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Old 16-06-2018, 14:11   #76
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Re: How to convert reading of amps into amp hours

+1. But I gotta add that for anyone who mostly understands the basics, but could learn more, this thread has been good for sorting out the wheat from the chaff, so gaining a more secure concept of power conversion & storage over time. So it has also been enlightening....

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Is it only me that finds some of these discussions intensely frustrating? It seems to me that it is always due to posters not taking time to really read and think about the question.
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Old 17-06-2018, 08:15   #77
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Re: How to convert reading of amps into amp hours

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+1. But I gotta add that for anyone who mostly understands the basics, but could learn more, this thread has been good for sorting out the wheat from the chaff, so gaining a more secure concept of power conversion & storage over time. So it has also been enlightening....

That is true.
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Old 17-06-2018, 08:27   #78
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Re: How to convert reading of amps into amp hours

Amp Hours are defined as the storage capacity of a battery. Not the work done by any device. If we draw higher amps from the battery, it lasts shorter time than the math would suggest. If we draw lower amps it will last a longer time than the math would suggest. The only way to determine power is with watts. If our battery is at higher voltage, then lower amps for the needed watts. If at reduced voltage, higher amps for the needed watts. The device just wants the watts.
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Old 17-06-2018, 08:36   #79
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Re: How to convert reading of amps into amp hours

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There was no way he was boiling water at 1.7 amps regardless of whether is was with 120, or 12 volts, and that should have been the clue to what needed to be the prime topic.
I beg to differ, okay its not boiling but you won't be putting your hand in it.

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Old 17-06-2018, 08:43   #80
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Re: How to convert reading of amps into amp hours

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Amp Hours are defined as the storage capacity of a battery. Not the work done by any device.
The 12VDC energy consumed by a load over time is usually expressed in AH.

As in, my fridge averages 2.8A while the compressor is cycling, and 37AH per 24hrs.

Watt-hours may be used also, but not watts or amps, those are instantaneous "snapshot" units of flow rate.
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Old 17-06-2018, 08:45   #81
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Re: How to convert reading of amps into amp hours

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I beg to differ, okay its not boiling but you won't be putting your hand in it.
The OP's example was an induction hotplate. Very different consumption patterns, more akin to usage of small microwave.
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Old 17-06-2018, 08:50   #82
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Re: How to convert reading of amps into amp hours

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The OP's example was an induction hotplate
He didn't say that.

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Very different consumption patterns, more akin to usage of small microwave.
You mean it is cyclic?
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Old 17-06-2018, 09:17   #83
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Re: How to convert reading of amps into amp hours

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He didn't say that.





?


Actually he did......

Copied from post #1.

“Oh yah...back to the multimeter...sorry...So, I took one of our induction modules in the kitchen and placed a steel pan with water on it. Turned that sucker up to high power. Put the jaws of the multimeter on it and got an amperage reading. 1.7 amps”
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Old 17-06-2018, 10:44   #84
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Re: How to convert reading of amps into amp hours

Funny thread.

lets look at this two ways:

(1) it takes 1 cal (heat energy) to raise 1 gram of water 1 degrees C (from room temp at standard pressure).
So if we wanted to boil 1lt of water = 1000 grams x 80 Deg C = 80kCal
80kCal = 93 watt-hours=7.75 amp-hours (@12v)
an induction heater is (roughly - this varies) 80% efficient
so it would really take (about) 10 amp-hours to boil a lt of water.
The amp draw would depend on how long it took to bring to boil (and the insulation efficiency/heat loss of the pot) . . . .but a 5 minute boil would create roughly a 120 amp draw @ 12vts or 12 amps @ 120vts

(2) a very typical induction hot plate is 1800 watts.
That would draw 15 amps @ 120vts and 150 amps @ 12vts
an 1800 watt induction hot plate will boil 1 lt of water in roughly 5 minutes (efficiency varies), which would create a draw of 150 amps @ 12vts for 5 minutes = 12.5 amp-hours
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Old 17-06-2018, 15:23   #85
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Re: How to convert reading of amps into amp hours

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You mean it is cyclic?
No the AH consumed per unit of time cooking.

As in a high-current load.

I am surprised your crock pot is that low, but then it's not for boiling up a pot of tea or frying some French Toast.
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Old 18-06-2018, 19:07   #86
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Re: How to convert reading of amps into amp hours

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I have a 36' trip and I use induction cooking. Decided early on not to use propane. I will say propane is the lowest cost. I have 400 amphr useable Li house battery with 20amp@110v inverter. The boat has 700watts of solar and 2000watt generator. Electrical use items are induction plate, toaster oven, coffee pot, hot water heater, and soon AC. I can use these one at a time for total time of about 2 hours per day. Depending on solar gain this doesn't require generator support. Not a cheap system but it does work.

Joules....digging your name. That is some valuable information. How much money do you think it cost you to set that up that way? If you don’t mind sharing it...much appreciated. I also like that you said what you achieve in how much juice you use and how you generate and store....cool
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Old 18-06-2018, 19:12   #87
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Re: How to convert reading of amps into amp hours

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Yes heavy inverter loads require in many cases heavier gauge cables for the DC side than charge sources, especially since distances can be longer.

Best of course to put high-watt inverters close to the bank and do the long run via AC wiring.
John, thanks, mate, that is a good way to do it and save on weight and cost of heavy wire.
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Old 18-06-2018, 19:25   #88
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Re: How to convert reading of amps into amp hours

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Ok

Batteries run at 12v, induction cooktop runs at 110v or 220v. You should probably figure out which.

1. I bet you cooktop is really 220v. That doubles your wattage and the current draw on the 12v side.

Your cook top should have a UL sticker somewhere that indicates normal voltage and maximum amperage. Look for the sticker. Failing that get the model number and go online to see what the published specs are.

Adeline, thanks for your write up. In the picture of the back of the induction top it says that it is 120 volt. Max power is 1800 watts. It is used in my rental apartment and just plug it into 110 power.

Some of the fellas also think I am measuring with an ac versus dc clamp multimeter. My multimeter has the capability of using either ac or dc. I will make my own splitter cord on next couple of days so that I can separate hot from neutral wire and plug that in and retake the reading. This has been a great thread for me to learn mucho .....I am indebted to those souls who went before me ....smile...alan
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Old 18-06-2018, 19:51   #89
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Re: How to convert reading of amps into amp hours

Trawlerman, in my defense I was left without adult supervision....smile...one of the fellas on here has that as part of his I.D.

You know, I can understand your point of view. But you don’t know me as a person so I don’t take it personally. People come from all sorts of backgrounds and education. I have a master’s degree in Microbiology and plenty of science in that discipline. It is not really a matter of brain power. As I have gotten older I have become more cautious in my nature and I acknowledge readily that absorption of information comes slower.

I have done tons of reading on Lithium, solar, inverters, ad nauseum....at my age I have more money than time. Still have a year to go before I retire. My trimaran is in Mexico so I can’t get to it until November. I bought it and drove home...literally...

So, what you find in this thread...is a guy who wants to be as fully loaded with correct ideas and information about what I can or can’t do ..and what will it cost to do it...and is it really worth the financial carnage?

The value of the CF org is information by real users ...in real time....and their willingness to share their experience. If only threads were allowed that people had researched for weeks (I researched for 3 months on and off) there would be very few posts. I, for one, thank God, I have the brethren and sisters on here to share information and help others sort out their questions. Respectfully, alan
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