Whats the deal with battery life

[Krazymaan]

I read here and there about people having to charge their batteries or they can't go boating all day long. Whats up with that.
My charging system is a 16amp and it runs tilt, trim, jackplate, fuel pump and a few gauges. I can run it all summer without charging the battery. But its Carbureted. Not EFI
Whats the scenario to why your performance boat has to have fully charged batteries or it ain't gonna make it all day?

[mjw930]

Although I always leave my "less used" vehicles on battery maintainers I don't understand why someone would have an issue running all day as long as there is enough juice in the battery to start the motor the first time. If that's not the case then they need to revisit their charging system as all modern outboards should be able to top off a battery in less then an hour of running.

However, I have absolutely no experience with modified true race motors like the older 260's and 280's. They might have a limited charging system to save weight and parasitic loss.

[Euroski]

Stereos, not unless you have a second battery for engine only?

2.5 280's have 50+amp alternator.

[2.5-21]

16 amp system as used on a 260 with 2 fuel pumps, a low pressure to fill the catch can and high pressure to supply engines is marginal to keep a single battery up to 13 plus volts after a full day of use with a combination of Idling around and some full speed runs, Then once the voltage begins to drop everything starts drawing more than usual amps and things go dead fast.

[superboattwin250]

Carb w/16a always seems fine. Efi w/ 16a = dead battery. The 280 has and alt. And is much better

[Krazymaan]

Is there a remedy?
Nobody wants more heavy batteries for performance reasons?
One day maybe I'll have that issue, but for now I'm still liking my carbs.

[90 5.0]

Small lightweight batteries and 16amp charging don't mix well for long boat rides with efi.

[Krazymaan]

So the charging system with a 16amp flywheel can't keep up to the demands of efi right from the factory or is this something the was only an issue while swapping parts from motor to motor.

I wonder what batter was recommended from Merc when brand new.

[mjw930]

So the charging system with a 16amp flywheel can't keep up to the demands of efi right from the factory or is this something the was only an issue while swapping parts from motor to motor.

I wonder what batter was recommended from Merc when brand new.

If I'm not mistaken the 260 was a "race" motor so I imagine the recommendation from Mercury would be "don't use it for general purpose cruising"........ Obviously with the 280 and subsequent 300's they rectified the problem so it's really just an issue for those running the older stuff.

[eli]

Ran 1optima blue on my 23 Daytona no stereo 245 carb ,s never went dead ,i would give a 30 min trickle before going out for the day to be sure it was going to start

[mrcrsr]

The answer is to run an alternator kit. I'm in the process now of building them using a 3 liter style alternator.

[Krazymaan]

I just have a regular battery on my 16 amp system with carbs and haven't had a charger on it for two years. In fact I went to storage and it fired right up again about a month ago. Just trying to figure out if i am missing something here.

[mjw930]

Perhaps adding one of these would be prudent for those with 16A systems, https://www.amazon.com/Antigravity-Batteries-AG-XP-1-Multi-Function-Starter/dp/B00I9HGMYO/ref=sr_1_1?s=automotive&ie=UTF8&qid=1490707519&sr=1-1&keywords=Antigravity+Batteries+AG-XP-1

[89LASER]

I work on airport equipment that only gets short runs, dead batteries were always a problem. I installed small solar panels with a regulator to keep the batteries charged when not in use. No more dead batteries. All the parts were bought at West Marine.

[JCSmile]

The old efi boxes also draw power any time they are connected to a battery. If you leave the 15 pin connector plugged in it will drain the battery over time. Efi's with 16 amp like to have a full charge before going out. If you have a low battery you will know, the performance losses are usually evident.

[David - WI]

Isn't one pin on the round 7-pin trailer light plugs intended for charging tow-behind RV trailer "house" batteries?

I would think it would be pretty simple to hook that up... a quick-disconnect plug at the back of the trailer and one in the boat? That way it would top off my batteries on the way home before I put the boat away... and again when I took it out and towed it to the launch.

[90 5.0]

I just have a regular battery on my 16 amp system with carbs and haven't had a charger on it for two years. In fact I went to storage and it fired right up again about a month ago. Just trying to figure out if i am missing something here.

Efi pumps are a lot higher pressure and draw more amps plus the injectors, ecu sensors etc that carbs don't have.

[90 5.0]

Isn't one pin on the round 7-pin trailer light plugs intended for charging tow-behind RV trailer "house" batteries?

I would think it would be pretty simple to hook that up... a quick-disconnect plug at the back of the trailer and one in the boat? That way it would top off my batteries on the way home before I put the boat away... and again when I took it out and towed it to the launch.

Yes I have thought about doing that a few times

[Krazymaan]

thats not a bad idea as long as you don't just hook 12 volts to it instead of a charging lead.

[David - WI]

I have a new trailer wire harness... tomorrow I'll try to check if all the pins have wires. Could be there's a special RV trailer wiring harness?

Also i think you have to either connect a wire or insert a missing fuse under the hood to power up that pin (at least on some vehicles).