Inverter question

O

OffLeash

New member
OK, I know I am no electrical generous but am I missing something.
My goal is to install a 1500 inverter to run a coffee maker and a small toaster over (1140 watts). Normally most people and the instructions talk about adding 10 ft of #2 or #3 wires from the battery to the inverter in the cabin.

Could I simply install the inverter at the battery compartment with the wires that come with it (mine is covered so it is dry) and run a simple AC extension line to the cabin where the toaster and coffee maker sit? I only will use it once is a while when I am on anchor and don't want to run the generator.
I know there is some kind of problem with this but don't know what.

Thanks and don't be too hard on me for not understanding something that is probably obvious.
Mike
 
Mike,
The thing to start with is how much power you will need for the 110 v AC--and in this case 1500 watts seems reasonable. But remember that 1200 watts at 120 VAC is equal to 100 amps 12 volt DC. Even you have a single dedicated group 31 battery, it will be effectively depleted in 30 minutes. The group 27 closer to 20 minutes and a group 24, as little as 15 minutes (depending on amp hours of the battery). For my Tom Cat, I put in two Group 31 AGM batteries inside of the cabin, put the inverter (1500 watts) close to them, so that the cable run was minimal. Then I dedicated one outlet over the hanging locker was dedicated to the 110 V AD. Simple and easy to use. I had a dedicated charger for those batteries. I also had #6 wire from the Voltage sensitive relay for the port engine directly to these batteries. (The starboard engine ran the house batteries, and starboard engine start. I also had a switch so that these two AGM in the cabin could run the freezer chest, and even electronics if I so desired.

You say that the area where your batteries are is protected. I have do disagree with you to some extent. Although there may not be any water directly on the batteries, or inverter, this is a high humidity environment, since it is open to the bilge. I would not put an inverter there. Even though your thoughts make a lot of sense, most inverters are not "happy" in a very high humidity environment. I have been using inverters on boats since about 1970, and have had large systems on large boats, along with very large battery banks--up to 1200 amp hours.

How are you going to recharge these batteries which run the inverter? To put 50 amps back in the battery, will require 30 amp charger over 2 hours, land even then the battery will not be fully charged. Battery charging starts at full charger output in the Bulk stage, but as the battery voltage rises, the charger goes to absorption phase, and amps put in gradually decrease. The last 15 to 20% of the battery charge is at the battery stages of charging--and take several more hours to over night at low amperage.

The charger which comes with the Tom Cat, is barely adequate for the factory house batteries.

There are always other options, but what I did seemed best for my installation.
You don't want to run your primary house batteries down with an inverter, unless they are massive. For example on my RV, I have a 2500 pure sine wave inverter, running off 440 amp battery bank, which has a 110 amp charger. The inverter is close to the batteries, but in a sperate compartment. There I use 2/0 wiring. I also have a thermal probe on the battery bank to avoid overheating the battery bank.
 
Wow...Thanks Bob.
I just put two 100 amp hr batteries for my house bank...It seems barely enough based on what you are saying but I have room for another. The charger well it is the original guest 5-5-10 and I have been a little concerned about it and have been looking at one of the pro mariner 3 bank charger that runs the power to what batteries need it most.
My Verado's have 70 amp alternators (I think????) and they have been doing a good job so far.
Dang...I knew this was going to be an expensive cup of coffee with a side of toast.
m
 
I have a 1500 inverter in my cabin to run a Kuerig coffee maker and a small microwave - one at a time of course. The cable I had to run from the battery is almost as big as my thumb and cost almost as much as the inverter, but I had to have the fancy looking control panel inside!

Even with the 2/0 cable from two marine batteries in parallel I still have the inverter's low voltage beeper going off for the whole time the Keurig is warming the single cup of water. I start the motor and bump the idle to even get it to keep up. And that is not a typo, I tried originaly with #2 battery cable but the voltage drop over the 15' run was too great to feed the inverter. It would shut itself off without ever making a stupid cup of coffee. I had the cable so it didn't cost anything, and since I had already cut the hole in the closet wall and mounted the inverter I bought the 2/0 cable to supply it.

If I did it again I would mount the inverter out back like you suggest and use the remote on/off that I can get for it. Using a heavy AC extension cord with GFCI would make it safe enough - a lot safer than running all those amps all that distance - and if the inverter only lasts a few years, well so be it. They are pretty cheap any more.

Since the inverter is only used intermittently I have no problems with the batteries. They still last me four or five years. Dr. Bob is going to put me in detention here, but I think we worry too much about those batteries. Costco sells them pretty cheap, really, and if they start to go weak before three years they prorate the warranty. The way I look at it, anyone who insists on having the fifty cents a cup Keurig coffee while fishing deserves to spend a little more on maintenance!

The microwave is a small 900 watt so it runs without the inverter beeping (the Keurig is 1400 watt), but I still start the motor to use it. And I never try to fire off the Wallas while the inverter is running.

I am going on four years now with the same batteries, so it's not really worth it to me to relocate the inverter. But I think about doing it often!
 
Dr. Bob is going to put me in detention here, but I think we worry too much about those batteries.
Click to expand...

No, detention...but I do hear folks complaining that batteries don't hold up--because they are routinely discharged to less than 12 volts (less than 40% State of charge),

That 70 amp alternator is adding a lot of "power"--it is putting out max amps, and probably at 14.4 volts (at the output point)--and adding enough voltage/amperage to allow the coffee maker to work on the inverter.

There are a few appliances which do not work on the modified sine wave inverters--I don't know what they are, so don't take a chance. But most appliances do OK on MSW inverters. These are fairly cheap. The PSW with high out put chargers are more expensive...
 
Hi Mike, For the Toaster Oven, I'd suggest a Honda 2000 Generator! The toaster oven fried my 2000w Outback inverter. And that was with the engines running and a 270 amp hour battery bank! Never tried that again...
 
I have a 1000watt inverter sold by WM . It will power a small hair dryer and charge up some phones and computers
we have 2 size 27 batteries one is 3 1/2 years and the other is 4 1/2 years old I usually only plug in the guest 10 amp charger once a month .My new merc 115 charges them at 14 .5 volts at 2000 rpm
 
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