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Fuel consumption


Flyinhy
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Has anyone sat down and calculated how much fuel is consumed under a semi load on their generator? I'm running my fridge and 1 a/c and I was just curious if my numbers were right. I'm seeing about 1/2 a gallon per hour. I'm sure it's in print somewhere but I'm not finding it.

Does that sound about right? At 6 bucks a gallon it's kinda expensive.

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My rule of thumb (based on experience) is about 1 gal/hr under full load (both ACs and misc loads), so with 1 AC (fridge uses minor amount compared to AC), and 1/2 gal/hr sounds about right. 

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36 minutes ago, Flyinhy said:

Has anyone sat down and calculated how much fuel is consumed under a semi load on their generator? I'm running my fridge and 1 a/c and I was just curious if my numbers were right. I'm seeing about 1/2 a gallon per hour. I'm sure it's in print somewhere but I'm not finding it.

Does that sound about right? At 6 bucks a gallon it's kinda expensive.

I have seen that number stated on here in the past.  It was usually in regards to running the gen while traveling so the roof A/Cs could keep everyone cool.  Of course back then the cost was considered negligable, now like you say it gets expensive.

Life just won't give us a break will it?  

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Look at your Genny manual Or down load it.  Most ONANS have a fuel consumption section.  Memory says mine is 1/2 GPH @ 50%.  50% equals 4 KW.  That’s about 35 amps.  Overkill for one AC & A REFER. MARGINAL for 2 AC….BUT 0.6 or 0.65 GPH is my best “Educated” guess.  If you have a 10Kw, then the 50% GPH is a good number for 2 AC and a refrigerator as well. Do the math.  An 8 KW @ 0.6 GPH will be 0.6 X $ 6.50 ($$/Gallon) or $3.25 Per Hour.

if you drive around 62 MPH on mostly level roads with cruise, you probably get 8 MPG.  62 MILES in an hour divided by 8 equals 7.75 gallons.  Multiplied by $6.50 equals $50.38 per hour.

use the front AC… the estimates vary from 10 - 15% lower MPG.  Use 12.5.  ONE minus 0.125 equals 0.875.  So your 8 MPG drops to 7 MPG.  ( 8 TIMES 0.875). Divide 62 by 7 equals 8.86 gallons in an hour.  TIMES $6.50 equals $57.57.  Subtract $50.38 (cost per hour @ 8 MPG) FROM $57.57 (cost per hour @ 7 mpg) equals $7.19 or the additional cost of running the front HVAC.  That is more than TWICE the cost per hour with the Genny ON and getting better mileage.

Use your own numbers….and price of diesel.  Generally speaking, your Genny is cheaper than the front HVAC and you have more comfort.  Opps, the air up front is not as cool.  So for driver comfort, have a small DC powered Trucker Fan OR a small 115VAC oscillating fan on the floor between the two front seats..  Use a piece of the RV non Skid rubber to keep it stable.  We do

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Pretty much exactly what Tom has outlined above...our experience after 300k miles split over two coaches.  I don't even have a belt on the dash a/c on this one, being in the South and West a lot, dash air is pretty much useless.

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