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bajapedro
Nomad
Posts: 144
Registered: 3-2-2016
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just returned from off grid casa south of San Felipe.
Ran a Sharkaire 8000btu 24VDC mini split in my bedroom all night. (500 watt draw) Insulated windows, white roof with 4" rigid foam insulation in
ceiling (R-26).
Supported with 4kw solar array and 4 200ah 24v lithium-iron batteries.
No generator.
No problems with power.
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RFClark
Super Nomad
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Registered: 8-27-2015
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We have a 220v 19 SEER 18K btu AC in our BR average draw is 200-300W we run it all nght!
[Edited on 6-23-2022 by RFClark]
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Udo
Elite Nomad
Posts: 6337
Registered: 4-26-2008
Location: Black Hills, SD/Ensenada/San Felipe
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Mood: TEQUILA!
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I have a house in San Felipe also. We are looking at spending more time there in the summer months.
We currently have 12 solar panels (450 W. each) and 16 standard golf cart batteries. I am considering using the Li batteries. Which ones are you
using? What voltage are they? How much were they and where did you buy them? Thanks for your help!
Quote: Originally posted by RFClark  | Come and visit us.
Humidity is our big problem. Right next to the beach the temperature runs mid 80s to 90 degrees daytime going down to 74 around 2:00 to 3:00 in the
early morning currently. Humidity runs 70-90% (we collect around 8 gal of water per day)
Currently we run the AC from 7:00 to 19:30. We hold the temperature around 75F. After sunset it takes 700W to hold that temperature (1200sq ft house).
That would be around 7KW of battery overnight. We have 15KW of Li Ion batteries available to use. When necessary we have a 9KW propane inverter
generator that can charge the batteries at 100A (5KW) and carry the electrical load. So we can generate a nights worth of electricity in under 2 Hrs.
To generate 100% of the 20KW we use a day would require running 5hrs! |
Udo
Youth is wasted on the young!
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RFClark
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Udo,
Are you running a 24V or 48V system? You should be! I bought my batteries on Amazon. I’m running these in 2 different systems and am very happy.
https://www.amazon.com/dp/B094NN5KWY/ref=sspa_dk_detail_0?pd...
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Bob and Susan
Elite Nomad
Posts: 8809
Registered: 8-20-2003
Location: Mulege BCS on the BAY
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| Quote: Originally posted by RFClark | We have a 220v 19 SEER 18K btu AC in our BR average draw is 200-300W we run it all nght!
[Edited on 6-23-2022 by RFClark] |
impossible...you are reading your data wrong
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Bob and Susan
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its never matters what the voltage you are running
higher voltage only means you can use smaller wire
the circuit boards in an inverter all act the same... dont be fooled by hype
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SFandH
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Hmm, two contradictory statements.
If you have long cable runs you'll spend a lot less money on wire of the proper gauge if you run at a higher voltage because your amperage will go
down. Also, heat loss is a function of the current. Less current, less loss to heat generation in the wires. Double the voltage and halve the current
for a given power level.
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JDCanuck
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Registered: 2-22-2020
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Udo: Lithium batteries have come down in price so far it seems unreasonable to use lead acid anymore. We can draw ours down 80 percent every day and
still get over 6000 cycles out of them. With lead acid you would have to almost double the rated size, draw them down no more than 50% and then expect
5 years at that draw rate before you had to replace them.
We have 6 of these batteries in a rack and we have never needed more for our fully electric 2800 sq ft house. Cost including installation labour was
10000 USD, would be cheaper now.
https://www.vpsolar.com/en/product/pylontech-us3000-lithium-...
[Edited on 6-23-2022 by JDCanuck]
[Edited on 6-23-2022 by JDCanuck]
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PaulW
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Now lithium price has gone up over 600% Maybe they are not as good of an investment now. Cobalt is higher as well but not a much a lithium.
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JDCanuck
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| Quote: Originally posted by PaulW | | Now lithium price has gone up over 600% Maybe they are not as good of an investment now. Cobalt is higher as well but not a much a lithium.
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I've noted all the battery types have risen very recently in price due to supply issues. Mine were purchased in early 2021, dropped since then while
lead acids rose, but you are right, have risen again recently. It will take a fair while for cost declines to begin again, and by then we will see
even more technology applied. I am still fascinated by how the F150 lightning packs 120kwh into a truck that cheaply. The truck itself is essentially
free outside of the batteries cost.
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RFClark
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B&S
Ever hear of Ohm’s Law or Inverter ACs?
The reason you run 48V inverter systems is not just because you can use smaller cables. It’s because it requires 1/4 the amps as a 12V system to do
the same job actually less than 1/4 because the losses are 1/16 that of a 12V system. The losses in cables, connectors and internal in the batteries
and inverters are the “R” in Watts = the Current squared times the Resistance!
Inverter vs non-inverter AC units! Old non-inverter AC turn on and off to control temperature. Most require 3 or more times their rated power to
start. More Amps, more losses!
Inverter ACs soft start (much less than the full rated power) and ramp up over 20-30S, as they run and as the area cools down they decrease the amount
of cooling to equal the heat load. They try not to stop but if the cooling load is less than their lowest level they stop until the temperature rises
and start at much less than full power. With the reduced power levels our 18K Btu 220V BR unit uses about .3KW per Hr average over 5-6 Hrs. We produce
about 700W from sunrise on a clear morning and 1.5KW by 8:15 right now (Trackers)! That’s why we can run AC off of batteries. The power requirements
are greater if it’s windy and damp obviously and greater when the sun is shining. But we don’t draw down the batteries when the sun is shining
either.
Our mid-day peak for both systems is about 5KW and 40KW Hrs per day!
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PaulW
Ultra Nomad
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True, the cycle of continued price reductions will continue once the cost of rare materials stabilize.
However new battery technology is nearby and will not use lithium or cobalt and provide significant performance improvement with predicted lower cost
once the EVs start using them. Of course then the existing batteries will get even less costly.
Not a useful comment for those like you that already are set with existing batteries. Newbies will be happy when the latest batteries show up. with
new or old technology based on lower cost.
=== ===
| Quote: Originally posted by JDCanuck | | Quote: Originally posted by PaulW | | Now lithium price has gone up over 600% Maybe they are not as good of an investment now. Cobalt is higher as well but not a much a lithium.
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I've noted all the battery types have risen very recently in price due to supply issues. Mine were purchased in early 2021, dropped since then while
lead acids rose, but you are right, have risen again recently. It will take a fair while for cost declines to begin again, and by then we will see
even more technology applied. I am still fascinated by how the F150 lightning packs 120kwh into a truck that cheaply. The truck itself is essentially
free outside of the batteries cost. |
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Bob and Susan
Elite Nomad
Posts: 8809
Registered: 8-20-2003
Location: Mulege BCS on the BAY
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| Quote: Originally posted by RFClark | B&S
Ever hear of Ohm’s Law or Inverter ACs?
The reason you run 48V inverter systems is not just because you can use smaller cables. It’s because it requires 1/4 the amps as a 12V system to do
the same job actually less than 1/4 because the losses are 1/16 that of a 12V system. The losses in cables, connectors and internal in the batteries
and inverters are the “R” in Watts = the Current squared times the Resistance!
Inverter vs non-inverter AC units! Old non-inverter AC turn on and off to control temperature. Most require 3 or more times their rated power to
start. More Amps, more losses!
Inverter ACs soft start (much less than the full rated power) and ramp up over 20-30S, as they run and as the area cools down they decrease the amount
of cooling to equal the heat load. They try not to stop but if the cooling load is less than their lowest level they stop until the temperature rises
and start at much less than full power. With the reduced power levels our 18K Btu 220V BR unit uses about .3KW per Hr average over 5-6 Hrs. We produce
about 700W from sunrise on a clear morning and 1.5KW by 8:15 right now (Trackers)! That’s why we can run AC off of batteries. The power requirements
are greater if it’s windy and damp obviously and greater when the sun is shining. But we don’t draw down the batteries when the sun is shining
either.
Our mid-day peak for both systems is about 5KW and 40KW Hrs per day! |
OMG... having a 220v appliance saves you NO MONEY
the appliance runs cooler but you still use the same energy
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RFClark
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B&S,
Politely as possible! I’ve done this for over 60 years! 220V uses 1/2 the Amps or less than 120V for the same work. 220 is a balanced load too!
1/2 the amps is 1/4 the wasted electricity be it CFE ($$$) or solar! Is there some part of less waste you’re missing? You even mention that the
equipment runs cooler on 220V! Where do you think all that heat comes from and who pays for it?
[Edited on 6-25-2022 by RFClark]
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4x4abc
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Location: La Paz, BCS
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CFE charges you for the kW hours (kW/h) used
so, you run a 2 ton AC during the heat 24 hours and it draws 9 amps wired to 220V
24hx9Ax220V= 47,520 W/h = 47.5 kWh
you run a 2 ton AC during the heat 24 hours and it draws 18 amps wired to 110V
24hx18Ax110V= 47,520 W/h = 47.5 kWh
CFE currently charges about 0.9 Pesos per kW/h - 42.75 Pesos per day
can you please calculate the losses in 200V and 110V in the above model in Pesos?
So we can understand the savings of 220V
[Edited on 6-25-2022 by 4x4abc]
Harald Pietschmann
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RFClark
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OK, I’ll see if I find the same AC in 120 & 220V. The losses in the inverter are real too and probably greater. Since this is about off the grid
AC I’ll see if I can do an end to end estimate. The first thing that comes to mind is inverter capacity. A 120V load uses the same capacity as a
220V load (220 split phase inverter) so unless you balance your 120V loads you could run out of capacity. Balanced loads is what 220 does
automatically.
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JDCanuck
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Posts: 1341
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Higher amps, more heat losses downstream of the meter. More heat losses, less useful work. Pretty simple explanation to me RFClark.
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SFandH
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| Quote: Originally posted by JDCanuck | | Higher amps, more heat losses downstream of the meter. More heat losses, less useful work. Pretty simple explanation to me RFClark.
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You deleted your VAR, inductance, capacitance, AC circuit engineering spiel. I thought that was pretty good.
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JDCanuck
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Sorry SFandH: I decided I was opening a whole other can of worms when we are still trying to get on top of this one. This is not an Electrical
Engineering site.
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SFandH
Elite Nomad
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| Quote: Originally posted by 4x4abc | CFE charges you for the kW hours (kW/h) used
so, you run a 2 ton AC during the heat 24 hours and it draws 9 amps wired to 220V
24hx9Ax220V= 47,520 W/h = 47.5 kWh
you run a 2 ton AC during the heat 24 hours and it draws 18 amps wired to 110V
24hx18Ax110V= 47,520 W/h = 47.5 kWh
CFE currently charges about 0.9 Pesos per kW/h - 42.75 Pesos per day
can you please calculate the losses in 200V and 110V in the above model in Pesos?
So we can understand the savings of 220V
[Edited on 6-25-2022 by 4x4abc] |
I think a big part of the savings is in the cost to build the system. If you have long cable runs higher voltage allows for higher gauge (smaller
diameter) wire which is significantly cheaper than low gauge wire. I'm not sure about the significance of percent savings on day-to-day operation. I
suspect JD knows.
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