Electric cooler drains battery when on shore power?

Dec 23, 2013
20
Hunter 23.5 and 27, 2006 Redbud Marina
Hi, I assumed the ice chest type cooler (Mobicool T45) was running from the shore power when docked. For the first time since I've owned the Hunter 27, 2006, I left the cooler running for several days. I came back to the boat and the batteries were nearly completely drained. Shore power was definitely on. I wonder if the cooler runs from the battery charger and the batteries instead of directly from shore power? I disconnected the cooler and the batteries have started charging. ANY IDEAS?
Martin in Tulsa
 
Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
You do not say how many amps your charger provides but must assume not enough to run the DC cooler as well as charge the batteries. Your cooler runs on DC not AC. If you have the AC to DC converter then it will run off of AC dock power. Bear in mind that most of these DC coolers do not have thermostats and run 24/7. They suck DC current like crazy at about the rate of 5 DC amps per hour! With the load these coolers present to the charger even putting the charger on the 6 amp switch position may not suffice. Output from the charger may not really provide quite enough for the cooler! Come back, Chief
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
I wonder if the cooler runs from the battery charger and the batteries instead of directly from shore power?
From the picture you describe:

-The shore power feeds 120V to the battery charger

- The battery charger supplies 12V to the batteries

- The batteries and charger supply 12V to the cooler.

The cooler cannot accept electricity directly from the shore power as it's 120V. Or as Chief RA says, the draw by the cooler is greater than the supply of the charger.

Beyond that, I'm lost. For some reason, the charger is not charging the batteries.
 
Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
Just for fun I will share how I run my DC "beer" cooler when out on the road in my RV. I connect an 80w/5a solar panel directly to the cooler and it runs it all day and remains cool when off at night. Be aware that the voltage output from an unregulated solar panel is high at about 18v but loads down when hooked up to the cooler. It could burn up your little DC motor in the cooler but I have done this for probably 5 years and never burned one up yet. Nice cold beer! Chief
 
Dec 23, 2013
20
Hunter 23.5 and 27, 2006 Redbud Marina
Thanks for the responses! I know the charger is a Pro Mariner Protech 4, not sure which model until I see it. I'm sure you're correct, the charger is not strong enough to charge the batteries and keep up with the cooler. However, I will go see where the cooler's charger is connected. I think it's under the counter top by the trash can, directly next to a 110 receptacle. That's why I thought the shore power would power it.
Thanks again!! Martin in Tulsa
 
Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
Martin: You can buy the AC to DC converters to fit the cooler connector. I am going to lay my solar panel on the finger pier and run my cooler while in port with it. Chief
 
Sep 25, 2008
7,075
Alden 50 Sarasota, Florida
The specs on their web site indicate it is a 12volt unit drawing approx 3amps which if interpreted as 3 amp-hours running continuously would draw 72amps per day maximum. It should not be operating at 100% duty cycle so the real demand is less.. It's hard to imagine your charger can't keep up with that demand unless it's tiny or malfunctioning.

Ralph is probably on to something.
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
I am going to guess that the little "cooler" is running almost full time. Note that it can cool only to 20C below ambient temperature. If the inside of the boat is say 90F (32c) as it might easily get to, the cooler cannot cool to below 54F.. at 98F that is only 62F of cooling power.. The little thermoelectric boxes are almost useless in the summer on the Gulf Coast because of the limited cooling capacity and low electrical efficiency. Even though the compressor models are a good bit more expensive, they are actually capable of cooling to and maintaining the low temperature required to have cold beers and non spoiled food.
Note that Igloo and Coleman state a 40 degree F reduction below ambient. again, fine if the ambient is air conditioned, but not so on a summer day in the cabin.
 
Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
People trying to use these 12v coolers in place of a reefer are just fooling themselves. I own both a Coleman and an Igloo. The smaller Coleman isn't as good as the Igloo and burns MORE than 3 amps per hr. The Igloo draws a full 5 amps and neither one of them ever shut off. Its 100% duty cycle for both models! The Igloo cools better but draws more. I use them on the coast as well as in the winter in Arizona. My boat & RV have a reefer as well, these are my beer lockers and work well where/when I use them!
If you run these on their own exclusive solar panels as I explained previously then you won't deplete your battery bank.
Chief
 
Dec 19, 2006
5,809
Hunter 36 Punta Gorda
Info

What type of cooler are we talking about and is it a portable ref or is it something that comes stock on your boat.
If you can't keep the batteries full charged at the dock what happens when at
anchor or sailing.
Nick
 
May 24, 2004
7,129
CC 30 South Florida
I think Hunter would be smarter than to hardwire a thermoelectric cooler. They usually come with a 12V plug or a 120V to 12V converter so the user may choose its source of power. To take away the ability to use the 120V source of power makes no sense whatsoever as these units are power hogs and will draw down batteries when used continuously on 12V. I use one in my van when taking long trips and I load it and pre-cool it the night before with the 120V converter and then place it in the van and let the 140A alternator take over. In sailboats however where alternators are smaller and the idea is to turn the engine Off as soon as the wind shows up then they do not pair very well. Get a set of a 12V plug and cable and a 120V converter and plug them in manually according to your needs.
 
Dec 15, 2009
25
Hunter 30 USA
Some smart chargers are confused by loads that don't behave like a battery. I installed a DC power supply to run the 12 V refrigerator, lights and stereo when connected to shore power. I use a relay that automatically switch between sources (battery or power supply).