Cinergi's 28 kWh / 4 kW Solar / 10 kW inverter RV build

[Hedges]

"Charging working temperature 0C to 60C"
"Standard charge 0.5C", "Max charge 1C", "Pulse charge 2C"

This doesn't mean that 0.5C can be done without damage at temperature 5 degrees C or 55 degrees C.
Based on other vendors recommendations, I would expect that to shorten life, and limit either charge rate or temperature at which charging occurs.

 

[cinergi]

I had a third mini-split cassette installed in the basement, so I can control the temperatures if I need to. It's the smallest size, 9k, which is way too much and causes cycling, which kills the performane of the entire system ... so I only use it when I really need it. I also need to install an external temperature sensor for it which will reduce the cycling.

Separately, I've had to remove and clean a few more bus bars/terminals (one of the IR's got bad enough - 1milliOhm - that the BMS threw an error (well, it's configured to do so at that value); the rest are typically 0.080 to 0.250). It didn't cause any problems with my system per se but the voltage graphs of each cell made it quite clear there was a problem. I checked torque and all that first, and all the nuts were still at 40in-lb so it's not like those are getting loose. It may have been due to me improperly cleaning when I did the first assembly ... but if this keeps up or recurrs on cells I've revisited, I'll add some anti-ox (shouldn't need to - it's tinned copper bus bars) and observe.

Other than that, my system continues to perform beautifully. With the AC properly tuned (that took some doing unfortunately) I'm maintaining low 70's even when it's 100 (and humid) outside. If the overnight lows are in the mid 70's, that means I'll eat about 25-30kWh of juice. Where I am now it's 90 (and dry) for a high with lows in the 50's ... so it's more like 15kWh/day .. battery is full by 2pm every day (Colorado, September).

I'm headed to Yellowstone for 2-4 weeks or so of boondocking next weekend. Much cooler temps (near freezing at night) ... I may use them in heat pump mode, depending on how much solar I get. Otherwise propane for heat.

Oh, I did measure the AC waveform induced on the batteries but as I was playing around, I ended up reversing polarity on the leads (didn't think that was important?) and blew the fuse to the BMS & contactor and shut the entire system down lol. oops. Around the same time, my Cerbo GX Touch stopped working - could very well be related. So I had to replace that. Alt-E/Victron was awesome about it ... sent me new one for free (no shipping either) w/out even asking for the old one back. Piece of cake.
EDIT: And since I blew the fuse, I didn't get a chance to capture the waveform and I didn't have the heart to try it again. There's definitely a waveform on the battery. As for the 120v output of the Victron Quattro's, it's incredibly perfect; some loads can warp it a bit but it's a perfectly smooth 60hz sine wave.

Public Victron stats for my system: https://vrm.victronenergy.com/installation/76892/share/d5bbdd04

 

[willo]

Mind sharing where you go? Yellowstone is on my to visit list, not too far from me.

 

[Boondock Saint]

Sorry to hear of your new travail.

You know I'm just North of there, down to nearly freezing at night. I'm stuck here a few more weeks so no catching up by the fireside. I'll prob meander WY after this. Thanks for all the behind the scenes support from you!

.

 

[cinergi]

Mind sharing where you go? Yellowstone is on my to visit list, not too far from me.

The most I'll share publicly is a boondocking area 20 minutes outside West Yellowstone (there's a lot to choose from!)

 

[luckielab]

With the AC properly tuned (that took some doing unfortunately) I'm maintaining low 70's even when it's 100 (and humid) outside.

That's great to hear. Did you do a recap anywhere of the tuning part? Curious to know more about that!

 

[cinergi]

That's great to hear. Did you do a recap anywhere of the tuning part? Curious to know more about that!

Really just came down to the proper amount of refrigerant (HVAC tech kept getting it wrong) plus making sure I have awnings over ALL my windows so I can keep the sun off. I've also learned that if one of the zones is cycling, that'll kill the other zones.. so I set my temp and fan speed settings to minimize cycling.

 

[CharlesK]

@cinergi : I wonder how well your system will work if you use the minisplits for heat instead of the propane furnaces. It would be an interesting test at least.

 

[cinergi]

@cinergi : I wonder how well your system will work if you use the minisplits for heat instead of the propane furnaces. It would be an interesting test at least.

Right now quite poorly due to the temp sensors being up in the intake with heat rising so it gets false temp readings. It also consumes a LOT more power (I was just pulling 2700 watts for 2 zones). So right now I'm using a combination until I get external temp sensors installed.

 

[cinergi]

My quick heating-with-minisplit notes that I just made in another thread: https://diysolarforum.com/threads/yes-rv-solar-li-and-ac-running-full-time.23979/page-10#post-348985

 

[Luthj]

My quick heating-with-minisplit notes that I just made in another thread: https://diysolarforum.com/threads/yes-rv-solar-li-and-ac-running-full-time.23979/page-10#post-348985

Thanks for keeping us updated. I recently acquired an older 40ft toy hauler to make an all season on/off grid cabin from, and your data on heating/cooling has be very valuable. Based on your numbers, I am looking at adding 1" XPS (R5) to most walls and the slides. Along with removing half the windows, and double pane the remainder, I think I can get my BTU needs down to about 50-65% of your numbers. I figure that's good for most seasons in the lower 48 when combined with occasional gen operation.

I am also leaning towards putting the (eventually to be built) battery pack in the living space to reduce heating/cooling needs. Dealing with tank and water line freeze protection will be interesting, but there is always hydronics...

 

[cinergi]

Thanks for keeping us updated. I recently acquired an older 40ft toy hauler to make an all season on/off grid cabin from, and your data on heating/cooling has be very valuable. Based on your numbers, I am looking at adding 1" XPS (R5) to most walls and the slides. Along with removing half the windows, and double pane the remainder, I think I can get my BTU needs down to about 50-65% of your numbers. I figure that's good for most seasons in the lower 48 when combined with occasional gen operation.

I am also leaning towards putting the (eventually to be built) battery pack in the living space to reduce heating/cooling needs. Dealing with tank and water line freeze protection will be interesting, but there is always hydronics...

I'll be curious how you do. New Horizons' insulation is very good 2" foam and 3.5" in ceiling I believe ... I can't find the pictures I took at the factory

 

[cinergi]

Another small but important update here: https://diysolarforum.com/threads/yes-rv-solar-li-and-ac-running-full-time.23979/page-11#post-350869

Also:

 

[Luthj]

very good 2" foam and 3.5" in ceiling I believe

I guess we have different reference points. If the whole of the walls averaged R6-7, then it would be pretty good for the space. However, the aluminum frame tubes are highly conductive, and the windows are also big thermal loss zones. Not sure about your model, but most I have looked at have less than 2" walls in the slides, especially on the floors. I would bet the average R value is around 3-4 all together. Of course that's fantastic compared to some Class As I have worked on, with literally no insulation behind the wall panels!

I would bet you could see a 15% improvement with draft tight window covers all around.

The unit I have is 2" sidewalls, 3-4" fiberglass ceiling, no floor insulation, and single pane windows all around.

My goal is to be comfortable in 100 to 0F, and tolerable at 110 to-10F. Not going to be easy though. I think a 24k unit will work, but might just move up to a 36k unit for better heating performance.

 

[cinergi]

I guess we have different reference points. If the whole of the walls averaged R6-7, then it would be pretty good for the space. However, the aluminum frame tubes are highly conductive, and the windows are also big thermal loss zones. Not sure about your model, but most I have looked at have less than 2" walls in the slides, especially on the floors. I would bet the average R value is around 3-4 all together. Of course that's fantastic compared to some Class As I have worked on, with literally no insulation behind the wall panels!

I would bet you could see a 15% improvement with draft tight window covers all around.

The unit I have is 2" sidewalls, 3-4" fiberglass ceiling, no floor insulation, and single pane windows all around.

My goal is to be comfortable in 100 to 0F, and tolerable at 110 to-10F. Not going to be easy though. I think a 24k unit will work, but might just move up to a 36k unit for better heating performance.

Indeed, aluminum and you can clearly see it:

New Horizons guarantees their rigs down to -10F and they're VERY well insulated (floors, slide floors, walls, ceiling, slide ceiling) ... but the aluminum and windows are working against me. Dual pane but not low-e and not much space between the panes. In the sun, the windows and metal window casings were getting above 130F.

With my overnight low of 25 the LR got to 45 (bedroom door closed and kept at 60) and I started the mini split ... 2 hours later, the LR was at 55 (outside 28). It was performing fine (120F output) but that's a lot of temperature to recover for a minisplit. Tonight will be even colder so I'll leave the minisplit set to 80 and see how cold the LR gets

In the summer, my biggest enemy is UV/IR load actually. I'm going to tint my windows but the awnings (and proper rig positioning) made a HUGE difference.

I don't think a bigger ODU won't help if your total IDU is 24k or less. The ODU will only run as "high" as it needs to. It was pretty obvious that the ODU consumed a different amount of power when I upgrade a cassette from 9k to 12k. Unless the specs of the 36k ODU specifically have better EER/SEER numbers...

 

[Luthj]

Unless the specs of the 36k ODU specifically have better EER/SEER numbers...

Looking through the Mitsubishi and fujitsu catalogs, its obvious that the heat optimized units are actually the larger chassis, downrated. So a 36k chassis is rated for 24k heating at very low temps. Its not a simple matter of de-rate though, as the components differ slightly. The big point of interest is heating output reduction at low temps, and a 36k unit will often continue to heat at decent output, even when the temps drop below their rated minimum. Which makes sense, as there is greater airflow at the ODU. Obviously its a matter of comparing the performance tables. Its pretty important to compare the SEER/EER for varying indoor unit numbers. In some cases its better to have 2, and in some have 3 units running. Here is a clip from an LG engineering manual.



Do you find the LG roof cassettes to be good noise wise? They seem reasonably priced, and have a good package size.

 

[Luthj]

I was talking to a HVAC tech a couple years ago, and he mentioned that some of these splits can benefit from a charge fine tuning. Increasing or decreasing the charge amount can improve performance at extreme high/low temps. This requires a very good tech, and some instruments to monitor superheat/subcooling in real time. You would think with an electronic expansion valve and real time feedback they wouldn't need it though.

 

[CharlesK]

In the sun, the windows and metal window casings were getting above 130F.

My motorhome has the same issue with the metal window casings. 130F is pretty accurate in the direct sun. I am considering painting the exterior part of the casings white (or whatever light color I might paint the coach). I am also considering ceramic window tint. I seem to remember that ceramic tint does better than regular tint. I need to double check that info when the time comes to tint the windows.

Thanks for the updates on the heating capabilities of your LG system. ?

 

[cinergi]

Looking through the Mitsubishi and fujitsu catalogs, its obvious that the heat optimized units are actually the larger chassis, downrated. So a 36k chassis is rated for 24k heating at very low temps. Its not a simple matter of de-rate though, as the components differ slightly. The big point of interest is heating output reduction at low temps, and a 36k unit will often continue to heat at decent output, even when the temps drop below their rated minimum. Which makes sense, as there is greater airflow at the ODU. Obviously its a matter of comparing the performance tables. Its pretty important to compare the SEER/EER for varying indoor unit numbers. In some cases its better to have 2, and in some have 3 units running. Here is a clip from an LG engineering manual.

View attachment 66994

Do you find the LG roof cassettes to be good noise wise? They seem reasonably priced, and have a good package size.

Yeah I remember that chart (I forgot there are heat rated ones) -- exactly what you should be looking at while figuring out the sizing. Most important, you do not want to oversize your IDUs and cause cycling. *all* of your zones will suffer if *any* one IDU starts cycling.

The Cassettes are very quiet. They *might* be a little louder than a wall unit because I've "closed" 2 of the 4 vents so the air movement is slightly elevated... but it's still stupid quiet, especially for an RV. I have zero complaints in that respect. However, if I were to do it again, I'd try to use wall-mount on the short walls due to the narrow walls creating poor airflow with the 4-way cassettes (even with the slides out -- because the air hits the wall BEFORE the slide cutout) and to maximize roof space for solar (I'm probably too tall to cover the cassettes with panels).

 

[cinergi]

Yeah I remember that chart (I forgot there are heat rated ones) -- exactly what you should be looking at while figuring out the sizing. Most important, you do not want to oversize your IDUs and cause cycling. *all* of your zones will suffer if *any* one IDU starts cycling.

The Cassettes are very quiet. They *might* be a little louder than a wall unit because I've "closed" 2 of the 4 vents so the air movement is slightly elevated... but it's still stupid quiet, especially for an RV. I have zero complaints in that respect. However, if I were to do it again, I'd try to use wall-mount on the short walls due to the narrow walls creating poor airflow with the 4-way cassettes (even with the slides out -- because the air hits the wall BEFORE the slide cutout) and to maximize roof space for solar (I'm probably too tall to cover the cassettes with panels).

To expand on sizing -- the sq. ft. per BTU does not work in an RV. So all I can say is that 12k is about right for my ~200SF living room/kitchen with tall ceilings and lots of window exposure. The 9k is too much for the 70SF bedroom with short ceiling and almost no window exposure.