Inverter Set-up (feedback needed)

[gmc]

Originally Posted by Chance

Regarding how to wire, the Xantrex Xi Installation Guide shows a typical diagram like gmc described in his post above. The difference here is that if you will have more than one circuit fed from inverter, you'd have to add a small AC load panel with separate breakers for each load. ...
.

Nice pic... Didn't mention adding load panel because he was only talking a 15A capability... More than one circuit didn't make sense...

Neighbors DP has two load panels - the second powered by inverter's transfer switch. Found that while helping him chase an electrical problem...

[rvfigs]

Thanks for the info fellas!

The next stage is to get rid of the Harris batteries.

Let me know if you have any recommendations. I was thinking of heading to either Walmart or Auto Zone to get some AGM's. I want to buy local just in case I have issues with the batteries.


Always Tinker

[gmc]

Battery choice really starts with what your power requirements are...
Then select a battery chemistry and configuration that delivers what you need.

AGM's are very good batteries - but you will pay a premium - and be sure your on board converter/charger can handle them... They are a different setting on manual chargers.

You can get some very good 'flooded' cells as well.

But comes back to what your power requirements are - and everyone's is different - between what you want to run - and how long you would be without shore power - do you have or are you adding solar charging option... etc.

[Becauseican]

Hello, I went a little different route. I installed a 2000 watt pure sine inverter. I ran the direct connection to a new 3 way transfer switch, power in. I then ran the power out wire from my original 3 way transfer switch (for shore power and gen) to power in on the new transfer switch. Finnaly I ran the power out wire from my new 3 way transfer switch to the control pannel/junction box and everything works. I just need to turn off the converter/charger before I turn on the inverter.
Check out the vid at youtube channel "metaldetectingrver".
Hope this helps
Phil

[Chance]

Originally Posted by Becauseican

Hello, I went a little different route. I installed a 2000 watt pure sine inverter. I ran the direct connection to a new 3 way transfer switch, power in. I then ran the power out wire from my original 3 way transfer switch (for shore power and gen) to power in on the new transfer switch. Finnaly I ran the power out wire from my new 3 way transfer switch to the control pannel/junction box and everything works. I just need to turn off the converter/charger before I turn on the inverter.
Check out the vid at youtube channel "metaldetectingrver".
Hope this helps
Phil

Phil, if I'm understanding this correctly, it sounds like your 2,000-watt inverter can power all items in the house. If so, do you ever operate the air conditioner or (electric) water heater off the inverter, or do you make sure those are turned off also?

Some of the newer Class Bs have done something similar by essentially replacing the generator with an inverter, which then powers the entire electrical panel. The ones I've looked at used an inverter/charger with built-in transfer switch, so there is not even a need to turn off the converter when running off inverter and batteries. The down side is they can't run major loads like AC, microwave, or hair dryer simultaneously off a 2,000-watt inverter. Granted, most Class Bs with 2,500- or 2,800-watt generators can't run multiple large loads either.

[rvfigs]

Some time in the future, I think we will see inverter and battery technology being able to fully power an air conditioner.

[Laco]

Originally Posted by rvfigs

Some time in the future, I think we will see inverter and battery technology being able to fully power an air conditioner.

Would be nice, but I doubt its anywhere in the foreseeable future. AC's just draw too much power to run more than just a few minutes off batteries, unless you have a bank of 20 batteries fully charged.

[Becauseican]

Originally Posted by Chance

Phil, if I'm understanding this correctly, it sounds like your 2,000-watt inverter can power all items in the house. If so, do you ever operate the air conditioner or (electric) water heater off the inverter, or do you make sure those are turned off also?

Chance, I have not. I just finished my install. I am not planning to use the A/C off the inverter as everything I have read says it can't/shouldn't be done. Havn't tried it. I currently have a small battery bank so I can't run high amps output for long untill I get my solar installed (which I am working on now) or my batterys drain quickly.

[Chance]

Originally Posted by rvfigs

Some time in the future, I think we will see inverter and battery technology being able to fully power an air conditioner.

The future is now. Kind of anyway.

There are companies manufacturing high-end and custom Class B motorhomes that power air conditioner from inverter and batteries. I'm aware of at least Sportsmobile and RoadTrek/Hymer, although I expect they may be others.

For these smaller motorhomes they typically use an energy efficient 11,000 BTU/hr AC that only pulls 1,000 watts of power, combined with a 2,000-watt inverter (some models use 3,000-watt inverter).

Run time is obviously limited by battery bank capacity, which unfortunately gets expensive if sized to run AC for more than a couple of hours. Roadtrek offers lithium batteries as an option that can run much longer, but again they are expensive. When batteries run down they start the engine which powers a second dedicated alternator which recharges batteries at over 200 Amps.

I've looked at running AC from batteries many times over the years with goal to run small 5,000 BTU/hr high-efficiency AC overnight, and it now looks very doable. The biggest problem I now see is that a 5,000 BTU/hr AC isn't large enough to cool even a small motorhome during the day, so a second AC would be required -- or even better would be a variable capacity AC (available but too expensive to be practical).

[rvfigs]

I think maybe coach manufacturer should consider smaller more efficient air conditioners.

Instead of having one massive 15,000 btu AC...use two smaller 5,000 to 6,000 btu ACs (middle and rear of coach). Run a pair of AGM's for each AC unit. Beef up the alternator or run two alternators.

This would seem too expensive though...

[Chance]

Originally Posted by rvfigs

I think maybe coach manufacturer should consider smaller more efficient air conditioners.

Instead of having one massive 15,000 btu AC...use two smaller 5,000 to 6,000 btu ACs (middle and rear of coach). Run a pair of AGM's for each AC unit. Beef up the alternator or run two alternators.

This would seem too expensive though...

Batteries remain the major expense. Everything else appears relatively cheap when mass produced.

Small window air conditioners in the 5,000 to 6,000 BTU/hr size range can cost as little as around $100 each, with high efficiency units with remote costing $200 retail. Manufacturers obviously would get them cheaper by buying in volume.

Thor uses 5,000 or 6,000 BTU/hr window-type AC in garage or rear bedroom of Outlaw motorhomes -- picture attached. They have also been used in small trailers for years. They are cheap, light, and can be efficient and quiet; although some can be noisy.

Second engine-driven alternators are also inexpensive when mass produced -- in range of $500. That's not bad for over 200 Amps or over 2,500 watts. It's cheaper than an Onan even if you add cost of inverter, which most motorhomes will have regardless before long.

If you eliminate cost, weight, and space of an Onan in a small diesel van motorhome (Sprinter, Transit, or ProMaster), you can buy a lot of batteries in its place. The main limitation is not being able to run air conditioning for days at a time without shore power. I personally don't do that, but others do. For those rare occasions I would run a portable generator if needed.

I wasn't surprised to read last week about a couple that removed the Onan generator from their Class B; instead relying on combination of solar and a second alternator. They also added lithium battery capacity. It will be years before these systems are mainstream, but the trend in that direction seems real.

[rvfigs]

I guess it is possible...with a lot of money

https://www.youtube.com/watch?v=B0rZY5uotKI

[Chance]

Originally Posted by rvfigs

I guess it is possible...with a lot of money

Thanks for posting video -- it confirms what numbers predict.

I've also seen similar video but based on Class B van camper, which would reduce cost significantly through smaller system size.

"A lot of money" is relative in my opinion, particularly when applied to motorhomes which are so expensive to start with. If I recall correctly from video, they have 960 watts of solar (6X160-watt panels????), and 700 Amp-hours of lithium batteries.

Batteries represent about 8.4 kWh of capacity, and at projected $300 per kWh in future, that's only about $2,500. No doubt that's a lot of money, but if you can eliminate the typical generator, then much of this battery cost is offset.

I did find interesting that inverter was pulling around 80 Amps (less than I would have expected), with about half coming from solar and rest from battery bank. That means solar was making about 500 watts at inverter and battery bank was supplying other 500 watts or so.

Running the most efficient "Power Saver" air conditioner would seem obvious, as well as a soft start to reduce start-up current. They should also consider window shades or awnings to reduce heat gain.

Finally, when systems get this powerful (3,000-watt inverter), to run air conditioners, microwaves, and other high-power items, the system would benefit from running at 48 VDC. That will cut current to 1/4 of a 12-Volt system. My understanding is that 48-VDC is becoming much more common in solar homes, so equipment already exists.

[rvfigs]

Very interesting...

The AC on the Axis is 1200 to 2400 watts correct? It's on a 20 amp breaker correct?

What would one need to run this system from batteries alone? Is this impossible without solar?

1. 3000 watt generator?
2. Soft start?
3. How many lithium batteries?

[JamieGeek]

Originally Posted by Chance

Batteries represent about 8.4 kWh of capacity, and at projected $300 per kWh in future, that's only about $2,500. No doubt that's a lot of money, but if you can eliminate the typical generator, then much of this battery cost is offset.

Thanks to EVs we're already a lot lower than $300/kWh of Li Ion batteries:
Electric-car battery costs: Tesla $190 per kwh for pack, GM $145 for cells
Granted those costs are in bulk for OEM's but still RV manufacturers should also be able to get those costs in quantity.

[Chance]

Originally Posted by JamieGeek

Thanks to EVs we're already a lot lower than $300/kWh of Li Ion batteries:
Electric-car battery costs: Tesla $190 per kwh for pack, GM $145 for cells
Granted those costs are in bulk for OEM's but still RV manufacturers should also be able to get those costs in quantity.

I certainly hope these prices trickle down to retail level before long. Last time I checked, a lithium battery bank was still close to $1,000 per kWh, which makes it a little pricey.

At the $145 to $190 cost, that makes them cheaper than flooded and particularly AGM batteries when adjusted for usable depth of discharge and greater life cycles.

[Chance]

Originally Posted by rvfigs

Very interesting...

The AC on the Axis is 1200 to 2400 watts correct? It's on a 20 amp breaker correct?

What would one need to run this system from batteries alone? Is this impossible without solar?

1. 3000 watt generator?
2. Soft start?
3. How many lithium batteries?

With enough lithium batteries, you should be able to power an RV air conditioner without solar. But eventually the batteries will run down and you'll need to recharge them one way or another. If not solar, you'll need shore power/converter and or engine alternator.

Solar would only help during the day, so at night you'd be running AC solely off batteries. My main interest, for example, is running AC overnight, figuring that battery bank can be charged from engine alternator while driving. In this case solar doesn't add as much value/benefit.

A 3,000-watt quality inverter with high surge capacity should be able to start a Power Saver AC. A soft start will reduce inrush current significantly. As mentioned before, some manufacturers are running 11,000 BTU/hr ACs powered from a 2,000-watt inverter.

[rvfigs]

Fellows campers,

I need some assistance...

I'm getting ready for my inverter install.

What do you think about powering the refrigerator with the inverter?

Does the refrigerator have a dedicated breaker? How many watts/amps does the refrigerator have?

My wife seems to think that running the refrigerator on inverter power is better than running the refrigerator on propane while going down the road.

[rvfigs]

Here are the specs on the Norcold refrigerator:

AC 120 VAC 2.5amps 300 watts

12VDC 0.8 amps 10 watts

[JamieGeek]

That really seems like an inefficient way to keep the refer cold. If you really don't want to burn the very little propane that the refer uses.

Unlike a residential refer, the 120V consumption of a camping refer is pretty much continuous. It will still run in cycles: On when it warms above the set point and off when it goes below it but those cycles are really long.