Inverter Questions.

[OhioMark]

Originally Posted by dagst1

I would love to but the dealer says that they are on backorder. All that are being produced goes to the manufactures first. Just trying to get by until i can get the rv one - unless the wife likes the residential one.

So I've been researching power needs to boondocking in our toy hauler multiple days back to back. It is a bit more complicated than just adding up watts and buying a new inverter and battery, the good news is there are tons of articles online to help sort it out.

For me it was figuring out how to draw needed wattage continuously overnight and recharging when I'm driving or running my onboard generator during daylight hours.

The long pole in the tent for us was upgrading our batteries. You need to figure your amp hour needs (Ah) for that inverter to run the fridge. Most likely a single basic RV/Marine deep cycle battery that are usually found in trailers won't cut it for you're needs, but you need to run the numbers. Also, you'll need to take into account depth of discharge (DoD). That is, you can't run the battery below its max level of discharge or you damage the battery. The rule of thumb I kept finding online was lead acid flooded batteries (most rv batteries) is 50% while AGM (sealed) batteries you can run down 80% capacity without damaging before a full recharge. For us, the AGMs seemed overkill since I really need to just get through the time (evening) when I can't/won't run my onboard generator and can recharge during daylight hours. Also the drawback for me was the concern if I had issues while traveling, the higher capacity AGM batteries are not readily available so I switched to flooded 6v golf cart pairs. I did some random searches of NAPA stores across the country and it seemed like everyone has them in stock or within a day of getting them. They have crazy number of Ah (4x) the RV deep cycle we had. You can move to AGMs, they are nice since no maintenance and can be drained down to 20% (supposedly) however are usually 2x expensive but you usually get a 2x longer warranty. The next step up is Lithium but that gets into real money. Like $1000's because the batteries in what I needed were 800-1000 and you need to most likely swap out your trailer converter to be compatible for the proper charging cycle.

Long story short, keeping that res fridge might cost you some money by the time you sink cash into the inverter and batteries, so do some research so your not running out of juice and losing a fridge of food or replacing batteries. I consider myself a techie and the power calculations are basic arithmetic (i had to take off my socks to count that high), however I got overwhelmed with all the considerations to keep the watts flowing when unplugged. Also, you need to take into account everything in the trailer that is plugged in. Just like when figuring the weight of the trailer, things add up quickly including vampire draw on things turned off. Here is a clip from a site I found that lists draws on some 12v accessories normally found in the trailer (I cannot verify accuracy here, I'm trusting the author):

Appliance Status Incremental Wattage
Power converter ON 428
DC Fridge (Dometic) On (gas) 32
AC Fridge On (AC) 294
BR fan On 97
Fantastic Fan Fan Low 78
Fantastic Fan Fan Medium 101
Fantastic Fan Fan High 125
Fantastic Fan Fan Off 0
Lamp One Lamp 94
Lamp Two Lamps 158
Air con (Dometic Penguin) Fan 282
Air Con Fan & Compressor 1350
Furnace Fan On 334
FUrnace Standby 3
Monitor Panel On 7
Pump On 150
Gas H20 Heater On 20
Radio ON 49
Radio Standby 24

Also the battery manufacturers can use different metrics to determine capacity (amp hours vs run capacity) just to make things interesting. Good luck and here are few links.

If anyone sees anything wrong in what I said, please blast me in response, I think I got this right but I learn something new everyday and still have my receipt for the batteries I bought


The 12volt Side of Life (Part 1)

https://rvnerds.com/2017/11/01/elect...-need-venting/

https://deepcyclebatterystore.com/ca...%20are%20using.

https://www.sailnet.com/threads/batt...apacity.63682/

[egrum]

Originally Posted by dagst1

So it seems we may have bought another camper.

The main drawback is it has a residential refrigerator with no inverter. It lived its life on a lake in the south and when the RV refrigerator went bad it was replaced with the residential one--Price and the camper not moving was a big factor.

So to fit our life style and not being able anytime soon to get a 18 cu ft rv refrigerator - thank you c___d - we will have to use the one it has now.

Just doing a few searches it would seem that i need a 1000 watt inverter with a built-in transfer switch.

Anyone with any experience with this type of setup or inverters in general your help would greatly appreciated. From my days on the road i have a 1000 watt modified wave inverter but i understand with the electronics today i need a pure wave.

Also the inverter setup would be just to run the refrigerator while traveling maybe up to 8 hours a day.

Your problem with trying to use an Inverter is that although the inverter would carry the "RUNNING" load of the fridge, it would NOT be able to supply the "IN-RUSH" current requirement when the fridge starts.

This is a similar problem with trying to use a 2000W generator to run the AC. The generator will carry the load of the AC but the generator will NOT have enough capacity to start the AC (once in a while out of fluke all the stars and planets line up and things work).

If you buy an inverter and the sale guy tell you that "Oh yea no problem" make sure that you can take it back for a refund. Most sales guys don't know squat about what they are selling. They only want the sale.

Electronic devices do not have the capacity to supply more current than their design. And if you try you will destroy the electronics.

A motor (standard household fridge compressor) will draw as much as 6-10 times the current that is required for it to run. In other words a motor (fridge) that draws 5 amps running will draw 30 - 50 ams starting. Although this is for a brief period (lets say 5 seconds) the electronic inverter can not supply this amount of current PERIOD.

[OhioMark]

Originally Posted by egrum

Your problem with trying to use an Inverter is that although the inverter would carry the "RUNNING" load of the fridge, it would NOT be able to supply the "IN-RUSH" current requirement when the fridge starts.

This is a similar problem with trying to use a 2000W generator to run the AC. The generator will carry the load of the AC but the generator will NOT have enough capacity to start the AC (once in a while out of fluke all the stars and planets line up and things work).

If you buy an inverter and the sale guy tell you that "Oh yea no problem" make sure that you can take it back for a refund. Most sales guys don't know squat about what they are selling. They only want the sale.

Electronic devices do not have the capacity to supply more current than their design. And if you try you will destroy the electronics.

A motor (standard household fridge compressor) will draw as much as 6-10 times the current that is required for it to run. In other words a motor (fridge) that draws 5 amps running will draw 30 - 50 ams starting. Although this is for a brief period (lets say 5 seconds) the electronic inverter can not supply this amount of current PERIOD.

Good point, you need to account for the surge watts. You
will damage the compressor in the fridge underpowering the load needed to start the compressor. Same issue as the AC. You can buy a capacitor but now your into yet one more gadget you'll need to do this.

[dagst1]

I plan on only powering the refrigerator outlet/circuit not the whole camper. It will only be on the inverter when traveling as soon as we get to a campground it will be on shore power.

I have been in contact with the people at AIMS and was going to get a 2000 watt/ 4000w surge and they told me for what i want to do the 1000watt/2000 watt surge will be more than enough. We also discussed the battery requirement for what i want to do. So we will see if it all works out. Got some more thinking to do before i order.

[egrum]

Originally Posted by OhioMark

Good point, you need to account for the surge watts. You
will damage the compressor in the fridge underpowering the load needed to start the compressor. Same issue as the AC. You can buy a capacitor but now your into yet one more gadget you'll need to do this.

Well buying a cap may solve the issue input current rush issue, however unless you know how and what you are doing, I wouldn't suggest running out and buying a cap. They do blow up, and that is not a figure of speech that is an actually event, very similar to a bomb.

So now you bought a 3000 W and bought a capacitor (of what size)?

Maybe an RV fridge is cheaper?

and pay somebody to hook it up?

[OhioMark]

Originally Posted by egrum

Well buying a cap may solve the issue input current rush issue, however unless you know how and what you are doing, I wouldn't suggest running out and buying a cap. They do blow up, and that is not a figure of speech that is an actually event, very similar to a bomb.

So now you bought a 3000 W and bought a capacitor (of what size)?

Maybe an RV fridge is cheaper?

and pay somebody to hook it up?

Yes, so do batteries and converters if not correctly sized and installed. Any misconfiguration on a system can potentially trigger an event.

You are driving the point being made implicitly by the responses including my previous. It boils down to time, money and knowhow.

Easily going to spend at least 1/2 the cost of a new RV fridge to maintain this setup on the road.

If it were me, I'd be scrubbing the RV fridge supply chain on the internet to find a replacement fridge. I've recently upgraded my hitch and pinbox, COVID has really impacted RV parts industry, well everything with much of the components coming from overseas. My point is the inventory is out there. I would not rely a a dealership to find one. I've installed one myself and can easily say less work and time than building out an inverter set up, which is my next project.

[dagst1]

A new refrigerator is very close to $5000 + install and none are available at this time. Not wanting to power the whole camper just and only the refrigerator and only while traveling. I know many campers came with residential refrigerators and inverter setups just trying to duplicate that. According to the brochure it was an option on this one.

Thank you all for the help/suggestions.

[OhioMark]

Originally Posted by dagst1

A new refrigerator is very close to $5000 + install and none are available at this time. Not wanting to power the whole camper just and only the refrigerator and only while traveling. I know many campers came with residential refrigerators and inverter setups just trying to duplicate that. According to the brochure it was an option on this one.

Thank you all for the help/suggestions.

I gotta ask, why the need for 18 cu ft fridge?

[dagst1]

Originally it came with a 17 cuft. That model was replaced by Norcold with the 18 cuft. I could put in a smaller one but then that would require a lot of custom wood work to fill in the extra space and turn it into useable space.

[OhioMark]

Interesting. I thought that was a trend to move to larger fridges in 5vers just in the last couple years. We have a 10 cf and store enough food for two weeks with just my wife and I now. I wouldn’t know what to do with that much space.

[woodwalker]

Originally Posted by dagst1

A new refrigerator is very close to $5000 + install and none are available at this time. Not wanting to power the whole camper just and only the refrigerator and only while traveling. I know many campers came with residential refrigerators and inverter setups just trying to duplicate that. According to the brochure it was an option on this one.

Thank you all for the help/suggestions.

I have a 1200 watt zantrex invertor that only runs our 18 c fridge. 2 agms will run it for over 14 hrs of travel

[dagst1]

What size batteries are you using? I know that this setup is available on some campers with the factory installed residential refrigerator.

[dagst1]

Originally Posted by OhioMark

Interesting. I thought that was a trend to move to larger fridges in 5vers just in the last couple years. We have a 10 cf and store enough food for two weeks with just my wife and I now. I wouldn’t know what to do with that much space.

Our current camper has a 8 cuft in it now. The new to us one came with a 17 cuft gas electric with a 17 cuft residential as an option.

[woodwalker]

Originally Posted by dagst1

What size batteries are you using? I know that this setup is available on some campers with the factory installed residential refrigerator.

At the time they were 2 group 27 agms
I have since gone to 3 27s and added 800w of solar