How Much Draw Is Too Much Draw?

l008com

Senior Chief Petty Officer
Joined
Jun 14, 2007
Messages
751
So I plan on re-doing all the electrical in my boat. I'm going to replace the nav lights with super bright LEDs, I may put small LED lights on the floor, I'll eventually add a radio with two speakers, a spotlight/headlight, fix up the bilge pump, and and a depth gauge. I'm not worried about any of this at all.

The point of this thread is that I was also looking at some small 12V coolers to keep drinks cold while I'm out. That would be nice to have when I'm out for 3 hours or more. However I have no idea of my boat can handle that much power drain, without sucking the battery dry even while the motor is running? My motor is a 3cyl 1989 90HP mercury. One cooler I found listed 60 watts as it's draw. What do you think?
 

wire2

Lieutenant Commander
Joined
Jun 25, 2007
Messages
1,584
Re: How Much Draw Is Too Much Draw?

60 watts is ~5 amps, same as 1 headlight. You will probably be ok with the Merc running, but stopped, will pull the battery down.
A safe solution is a 2nd battery for just the cooler. A small garden tractor size will give several hours of cooling, then bring it ashore to charge.
 

l008com

Senior Chief Petty Officer
Joined
Jun 14, 2007
Messages
751
Re: How Much Draw Is Too Much Draw?

Is it possible to upgrade the alternators in these motors so they put out more power? Or is that not possible/easy to do?
 

JoLin

Vice Admiral
Joined
Aug 18, 2007
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5,146
Re: How Much Draw Is Too Much Draw?

You can upgrade the alternator, but it's expensive and usually of limited benefit unless you actually run the motor for hours at a time.

Good energy management practices help, and a second battery on a switch will, too. Personally, I'd use an ice cooler rather then a 12v. You really need that drain for a few hours on the water?

I'm also in the process of upgrading to LED's as I have some cash. I changed over the 3 lights in the cabin and head. Next up will be the v-berth reading lamps and the stern/anchor light. Finally the courtesy lights in the cockpit. We usually use a battery-operated camping lantern there anyway. I'm not going to bother at all with the bow nav light- that one's only used when the boat is underway and charging anyway. LED there is an unnecessary expense.

My .02
 

l008com

Senior Chief Petty Officer
Joined
Jun 14, 2007
Messages
751
Re: How Much Draw Is Too Much Draw?

I'm LED'ing my NAV lights because I want bright, vivid NAV lights, not dim, faded NAV lights. My boat is ooooold. And still, even under way, why waste the energy.
 

JoLin

Vice Admiral
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Aug 18, 2007
Messages
5,146
Re: How Much Draw Is Too Much Draw?

I'm LED'ing my NAV lights because I want bright, vivid NAV lights, not dim, faded NAV lights. My boat is ooooold. And still, even under way, why waste the energy.

Hey, do what you want. Just providing a different viewpoint. :)

Nav lights are nav lights. Our sized boats require CG-approved, 2-mile visibility nav lights. What are you planning to replace the incandescents with, that'll give you more light than that? A brighter LED 'bulb' probably won't fit in the housing, and if you replace the whole unit, you're (hopefully) going to get a CG-approved LED unit instead... and it'll have the same light output.

My .02
 

l008com

Senior Chief Petty Officer
Joined
Jun 14, 2007
Messages
751
Re: How Much Draw Is Too Much Draw?

I'm replacing the whole unit. The light would probably be on par with what i have now if I replaced the bulb and the colored shield. But for $35, I'd rather just replace the whole thing with an LED. Nice vivid color, no heat, no electric draw, no replacing bulbs. I likey.
 
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