pianotuna
Regina, SK, Canada
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Hi bldrbuck,
That is incorrect. 100 watts draws about 10 amps @ 12 volts.
Volts X Amps = Watts
12 v X 10 a = 120 watts
120 v X 1 a = 120 watts
bldrbuck wrote: You are using 10 amps from the batteries at 12 volts for each watt of 120 that you use.
Regards, Don
Kustom Koach Class C 28'5" 256 watts solar, 875 amp hours in two battery banks 12 volt batteries 2500 watt inverter.
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McZippie
USA
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Jennifer, I have about the same Amp Hours battery bank as you, except that they are 12 volt AGM batteries. What works best for us, is to use our 900 watt micowave right after stopping, before the batteries are used for anything else. I'd guess'tamate we have about 10 minutes of microwave useage before the invertor starts to low voltage alarm.
Once the microwave is turned off, the batteries are still good for many more hours of low wattage usages. ie "Peukert Law" is the effect upon battery discharge. It basically means the higher the discharge rate the less available Amp Hours the battery will give. The lower the discharge rate, the more Amp Hours they will give.
There are two basic ways to wire in an inverter:
1. Have it power all the 120 volt outlets. This requires transfer switches and interfacing with your electrical panel.
2. Hard wired directly to the battery. Your microwave or coffee pot would then be plugged directly into the inverter.
Decide first between the above and this will determine the features needed on the inverter. Oblivious choice '2' is much easier to wire and the inverters are less expensive.
If you decide on '2' because it's less costly, don't get too concerned about the raging debate of a modified sine wave vs pure sine wave inverter powering a microwave. We can talk about that more when you decide how you want to wire it to the batteries.
What's the wattage of your microwave?
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Wayne Dohnal
Bend, OR.
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I agree with this statement "You have roughly 230 amps of batteries. Not discharging over 50% means you have roughly 100 amps to play with. That's plenty to make a pot of coffee, short microwave maybe a little TV. ", except it's 230 amp-hours and 100 amp-hours. There are two important things that nobody mentioned yet: (1) With this big of an inverter, you must have very heavy wires connecting the battery and inverter and they must be as short as possible. Unless somebody grossly oversized the wires going to the 300 watt inverter, they won't work. (2) If this is a "modified sine wave" inverter, the microwave won't produce its full power. That's ok, it will just take longer to heat things up. The coffee pot should be ok heating-wise, but if it has electronic controls they might or might not work. If it's a True Sine Wave or Pure Sine Wave inverter (same thing), everything will work normally.
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pianotuna
Regina, SK, Canada
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Hi,
A transfer switch is not necessary, but turning off the breaker for the converter is.
With these large amperages it is needful to have a catastrophic failure fuse.
Mount the inverter as close to the battery bank as is humanly possible without it being in the same compartment.
* This post was
edited 09/02/10 10:10pm by pianotuna *
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KendallP
Grants Pass, OR
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pianotuna wrote:In real life, there likely would be so much voltage drop that at 2000 watts the inverter would fault out from low voltage. You might be able to manage five minutes--if the batteries are really new and well charged. Or if they were AGM format they would run a lot longer.
Really a 750 watt inverter is about all two golf cart batteries can manage to power, other than for "brief" bursts of power (one minute to warm a cup of soup in the microwave, etc.)
To me, this is the best, most succinct post. There's your answer.
Unless you want to change battery type and/or add extra batteries, a 750W inverter is about all you want to do. This will run neither the mic, nor the coffee maker.
So... moving on to plan B...
A French Press is considered one of the very best ways to brew coffee. I have one that will do a good 3 mugs at a time (6 "cups')
For a single mug...
1. Heat water to about 190 - 200 deg. F or just below boiling (boiling water burns coffee, a-la a percolator which... CONTINUALLY burns the coffee as it percolates over and over.)
2. Grind coffee coarsely and add amount to taste to French Press.
3. Fill mug with hot water from pan to measure amount. Then pour mug into French Press and add a few tablespoons more water from pan.
4. Stir (some also stir again after a minute or so)
5. Press and pour after 2-3 minutes. Never go past 3 minutes or coffee will become bitter.
6. Leave the last bit of coffee in the press when you pour. It will be gritty and nasty. Same may go for your mug. Depending on how much grit you left or didn't leave in the press, is how much may be at the bottom of your mug.
Voila!
In no time you'll have it all figured out!
Now enjoy your coffee as it was meant to be and start a whole new chapter in your life!
EDIT: Added #6
.
* This post was
edited 09/03/10 08:56am by KendallP *
Cheers,
Kendall
1986 Winnebago Chieftain 22RC
Our Camper (with no payments)
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Old & Slow
Texas
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Joined: 07/25/2007
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KendallP wrote:pianotuna wrote:In real life, there likely would be so much voltage drop that at 2000 watts the inverter would fault out from low voltage. You might be able to manage five minutes--if the batteries are really new and well charged. Or if they were AGM format they would run a lot longer.
Really a 750 watt inverter is about all two golf cart batteries can manage to power, other than for "brief" bursts of power (one minute to warm a cup of soup in the microwave, etc.)
To me, this is the best, most succinct post. There's your answer.
Unless you want to change battery type and/or add extra batteries, a 750W inverter is about all you want to do. This will run neither the mic, nor the coffee maker.
So... moving on to plan B...
A French Press is considered one of the very best ways to brew coffee. I have one that will do a good 3 mugs at a time (6 "cups')
For a single mug...
1. Heat water to about 190 - 200 deg. F or just below boiling (boiling water burns coffee, a-la a percolator which... CONTINUALLY burns the coffee as it percolates over and over.)
2. Grind coffee coarsely and add amount to taste to French Press.
3. Fill mug with hot water from pan to measure amount. Then pour mug into French Press and add a few tablespoons more water from pan.
4. Stir (some also stir again after a minute or so)
5. Press and pour after 2-3 minutes. Never go past 3 minutes or coffee will become bitter.
Voila!
Now enjoy your coffee as it was meant to be and start a whole new chapter in your life!
Not much life left at age 76, but the two posts above just about do me in
First, I had allusions I could get meself 4 nice T105's and a Aims 3000w Inverter (cheap skate me) and cool the 'rear' BR with a 6000 btu A/C for a rest stop for 3/4 hours. Now, that big idea just flew de coop.
Second, I grew up on the Kuskokwim River in Alaska with a Dog Sled for the RV. Moon light and candles for light, matches to light the fire and the big pot to boil de water. Through in 'coffee' let her boil and 'oh that taste'. Take me back to 44 and my Native/'French' girl friend and my boiled coffee. Life was never better
Carry on,
Old & Slow
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JenniferW
In my RV, somewhere
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Joined: 04/07/2009
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I realized I was asking the wrong question!
But, thanks to all of your for your help. My goal is still to really understand my electrical system. Since I want to eventually move to solar, I appreciate the detailed explanations.
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vermilye
Oswego, NY, USA
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No one has mentioned the Melita drip method. Heat the water on the stove & use a Melita filter & cone. No different from a standard drip coffee maker:
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KendallP
Grants Pass, OR
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vermilye wrote:No one has mentioned the Melita drip method. Heat the water on the stove & use a Melita filter & cone. No different from a standard drip coffee maker:
Yeah, I did in my first reply. I just didn't call it by name.
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KendallP
Grants Pass, OR
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I'm pleased to report that I received a PM from Jennifer stating that we have solved her problem with our alternate coffee brewing methods! She said she had tried the percolator method and was unimpressed. Sounds like she's going to try the French Press.
She no longer feels any need for a high capacity inverter.
Good work, you bunch of RV superheroes!
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