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Old 04-29-2022, 12:25 PM   #11
rickst29
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Exclamation still focusing on AC (and not smaller appliances).

Quote:
Originally Posted by rich2468 View Post
(Adding some clarity to what's already been shared by others)

Hi Mike- to accomplish what you've stated you'd like to accomplish (the ability to run the A/C from battery power) using off-the-shelf materials starting with an "average/factory" build TrailManor, you'd need around 100 Amp Hour of battery energy per each hour of A/C use.

Rich
That 100Ah per hour figure seems a bit short, even for the new and MUCH more efficient TrailManor AC units, due to the "100Ah" battery pack BMS stopping discharge before 100Ah has actually been used. If we forget about lead-acid battery types and focus only on LFP, the following math will apply. (Lead acid batteries can't handle all the rotor-start current, and they can't be discharged as deep.) In this, which is mostly an addendum to your excellent post about your results with a new AC unit, I focus on the much worse situation with older models:

The average running watts of those older 13,500 BTU air conditioners is 1600-1800 watts while the compressor is running (depends on weather, and the condition of the AC compressor motor, and which model it actually is). The total capacity of each "100Ah" LFP battery, discharging from 100% full down to ZERO, would be around 1280 watt-hours, if such a battery could be discharged that far.

Discharging to 0% destroys LFP batteries. Their on-board "Battery Management Systems" will shut down before reaching zero, typically at only 10% left. But going that far down, on a frequent basis, would still hurt battery lifespan pretty badly. I don't go past about 20% left. I further reserve the first 100Ah of my batteries to run TM 12v loads and appliances (including a fridge) through the night and into mid-morning of the following day, when significant solar power again becomes available for recharging the batteries.

So, we have 80% maximum usable from 1280Ah nominal capacity, right around 1024 watt-hours per 100Ah. Conversion from 12.8-VDC to 120-VAC (in the inverter) consumes about 15% of that power, resulting in maybe about 850 watt-hours of 120-VAC power from each 100Ah of Lithium (LFP) battery. To run the older 13,500 BTU AC for one hour, with the compressor mostly "on", you would need around 1600 watt-hours. That's roughly 200Ah of LFP batteries, not just one.
- - -
In addition to the raw power consumed from the batteries, everything also needs to handle the extremely high extra "current load" which is required, for just a fraction of a second, to start the compressor motor. Each time the compressor turns "on" from an "off" State, the Coleman Mach 13,500 BTU compressor motor demands around 55 amps of current. (That's about 7000 watts). An Inverter smaller than "3500 continuous / 7000 peak" watts is unlikely to handle this "rotor start" loading, unless assisted by a high-quality "start-assist" device. With such a device handling "rotor start" peak loading, e.g. the 'SoftStartRV' (a load learning and really expensive one), you could get by with a somewhat smaller Inverter.

But not anything smaller than 3000/6000, because you'd be running at a high proportion of it's maximum continuous rated output. They're less efficient while being run that hard, and they burn out faster.

To feed a 3000/6000 Inverter, which will use more like 3500/7000 input watts at peak loading (because it is only around 85% efficient), you need "12VDC" wiring which provides a capability for more than 300 Amps. My own 2/0 wire pairs barely meet that requirement.

The costs add up, pretty fast. I know of only a 3 people who actually do this - JoeyCharismatic, Rich2468, and myself.
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Old 04-29-2022, 03:18 PM   #12
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Originally Posted by Bill View Post
Interesting. I can't imagine that TM has downsized the BTU capacity of the air-co, so perhaps they have found a more efficient unit for new builds. The online specs just say "Low profile roof air conditioner", which isn't much help.

Bill
I need to update my previous A/C load values reported.

I've realized that I had taken those in the evening, so it looks like my solar array was contributing to lower than expected numbers load numbers (despite it being well after 6 pm in March when I took those readings).

Here are my actual load numbers (today) with my breakers to the solar array switched off and 80 degrees Fahrenheit ambient temperature:

1350 Watts with the AC on high
1280 Watts with AC on low
187 Watts fan high
125 Watts fan low.

I do not see any major spikes to 1800 Watts through Victron Connect (when my A/C compressor kicks in) but am adding an A/C soft start as a proactive measure.
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Old 04-29-2022, 04:28 PM   #13
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Originally Posted by mikegascon1 View Post
I am still at the thinking stage for solar. If I were to install a solar setup up, I would definitely want to install an inverter so my AC would work. How does that get wired in? To the power box under the shower? I assume they come with detailed instructions? I am not an electrical whiz bang and this is stumping me. I assume I am over thinking it and it is straight forward. Right?
Thanks

2007 3124
Vancouver, WA (close to Portland, OR)
To address your original question:

Technically, the inverter is totally separate from the solar. All the solar does is "CHARGE" the batteries, that's IT.... nothing magic here.... just an expensive battery charger.. All the "inverter" does is convert your 12V DC battery power to 110V AC (until the battery goes to low voltage) Lots of magic going on there...
It's just the solar panel's job to keep the batteries from going to low voltage.

The amperage draw from the 12V battery to the 110V inverter is approximately 10x the demand from the appliance. In other words, a 10A appliance is run off of the inverter, the inverter will pull (approximately) 100A from your 12V battery (which is hopefully, actually at 13.2V or higher). This is an important and easy formula to keep in mind when thinking about running your 110V appliances on your inverter.

Knowing all this, helps you understand why the inverter MUST be installed as close as possible to the batteries. The cables from the batteries to the inverter must be large enough to handle 10x the load that the appliance itself is demanding. I used the 16" long, 2G wire from my 225AH batteries to my 2000W inverter (the cables came with the Powall inverter). I placed a 300A inline circuit breaker near the battery positive terminal to avoid problems from a short. DO NOT switch the circuit breaker to the "ON" position until both cables are connected. The negative cable can go straight from the inverter to the negative terminal on the battery. If you select a larger inverter, larger cables and circuit breaker must be used if you are going to have a larger load. The largest load that I have is a 900W (approx 10A) microwave oven.

Having said all that, now that your inverter is all ready to go, there are a few ways to get the 110V current from your inverter to your appliances. Some people simply run a 12G extension cord from the inverter to the appliance and forgo the complications of wiring it through the trailer's wiring all together. This is actually easy and very efficient. It may be the best way to go until you've done a couple trips to see how everything goes.

Other people simply plug the trailers 30A power cord directly into the inverter, thereby powering up everything in the trailer. However, if doing that, one should disable the campers "converter" or you will have the converter trying to charge the battery from the inverter which is quite inefficient. The Air Conditioner breaker should also be switched off.

Another way is to run romex (or other 14G stranded wire) from the inverter to the bus bar in the power panel of the converter. Again, the converter and A/C must be bypassed.

I chose to stay away from the converter altogether. I installed 3-dedicated 110V outlets in our trailer. One is located on the back of the bathroom wall, in the hallway. The 2nd is on top of the counter, next to the stove-top (next to the existing 110 outlet). The third is next to the existing outlets by the refrigerator. Each outlet is labeled "inverter" to avoid confusion. Running the 110V wiring through cabinets is pretty straight forward. I originally used 14G romex to run to the outlets but I just bought 3, 20' long 12G extension cords to replace the romex wiring for wiring my outlets. I didn't feel comfortable with the romex (that's just me).

By the way, I am quite impressed with the Powall 2000W pure sine wave inverter. I also purchased the remote control so that I could see the power reading (both 12V and 110V) from inside the trailer and I can turn the (very silent) inverter on/off from inside. Although, I now just leave it on as it draws about nearly 0W when at idle (as you can see in the second picture).
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Old 04-29-2022, 04:46 PM   #14
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Quote:
Originally Posted by Wavery View Post
To address your original question:

Technically, the inverter is totally separate from the solar. All the solar does is "CHARGE" the batteries. All the inverter does is convert your DC battery power to 110V AC (until the battery goes to low voltage). It's the solar panel's job to keep the batteries from going to low voltage.

The amperage draw from the 12V battery to the 110V inverter is approximately 10x the demand from the appliance. In other words, a 10A appliance is run off of the inverter, the inverter will pull (approximately) 100A from your 12V battery (which is hopefully, actually at 13.2V or higher). This is an important and easy formula to keep in mind when thinking about running your 110V appliances on your inverter.

Knowing all this, helps you understand why the inverter MUST be installed as close as possible to the batteries. The cables from the batteries to the inverter must be large enough to handle 10x the load that the appliance itself is demanding. I used the 16" long, 2G wire from my 225AH batteries to my 2000W inverter (the cables came with the Powall inverter). I placed a 300A inline circuit breaker near the battery positive terminal to avoid problems from a short. DO NOT switch the circuit breaker to the "ON" position until both cables are connected. The negative cable can go straight from the inverter to the negative terminal on the battery. If you select a larger inverter, larger cables and circuit breaker must be used if you are going to have a larger load. The largest load that I have is a 900W (approx 10A) microwave oven.

Having said all that, now that your inverter is all ready to go, there are a few ways to get the 110V current from your inverter to your appliances. Some people simply run a 12G extension cord from the inverter to the appliance and forgo the complications of wiring it through the trailer's wiring all together. This is actually easy and very efficient. It may be the best way to go until you've done a couple trips to see how everything goes.

Other people simply plug the trailers 30A power cord directly into the inverter, thereby powering up everything in the trailer. However, if doing that, one should disable the campers "converter" or you will have the converter trying to charge the battery from the inverter which is quite inefficient. The Air Conditioner breaker should also be switched off.

Another way is to run romex (or other 14G stranded wire) from the inverter to the bus bar in the power panel of the converter. Again, the converter and A/C must be bypassed.

I chose to stay away from the converter altogether. I installed 3-dedicated 110V outlets in our trailer. One is located on the back of the bathroom wall, in the hallway. The 2nd is on top of the counter, next to the stove-top (next to the existing 110 outlet). The third is next to the existing outlets by the refrigerator. Each outlet is labeled "inverter" to avoid confusion. Running the 110V wiring through cabinets is pretty straight forward. I originally used 14G romex to run to the outlets but I just bought 3, 20' long 12G extension cords to replace the romex wiring for wiring my outlets. I didn't feel comfortable with the romex (that's just me).

By the way, I am quite impressed with the Powall 2000W pure sine wave inverter. I also purchased the remote control so that I could see the power reading (both 12V and 110V) from inside the trailer and I can turn the (very silent) inverter on/off from inside. Although, I now just leave it on as it draws about nearly 0W when at idle (as you can see in the second picture).
That is incredibly helpful. Thank you for the details.
In my original post, I said I wanted to figure out ac. I actually meant ac/DC. I will NOT plan on running my air conditioner from batteries. Sorry for the confusion.

2007 3124
Vancouver, WA (close to Portland, OR)
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Old 04-29-2022, 04:55 PM   #15
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Originally Posted by mikegascon1 View Post
In my original post, I said I wanted to figure out ac. I actually meant ac/DC. I will NOT plan on running my air conditioner from batteries. Sorry for the confusion.

2007 3124
Vancouver, WA (close to Portland, OR)
You didn't create the confusion. We did that all on our own........ wait until you get a little old. Then you'll understand.

Did you see my post on the solar wiring?
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Old 04-29-2022, 10:11 PM   #16
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You didn't create the confusion. We did that all on our own........ wait until you get a little old. Then you'll understand.



Did you see my post on the solar wiring?
I did see your post. Extremely helpful.
I have a 3124 and the battery is on the tongue. I plan to update to 2 6 volt golf cart batteries in the future.

It is new to me so, I am having a tough time estimating my needs.

Scenario 1 is the kids and I. I will need fans, or heat, television, recharge phones, interior and exterior lights. I would assume anywhere we go, I will look for hookups. It would be nice to have the option to boondocks though.

Scenario 2 is odd. Definitely no hookups. But less need for power also. I will be at fire camps that are 99% remote. In past years I only use my tent for sleep or maybe to sit for a short time after a shower to zone out. So, my power needs will be heat fan (and propane of course) and fans. Air conditioner would be awesome but not realistic. We usually work 16 hour days so not a lot of need for power consuming niceties.

If anyone has recommendations on low power consumption fans, that would be appreciated. One to move the air and one to blow on me at night. It is either hotter than heck or cold. No happy medium at camp. :-)

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Old 04-30-2022, 08:48 AM   #17
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Mike, when I dry camp I bring several battery packs. I use a CPAP and depending on how long I'm out. I either bring a 299W pack or a 400W pack. I use the DC side of those batteries so they last longer than the AC side. Extra adapters required, but worth it.
I have several AA fairy lights with remotes, Goal Zero USB string lights, where you can add an extra light if needed.
Also several portable 26800 mAH batteries for the usb fan and lights. I use a 18v Ryobi fan with backup batteries and a smaller usb fan.
If your kids are old enough, give them a project to estimate how much power they/you need for electronics for a weekend.
I use a Mr Heater buddy when it gets colder, others have retro fitted their rigs with a Camco Wave heater.
Oh and scenario 2 is not odd, it's life.
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Old 04-30-2022, 10:43 AM   #18
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Default Lets start with the Solar.

Quote:
Originally Posted by mikegascon1 View Post
I did see your post. Extremely helpful.
I have a 3124 and the battery is on the tongue. I plan to update to 2 6 volt golf cart batteries in the future.

It is new to me so, I am having a tough time estimating my needs.

Scenario 1 is the kids and I. I will need fans, or heat, television, recharge phones, interior and exterior lights. I would assume anywhere we go, I will look for hookups. It would be nice to have the option to boondocks though.

Scenario 2 is odd. Definitely no hookups. But less need for power also. I will be at fire camps that are 99% remote. In past years I only use my tent for sleep or maybe to sit for a short time after a shower to zone out. So, my power needs will be heat fan (and propane of course) and fans. Air conditioner would be awesome but not realistic. We usually work 16 hour days so not a lot of need for power consuming niceties.

If anyone has recommendations on low power consumption fans, that would be appreciated. One to move the air and one to blow on me at night. It is either hotter than heck or cold. No happy medium at camp. :-)

2007 3124
Vancouver, WA (close to Portland, OR)
Let's focus on scenario two, with the first objective being a solar system which can recover your usage each day, if the sky isn't completely obliterated by smoke.

A 3124 has lots of surface area for panels, both front shell and back shell, but the lifting weight will be increased (by the weight of the panels). You could do a bunch of small 100w panels and wire them together, or you could go big, with just one (at most 2) residential-type panels.

As we speak, I'm discussing a new solar install with another TM owner up there in Washington State. He has a slightly smaller 2720, and can fit one of these residential-type panels on the rear shells. These are too large to be shipped from an Internet Seller, but many installers in USA are using them (including some in the Portland area) and some of those local home-installation companies will have some leftover panels from their "full-pallet" and larger truckloads purchases, which they can sell to you for a local pick-up.

Using newest PERC technology and built with a bit more durability, the Q-Peak DUO G10+ provides 385-400 nominal watts, but they're expensive. Efficiency ios the best in the business, at nearly 21%. These are widely used in residential roof installations, I have some of those on my own house (in Reno NV).

Using older technology, the 'REC Twinpeak 2' is only 18% efficient delivering 275-300 watts in a slightly larger area. But it has a much lower cost per watt. I've attached both of their data sheets, and the length of these panels does fit into TM trailer width.
- - -
Keep in mind that "nominal watts" are maximum power under "standard test conditions", which are so bright (and with such cool temps) that you will never EVER come close to that figure. The biggest factor in reduced performance, for a panel mounted flat on a TM roof, is the horizontal mounting. Even on June 21, the sun is never directly overhead at 90 degrees (due to latitude), and a "flat" panel gets less irradiance than the standard rating conditions. For long fire stays, you could consider using an adjustable mount. But that adds the trouble of climbing up there and adjusting the mount, which would be 1-2 feet inwards from the "long side" edge of the horizontal to vertical transition. The mounting would be more complex, adding more weight, and you'd need a ladder to get at it.

Summary hint: the most I ever get from my own "490 watts" of panels is about 420 watts, on a perfect day June day at 1pm daylight time. But from that, we also need to downgrade your panel output rating for the sunlight versus smoke conditions at a fire camp. They can be severe, leaving you with effectively no power at all. But even when the camp seems excellent, the haze has a big effect. As a wild guess, let me toss out a minimum of "800 rated watts" as the minimum panel configuration you should install for this usage. That would be at least one panel on each shell, running them in parallel to the solar charge controller.

In really bad smoke conditions, you will need to rely on a generator, or use a fairly high powered DC->DC converter through a separate pair of big wires, running from the truck to charge your TM batteries. The input current of those devices is large, too much for both the bargeman cable "Trailer battery Charge" and "ground return" wires. You'd need to size those cables according to the input current, being approximately like long jumper cables (but probably using Anderson connectors at both ends, rather than mere clamps). It's good for up to 660 watts nominal (and with a decent truck, that's darn near actual as well, rain or shine or dead-of-night). https://www.renogy.com/dcc50s-12v-50...ger-with-mppt/
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