Thank you!!!

[Barry Timm]

Dacian, my wife and I have been boondocking for a few months now, in Idaho and Montana, as far north as Glacier National Park, in our little "summer travel" fifth wheel RV, towed behind our Ford F350 truck.

This note is just a brief (sic!) note to say that the solar system that I put together with your SBMS0, 3 x DSSR20s, 6 x 315w 120 half-cell PV, and 16 x 150ah Aluminum cased LifePO4 cells in a 24v 300ah configuration, feeding into a Victron Multiplus 24/3000 120v inverter-charger and a Victron Orion 24/12-70 DC-DC converter, has been absolutely life-changing for us!

We run all our electronics, including lights, TV, 2 x laptops, 2 x tablets, 2 x phones, water pump, RV fridge, coffee machine, electric kettle, 46" overhead 120v residential fan, 3 x Maxxair 12v overhead fans, an extra residential 120v vertical fan, Dish self-seeking satelite globe and power unit, DIsh DVR receiver, Apple TV, cooktop fan, toaster, CPAP, weather radio, microwave, electric RV slides, electric RV leveling jacks, etc, etc, etc. with absolutely ZERO restrictions! 

We don't own a generator, and despite some days with heavy overcast and rain, we've never had to cut back or change our lifestyle, thus far.  Of course, our system is primarily for summer RV travel, so we generally have good solar and little need for warming devices, but I've sized this system for a highly efficient 230w mini-split AC for the cooling needed.

The freedom that this system has given us to enjoy the outdoors while traveling this beautiful country, is mind-boggling, and your system just flat-out WORKS. No fuss, no hassles, no ongoing maintenance other than simply cleaning the rooftop solar panels every month. I glance at the wifi monitor display about 2-3 times per day, for curiosity more than anything else.

I even went as far as reducing the SOC% "refill" level after the initial daily 100% charge, to 80% in an attempt to extend the life of the battery further, and it seldom drops below 55% by morning, after our early morning coffee and kettle usage.

We are absolutely THRILLED with your system. Thank you for an INCREDIBLY smart and effective system. Your focused design parameters have made what I think is the best solar system for RVs, bar none. I'm quite sure the same applies to off-grid house systems.

THANK YOU!

Barry.

[ReinholdU]

👍 😍

Congratulations. You are obviously enjoying your "new found electricity liberty".

My eyes bleed reading what you do support with your 6 panels when I think about the mere 2 ...for which I have to "rebuild" my boat for.
(...and (insult to injury!) a 5th wheel setup like yours would be basically "undriveable" in most of europe ;-/ )  <BIGGRIN>.

Would you mind sharing your "16 x 150ah Aluminum case"-battery (brand&supplier)(diy?->foto pls).
Enjoy
Reinhold

[Dacian Todea]

Thanks for the review Barry.

Glad to hear the system works as expected and can power all your loads.

[Casey & Gina]

This was a nice success story to read!  I hope to have my own to share in time...

Glad your system is working well for you and that you are enjoying your travels!

[Barry Timm]

Sorry, I thought I'd replied to your request for info on the aluminum cased LifePO4 cells that I'd purchased, Reinhold!

I used AliExpress and the vendor supplying the cells is BLS. Very happy with the cells, packaging and delivery speed.

https://www.aliexpress.com/item/4000108447273.html?spm=a2g0s.9042311.0.0.760a4c4dR31G1T

[Barry Timm]

I have to laugh at myself! I jinxed myself with my bragging about never running out of battery!  Well, today it happened, and I had to go and buy a small 1600w continuous inverter-generator! :-) :-)

Yesterday, in the clear sun, I switched my RV fridge from propane mode to Auto, which senses if there's incoming 120VAC power (which there is, from my solar and Multiplus inverter) and had it run off my solar. The draw is 330w on average, continuously.

I had also reconfigured my SBMS0 to let the charging on the battery go only to 80% SOC, instead of the default 98-99%.

Well, I forgot to switch the fridge back to propane mode when the su went down, and so the battery was drawn down at 330w extra load, and by this morning, we were at 50% battery and simultaneously, we woke up to full overcast and rain the entire day, making only 90w-150w solar power!

So......into Helena, MT I drove and picked up a cheap little 2000w / 1600w continuous Predator inverter generator at Harbor Freight. Seems to be charging fine now. 

At my age, I should know not to brag too much, too quickly, with any systems that I built! :-)

BTW, I reconfigured the charging to 93% SOC that it cycles between 90% and 93% during the day! 

[Dave Festing]

Hi Barry,

I was going to query your fridge consumption before ... mine draws about 400Watt/hours/day.  Samsung Digital inverter.  Quite a few RVers use them in NZ.  The problem will be if  you get a few cloudy days then you might wish to be able to turn the propane back on!

Dave

[Don Fukushima]

Well, I forgot to switch the fridge back to propane mode when the su went down, and so the battery was drawn down at 330w extra load, and by this morning, we were at 50% battery and simultaneously, we woke up to full overcast and rain the entire day, making only 90w-150w solar power!

Barry, your system sounds much like what I've done except my battery bank is 24v x 480aH Li-Ion. The system is now operational and

 testing various loads including a standard RV refrigerator. It's an energy hog too and my plan is installing a larger, high-efficiency 120vac residential unit; thereby, eliminating propane for that appliance. The stove is the last propane-powered device; that is slated for replacement with a movable 2 burner induction unit. Propane tanks be gone! 

Next, decommission the large diesel generator but a major concern is just what you experienced. I'll carry a small portable for those unusual days where electrical demand and poor weather aren't able to fully charge battery.  One other purchase may be a 24v power supply that can be used to assist charing battery bank where a pole is accessible.

[Barry Timm]

Dave, the RV fridge is a huge energy hog. It's the OE equipment Dometic 10 cu ft absorption type propane/electric that came in our 14-year old camper that we use for summer travels.The SBMS0 Loads monitor shows a continuous 320w to 340w current draw increase when I switch the fridge to electric mode from propane. It is a steady, 100% duty cycle in ambient temps above about 70F. 

[Barry Timm]

Don, sounds good.

I'm probably going to add another 8 x 150ah cells next year to make my battery a 24v 450ah capacity, along with another 2 x 315w PV panels, after I fit the 37.5 SEER mini-split when we get back to Yuma. 

I was looking quite seriously at the 12/24v DC Unique fridges sold by Home Depot because they are so incredibly energy efficient, but am concerned about two things - the open drain water tank in the bottom, spilling onto my camper floor when traveling, and the lack of latching doors. I think I could work out some kind of small automatic pump to drain the excess water from the drain tank, and I suppose I could work out some way to effectively lock the doors from opening on the bumps when traveling, but it's probably not the ideal solution.

[Barry Timm]

Don, what are you doing for heating in the coach, if you remove the propane? Some kind of Webasto type diesel heater, or are you thinking of trying the PV diversion heater with solar panels inside the coach?

[Don Fukushima]

37.5 SEER mini-split
Seriously? What brand, model, price is that? 

I'm waiting for the delivery of the MRCOOL Advantage unit with a 19 SEER rating. Once the rating gets over 22-25, the price really starts jumping and the amount of incremental energy savings drops off. It is far cheaper to add some battery and PV panels to overcome any energy saving.

I've also planned for two to four more 320 watt PV panels to mount on the roof. The balance of the system overall should be optimal - that is, in fair weather, PV output is sufficient to charge batteries from energy consumed during the evening and supply all that is needed during the day. Once the mini-split goes in next week and refrig goes back to propane, the system should be pretty balanced.

[Don Fukushima]

The bus is equipped with a 100k BTU Webasto hydronic heating system and a half dozen fan-powered registers. Works awesome so using the MRCOOL only for cooling. Since heating is handled by another source, I did zero research into the heating capabilities of the MRCOOL. If the need for heating is quite mild, I'll give the mini-split a go and assess the performance but definitely assume the Webasto will handle more challenging heating demands.

[Barry Timm]

37.5 SEER mini-split.

It's the Innovair Elite Gold series 230v 9k BTU unit. 

Users report an average of less than 150w draw once it's up and running. It's a fairly low output (9k) with a huge external unit. 

I'll report on the actual daily average running consumption once installed, but theoretically, it should not be drawing more than approx 240w at full power. Of course, the proof will be in the pudding! :)

It was $1149, plus taxes when I bought it in March. It's no longer available on Amazon, although I think the less efficient larger units are. 

[Airtime]

Hey Barry, congrats on completing your build!

But that fridge--really?  You built such a high end system and used that fridge???  That is 12.4A continuous on a 26.6V (24V nominal) system.  My Isotherm 115 uses average 0.45A which is about 4% of your fridge.  I have a 280Ah 24V system and it will run my fridge for 3 weeks--I tested it.

[Casey & Gina]

Yeah, absorption fridges common in RV's and campers are terribly inefficient, especially when looking at the total kWh/day.  We've chatted about this in another thread.

[Graham Bebbington]

Yes, I am going to say thank you to Dacian as well. 

He is very prompt in replying to enquires etc., would like to know when he sleeps with the building of the SBMS’s and replying to emails as well as this forum.

I have the earlier version of sbms, a sbms120, had it in storage for a while due to medical issue (knee replacement) and since April have started to redo my system in our OZ made 5th wheeler.

I turfed out the 12v rv fridge as it was 10 years old and couldn’t keep the ice cream hard 😋. Replaced it with a domestic 240v Samsung Inverter fridge running from a 12/240 Victron 375watt Inverter.

Electrical so far, 6x130w panels, sbms120, 8x280ah cells = 560ah 12v and the 375watt Inverter. Later will install the 12/3000 240v Inverter/charger. The fridge has been running now for 2 weeks and the battery has to gone below 95% SOC. Have also turfed out the rooftop a/c and replaced it with a domestic cassette Daikin 3.2kw Inverter system, should be better in our summer temperatures, sometimes in the mid to late 40C’s +.

[Casey & Gina]

You think your RV fridge was bad - I have one running now from 1992.  The freezer does keep things frozen, but the fridge runs full-bore 100% of the time, and I'm lucky to see the fridge temperature drop below the mid-50's.  It's just a stopgap until my new compressor fridge comes (I ordered a Dometic DMC4101).

Is the rooftop A/C unit you ordered AC or DC?  I'm contemplating switching from a mini-split A/C to a rooftop system to save space, but only if it's not going to be a lot less efficient.  DC operation would be ideal!

[Barry Timm]

LOL, yeah. But when I run it on propane, which is the "normal" mode, it uses even less electrical than your fridge! :) :)

Jokes aside, I will be replacing the fridge with a DC compressor unit. I was very keen on the very efficient Unique brand sold by Home Deport but there are some use case issues with them in an RV that I need to decide to go with that brand, or something else. I'm not crazy about the Dometic compressor fridge as it's not that efficient, but it has a big bonus in being designed for RVs with the right size and latching doors and no open drain tanks etc.

I suspect I'll still be going with the Unique, but the current fridge works OK on propane, and I can always utilize the excess solar via DSSR20 diversion to run it on AC even though it's inefficient, as otherwise my excess solar is simply being wasted.

On Wednesday, September 16, 2020 at 2:32:52 PM UTC-6 Airtime wrote:

[Graham Bebbington]

The a/c is 240v, same type you see in office roofs.

 Regarding the image.

Not our tow vehicle but same make of van that we travel on these type of roads, van has air suspension and doesn’t knock domestic fridges around, in Australia we have used domestic fridges for quite a while due to the high temperatures.

[Casey & Gina]

Barry,

Why do you think the Dometic compressor fridge is not efficient?  It has a variable speed compressor and while I'm not sure how it compares to the Danfoss/Secop compressor, it shouldn't be much less efficient if at all.  If I had a reason to believe it was much less efficient than the Unique, I wouldn't have ordered it.

There is relatively little data available on this fridge, and Dometic unfortunately does not publish figures for kWh/day in a controlled environment, for which there is no independent standard set.  Don't read too much into the 156W rating - that's a worst case maximum, not what it should be requiring all the time.  That may be for a defrost feature or something that only kicks on for a couple minutes in a day.  At least Dometic claims that it's "very efficient".  My expectation is that it should actually be a little better than the 13 cu. ft. Unique that I had, since it's 3 cu. ft. less.  If the compressor can actually draw 156W itself when it's running at the highest possible speed, that's probably a good thing since it means that the fridge will cool down faster when needed (e.g. after I load a bunch of warm groceries into it), which is more important to me than keeping the wattage draw very low.  ANY compressor fridge is going to run a lot less than an absorption fridge, since it can cool down much faster.

I talked to the distributor I ordered through yesterday - they said that it has been taking a long time to get certain things shipped in including Refrigerators since COVID started, and we're not sure how soon to expect it - it's already been longer than anticipated.  But once I get it, I will install it and let you know how it looks from a power consumption standpoint.  I'm willing to bet that it will end up being more efficient than my Unique was, but that's not a very fair comparison since the Unique wouldn't get cold enough and was running almost non-stop 24 hours a day.

There are numerous other brands including Furrion who also make RV-style compressor fridges that you could consider as well.  At least a half dozen different brands on the market now.  I chose the Dometic because they have the most experience with RV's (most popular and have been doing it for the longest), and the feature set of the Dometic looked the best.

I really think that it would be hard to go wrong, from an efficiency standpoint, by switching to ANY compressor fridge.  An AC fridge would draw more power when running but would cool down even faster, so over the course of a day would still be a massive improvement over an absorption fridge even considering inverter loss.  It would probably be fairly easy to modify the Unique and connect the drain that goes into the open pan inside the bottom to instead feed into your grey water tank, and come up with some mechanism to hold the door shut while traveling.  But it'll still be heavier than necessary, since it has an outer metal shell that you don't need in an RV installation, and will require significant modification to your kitchen space to fit it in since it's not designed to fit the opening that's already there.  I expect that as solar is becoming more commonplace over time, the availability of RV-size compressor fridges will increase over the coming years, so should you need to replace your fridge years down the road, it's probably easiest to use a standard size.  That said, compressor fridges are pretty easy to have serviced, and you likely won't need a new fridge until it's old enough for the seals to start falling apart and other damages to add up over time.  A few years ago, I was happily using a GE compressor fridge that had been in continuous operation since the 1920's - still going strong nearly ~90 years later.  Super heavy but I'm guessing that even it on an inverter would have been more efficient that any absorption fridge, even considering lower fuel efficiency and more frequent need to replace axles from hauling the extra weight. ;-)

[Barry Timm]

Unfortunately, with Dometic not providing ANY sort of energy efficiency ratings, other than their "rated input power" of 156w, we are all left to guessing. It feels VERY peculiar to me that if they really built a highly efficient fridge, they would not provide all sorts of documentation and advertising related to that efficiency. It would SURELY be a very key performance drawcard for them, in this day of energy efficiencies, solar power and renewables. I think it makes any logical person question whether the efficiency is perhaps not quite as good as we'd all hope, but that's clearly supposition at this time.I'll be very interested to hear what yours draws over a period of time with normal usage!

[Barry Timm]

Oh, and I'm not a Furrion fan at all, after the experience we've had with their truly crappy range and oven in our Montana. The materials used are cheap, and the "stainless steel" is anything but! The oven does not work properly, and it's a major PITA to get it lit and keep running, and then the temp control is WAY off.They look nice when sitting in the showroom, but not in actual usage, in my experience!

[Barry Timm]

OK, I've just about decided to go with a 120v AC compressor conversion kit for my existing Dometic RM-2852 LB fridge. Only $595 for their 0.8a compressor (96w), which is a fairly easy install onto the back of my current fridge, and uses less than 25% of my current fridge running on AC power.

They also have 12v/24v DC conversion kits which are even more efficient, but a bit more involved for the install.

You can see the convesion being done by the YT channel, "Mortons on the Move".

Here is the product page for the AC version....  https://jc-refrigeration.com/product/dometic-2852-series-hvac-120v-8a-96w-120v/

FWIW, this conversion appears to use around HALF of the wh/day consumption compared to a new Furrion compressor fridge replacement for the Dometic, and it's 3x the price of the conversion (although it does off a 25% increase in interior capacity).

On Wednesday, September 16, 2020 at 9:06:45 PM UTC-6 Casey & Gina wrote:

[Don Fukushima]

The JC-refrigeration upgrade kit looks like a good option to improve the efficiency of an existing RV refrig. The pricing matches what they quoted me. Running on propane now and it really is super efficient but need to deal with the tanks. Another route is installing a small (~10 cf) residential refrigerator. for about the same money than the upgrade unit plus bigger, and highly efficient.

[Barry Timm]

Yep. The fridge is OK on propane, but does not get down to really cold temps as much as I'd like. Let me know if you find a standard residential fridge that fits - that seems to always be the issue, and then you have to think about latches for the doors, etc.

[Barry Timm]

Casey & Gina

Have you see the new Recpro 12V fridge. 10.7 CU FT in size, direct RV replacement.

It apparently uses 7 amps to startup and only 1 amp (12V) to run.

Seems almost impossibly efficient to me, and at a very good price $1149.95 for the stainless model.

It is made by Ever Chill.

Wish there was more feedback on it and especially its efficiency claims!

https://www.recpro.com/rv-refrigerator-10-7-cubic-feet-12v-stainless-steel/

[Dacian Todea]

Seems that thermal insulation is not that great that is what requires the energy once it got to set temperature. And if it continuously uses 1A (possible that it never turns off to be more quiet it works all the time at lower power) then that will be around 288Wh / day and that is not particularly efficient (it is of course huge improvement over the propane/electric one you have) not not vs commercially available fridges.

The one I had when renting the apartment used 100W with just around 30% duty cycle so 720Wh/day but a relatively old not particularly efficient model.  Ambient temperature also plays a big role.

But yes around 300Wh/day or below is what I expect for any decently efficient fridge and even substantially less is possible with proper thermal insulation and in theory with infinite thermal insulation the fridge will use zero energy to maintain temperature.

[Barry Timm]

It's the best I've seen of any "normal" sized (10 cu ft) RV fridges, and better than many/most larger residential fridges. I'm sure there may be some very specific, very expensive, well insulated chest type fridges that are more efficient, but I've yet to see anything running at an average of 12-13w, even if that is full duty cycle,

If you're aware of any more efficient 12v/24v DC fridges of that size, (that are not the less user-friendly chest style), could you share the make/model here? I think a number of us RV folks are interested!

Thanks!

[Dacian Todea]

I have not looked in to compressor based fridges. I'm OK with a very small 40liter fridge (about 1.4 cu ft) and size is less relevant and this uses about 10 to 12W continues to maintain about 17 to 18C below ambient. It is a peltier type fridge so super inefficient compared with a quality compressor.

The DC compressors are still nowhere near mass produced so it is a niche market with expensive units.

Sorry I made a mistake when I mentioned the old inefficient fridge freezer I had in a rented apartment used 300Wh/day it was around about 800Wh/day as it was 100W while compressor was running as it was running about 30% of the time.

The energy that a fridge needs to use can be calculated is based on how much energy it will lose based on surface area of the fridge and delta between internal fridge temperature and ambient temperature and amount of thermal insulation. On top of that it is also how much new things you put in the fridge that are maybe at room temperature and will need to be cooled.

So say you add 10 liters of room temperature water (can be juice or beer or almost any other food containing that amount of water) and say water starting temperature is +26C and fridge is set at +3C then 10liters * 23C * 1.16 = 267Wh  on top of the normal fridge energy loss through thermal insulation so if compressor has a COP of 1 (not unlikely on cheap compressor fridge) then that is what you will need 267Wh but if COP is 3 then you need just 89Wh

You can check this video on how thermal insulation affect the energy a fridge will be using https://www.youtube.com/watch?v=dU2-Qm45OHg

If you run the inverters 24h/day then just get a energy efficient 120Vac fridge as will likely be better build quality and even more efficient than the 12V / 24V DC models. But I'm not sure about the resistance to vibrations as typical house refrigerators are not designed with vibration in mind.

[Don Fukushima]

If you run the inverters 24h/day then just get a energy efficient 120Vac fridge as will likely be better build quality and even more efficient than the 12V / 24V DC models. But I'm not sure about the resistance to vibrations as typical house refrigerators are not designed with vibration in mind.

This is on the list very near the top. There are some very efficient 120vac refrigerators in the 10 cf range for less than $400. Here's a link to a couple. Both average less than 1kW per day. To me it is a no brainer as the amount saved over specialty unit can buy more panels or batteries. They are also less than 24" to fit through door.

https://www.homedepot.com/p/PREMIUM-11-5-cu-ft-Frost-Free-Top-Freezer-Refrigerator-in-Black-with-Stainless-Steel-Door-PRN12160MS/302466146

https://www.homedepot.com/p/Magic-Chef-10-1-cu-ft-Top-Freezer-Refrigerator-in-Black-HMDR1000BE/302245062

Depends on the amount of vibration in your vehicle but mine is very vibration free so not worried about durability. And if worried appliance warranties on such low cost items can not be much to offer more peace of mind.

[Barry Timm]

The manual for this fridge says to not build it in. It is a free standing fridge only, requiring a minimum of 5" air gap on the sides and back, and it specifically says it is not suitable for an RV.....

[Don Fukushima]

Very interesting. That section of the manual of each product is verbatim, so a very close association at the manufacturer level. The inverter warning is probably targeted at modified sine wave inverters as those can create operating issues with some appliances. I have never heard that an appliance had problems with pure sine wave inverters when properly matched together. Spacing requirement is to minimize heat issues as is not putting in a garage, really? Either thing is too weak or the company is just very concerned units will be operating in harsh (hot/cold/humid) environmental conditions.

[Don Fukushima]

https://www.homedepot.com/p/Danby-10-1-cu-ft-Top-Freezer-Refrigerator-in-Stainless-Steel-ENERGY-STAR-Rated-DFF101B2WDB/311656768

This one has no inverter warning but does call out free air and inside use.  I'm still very inclined to find a residential house 10 cf AC unit