FAQ: Can I run an Air Conditioner on battery/solar?

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Re: FAQ: Can I run an Air Conditioner on battery/solar?

Postby capnTelescope » Tue Nov 07, 2017 6:27 pm

Aguyfromohio wrote:... I sure would like to hear more about what you think went wrong with yours...

A few things went wrong. I use the (in)famous DC-AC-DC method, where the TV supplies 12V to the trailer to run an inverter that runs a smart charger. This worked fine until I put the Indel fridge in. This is good for two-three days without shorepower, but would take seemingly forever to top off the battery. I upgraded from an 8 amp charger to a 15 amp one. Also upgraded the inverter from 400 to 600 watts. Also upgraded the (hot while the TV is running) 10 AWG feed line to 6 AWG.

What could go wrong, right? Well, the 6AWG was CCA (copper coated aluminum) el cheapo Harbor Fright jumper cables. Thought I was saving money by using that for the wire. I discovered the meaning of CCA after I voided the warranty on the jumpers. The voltage drop on this line was HUGE (2 to 3 volts) from battery to inverter. Shoulda used all-copper wire. The new inverter didn't like the low volts and would fault out. I also think the new inverter used a lot more current than the old 400W one, which contributed to the voltage drop. I'm going back to the 400W inverter even though it is slightly marginal.

But wait, there's more. I was using a 120V DPDT (double pole, double throw) relay, powered by the inverter, to handle the automatic changeover from shore to TV power. The relay would drop out when the inverter output got low, meaning that intermittently no power got to the charger or fridge. I'm upgrading to a DPDT relay with a 12 volt coil. The coil will be activated by the old 10AWG line, and the inverter power will come from the new-new 6AWG copper through a single pole connector. Putting the relay on its own 12V line should eliminate the low relay coil voltage problem.

Aguyfromohio wrote:... so we can make entirely different mistakes instead of repeating your mistakes.

I heartily endorse that idea. I seem to remember someone somewhere advising against CCA wire. Consider using 4AWG copper. Or larger.

Socal Tom wrote:a little inverter genny is a often the best option.

I agree. OTOH, :thinking: if you're running a generator so you can have A/C at night, are you really boondocking, or are you just glamping out in the sticks? :NC
I'll burn that bridge when I come to it.

Brad
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Re: FAQ: Can I run an Air Conditioner on battery/solar?

Postby Socal Tom » Tue Nov 07, 2017 8:53 pm

I’m just using a 12ga wire in a 7 pin connector. Last trip the TD battery was at 12.2 volts when I checked in the am, over 13v when I got home 2 hours later. What’s the advantage of the dc-ac-dc method?


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FAQ: Can I run an Air Conditioner on battery/solar?

Postby Socal Tom » Tue Nov 07, 2017 8:54 pm

capnTelescope wrote:
Aguyfromohio wrote:... I sure would like to hear more about what you think went wrong with yours...

A few things went wrong. I use the (in)famous DC-AC-DC method, where the TV supplies 12V to the trailer to run an inverter that runs a smart charger. This worked fine until I put the Indel fridge in. This is good for two-three days without shorepower, but would take seemingly forever to top off the battery. I upgraded from an 8 amp charger to a 15 amp one. Also upgraded the inverter from 400 to 600 watts. Also upgraded the (hot while the TV is running) 10 AWG feed line to 6 AWG.

What could go wrong, right? Well, the 6AWG was CCA (copper coated aluminum) el cheapo Harbor Fright jumper cables. Thought I was saving money by using that for the wire. I discovered the meaning of CCA after I voided the warranty on the jumpers. The voltage drop on this line was HUGE (2 to 3 volts) from battery to inverter. Shoulda used all-copper wire. The new inverter didn't like the low volts and would fault out. I also think the new inverter used a lot more current than the old 400W one, which contributed to the voltage drop. I'm going back to the 400W inverter even though it is slightly marginal.

But wait, there's more. I was using a 120V DPDT (double pole, double throw) relay, powered by the inverter, to handle the automatic changeover from shore to TV power. The relay would drop out when the inverter output got low, meaning that intermittently no power got to the charger or fridge. I'm upgrading to a DPDT relay with a 12 volt coil. The coil will be activated by the old 10AWG line, and the inverter power will come from the new-new 6AWG copper through a single pole connector. Putting the relay on its own 12V line should eliminate the low relay coil voltage problem.

Aguyfromohio wrote:... so we can make entirely different mistakes instead of repeating your mistakes.

I heartily endorse that idea. I seem to remember someone somewhere advising against CCA wire. Consider using 4AWG copper. Or larger.

Socal Tom wrote:a little inverter genny is a often the best option.

I agree. OTOH, :thinking: if you're running a generator so you can have A/C at night, are you really boondocking, or are you just glamping out in the sticks? :NC
If you’re in a TD you are glamping.


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Re: FAQ: Can I run an Air Conditioner on battery/solar?

Postby capnTelescope » Wed Nov 08, 2017 12:34 am

Socal Tom wrote:If you’re in a TD you are glamping.

:ok: I was wondering if anyone would catch that. :D

Socal Tom wrote:I’m just using a 12ga wire in a 7 pin connector.

That's nicely heavy duty IMHO. I'm running 12ga for the brakes, running lights are tapped into the TV's tail lights, which look to be about 18ga or similar metric size, Then there's 10ga and 6ga coming off the battery thru a solenoid that's hot when the TV's key is in the run position

Socal Tom wrote:What’s the advantage of the dc-ac-dc method?

:scratchthinking: Mostly, you get to use a smart charger while you are driving, which pampers that expensive battery in the TD. It also allows the TV's computers to properly charge the TV's battery without overcharge. I wasn't particularly sold on the idea of running TV voltages to the TD's battery way back under the galley. You get a little 120VAC in the TD to do with as you wish. (I keep a power strip plugged into it to run chargers or whatever.) I like playing with electricity.
I'll burn that bridge when I come to it.

Brad
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