Power usage in watts February 18, 2020, 07:08:59 pm I recently ran across a chart of estimated wattage for various appliances. We've discussed power usage before, but this is the most extensive listing I've seen.Tip: to convert the wattage numbers in this chart to amps at 12 volts, assuming you're going to run one of these appliances from an inverter, divide by 11. That'll give you a pretty good approximation, factoring in the inverter's less-than-100% efficiency.For example, a 50 W television will draw about 4.5 amps when powered from your house batteries by an inverter, while a 1,200 W coffeemaker will draw about 109 amps. Using this table will help you estimate your power needs when speccing an electrical system. 11 Likes
Re: Power usage in watts Reply #1 – February 19, 2020, 11:19:37 am Very useful site, not only because of the wattage chart, but because information on factoring in 'start surge' when calculating power draw/inverter size needs is stated in the opening paragraph. 1 Likes
Re: Power usage in watts Reply #2 – February 19, 2020, 01:37:39 pm I like the tip about using eleven as the multiplier, to account for the inverter's inefficiency.Larry 1 Likes
Re: Power usage in watts Reply #3 – February 20, 2020, 11:04:57 am I have a 1000W microwave that draws its electrical current through a 1000W Xantrex inverter with a 12V 4D battery (on a dive boat). The Xantrex has an ammeter on its display. It displays 95A draw at startup and a full 90A during cooking. Dividing the 1000W by 12 would indicate 83 A draw, but the actual 90-95A draw must be determined by dividing by 10.5.The inverter is wired to the batteries with 3/0 Gauge welding cable to reduce line loss in the 12 foot run from the battery to the inverter.Making 120V from 12V is expensive in $$$, equipment, and weight. We re almost completely 12V in the Lazy Daze.Harold 1 Likes
Re: Power usage in watts Reply #4 – February 20, 2020, 03:57:09 pm Harold, if you had placed the inverter next to the battery, most of those 12 feet could have been covered with 14 gauge wire, saving a ton of money for copper. Ken F in NM
Re: Power usage in watts Reply #5 – February 20, 2020, 04:32:14 pm Ken,Good idea.However it is an open deck work boat and batteries are under the deck amidship and the microwave and inverter are in the cabin forward. I do understand that there is less line loss with the inverted 120v, but that isn't the way the boats are designed. It would be a good idea in a pleasure boat.The 2500W 12v anchor windlass is in a worse position at the bow. 3/0 Ga cable all the way. With an all chain rode (360 ft) and if the anchor is buried well, the puller will grind all the way down to 0rpm trying to pull it up. That pulls BIG amps. When that happens, we snub and cleat the chain and let the buoyancy of the boat and the action of the swell work the anchor out from the sand. We haven't had any problem with the puller, but last year we were out in a big swell and had to leave an anchorage at the last moment. The anchor was stuck and an extra large swell rolled through, pulling the bow down and folded the bow roller down nearly vertical. I've never done, or even seen that before. I had to send my son down in his diving gear while I handled the boat. He used a crowbar to work the anchor out of the rocks.One more thing to fix... Harold 1 Likes
Re: Power usage in watts Reply #6 – February 20, 2020, 05:56:41 pm Quote from: Blueox25 - February 20, 2020, 11:04:57 amI have a 1000W microwave that draws its electrical current through a 1000W Xantrex inverter with a 12V 4D battery (on a dive boat). The Xantrex has an ammeter on its display. It displays 95A draw at startup and a full 90A during cooking. Is the '1000W' listed as power consumption on the UL label, or the μ-wave output power? If the latter, the power consumption would be more than 1000W.Steve
Re: Power usage in watts Reply #7 – February 20, 2020, 06:40:02 pm No picture, it didn't happen:How many tons does it take to bend a 3 inch wide channel?Steve: UL label. 2 Likes
Re: Power usage in watts Reply #8 – February 20, 2020, 06:59:19 pm Quote from: Blueox25 - February 20, 2020, 06:40:02 pmNo picture, it didn't happen:How many tons does it take to bend a 3 inch wide channel?A lot of tons, your are lucky something else didn't break sooner. Now you know the weak link.Larry 2 Likes
Re: Power usage in watts Reply #9 – February 20, 2020, 09:12:53 pm The Ox was built to exceed commercial standards and is stout as a brick **** house.It was still frightening.The builder may stop by our camp at Morro Bay. He is a really interesting guy.Harold
Re: Power usage in watts Reply #10 – February 21, 2020, 12:46:47 am "Is the '1000W' listed as power consumption on the UL label, or the μ-wave output power? If the latter, the power consumption would be more than 1000W."Good point, Steve. Microwave ovens are usually rated in μ-wave output power, not AC power consumption. From what I've seen over the years, a 1,000 W-rated microwave oven typically draws about 1,500 watts from the outlet. Even a 600 W "dorm-sized" microwave draws almost a kilowatt.
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