyte, which cannot be replaced. For that application a flooded-cell vented lead-acid battery is best. The problem of over-charging remains, but the electrolyte can at least be periodically replaced.

If the outboard engine is more modern and provides a well-regulated charging voltage, typically limited to around 14.4-VDC, then a lead-acid battery with a sealed case can be used.

Another important consideration is the required cranking current for the outboard engine. The engine manufacturer should specify the recommended minimum marine cranking ampere (MCA) rating for the engine’s cranking battery.

For a 90-HP outboard engine I am guessing the minimum MCA rating would be about 750-MCA.

The simplest arrangement will be to get two batteries of the same type and capacity.

If the charging voltage allows, you can use a battery with a sealed case. Today this would typically be an starved-electrolyte absorbed-glass-mat or AGM battery.

For a 120-VAC shore power battery charger, I suggest a modest 4 or 5-Ampere dual-bank charger from ProMariner. Install the charger permanently in the boat and connected to the two batteries. I use a charger like this, and I find it to be very handy. I plug the charger into 120-VAC via an extension cord while the boat is in the driveway for an hour or two to top-off the battery charge. A charger like this only costs about $125.

MOCON4TN
Posts: 4
Joined: Sun Aug 05, 2018 7:46 pm
Location: Middle Tennessee

Re: Battery for 17-foot Boat with Older 90-HP engine

Postby MOCON4TN » Mon Aug 06, 2018 9:23 pm

Thanks Jim! Appreciate your guidance.
1989 Montauk 17
Old Hickory Lake, TN

MOCON4TN
Posts: 4
Joined: Sun Aug 05, 2018 7:46 pm
Location: Middle Tennessee

Re: Battery for 17-foot Boat with Older 90-HP engine

Postby MOCON4TN » Mon Sep 10, 2018 10:05 pm

Purchased and installed the ProMariner Prosport 8. Easy installation and seems to work great. Thanks.
1989 Montauk 17
Old Hickory Lake, TN