inverter/chargers

[Chuck Creel]

i just ordered a solar system that charges at 7.5 amps peak sun 5 hrs a day/ .i see inverters that would run my 110v A/C system and some say " inverter/charger".does this mean that you are recharging the battery bank while using the inverter?The A/C systyem draws 11 amps at 110v but im not sure what the drain would be on the battery bank while running it. Possibly plugging in a battery charger to the inverter? Just a bit confused.

 

[Peter]

power consumption on DC

Inverter/chargers are special dual-purpose units that have two functions as the name suggests. When your boat is connected to shore power, the unit is through-wired to power your onboard A/C circuit and charges the batteries. Without shore power, it acts as an inverter, drawing power from the batteries. 11 amps@110VAC is a power need of 1,210 watts, so in a perfect world you're drawing 100.83A (1210W/12V) off your batteries. Inverters are not 100% efficient so estimate another 10-20% of draw off the batteries to accomodate the load depending on the capacity of the inverter. The closer to the max load, the less efficient it runs. So in reality, anywhere from 110A-120A.

 

[Landsend]

What Peter said is that...

you need a very large battery bank tat can produce in excess if 100 amps an hour. Thats why all boats that run the a/c units have generators or shore power.

 

[sailaway78]

AC/Refrigeration

Just no way you are going to be able to run an AC unit from a battery bank, unless of course you have a bank larger than any I have ever seen on a sailboat. Other advice given is correct. Your AC unit will draw over 100 amps from the batteries when running. To simplify Peters post, if you draw 11 amps at 110 volts, you can just multiply by ten to get an approximate amp draw at 12 volts. Close enough to give you a pretty close idea of the amp draw. If you have refigeration, you should be able to run that with no problems. A fridge. doesn't draw nearly as much current, and runs far less hours.

 

[Stu Jackson]

AC and DC

I recommend that you read the West Marine Advisors electrical sections and begin to understand the differences between chargers and inverters.Charges put power INTO batteries. AC power gets transformed to DC power.Inverters take the DC OUT of the batteries and convert DC into AC.Inverters don't need to work when plugged into shorepower, which is the only place you can use a charger (unless you have a generator on board).The Advisors are in the related link. Additional information can be found at http://www.amplepower.com, download their Ample Power Primer, as well as at BoatUS, Don Casey's Forum.

 

[LKYusnret]

I run my Air conditioner off of batteries

for about 12 hours. I have a 5.2KBTU reverse cycle AC and four type 31 gels on my little Hunter 260. After running the 2300 watt inverter for 12 hrs the batteries go down to about 50%. The current draw off the batteries is about 35 amps DC for maybe 20 to 30% of the time. So never say never. I charge the battery bank during the next day with a 40 amp true charger and a Honda 2k generator. LKYusnret on Baums Rush,,,,,, doing the loop and the wife and I have lived on board since Feb. 2 2007.

 

[sailaway78]

I stand corrected

LKY, must say I have never heard of anyone doing this before. Pretty large and expensive battery bank for a 26 though. From what you stated you must have about a grand or more in batts and inverter. Thats as much batt power as I have in my 37, and a larger inverter than I have. Whatever works though. There is of course a big difference between your usage and the 100+ amps we were talking about. Just for the sake of argument, using your system as a referance point, it would take approx. three times the battery power to run his system. So 12 group 31's and a really BIG inverter would be required. Could be done though. All it takes is the bucks.

 

[Don S/V ILLusion]

Interesting use of AC

Guess it is another argument in favor of a mid to small sized boat. In order to cool a larger one and depending on what part of the country it is located, an AC unit of at least 3 times that capacity, if not two units, would be required with a corresponding increase in battery capacity. Some quick calculations here mean I'd need 18 golf cart batteries, a 900 amp alternator driven by a 200 HP engine and an inverter the size of Rhode Island to go the night.Sounds like a winter project.

 

[LKYusnret]

I just had to answer your E-mail

all in good fun, LOL. When we get back to Jacksonville FL after the great Loop we are going on our Corbin 39 and do a circumnavagtion we figure about 12 years. We have traveled about 1300 nm so far and now in Waterford NY, the entrance to the Erie Canal. LKYusnret S/V (with an un steped mast) Baums Rush,

 

[sailaway78]

You must be

LKY you must be a wuss, LOL, that far north, traveling and running an AC.Hell, most of us here on the gulf coast don't have an AC, and the temp and humidity are both right around 100. If I lived on a boat, in a slip, I would probably have an AC and have it on 24/7. But during the day, am usually in the cockpit, and at night, it isn't that hot with hatches open, and usually some breeze blowing.

 

[Roger]

Erie Canal...

...Into Lake Ont? Then down Ont to the Trent Canal?? Then thru that system to Georgian Bay??? IF/when you reach Lock 32 on the Trent, the busiest Lock in the system, you'll be in Bobcaygeon...where the Pigeon Lake Yacht Club keeps my boat safe, and me happy! When are You expecting to pass-that-way? What's the name of yer BOAT?? Maybe we could meet up, eh ??? Roger

 

[Chuck Creel]

answers on inverters

Thanks for all the responses and clearing up the issueof the A/C.The installation of the a/c was an intisment to get my wife more involved in cruising and just might did the trick. IT seems that we would be better off running the honda generator for the a/c onboard while at anchor and we really don,t need the A/C running 24/7. The funds would be better spent on a CANDLE LIGHT DINNER watching the sunset rather than installing the inverter/charger system.. ... Thanks again for the tips and links.

 

[LKYusnret]

Roger

We plan in going thru the Erie to the Oswego Canal to Lake Ontario than thru the Trent-Severn and then across and down to Chichgo.... etc Thanks for the invite though. Name of boat is Baums Rush my e-mail is ****LKYusnret2@aol.com**John

 

[camaraderie]

Wait a minute LKY...

A 5200 amp marine unit with pump draws at least 6 amps at 120V...or 60 amps at 12V. That is BEFORE conversion losses at your inverter. The best portable home air conditioners draw a little over 5 amps @120V or 50 amps+ from your 12V system. How is it that you are only using 35 amps??Next question assuming 35 amps is correct: At 125 a/h per group 31 you are looking at a 500 A/H bank. Half capacity is 250 amps. Running a 35 amp load for 12 hours is 420 amp hours or over 80% of your capacity. Effectively killing your battery life. Then...running your Honda and the 40amp charger the next day would take you more than 10 hours of run time to charge back up. What do you do for air conditioning while you are running through 3 tanks of gas on your Honda??By my way of thinking you might be able to run a marine A/C drawing 60 amps at 12V for about 4 hours before hitting the magic 50% point (assuming no other loads) and then you'd need to charge for at least 6 hours. What part of your story am I missing here? Not saying you are not truthful...just that the data you supplied does not make sense to me so far.

 

[Terry Cox]

Our boat came equipped with two reverse...

cycle heat pumps that operate on 120 volts AC. The main cabin is 16K BTU and the aft cabin is 9K BTU. Running both units along with the AC raw water pump that supplies them consumes about 20 amps AC, or around ten amps each. No way would I consider running them with AC supplied through the inverter.Terry