newbie questions, solar/lithium in a 5th wheel, where to start?

corn18

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Sep 9, 2021
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Very nice diagram! This looks very close to what I envision except I will start about half this size and possible expansion. Wondering if this sounds reasonable: 2 100ah lithium, 2 100w panels portable for now, multiplus II (like simplicity, both lines back to rig panel, doesn't seem $$more than separate pieces), lynx power-in, 1 solar CC, & no Cerbo, display,etc? Questions: Would I be extremely oversized using your fuse and cable specs?
Fuses are for the wires, not the equipment. Using larger wires and the correct fuses to protect those wires is fine. Saves money if you plan to upgrade later.
Could the 50A breaker before the MP II be the Blue Sea din box or their breaker with the pushbutton/lever (not sure of technical name)?
Not sure what you mean. The 50A fuse is a dual pole 240V AC circuit breeaker. The Blue Sea breakers are DC. Maybe they make an AC 240V/50A dual pole I haven't seen.
Is there a direct way to power the DC side of the rig panel?
The MPII powers the DC side of the rig panel, even if the batteries are disconnected. I know this because I did it yesterday while troubleshooting a buzz. You can also power the DC side with just solar or just batteries or just the TV. I don't have switches in place to isolate all the systems, so the DC side just takes whatever is feeding it and sends it off to the batteries for charging or the DC loads.

Two days ago I was running the inverter off the solar only. Panels were getting 800W and that was plenty to power the inverter and run the residential fridge.
I see the DC/DC charger, but from what I gather from reading posts is that I don't need that with my TV ('21 F350 6.7) unless I want to fully charge the batteries-what is your TV?
My TV is a 2015 Chevy 2500HD gasser. I have a 160A alternator, 10ga wire to the 7 pin connector through a 30A fuse in the truck. That can deliver a whopping 13.2V @ 7 amps to the 5er batteries. I added a Victron 12-18 smart charger and that works a lot better. Just used the factory wiring.
 

Paul_R

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You don't need a dedicated circuit. I use a Victron 12/18 smart charger. My 10ga wire to the 7 pin and 30 A fuse on the tow vehicle are more than adequate to feed the 22-24V that the Victron needs to maintain a steady 14.2V @ 18A. And 18A is plenty while towing. It easily runs the residential fridge with some left over. The 1200W of solar on the roof takes care of charging.

Yes, as long as you can dial up your charger to compensate for the losses you'll get in the wire between it and the batteries so the batteries actually see 14.2V you'll be fine. Just curious, how long is the run between the charger and the batteries?
 

corn18

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Yes, as long as you can dial up your charger to compensate for the losses you'll get in the wire between it and the batteries so the batteries actually see 14.2V you'll be fine. Just curious, how long is the run between the charger and the batteries?
For my install, it's 4 ft through 8ga wire.
 

Scycle

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Feb 13, 2022
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Fuses are for the wires, not the equipment. Using larger wires and the correct fuses to protect those wires is fine. Saves money if you plan to upgrade later.
I'm going to use your sizing, it's makes sense.
Not sure what you mean. The 50A fuse is a dual pole 240V AC circuit breeaker. The Blue Sea breakers are DC. Maybe they make an AC 240V/50A dual pole I haven't seen.
Yes right that's AC, too much rolling around in my pea brain.
The MPII powers the DC side of the rig panel, even if the batteries are disconnected. I know this because I did it yesterday while troubleshooting a buzz. You can also power the DC side with just solar or just batteries or just the TV. I don't have switches in place to isolate all the systems, so the DC side just takes whatever is feeding it and sends it off to the batteries for charging or the DC loads.

Two days ago I was running the inverter off the solar only. Panels were getting 800W and that was plenty to power the inverter and run the residential fridge.

My TV is a 2015 Chevy 2500HD gasser. I have a 160A alternator, 10ga wire to the 7 pin connector through a 30A fuse in the truck. That can deliver a whopping 13.2V @ 7 amps to the 5er batteries. I added a Victron 12-18 smart charger and that works a lot better. Just used the factory wiring.
My window sticker lists 240CMP alternator, I see one up top, I thought there were two because I have two batteries-I need to check. I don't know what gauge wire is in the 7-pin. So I should be fine if I get the smart charger?
 

Scycle

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Fuses are for the wires, not the equipment. Using larger wires and the correct fuses to protect those wires is fine. Saves money if you plan to upgrade later.

Not sure what you mean. The 50A fuse is a dual pole 240V AC circuit breeaker. The Blue Sea breakers are DC. Maybe they make an AC 240V/50A dual pole I haven't seen.

The MPII powers the DC side of the rig panel, even if the batteries are disconnected. I know this because I did it yesterday while troubleshooting a buzz. You can also power the DC side with just solar or just batteries or just the TV. I don't have switches in place to isolate all the systems, so the DC side just takes whatever is feeding it and sends it off to the batteries for charging or the DC loads.

Two days ago I was running the inverter off the solar only. Panels were getting 800W and that was plenty to power the inverter and run the residential fridge.

My TV is a 2015 Chevy 2500HD gasser. I have a 160A alternator, 10ga wire to the 7 pin connector through a 30A fuse in the truck. That can deliver a whopping 13.2V @ 7 amps to the 5er batteries. I added a Victron 12-18 smart charger and that works a lot better. Just used the factory wiring.
So I think I've come full circle on the planning side from basic to full blown and no where on the decision side. I'm curious about your opinion corn18 since you started small with separate/different branded components then updated and expanded if you think that's the way to go cost wise? I like the AIO for it's ease and right now looks like Victron has the only split phase output, but there is the MPP brand with one output only 1000w inverter. Even if I went with the MPII, I'm looking at other CC like the EPever and others but I know Victron is supposedly the best or at least more popular and many people go all Victron. I'm not so concerned about everything talking or the phone app, but do you think all-in-all there is substantial saving in using different brand components of equal quality?
 

HRTKD

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It's hard to beat an all-in-one for a quick and easy install. But the need for split phase limits your options.

Look in the Solar Charge Controller subforum. There are a not insignificant number of problem posts about the EPEver controller. It's not a Tier 1 device like Victron or Midnite Solar. I would likely take an EPEver over Renogy.


 

Scycle

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It's hard to beat an all-in-one for a quick and easy install. But the need for split phase limits your options.

Look in the Solar Charge Controller subforum. There are a not insignificant number of problem posts about the EPEver controller. It's not a Tier 1 device like Victron or Midnite Solar. I would likely take an EPEver over Renogy.


I don't know if it's a need for split phase, but would be nice and also easier than arranging the rv panel to power certain items on one line. I haven't researched extensively but it seems the tier 1 components are evenly priced to each other.

I see you have a F350 as well, mine is a 2021 and I'm wondering from your experience if a dc/dc unit is needed if I put lithium in the RV?
 

HRTKD

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I don't know if it's a need for split phase, but would be nice and also easier than arranging the rv panel to power certain items on one line. I haven't researched extensively but it seems the tier 1 components are evenly priced to each other.

I see you have a F350 as well, mine is a 2021 and I'm wondering from your experience if a dc/dc unit is needed if I put lithium in the RV?

I have a 30 amp RV trailer, so split phase wasn't part of the equation. The Victron Multiplus II handles the two sides of the RV's main distribution panel. I helped a friend install one and the hardest part was setting the parameters.

I don't have the 7-pin circuit from the truck charging my LiFePO4 battery bank. I decided that I didn't want to deal with a DC-DC charger to enable a charge from the truck. I set up a small lead acid battery on the tongue to provide power to the trailer's breakaway brake system and that battery does get a charge from the truck through the 7-pin circuit. The LiFePO4 and lead acid batteries are distinct systems.
 

Scycle

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I have a 30 amp RV trailer, so split phase wasn't part of the equation. The Victron Multiplus II handles the two sides of the RV's main distribution panel. I helped a friend install one and the hardest part was setting the parameters.

I don't have the 7-pin circuit from the truck charging my LiFePO4 battery bank. I decided that I didn't want to deal with a DC-DC charger to enable a charge from the truck. I set up a small lead acid battery on the tongue to provide power to the trailer's breakaway brake system and that battery does get a charge from the truck through the 7-pin circuit. The LiFePO4 and lead acid batteries are distinct systems.
I'm not looking to fully charge the rv battery bank with the truck only enough for breakaway system, but I haven't been able to get a consistent answer if there will even be an issue. I wouldn't think the truck manufacturer would not have the vehicle system protected from whatever might be plugged into it.
 

corn18

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So I think I've come full circle on the planning side from basic to full blown and no where on the decision side. I'm curious about your opinion corn18 since you started small with separate/different branded components then updated and expanded if you think that's the way to go cost wise? I like the AIO for it's ease and right now looks like Victron has the only split phase output, but there is the MPP brand with one output only 1000w inverter. Even if I went with the MPII, I'm looking at other CC like the EPever and others but I know Victron is supposedly the best or at least more popular and many people go all Victron. I'm not so concerned about everything talking or the phone app, but do you think all-in-all there is substantial saving in using different brand components of equal quality?
For us, it came down to simplicity of use. The original, complex system did everything we wanted, but it was a cluge. Now that we have the MPII powering the whole AC distro panel powered via the MPII, the user experience is identical to being on shore power with the exception of load management while on batteries. Not much different than when we are at a campground with only a 30A hookup.

As far as brand, I got the blue disease. Once I got the Cerbo, I wanted everything on that slick panel. The only way to do that was to go all blue. I am even going to convert my tank monitors over to work on the Cerbo display.
 

sunshine_eggo

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For us, it came down to simplicity of use. The original, complex system did everything we wanted, but it was a cluge. Now that we have the MPII powering the whole AC distro panel powered via the MPII, the user experience is identical to being on shore power with the exception of load management while on batteries. Not much different than when we are at a campground with only a 30A hookup.

As far as brand, I got the blue disease. Once I got the Cerbo, I wanted everything on that slick panel. The only way to do that was to go all blue. I am even going to convert my tank monitors over to work on the Cerbo display.

The fever is WORSE than cowbell!

84fd7de047ded4e2eb113ec91f78ac86--cinema-movies-movie-tv.jpg.2b408fedf14b8bc4d2a7b8fe17c5025e[1].jpg
 

Scycle

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Here's my diagram for my MPII install:

View attachment 79247
On your previous diagram with bus bars instead of the Lynx dist. you were fused 250A at the battery and now at 400A, so I was wondering the reason? I'm starting to sketch my system and fusing and wire gauge is my big hang up-where, what size fuse & wire.
 

corn18

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On your previous diagram with bus bars instead of the Lynx dist. you were fused 250A at the battery and now at 400A, so I was wondering the reason? I'm starting to sketch my system and fusing and wire gauge is my big hang up-where, what size fuse & wire.
I only had 2/0 wire going to the MPII for a short period. 2/0 is good for 250A. Once I switched to 4/0, I went to the 400A class T.
 

Scycle

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I only had 2/0 wire going to the MPII for a short period. 2/0 is good for 250A. Once I switched to 4/0, I went to the 400A class T.
I posted this in a different forum, but wondered if you would take a look at it and critique it?
 

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DonPhillipe

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Are you starting to see the picture?
No, I'm not seeing it for my own personal environment. The reason that mfgs go to higher voltages is as you pointed out, to save money on copper. (Plus there's the inherent advantage of an ignorant public that believes e.g. a 18V rechargeable drill is twice the device a 9V rechargeable is and will buy the high voltage unit over lower voltage every time.) What we are doing in upgrading is a one-shot and to save a few dollars on copper is not worth adding and dealing with the additional number(s) of a fiiniky buck converter(s) or a single one running all appliances which also hopefully assumes people are using 12V appliances and not running an inverter 24x7 like in a large home installation and thus using everything powered off 120V. Something also I have not seen anyone talk about here is as I have just done, going from 230Ah (115Ag) usable lead/acid, once I switched to lithium I found the overhead of all my fancy new equipment rendered my old 480W solar array incapabile of supplying my previous daily requirement of energy and that is because when you add fueling the additional overhead of "intelligent" BMS, "intelligent" solar charge controllers and all the additional blue tooth radios, and new interface devices, you've shot yourself in the foot due to the limited real-estate of the vehicle rooftop needing to be expanded just to keep up with the new amp-demand of all the monitoring equipment. Also regarding the concept of the base battery voltage not mattering, in a house, it's true that most people ignore and don't care what voltage level is on the feed line to the massive house inverter. In a vehicle, all your 12V appliances will be best run off direct battery connect and thus minimizing the points of failure and reducing the very hungry losses of a constantly running inverter or the lower but still notable energy loss through one or more buck converters. Also if you travel to remote areas, the least components to fail, the better off you are.
 

DonPhillipe

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I spend more time designing things thinking what happens if something goes wrong
Always good to find a kindrid spirit. Don't loose the positive "negative attitude" I always say. Cheers to you my friend! You and I have shared bread with our fellow Murphy ;-)
 

DonPhillipe

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purpose of adding a DC-DC
Another option if you have a high performance alternator, e.g. a Sprinter 150a has a common steady 30A commitment to keep the chassis components energized (45a if the A/C is going), so it makes a lot of sense to tap off that extra 120a that is just dormant with no need for a B2B/DC-DC If you then want to shut down the charge after you reach 90% capacity with that alternator "boost" and let the solar setup later "baby" the top-off routine, you can. Otherwise how much would someone be spending to add a DC-DC that would handle that extra 120A? Not sure if a 120a DC-DC is available but it's likely expensive. Secondly, most RVs have at least 2/0 going through a 200A solenoid to charge the "house/leisure" battery so if the alternator has the capability, the batteries take that much current, and the alternator is not of the modern/smart where coasting turns it into a electric brake category then that extra 120A is a lot of resource to be wasted stifling it down via a 30A DC-DC that most people can afford.

*** EDIT: My apologies, the topic is on a "5th wheel", there is no practical way to get that much DC current from an alternator to a vehicle towed behind. Therefore I retract my statement. A DC-DC or B2B will be required and for this I'd hope for one that used the highest internal voltage. In fact what I recommend to many 5th wheel drivers is assuming they have already laid out a sizable cash sum for an extremely elaborate 120VAC charger for the LiFePo4 in their rig, it makes a lot of sense to just put a heavy duty 120VAC inverter near the truck chassis battery and to run 120VAC back to the trailer, where the equipment you have already paid for can do it's normal job
 
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