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Old 11-28-2016, 07:25 PM   #11
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my 28' camping trailer uses 12v for fridge (when on propane), the radio and lighting, and thermostat/elec ignition for the furnace (propane also).

To use a microwave or any of the 120v outlets i need to be plugged into shore power (30 amp, which runs everything including 220v 13,000btu a/c unit).

I have a 30amp/220v plug to normal 110v plug adapter (and a 30 to 50 as well) and that runs all but the a/c (since it needs 220).

Haven't torn the camper apart, but the charger/converter takes care of charging the house battery when plugged into shore power.

the panel look ssomething like this - with 110v breakers and 12v fuses.



when i turn on a lot of 12v lights a fan in the inverter kicks on to keep it cool.

As for converter - turning 12v into 110v..other than a microwave or charging a laptop you probably don't need 110v from a battery source.

The few i've used seem to kill a battery pretty darned quickly.
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Old 11-28-2016, 07:27 PM   #12
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I'll add a very minor improvement to AlleyCat67s diagram:



If you pull off of opposite corners of the bank the batteries are more likely to stay equalized. Pulling off of one end of the bank will tend to tax the first set of batteries more than the next set due to that bit of resistance in the longer leads.


Actually, the bottom diagram in this next picture might better explain what I'm talking about:
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Old 11-28-2016, 07:35 PM   #13
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if i'm doing this right...

a 1500w 120v hair dryer running off 12v for .2/hr (12min) will need/consume 214ah of battery capacity.

HP and fuel engines i get..elec i get the concept (ohm, volts, watts, etc) but trying to take a load and work back to capacity seems to trip me up...

I used these sites to get my answer..am I right?

https://www.batterystuff.com/kb/tool...-inverter.html

https://www.batterystuff.com/kb/tool...to-a-load.html

and the math behind it all...and they why's and what fors.
https://www.batterystuff.com/kb/tool...-capacity.html
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Old 11-28-2016, 08:53 PM   #14
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Not quite 214Ah ☺️
1500w at 12v is 125a (1500 / 12 = 125).
Running that dryer for an hour would consume 125 amp hours (amps per hour).
12 minutes divided by 60 minutes is 0.2 hours.
125Ah multiplied by 0.2 is 25Ah.
So running for 12 minutes should consume 25amp hours from the battery bank plus a bit more due to wire resistance and inverter inefficiencies..
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Old 11-29-2016, 02:11 AM   #15
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who's got the best price on panels right now. I heard a mention of California company green something maybe? they make there own. 100 or 139?
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Old 11-29-2016, 02:35 AM   #16
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Maybe it was these guys?

Buy Solar Panels, Solar Power Kits, DIY Solar Panel Kits for Sale

When I get ready to get my panels I don't necessarily care if they're made in USA, just so they're not made in China.
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Old 11-29-2016, 07:06 AM   #17
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ive dealt with this company, good service.
https://www.altestore.com/store/sola...-frame-p11195/
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Old 11-29-2016, 07:32 AM   #18
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We got all our components, including panels, from Solar Panels from Wholesale Solar. They were very helpful and the prices seemed comparable to, if not better than, most. Probably not as cheap as building your own system, though.
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Old 11-29-2016, 08:37 AM   #19
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A hair dryer is 1500 w at 120v, not 12.
the site also talked about a 15-20% loss during the conversion process from 12v to 120v.


Quote:
Originally Posted by jazty View Post
Not quite 214Ah ☺️
1500w at 12v is 125a (1500 / 12 = 125).
Running that dryer for an hour would consume 125 amp hours (amps per hour).
12 minutes divided by 60 minutes is 0.2 hours.
125Ah multiplied by 0.2 is 25Ah.
So running for 12 minutes should consume 25amp hours from the battery bank plus a bit more due to wire resistance and inverter inefficiencies..
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Old 11-29-2016, 09:31 AM   #20
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Quote:
Originally Posted by prof.fate View Post
A hair dryer is 1500 w at 120v, not 12.
the site also talked about a 15-20% loss during the conversion process from 12v to 120v.

True! It runs at 120v, but it's 1500w. That 1500 watts is static and can be used to calculate the amps for other voltages as well.

1500w at 120v converts to 12.5 amps (1500 / 120). That's why it can run on a 15a household breaker, but may trip if other appliances are also run.

1500w at 12v converts to 125 amps (1500 / 12). That's the relationship between watts, amps and volts.. Since you're trying to figure out the draw on the batteries you need to use the bank voltage which is 12 volts. Add the inefficiencies later.

20% is way on the high end for losses. If you size you're wiring appropriately you'll probably be closer to 10%. Resistive devices (in this case the heating element of the hair dryer) don't lose as much efficiency as motorized devices (e.g. circular saw) when used with a modified sine wave inverter.

Now looking at my last post if you tack on 20% to 25Ah you're up to 30Ah. Not a significant difference, but it's sad to see those electrons wasting away...
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