rfrogger120
Expert Expediter
for a 5000 BTU airconditioner, will a 750 watt inverter be enough, this is for a cargo van.
inverter question
- Thread starter rfrogger120
- Start date
I run a 5200BTU...and the label says 525 watts, BUT I don't believe a 750 will handle the surge when the compressor comes on..I could be wrong..
riverrat2000
Seasoned Expediter
750 watt inverter should be able to handle a 1500 watt surge, however a 750 watt inverter is awful small, I run a 3000 watt unit that works well. The smallest I ever had was 1500 and it didn't last long until it stopped working, my way of thinking is in this instance bigger IS better
dhalltoyo
Veteran Expediter
Thornapple
Seasoned Expediter
How long will a pair of deep cell batteries last running an airconditioner like that?
Wouldn't it be be better to get a small generator?
t.
Wouldn't it be be better to get a small generator?
t.
>How long will a pair of deep cell batteries last running an
>airconditioner like that?
Kinda depends on the total amp hours of the deep cycle batteries.
If it's a 525 watt air conditioner, which is a 120-volt unit, probably not very long, regardless of the amp hours of the batteries. 525 watts divided by 120 volts is 4.375 amps AC. Going from AC to 12-volts DC you have to multiply by 10, so the 4.375 amps becomes 43.75 amps DC. Then give it 10% for the loss in the inversion process and you're at 48.125 amps.
If you've got a couple of 100 amp hour batteries, 200 amp hours total, then you could run that AC for 4.155 hours, except that the Peukert Effect turns the 200 amp hours into 124.93 amp hours, and it'll be run down to dead in about 2.6 hours (and then it'll take about 4 hours to fully recharge them using an alternator). Except that when discharged down that low, below 50%, it'll never be able to be fully recharged to 200 amp hours again, and the next time it's fully recharged (at least to the amount of amps that the battery will now hold), assuming that it actually is fully recharged before using it again, you'll be lucky to get 180 amp hours available. So the [/i]next[/i] time you run it dead, it'll be run down in 2.27 hours instead of 2.6, and the next time after that it'll be dead in about 2.0 hours, and so on and so on until pretty soon you'll be mad and wondering the batteries don't work anymore.
>Wouldn't it be be better to get a small generator?
>t.
That, or several high end deep cycle batteries and a very efficient DC air conditioner.
Every battery expert and renewable energy expert will tell you, unless you are using 12 volt or 24 volt DC appliances (air conditioners, refrigerators, etc.) that long-term high draw, resistive heat applications like air conditioners and electric heaters from battery power is easily the least cost effective method versus a generator or DC powered appliances. You're lucky if even 50% of the energy created by the vehicle's engine and alternator is transferred into the storage batteries, and you'll lose 10% of the stored power right off the top in the inverter process, so you're essentially getting perhaps 40% of the power that was generated, wasting at least 60%. Wasted in heat energy in the engine, wear and tear, and fuel and oil costs. Unless you are using high end batteries specifically designed for high load amp draws, you're wasting even more potential energy, and add to that the Peukert Efffect and it's even more dismal.
If you want to run a 525 watt appliance for 8 hours, and do it efficiently, you'll need at minimum of 930 amp hours worth of batteries (roughly 500 pounds of lead), which will bump the Perkert Effect up to give you enough amp hours to keep from running the batteries down more than 50% after 8 hours. And after 8 hours you need to figure a way to get 450 amps back into the batteries, which will take around 8 hours with a 150 amp alternator.
Slow and steady, even in expediting, wins the race - Aesop
>airconditioner like that?
Kinda depends on the total amp hours of the deep cycle batteries.
If it's a 525 watt air conditioner, which is a 120-volt unit, probably not very long, regardless of the amp hours of the batteries. 525 watts divided by 120 volts is 4.375 amps AC. Going from AC to 12-volts DC you have to multiply by 10, so the 4.375 amps becomes 43.75 amps DC. Then give it 10% for the loss in the inversion process and you're at 48.125 amps.
If you've got a couple of 100 amp hour batteries, 200 amp hours total, then you could run that AC for 4.155 hours, except that the Peukert Effect turns the 200 amp hours into 124.93 amp hours, and it'll be run down to dead in about 2.6 hours (and then it'll take about 4 hours to fully recharge them using an alternator). Except that when discharged down that low, below 50%, it'll never be able to be fully recharged to 200 amp hours again, and the next time it's fully recharged (at least to the amount of amps that the battery will now hold), assuming that it actually is fully recharged before using it again, you'll be lucky to get 180 amp hours available. So the [/i]next[/i] time you run it dead, it'll be run down in 2.27 hours instead of 2.6, and the next time after that it'll be dead in about 2.0 hours, and so on and so on until pretty soon you'll be mad and wondering the batteries don't work anymore.
>Wouldn't it be be better to get a small generator?
>t.
That, or several high end deep cycle batteries and a very efficient DC air conditioner.
Every battery expert and renewable energy expert will tell you, unless you are using 12 volt or 24 volt DC appliances (air conditioners, refrigerators, etc.) that long-term high draw, resistive heat applications like air conditioners and electric heaters from battery power is easily the least cost effective method versus a generator or DC powered appliances. You're lucky if even 50% of the energy created by the vehicle's engine and alternator is transferred into the storage batteries, and you'll lose 10% of the stored power right off the top in the inverter process, so you're essentially getting perhaps 40% of the power that was generated, wasting at least 60%. Wasted in heat energy in the engine, wear and tear, and fuel and oil costs. Unless you are using high end batteries specifically designed for high load amp draws, you're wasting even more potential energy, and add to that the Peukert Efffect and it's even more dismal.
If you want to run a 525 watt appliance for 8 hours, and do it efficiently, you'll need at minimum of 930 amp hours worth of batteries (roughly 500 pounds of lead), which will bump the Perkert Effect up to give you enough amp hours to keep from running the batteries down more than 50% after 8 hours. And after 8 hours you need to figure a way to get 450 amps back into the batteries, which will take around 8 hours with a 150 amp alternator.
Slow and steady, even in expediting, wins the race - Aesop
Here is a 12 Volt cooler...Sounds to good to be true. Prob needs tons of ice. "Testimonials" are interesting.
http://www.kooleraire.com/kooleraire25.htm
http://www.kooleraire.com/kooleraire25.htm
rfrogger120
Expert Expediter
after reading all the replies, I think my best bet would be to get a generator, I think a 2000 watt generator will do it. I can get a 2000 watt generator for $200.00 and it only weighs 60lbs.
Kinda in response to Turtle's post, we have went to a two banks of batteries set up. We have the three standard batteries on one side under the driver door, and on the passenger side is three golf cart batteries. There is a selenoid between them that controls the charging. It determines the source (engine or APU) and what needs the charge between batteries.
So far it seems to be working well. This setup prevents the actual truck batteries from ever being drawn down from sleeper usage.
Davekc
owner
23 years
PantherII
EO moderator
So far it seems to be working well. This setup prevents the actual truck batteries from ever being drawn down from sleeper usage.
Davekc
owner
23 years
PantherII
EO moderator
Dave, are you doing this to cut down on APU use? If so, do you have an estimate on cost effectiveness? So far I'm pretty happy with my factory batteries and the Rig Master.
That's the way to do it - i.e., leave the starter batteries alone, that way when it's really cold they'll still have as much juice as the cold will allow them to have, and then run everything else off the house bank, using the APU to recharge them and to run high draw stuff like an air conditioner.
Slow and steady, even in expediting, wins the race - Aesop
Slow and steady, even in expediting, wins the race - Aesop
Turtle is right. It is in response to the massive draw down from microwaves and hair dryers etc. We so far have wiped out the batteries on our Sterling the first six months or so. On our KW is where we put this setup. The rigmaster is set to come on when the voltage on either battery bank gets too low. You can run everything in the sleeper for quite some time before the generator will come on in favorable weather. The rigmaster runs now more often because it is sitting in 100 plus temps.
It throws a charge to the main batteries if they need it, but uses the deep cycles for everything else including the starting.
If it performs well over time, then I will throw this setup on the Sterling. It does add a few extra pounds but nothing major.
Davekc
owner
23 years
PantherII
EO moderator
It throws a charge to the main batteries if they need it, but uses the deep cycles for everything else including the starting.
If it performs well over time, then I will throw this setup on the Sterling. It does add a few extra pounds but nothing major.
Davekc
owner
23 years
PantherII
EO moderator