Airstream factory installed 80 watt solar system

[uncle_bob]

Originally Posted by lsbrodsky

I agree, Bob. I think part of the issue is that people do not generally know what battery voltage means in a lead-acid battery and when/how to use the reading. I think once that is understood a plain old voltmeter can tell you a lot. No question that a shunt device with the "computer" to give you a variety of results is way better. I see more of our members taking the plunge and installing battery monitors, almost exclusively Victron. I wonder if Victron ever knew that they would be so big into RV's?

Larry

Hi

Apparently, if you talk to Victron, the biggest chunk of their business goes into stand alone / fully off grid systems in Africa. I never would have guessed that to be the case. I also have no way to verify if that really is the case today.

So no, I don't think they fully understand the RV market. That comes across pretty clearly in their advertising. It comes across even more clearly in their documentation and manuals.

====

The gotcha with voltages is that it's a lot of work. You pull the battery cover. You probe this and that. You take the battery temperature. You come back in a half hour and repeat and then agin a half hour after that. You do some math. If all the readings make sense you have your data point. If not, you keep on trying. This is supposed to be a vacation

Of course it's not just voltages. It's currents as well. Pull out the (expensive so it has adequate resolution) clamp amp. See what's going on. Go check the solar output. Now back to the battery. Now over to the load wires .... yikes ....

We live in a world where information is instantly available (just ask Alexa ...). That's what everybody expects. You look at a panel and it instantly gives you an exact answer. You see "82%" and move on. It's very hard to stop and then fiddle things.

Bob

[farafield]

Originally Posted by uncle_bob

Hi

If you are after furnace + lights + fridge, you are going to use a lot of amp hours.

(Yes there is some guessing here)

Furnace 6A for 10 hours = 60AH
Fridge 1A for 24 hours = 24 AH
Idle drain on the trailer 1A for 24 hours = 24 AH
Lights, water pump, fans ???? guess another 20AH

That's 128AH over 24 hours. Maybe you will get down to half that ... maybe.


Bob

Is this fridge number--1A-- with the fridge on propane?

[TheSquire]

Originally Posted by uncle_bob

Hi

The panel on the stock solar setup is at best making a guess at the battery state. If solar is "running" at the time, the guess is worse than if it isn't running. It will overstate the percent you have and thus fake you out. The best number it will give you is with no solar and nothing going on in the trailer.

A somewhat better approach is to use a multimeter on the battery posts. The same qualifiers apply. You also need to convert what you get based on battery temperature. Indeed this is all a lot of work. Unfortunately the only real solution is a shunt based monitor like the Victron BMV-712.

Bob

I agree with Bob. A shunt style battery monitor (we have the Victron 712 ~$200)is a great first investment. It will teach you everything you need to know to size a battery & solar panel system to meet your usage needs. You can measure actual amp draws as you turn various lights, fans, heater, radio, TV, etc. once my wife and I knew how much power we used on a typical trip, we sized the system to provide the power we needed.

-Rich

[uncle_bob]

Originally Posted by farafield

Is this fridge number--1A-- with the fridge on propane?

Hi

It's the power to the control board. The typical fridge pulls it when on propane or on 120V AC. The "three way" fridges have another wire to get 12V to the heater, so technically they pull 1A to to the control board as well.

All the numbers are "typical" and there *is* variation between different models. Not every trailer model gets exactly the same stuff. You really need to measure the current the gear on *your* trailer pulls.

Bob

[farafield]

Originally Posted by uncle_bob

Hi

It's the power to the control board. The typical fridge pulls it when on propane or on 120V AC. The "three way" fridges have another wire to get 12V to the heater, so technically they pull 1A to to the control board as well.

All the numbers are "typical" and there *is* variation between different models. Not every trailer model gets exactly the same stuff. You really need to measure the current the gear on *your* trailer pulls.

Bob

Thanks UB, that's what I thought but wanted to be sure.

[waninae39]

i mounted all the victron and other electrical and electronic items, fuses etc and 3/4"plywood.
this was precut to fit on the wall under the bed in the front left corner
that is where the 7way, solar and other cables are in the as 22fb

i left posts for all other cables that need to connect to the parts on the board
i crimped each cable with a round connector, thus nothing can slip or fall off

after mounting the board, all external cable were screwed down with washers to ensure a good connection.

note
all connection, cables etc were labelled.
i leave a schematic next to the board
all connections have anti oxidation paste applied
all cables are crimped, no bare wires


i made 3 shut off switch, they were mounted on the bed wall facing the sink
1. solar shut off
2. controlled power shut off
3. front jack shut off