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Old 11-03-2023, 09:27 PM   #1
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Name: Derek
Trailer: Bigfoot 25RQ
Washington
Posts: 96
Trip report—Solar system performance

This spring I installed solar panels, an inverter, and a lithium battery (2, 200W Rich Solar panels, a single 270ah Batttleborn battery, and all Victron equipment—Multiplus 12/3000/120-50 120V, SmartSolar MPPT 100/50 solar charger, Cerbo GX Monitor w/Touch 50 Screen, Smart Shunt, and a Orion-Tr Smart 12/12-18DC-DC charger). All equipment was sourced through AM Solar in Oregon, who were very helpful (I posted photos of the install in an earlier post). We just returned from a 48 day trip across the western U.S. and I thought that I should report on the performance of the new system.

Our main usage of the inverter was to run a toaster, hair dryer, and microwave. Both computers and phones were charged directly with DC each day and the cellular router and Cerbo used about 15 W combined on standby. We ran the Fantastic fan much of the day, and there is also a small draw from the propane fridge circuit board. We turned the inverter off when not in use to avoid the roughly 20 W standby draw.

Each morning, after finishing our tasks but before the sun came up the battery was usually at about 75-80% charge. At one campsite we had a shady site for 3 days straight and we got down to the low 60’s. We would have been at an even higher state of charge, I think, but it took us awhile to realize that the fridge was on auto and was switching to AC every time we turned on the inverter.

So, let’s say that we drop to 70% charge. With a 270 ah battery this is about 80 ah. I was able to monitor the system while driving by using the Victron Connect app that connects directly to the different equipment via bluetooth. I could see in real-time how many watts the solar panels were producing, the performance of the DC-DC charger, and the state of charge via the Smart Shunt. I could literally see the impact of a single cloud drifting in front of the sun. While I saw as high as 350 watts from the panels, a more typical number was around 200 W or 15 amps. At this rate, it would take about 5 hours to recharge the battery to 100%. However, the DC-DC charger was providing 15-18 amps, for a total of about 30 amps. If we were driving our battery was fully recharged in about 2.5 hours.

A word about the DC-DC charger. I have read many posts about these on the solar forums and I think there is a lot of confusion. Here is how my setup functioned on an older F150 with a regular alternator. While my alternator puts out 14.1 volts, if you try to provide 18 amps to the trailer through the factory 7 pin wiring (10 gauge, 30 amp on my truck), the Orion only sees 10.2 volts at its input—the voltage drop is huge due to the small wiring. This, of course, is not enough to charge a lithium battery. So, the Orion transforms the 10.2 volts up to 13.8 volts and outputs 18 amps. In order to do this, it has to draw more than 18 amps from the alternator (low voltage & high current gives the same power as higher voltage & lower current; P=IV). I probably have 25-27 amps coming out of the alternator depending on the inefficiencies in the DC-DC charger. This is the reason for using the Orion 12/12-18 instead of the 30 amp version. The 18 amp version works with factory 7 pin wiring without blowing the fuse. If you want 30 amps you have to run bigger wires, which I didn’t want to do and didn’t need. Some have questioned whether I need the DC-DC charger at all, but I wanted the insurance that my batteries would get fully charged while driving on a cloudy day.

The Orion DC-DC charger is, however, the most difficult piece of equipment when it comes to finding the right settings. The trick for my setup was I had to lower the lock-out voltage to 9.5 volts. The large voltage drop was sometimes dropping things to just under 10 volts, which turns off the charger even if the voltage drop is only for an instant. The charger then turns back on, the voltage drops again, and then it continues to cycle on and off. You know you have the setting right when you are seeing an extra 15-18 amps going in on the Smart Shunt.

Anyhow, my conclusion is that for my current needs 400 watts of panels is sufficient and 200 ah of batteries would have been enough. If you don’t try to run air conditioning I think you can be perfectly happy with a pretty small system. We did inadvertently run an experiment on this—we thought we were plugged in to shore power when actually the circuit breaker wasn’t on—the inverter had kicked in without us realizing it. We turned on air conditioning and discovered that we can run it for about 2 hours… We drained our battery to zero. The BMS in the Battleborn battery shut things down and the Victron equipment sent us an alert and an email. Luckily we were able to recharge from shore power, as it would have taken 9 hours of driving in partly sunny weather to completely recharge. The Multiplus charges at 120 amps.
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Old 11-04-2023, 10:13 AM   #2
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Name: John
Trailer: Roamer 1
Smith Valley, Nevada
Posts: 2,900
Derek,

Excellent report! Thank you.

I'm wondering how the seven pin charging wire can have a voltage drop to under 10 volts and not heat up, or blow an appropriate sized fuse. But I guess it works just fine. Interesting to run it right at the limit and have it work so well. And, of course, it would never work without the DC-DC charger.

On my last two trucks, I ran sets of heavy conductors, #4 on one and #6 on the other, to an Anderson plug at the back bumper. With an earlier trailer and 400 AH of AGMs, I charged directly without a DC-DC charger and it worked very well. But of course with the newer lithiums, a DC-DC is required for proper charging. So on my X22 trailer I installed a Victron 30 amp DC-DC charger. The only problem was that I had a GoPower solar controller that could not talk to the Victron DC-DC charger, so in daylight and while charging from the truck, one system would shut off as it thought the charging voltage from the other meant the batteries were fully charged. Consequently, I ran the DC-DC charger at night while towing.

On your system, with the seven pin charging positive wire at max capacity, which of course would include the negative ground wire to complete the circuit, have you noticed any reduction in braking performance? The brakes use the same ground wire as far as I know.

You truly are getting the most out of your relatively small system. Good job.

My last Trailer, an Imperial X22, had 660 watts of solar that I installed, and 480 AH of lithium batteries. It was an off grid trailer under almost all circumstances, while still being very convenient and comfortable. My new one, a Roamer 1, has 1240 watts of solar and 1080 AH of lithium and it is not able to keep up with demand.

Once again, demand has risen to meet supply, as I so often claim will happen. In my case the trailer came with an induction stove and I have Starlink, as well as a compressor fridge.
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Old 11-04-2023, 10:53 AM   #3
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Name: You can't call me Al
Trailer: SOLD: 1977 Scamp 13'
Massachusetts
Posts: 824
Smile 400 watts of solar a 270 AH battery is quite large in the world of fiberglass campers

Quote:
Originally Posted by Raspy View Post
You truly are getting the most out of your relatively small system.


400 Watts of solar and a 270 Amp-Hour battery is a LARGE system in my opinion.

I've got a 30 Watt solar 35 AH battery and it's great for our 13' Scamp.

Two Etch Is Own.

But saying this is a relatively small system just because you have a huge system doesn't really give the nonexperts in the group a proper evaluation of systems in the real fiberglass RV world.
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Old 11-04-2023, 11:16 AM   #4
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Name: Derek
Trailer: Bigfoot 25RQ
Washington
Posts: 96
Thanks for bothering to read it.

How much a wire heats up depends upon the current passing through it, not the voltage. For example, a wire can have a high voltage (electrical pressure) but no current (flow rate) and not heat up when a switch is off. According to the specs, the Orion DC-DC charger can handle an input voltage as low as 7 volts, so I assume they expected some low input voltages. I should probably measure my actual current to see how close I am coming to the 30 amp limit.

Running heavier wires is definitely the way to go to maximize charging. I will use Anderson plugs as well if I ever do this in the future .

I didn't have any problem with the solar operating at the same time as the DC-DC charger. The solar charger might read 15 amps and the smart shunt would show 30-33 amps going in to the battery, with the extra 15-18 amps coming from the charger. When the smart shunt decided that the battery was at 100% charge the solar would drop to 0 amps and the DC-DC charger would continue on for awhile in absorption mode. I am still tweaking some of the settings such as length of absorption time. The DC-DC charger isn't as smart or capable as the other Victron components. It doesn't talk or share data with them and you can't set a tail current to terminate charging like with the solar charger. I don't know why the GoPower charger wouldn't work--my guess is that because the Victron Solar charger is communicating with the smart shunt and the Cerbo it is better able to figure out what is going on. The smart shunt is directly connected to the battery terminals.

I don't know about the brakes--hadn't thought of that. I'll have to research it. If anyone know anything about this please chime in. I didn't notice any problems with the brakes but I was usually drawing the most amps going down the freeway where I wasn't braking much. I have a pretty nice brake controller, the P3 with the digital readout. I didn't change the settings from before the new system was installed. My biggest issue is usually having to change the boost setting when going from freeway to in-town driving.

I designed my system so that I could upgrade if necessary. I have room on the roof to add an additional 400 W and space in the AM Solar combiner box to connect them by just popping out a knockout. The solar charger is oversized in order to handle the additional panels. I also have room for another 270 ah battery. At the moment, though, I think I'm good. I'll probably look into a Starlink eventually and that will use some power. I'm fine with our propane fridge and stove, but there is sure a lot of talk about the new compressor fridges. Not sure what I would buy if my propane fridge died tomorrow. Adding these two items would probably lead to a solar upgrade. (Side note: Our 6 year old, $2000 LG home refrigerator went out while we were on our trip. Apparently everyone but us knows that LG linear compressors suck. Our new fridge is a Bosch.)


Derek






Quote:
Originally Posted by Raspy View Post
Derek,

Excellent report! Thank you.

I'm wondering how the seven pin charging wire can have a voltage drop to under 10 volts and not heat up, or blow an appropriate sized fuse. But I guess it works just fine. Interesting to run it right at the limit and have it work so well. And, of course, it would never work without the DC-DC charger.

On my last two trucks, I ran sets of heavy conductors, #4 on one and #6 on the other, to an Anderson plug at the back bumper. With an earlier trailer and 400 AH of AGMs, I charged directly without a DC-DC charger and it worked very well. But of course with the newer lithiums, a DC-DC is required for proper charging. So on my X22 trailer I installed a Victron 30 amp DC-DC charger. The only problem was that I had a GoPower solar controller that could not talk to the Victron DC-DC charger, so in daylight and while charging from the truck, one system would shut off as it thought the charging voltage from the other meant the batteries were fully charged. Consequently, I ran the DC-DC charger at night while towing.

On your system, with the seven pin charging positive wire at max capacity, which of course would include the negative ground wire to complete the circuit, have you noticed any reduction in braking performance? The brakes use the same ground wire as far as I know.

You truly are getting the most out of your relatively small system. Good job.

My last Trailer, an Imperial X22, had 660 watts of solar that I installed, and 480 AH of lithium batteries. It was an off grid trailer under almost all circumstances, while still being very convenient and comfortable. My new one, a Roamer 1, has 1240 watts of solar and 1080 AH of lithium and it is not able to keep up with demand.

Once again, demand has risen to meet supply, as I so often claim will happen. In my case the trailer came with an induction stove and I have Starlink, as well as a compressor fridge.
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Old 11-04-2023, 11:17 AM   #5
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Name: John
Trailer: Roamer 1
Smith Valley, Nevada
Posts: 2,900
Quote:
Originally Posted by AlanKilian View Post


400 Watts of solar and a 270 Amp-Hour battery is a LARGE system in my opinion.

I've got a 30 Watt solar 35 AH battery and it's great for our 13' Scamp.

Two Etch Is Own.

But saying this is a relatively small system just because you have a huge system doesn't really give the nonexperts in the group a proper evaluation of systems in the real fiberglass RV world.

I'm sorry you don't understand that he is getting a lot of performance for the size system he has. He is doing a lot with the power he has. That is the point.

You are probably getting a lot out of your system too, if all you want are a few LED lights. Systems, in general, are getting bigger as times goes on. Not everyone wants to camp so simply. I used too, and was glad to have one 50 watt panel and one group 27 lead acid battery. It seemed luxurious at the time. Now, I'm enjoying not only having more power, but having better systems and also fine tuning and building those systems. I want to never plug in, or carry a generator, which provides a lot of freedom. It's all part of the fun of being more and more self sufficient, and each of us doing it in our own way.

Not everyone can put a system together creatively that matches their needs, and explain it with the clarity that Derek has. I appreciate it when someone does.
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Old 11-04-2023, 11:39 AM   #6
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Name: John
Trailer: Roamer 1
Smith Valley, Nevada
Posts: 2,900
Derek,

There is a lot of talk about the new compressor fridges because they can be so good. Just like at home, you can dial in the temp you want and it will get there quickly. Nothing like the absorption units.

I had a Furion 10 cu ft model compressor fridge in my X22 and it worked very well. It was also quite large. The new one in my Roamer 1 is an Isotherm with dual compressors for the freezer and fridge. Is is only 8.5 cu ft, but still relatively large. Unfortunately, the thermostat in the fridge has already gone out after only a few months. I've also improved the venting to help it perform. Other advantages of the compressor system are no outside vents or flame heat.

For me, a new basic function level has been reached in the trailer. Compressor fridge and waterless toilet (with no black tank) are mandatory upgrades. And sufficient solar/battery to be mostly or completely off-grid. It seems too, that Starlink is moving up the list as a basic part of the system, as is a good inverter. Water heating is still a variable and not very satisfying without modifications.
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Old 11-04-2023, 11:46 AM   #7
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Name: Derek
Trailer: Bigfoot 25RQ
Washington
Posts: 96
Yes, everything is relative (I'm actually a retired physics teacher.

If you spend some time researching RV solar on the different forums and websites you will be amazed by some of the systems out there. I've been particularly surprised by the size of the systems installed in some of the transit vans. Some of them have four of my batteries! What in the world are they doing in these things? Anyhow, I am comfortable saying that my system is modest compared to the majority of systems I have seen. My 25' fiberglass trailer, the largest molded fiberglass trailer made, was usually the smallest trailer in the campground on our recent 48 day trip. It is a modest trailer by most of these folks standards, while it is huge by FiberglassRV standards (and my own--our last trailer was a very basic 16' Scamp).

What is not modest about my system is the quality of the components. I went all Victron. If I worked harder I'm sure I could build an equivalent system for less money using less expensive components. I could have even built my own battery. I am happy, though, with my choice. The Victron equipment is well integrated. In particular, I love the touch screen and the phone app and how they tell me exactly what is going on. I should have raved about this in the first post but I forgot. It was quite a step up from my Bogart Engineering Trimetric (which was also a game changer when first installed--I have one for sale if interested. It would go great in a 13' Scamp...

Derek
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Old 11-04-2023, 09:40 PM   #8
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Name: John
Trailer: Bigfoot 25 RQ
Ohio
Posts: 332
Quote:
Originally Posted by Derek Johnson View Post
This spring I installed solar panels, an inverter, and a lithium battery (2, 200W Rich Solar panels, a single 270ah Batttleborn battery, and all Victron equipment—Multiplus 12/3000/120-50 120V, SmartSolar MPPT 100/50 solar charger, Cerbo GX Monitor w/Touch 50 Screen, Smart Shunt, and a Orion-Tr Smart 12/12-18DC-DC charger). All equipment was sourced through AM Solar in Oregon, who were very helpful (I posted photos of the install in an earlier post). We just returned from a 48 day trip across the western U.S. and I thought that I should report on the performance of the new system.

Our main usage of the inverter was to run a toaster, hair dryer, and microwave. Both computers and phones were charged directly with DC each day and the cellular router and Cerbo used about 15 W combined on standby. We ran the Fantastic fan much of the day, and there is also a small draw from the propane fridge circuit board. We turned the inverter off when not in use to avoid the roughly 20 W standby draw.

Each morning, after finishing our tasks but before the sun came up the battery was usually at about 75-80% charge. At one campsite we had a shady site for 3 days straight and we got down to the low 60’s. We would have been at an even higher state of charge, I think, but it took us awhile to realize that the fridge was on auto and was switching to AC every time we turned on the inverter.

So, let’s say that we drop to 70% charge. With a 270 ah battery this is about 80 ah. I was able to monitor the system while driving by using the Victron Connect app that connects directly to the different equipment via bluetooth. I could see in real-time how many watts the solar panels were producing, the performance of the DC-DC charger, and the state of charge via the Smart Shunt. I could literally see the impact of a single cloud drifting in front of the sun. While I saw as high as 350 watts from the panels, a more typical number was around 200 W or 15 amps. At this rate, it would take about 5 hours to recharge the battery to 100%. However, the DC-DC charger was providing 15-18 amps, for a total of about 30 amps. If we were driving our battery was fully recharged in about 2.5 hours.

A word about the DC-DC charger. I have read many posts about these on the solar forums and I think there is a lot of confusion. Here is how my setup functioned on an older F150 with a regular alternator. While my alternator puts out 14.1 volts, if you try to provide 18 amps to the trailer through the factory 7 pin wiring (10 gauge, 30 amp on my truck), the Orion only sees 10.2 volts at its input—the voltage drop is huge due to the small wiring. This, of course, is not enough to charge a lithium battery. So, the Orion transforms the 10.2 volts up to 13.8 volts and outputs 18 amps. In order to do this, it has to draw more than 18 amps from the alternator (low voltage & high current gives the same power as higher voltage & lower current; P=IV). I probably have 25-27 amps coming out of the alternator depending on the inefficiencies in the DC-DC charger. This is the reason for using the Orion 12/12-18 instead of the 30 amp version. The 18 amp version works with factory 7 pin wiring without blowing the fuse. If you want 30 amps you have to run bigger wires, which I didn’t want to do and didn’t need. Some have questioned whether I need the DC-DC charger at all, but I wanted the insurance that my batteries would get fully charged while driving on a cloudy day.

The Orion DC-DC charger is, however, the most difficult piece of equipment when it comes to finding the right settings. The trick for my setup was I had to lower the lock-out voltage to 9.5 volts. The large voltage drop was sometimes dropping things to just under 10 volts, which turns off the charger even if the voltage drop is only for an instant. The charger then turns back on, the voltage drops again, and then it continues to cycle on and off. You know you have the setting right when you are seeing an extra 15-18 amps going in on the Smart Shunt.

Anyhow, my conclusion is that for my current needs 400 watts of panels is sufficient and 200 ah of batteries would have been enough. If you don’t try to run air conditioning I think you can be perfectly happy with a pretty small system. We did inadvertently run an experiment on this—we thought we were plugged in to shore power when actually the circuit breaker wasn’t on—the inverter had kicked in without us realizing it. We turned on air conditioning and discovered that we can run it for about 2 hours… We drained our battery to zero. The BMS in the Battleborn battery shut things down and the Victron equipment sent us an alert and an email. Luckily we were able to recharge from shore power, as it would have taken 9 hours of driving in partly sunny weather to completely recharge. The Multiplus charges at 120 amps.
Thanks for the tip on the Orion 18, I was having then same issue, I’ll try your solution! I have 400 ah of SOK batteries in parallel. I did however only bought the 12/2000 multiplus so no ac for me. I may upgrade it later. My Ram has 10 gauge wiring to the 7 pin which should carry the 18 amp of the dc to dc charger at the wire length. My ram has the upgraded alternator which the snow chief package so load on it is not an issue. I have heard that the next gen dc to dc will integrate into the Cerbo much better and will talk to the Solar controllers like the solar charger and the multiplus. If I had to do,it again I would have spent the extra money for the Victron battery (330 ah) with the external bms for the superior continuous output which is desirable for inverter use.

I only have 300 watts of solar but plenty of room for more in then future so a solid dc to dc is desired. Thanks again for the tip.
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