Inverter for boat

Larry Patrick · Posted: Sun May 10, 2015 6:53 pm Post subject: Inverter for boat

What recommendations for running on boat? Guessing true sine wave any brand suggestions? I just want to plug it into 12volt outlet. Guess use it for I-pad ect, would 400 watt be sufficient or any reason to get a 600 watt? Thanks, first time purchasing one.

redbaronace · Posted: Sun May 10, 2015 7:26 pm Post subject:

The inverter we installed in previous boats was hard wired to the house battery.

We have used the portable inverters purchased from Costco for around $40 and they worked fine for laptops, etc.

anchorout · Posted: Sun May 10, 2015 9:07 pm Post subject: watts

On inverters, remember Watts = Volts X Amps. Divide 120V into your inverter rating to see its working Amp output. My laptop uses 2.5 Amps, so a 400 Watt inverter would run it. But you must consider if you are powering a motor, such as a drill, the starting surge may draw considerably more than the working current, so don't short yourself on Wattage if you plan to run more than laptops or DVDs.

BrentB · Posted: Sun May 10, 2015 9:40 pm Post subject:

for cell phones, ipad, etc I use a cig lighter charger

ex
SCOSCHE USBC242M 12 Watt USB Car Charger for iPhone/iPad/iPod Lightning/Micro - Retail Packaging - Black

2.4 Amps per USB port

I ordered a Blue Seas dedicated dual USB ports plug but it has not arrived

Robert H. Wilkinson · Posted: Sun May 10, 2015 9:48 pm Post subject:

If you are using a 12v(cigarette lighter type) outlet don't forget that you can only draw the amperage from that outlet that it is wired to handle.

Once you get up to 600 watts or bigger I think they are best hard wired close to the battery with an inline fuse. Of coarse it depends on what percentage of the available watts you will be using. It is best though to somewhat match the unit to its normal load as powering a small load with a large invertor is less efficient.

There are lots of cheap smaller units on the market but I don't know what ones might have a true sine wave. Check all the appliances you plan to use to see if they will work with a modified sine wave unit. If they will then you can get away with a lot less expensive invertor.

Not sure of the brand or wattage but they have one that is designed to fit into a cup holder - might be handy on a boat.

Regards, Rob

hardee · Posted: Sun May 10, 2015 11:21 pm Post subject:

I use a 400 watt Cobra 12VDC plug in to a cig lither type inverter. It has a small fan, 2each, 110 plugs and 1 or 2 USB plugs -- don't remember for sure and it is on the boat not right here to check.

It charges camera batteries primarily. Have not tried it on the lap top but that would be nice. It also runs a small crock pot and I have done that in the car and truck but not in the boat -- might be a good idea then not have to heat up the Wallas, and still heat on the run. Have used it to bake potatoes mostly.

Harvey
SleepyC Moon

journey on · Posted: Sun May 10, 2015 11:31 pm Post subject:

Rob points out a very pertinent fact. Going from DC to AC usually requires current, as a matter of fact the DC input current is 10 times the AC output current since the voltages are an order of magnitude apart; 12 V vs 120 V.

So most cigarette lighters are rated for 10 amps, which for 12.6 VDC is only 126 watts. That's fine for a cell phone or tablet, on the low side for a laptop (but possible,) and out of the question for a TV or even, heaven forbid, a microwave. And good inverters are ~90% efficient at full load.

Thus for anything over 100 watts AC (~ 1 amp) needs a hard wired inverter. This requires big wires, say 8 ga., and proper fusing. Easier done than said, because it's just wiring. And connect directly to the battery. Whatever they say about a 400 watt inverter plugging into a cig lighter, remember they're not rated for more than 10 amps. A 400 watt inverter will pull 40 amps, so beware.

Costco inverters are square wave ( I believe) which is OK for chargers since the transformer filters out the high frequency harmonics. But for anything else, a sine wave is nice. Those square wave inverters are cheap and those from Costco are certainly not marinized against high humidity/dampness. However that may be OK for inside a C-Dory cabin.

I use a Xantrex PROsine 1000 Pure Sine Wave Inverter which has lasted for 10 years, so I'm happy with it, it's <$600. There are many good marine sine wave inverters, so look around. If you need a good battery charger, there are a lot of charger/inverter combinations but they're more expensive.

Boris

hardee · Posted: Mon May 11, 2015 12:23 am Post subject:

Boris,

Thanks for the heads up. I'll check the Cora Inverter for amps. If it is only running the battery charger for the camera battery I'm thinking it is drawing far less. The crock pot draws only 75 watts. the inverter with the fan will add to that I'm sure. I'll find out how much.

Harvey
SleepyC Moon

Larry Patrick · Posted: Mon May 11, 2015 8:00 am Post subject:

Lots of good information thanks.

Casey · Posted: Mon May 11, 2015 8:42 am Post subject:

For the he past few weeks we have noticed that our navigation iPad3 was slowly loosing its charge over 6-8hours of cruising. By late afternoon the iPad would be down to <10% even though it had been plugged in to a 12V socket all day. The iPad simply required more energy than the 12V plug was providing.

As a test, we plugged our small (140W) RadioShack inverter into the 12V source, then plugged the somewhat larger iPad 110V charger into the inverter. Problem solved - but the arrangement was rather cumbersome. Using this arrangement the iPad maintained its charge all day.

When we met Steve Baum (CD22 "Osprey") few days ago, he had experienced the same iPad power-loss issue that we experienced. His solution was to use a PowerGen 12V plug that supplies more current. He set me up with one, and it seems to be working fine, and it's a simple USB adaptor that goes into the 12V socket. I've seen several of these, and most seem to supply 2.1A. The PowerGen supplies 4.2A (if you only have one device plugged in).

Here's the PowerGen link on eBay:

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.XPowerGen+4.2.TRS0&_nkw=PowerGen+4.2&_sacat=0

Best,
Casey&Mary

lloyds · Posted: Mon May 11, 2015 1:24 pm Post subject:

Harvey, curious about baking potatoes. Do you have to do something special to do them in a crock pot?

hardee · Posted: Mon May 11, 2015 3:50 pm Post subject:

thataway · Posted: Mon May 11, 2015 4:29 pm Post subject:

Aurelia · Posted: Mon May 11, 2015 8:21 pm Post subject:

If you mainly plan to use it for device charging, How about just getting some 12v charging cables for you devices and skip the inverter entirely? I put our current boat together with minimized AC power needs in mind. We have one little single outlet inverter that we use to charge a hand vacuum. Thats been out needs thus far. We are device heavy and just use lots of 12 outlets and USB power sockets.

Greg

journey on · Posted: Tue May 12, 2015 11:35 am Post subject:

Aurelia/Greg is right. If you want to charge cell phones, tablets, etc., buy the 12 v chargers. They output the correct voltage for the device and it's a low DC voltage, For USB it's 5 VDC, for a HP laptop it's 18 VDC. We're not talking about lots of 120 V AC power here. For 2 A @ 5 V, that's 10 watts: for a HP laptop, we're talking about 65 watts. All DC power.

So, converting from the battery 12.5 VDC to 120 VAC and then back down to 5 or 18 VDC would seem to be an inefficient way to do it, in addition to the extra equipment. Judy's cell phone comes with a DC charger as does her tablet. You can buy a DC laptop charger for ~$20 which will make sure the laptop is charged. All those are designed to charge the device correctly from 12 VDC.

So for charging those electronic devices, instead of getting an inverter and guessing if it'll work with the AC charger, buy the correct DC charger and quit worrying. It's worked well for us.

Boris