12 volt AC unit

[Steve Hunt]

Anyone have any experience with this brand of AC? It's a 12volt with a 14"x14" roof hole which seems to be rare on 12v units for some reason.

https://dcpowersales.com/products-2/b-cool12000rm-rv/

[posplayr]

If you search on Amazon or Aliexpress you will find a growing number of lower-power (600--800 watts) 12V models. PRices have been dropping close to $1-1.3K

Most of the ones that are direct from China will need to be charged (freon). Those you can order domestically are more likely to be already charged.

This is a cheap DIY model

https://www.amazon.com/Universal-ele...15080874&psc=1

This is an integrated unit which costs more.

https://www.amazon.com/Conditioner-E...08273191&psc=1


This integrated unit is 300-800W
https://www.amazon.com/RV65F-Univers.../dp/B0B3BQV177

[posplayr]

This is a Treeligo brand you can order direct from AliExpress $800 shipped or for about $1260 from Amazon. With Amazon, you can buy 3-4 years of insurance.

https://www.amazon.com/dp/B09WMNQ5LF...xpY2s9dHJ1ZQ==

900 watts 30-70 amps and minimum recommended battery of 200 Amp-hr




https://www.aliexpress.us/item/32568...andl_shipto=US

[Steve Hunt]

Originally Posted by Steve Hunt

Anyone have any experience with this brand of AC? It's a 12volt with a 14"x14" roof hole which seems to be rare on 12v units for some reason.

https://dcpowersales.com/products-2/b-cool12000rm-rv/

Looks like Thompson Tractor, the Caterpillar dealer, is their distributor for Alabama. So that is a good sign.
Well that never happens for me, they have a Florida distributor in Jacksonville, I'll go over there and take a look this week.

[Steve Hunt]

My primary draw to the DC air conditioner is for lunch stops and the like (1hr or less) and the overall noise or lack off. According to the spec sheets the DC air conditioners are considerably more quiet. The thing i don't 100% know is if sleeping with the DC air conditioner running and also plugged into shore power...when my 200 amp hr of Lithium runs low does the inverter/charger just simply start charging the batteries before they run completely out and so I won't really know anything is happening, the air conditioner just keeps running uninterrupted ? If so then the only downside i see on a DC air conditioner is the initial cost. Am i missing anything?

[posplayr]

On the compressor look for a "scroll type variable frequency". I have never tested one but the variable frequency implies a solid-state inverter that can drive at higher or lower frequencies where power output is proportional to frequency.

In contrast, from my testing with a typical house/window AC unit (5000 BTU), the power (using a Kilowatt meter) pretty much stays the same regardless of fan speed. I presume that power consumption is dominated by the compressor that is constan6t/synchronized to the 60 hz AC.

[posplayr]

Originally Posted by Steve Hunt

My primary draw to the DC air conditioner is for lunch stops and the like (1hr or less) and the overall noise or lack off. According to the spec sheets the DC air conditioners are considerably more quiet. The thing i don't 100% know is if sleeping with the DC air conditioner running and also plugged into shore power...when my 200 amp hr of Lithium runs low does the inverter/charger just simply start charging the batteries before they run completely out and so I won't really know anything is happening, the air conditioner just keeps running uninterrupted ? If so then the only downside i see on a DC air conditioner is the initial cost. Am i missing anything?

The lowest specs I have seen are 30-80A (presumably Low/Hi)for the 12V AC Units. So if you have a big enough 120VAC to 12V DC battery charger then you can run continuously all night.

In not, but your batteries are fully charged by evening, you can probably last most of the night between your 200 Amp-hrs stored and the additional charging current coming from a Shore power DC Charging.

Considering only stored battery power, If you can run the AC unit at 30 amps (on Low) then you have 200/30*80%=5.3 Hours of run time. At that point, even just an additional 20 amp charging from shore power should get you through the night. 8 hours (overnight) @ 20 amps is an additional 160 Amp-hrs which is again 5.3 hours compared to the stored battery power.

[Steve Hunt]

Originally Posted by posplayr

The lowest specs I have seen are 30-80A (presumably Low/Hi)for the 12V AC Units. So if you have a big enough 120VAC to 12V DC battery charger then you can run continuously all night.

In not, but your batteries are fully charged by evening, you can probably last most of the night between your 200 Amp-hrs stored and the additional charging current coming from a Shore power DC Charging.

Considering only stored battery power, If you can run the AC unit at 30 amps (on Low) then you have 200/30*80%=5.3 Hours of run time. At that point, even just an additional 20 amp charging from shore power should get you through the night. 8 hours (overnight) @ 20 amps is an additional 160 Amp-hrs which is again 5.3 hours compared to the stored battery power.

That’s great info/summary. Mine is a 2000w Renogy inverter/charger. The spec sheet says 5-65 amps dc charge current. What is the 80% in your example? assumed max out of my batteries?

[posplayr]

Originally Posted by Steve Hunt

That’s great info/summary. Mine is a 2000w Renogy inverter/charger. The spec sheet says 5-65 amps dc charge current. What is the 80% in your example? assumed max out of my batteries?

That is an interesting device. It seems more like a UPS that any RV-type device I have seen. It looks like it is what is called "Double Conversion". That basically means that AC input is converted to DC to charge a battery bank and that same battery is used for power into a DC-to-AC inverter. The other topology is called line-interactive. It doesn't have this strict (double conversion) separation between AC->DC and DC->AC .

This provides essentially total isolation between AC in and AC out. This is probably why you are not sure what is going on when you run the AC all night

https://www.eaton.com/us/en-us/produ...20and%20online.


It looks like you also have a DC-DC On-Board battery Charger with MPPT; is that correct? So you in addition to the unit above you connect direct to the battery as well for DC loads and Alternator/ Solar charging. That is a quiet capable setup in only two devices. I don't remember but doesn't that DC-DC also back charge to the start battery if it is low?

>>>What is the 80% in your example? assumed max out of my batteries?

Yes this assumes Lithium and 80% effective depth of charge (90%->10%) vs. 50% for lead Acid.

It seems you could go either way (AC AirCon or DC AirCon). If you want the off-grid capability and what is probably quieter operation then I would go with the 12V AirCon. The double conversion (if true) essentially means you should have no startup overload issues.

Most of the 12V ACon units are less than 1000W and you can run any combination of shore power or generator and the Battery to AC Out conversion essentially isolates your AirCon from the course especially if you are using Lithium (super low impedance).

I don't have any first-hand experience with either of these devices just reading the manual and I'm an aerospace EE.

[Steve Hunt]

Originally Posted by posplayr

That is an interesting device. It seems more like a UPS that any RV-type device I have seen. It looks like it is what is called "Double Conversion". That basically means that AC input is converted to DC to charge a battery bank and that same battery is used for power into a DC-to-AC inverter. The other topology is called line-interactive. It doesn't have this strict (double conversion) separation between AC->DC and DC->AC .

This provides essentially total isolation between AC in and AC out. This is probably why you are not sure what is going on when you run the AC all night

https://www.eaton.com/us/en-us/produ...20and%20online.


It looks like you also have a DC-DC On-Board battery Charger with MPPT; is that correct? So you in addition to the unit above you connect direct to the battery as well for DC loads and Alternator/ Solar charging. That is a quiet capable setup in only two devices. I don't remember but doesn't that DC-DC also back charge to the start battery if it is low?

>>>What is the 80% in your example? assumed max out of my batteries?

Yes this assumes Lithium and 80% effective depth of charge (90%->10%) vs. 50% for lead Acid.

It seems you could go either way (AC AirCon or DC AirCon). If you want the off-grid capability and what is probably quieter operation then I would go with the 12V AirCon. The double conversion (if true) essentially means you should have no startup overload issues.

Most of the 12V ACon units are less than 1000W and you can run any combination of shore power or generator and the Battery to AC Out conversion essentially isolates your AirCon from the course especially if you are using Lithium (super low impedance).

I don't have any first-hand experience with either of these devices just reading the manual and I'm an aerospace EE.

Yes the other device is a Renogy 50A DC to DC charger with MPPT. I don't have any solar but wanted to go ahead and be able to add it in the future. I suppose I may change my mind but at this point it's pretty distant on my projects list. Trying to make a decision on AC or DC air cond has made it to the top of the list. My biggest issue right now is any experience to confidently make the decision on the Air conditioning. It's got to happen though, it's impossible to sleep in the Southeast when ambient is a low of 78 and 90% humidity. Thanks for your input, very helpful.