Solar Questions from a Solar Noob

[IchLiebeBier]

All,
I've been trying to figure this stuff out for a few days now, and I'm not really any closer to understanding this than when I started. Electrical stuff is not my thing.

I want to be able to do short boondocking trips (up to 7 days) if the mood hits me, because I like the camping feel of remote campgrounds more than places like KOA (not that there's anything wrong with that).

Here's my camper equipment info for a starting point. It’s in storage, so I can’t just run out and get specific info right now.
1. One battery (don't know the amp hour rating. It came with the camper. I'd upgrade it anyway).
2. Whirlpool 10.7 cu ft residential wired through inverter (don’t know size off hand, but it only runs fridge)
3. LED lighting throughout
4. Furrion solar ready
5. Champion generator

Now that equipment is listed, here’s what I would plan to do: purchase minimum batteries needed to run fridge all day/night, run water pump, run lights at night (2 lights on at a time/2 hours max), and run furnace fan as necessary if heat is needed in the middle of the night (which probably wouldn’t really be necessary given when we’d camp). Of course, alarms too.

I would probably run the generator in the morning after quiet hours just long enough to recharge the batteries, make coffee and anything else, and again at night before quiet hours to top off the batteries as necessary. But I would like to add the solar to trickle charge it during the day so I could minimize generator use at night.

So here are my questions that I cannot figure out from researching:

1. What will my refrigerator amp rating be? I’ve seen several numbers such as 6.5 amps and 3 amps, and several discussions about compressor kick on, defrosting, etc. I found one post that said count on anywhere from 100-150 amp hours per day.
2. If 150 is correct, and with other electrical requirements, I assume I should shoot for at least 400 amp hours for batteries to keep the charge above 50%. So we’ll assume 4 x 100ah batteries for the sake of discussion. Correct?
3. How long would it take a 3500 watt generator to charge the 4 batteries wired in parallel from 50% to full?
4. If I get 6 hours of full sun and can use solar, how much solar wattage would I need to keep the batteries full throughout the day (following generator charging), if only the fridge is running?
4a. What amount of solar would I need to NOT use the generator, given good sun to get from 50% to full?
5. Is my Furrion solar ready wiring of a sufficient gauge to handle the required wattage from #4 above, or should I attach directly to the batteries?
6. And finally, if I plug the solar into the Furrion plug, or even directly to the batteries, should I remove them before turning on the generator, or can they remain connected?

Thanks in advance.

[boondocking]

That fridge should draw (according to energy star specs) about 6.5 amps running. With a 50% duty cycle (average for a fridge) that would be about 3.25 amps per hour x 24 hours = approx 85 amp hours per 24 hr day.
A 100 watt solar panel will put out about 5 amps on a sunny day x 6 hours per day = 30 amp hours. So 400 watts of solar should keep your fridge happy with some amp hours left over.
I would go with (4) 6 volt deep cycle batteries which would give you 420-460 AH depending on the brand of battery.
I doubt that the Furrion wiring is of sufficient qauge for 400 watts of solar.

[IchLiebeBier]

boondocking,
Thanks. I figured the wiring probably wouldn't handle the load for that. I'm glad I asked, but I'll check the gauge of the wire when I winterize tomorrow.

Would I need to remove the solar from the battery if/when I fire up the generator? I assume the smart controller of the solar system would protect it from being overcharged, but you never know. well, I don't anyway.

[boondocking]

No, you do not need to disconnect the solar from the system when running the generator or plugged into shore power. Both the solar charge control and the converter will sense the battery charge and adjust accordingly.

[richp]

Hi,

Be aware that the non linear charging characteristics of flooded batteries may cause you to run the generator more than what you describe, depending on the daily fluctuating benefits you get from whatever solar array you install.

Sadly, most residential refer setups can make power management a chore when boondocking.

FWIW.

Rich Phillips

[Larry-NC]

Originally Posted by IchLiebeBier;2214095I want to be able to do short [COLOR="Red"

boondocking[/COLOR] trips (up to 7 days) if the mood hits me, because I like the camping feel of remote campgrounds more than places like KOA (not that there's anything wrong with that).
...
I would probably run the generator in the morning after quiet hours just long enough to recharge the batteries, make coffee and anything else, and again at night before quiet hours to top off the batteries as necessary. But I would like to add the solar to trickle charge it during the day so I could minimize generator use at night.

If you are boondocking (alone in the woods) there are no quiet hours or anyone around to enforce them.

Run the generator whenever you feel like it.

[aircommuter]

Depending on the charge controller you use maybe you could series the panels to keep the amperage down and add more solar if needed. Second thing is that lead acid batteries need some absorption time when charging, so to get a full charge you need to keep it at peak for another 1-2 hours depending on the battery.

[DogFather]

Fridge demand could vary a lot depending upon ambient air temp along with how long and often anyone opens the door and stares at the food. And I wouldn't set it for any colder than necessary.


Also, if you change the wire gauge, recommend sizing it for the maximum you might need in the future if you have available room for more panels. Modding doesn't seem to have any brakes...

[aircommuter]

I used to make my kids drop money in a box for keeping the door open, and leaving lights on. Probably the easiest form of energy to waste.

[Comanchecreek]

Originally Posted by Larry-NC

If you are boondocking (alone in the woods) there are no quiet hours or anyone around to enforce them.

Run the generator whenever you feel like it.

Just the kind of camper people love to be next to.

[IchLiebeBier]

Thanks all. Still got some deciding to do on what I want to do and if it's worth it. We wouldn't boondock that often, though I'd like to be able to whenever I feel like it.

[boondocking]

You're Welcome!

[Larry-NC]

Originally Posted by Comanchecreek

Just the kind of camper people love to be next to.

Having a little trouble reading there, Comanche Creek?

I said "If you are boondocking (alone in the woods) there are no quiet hours or anyone around to enforce them." The entire thread is about boondocking.

Who do you think would be next to them when they are all alone in the woods?

[IchLiebeBier]

Winterized the camper today and while out there, I took at look at my battery space. I don't think I'd be able to put 4 batteries there as is. I'd have to make a platform shelf, but the L brackets for the WD hitch are in the way. Three could go side by side with a little work, but 4 would require a shelf build.

I'll have to put some thought as to how to do it. Or cough up a ton of bucks for lithiums.

thanks all.

[IchLiebeBier]

I've spent the last few days researching this heavily, and I've decided I'd really like to do this, but I have some more questions that I'd appreciate some help with.

1. Converter: my understanding is that if I stay with lead acid, then I can keep the converter I have (three way). If I upgrade to AGM or LiFePO4, then I'd need to switch out my converter (even though they say the batteries are drop-in replacements). Correct?

2. Inverter: current one is Xantrex Freedom X. would I need to swap it out to switch to LiFePO4? I don't know why I would, but better ask now.

3. If I choose LA or AGM, either 6v or 12v, then I'd need 4 x batteries. Will my wiring between the camper and the battery support this, or will I need to install heavier gauge? I couldn't tell you right now what the wire gauge is between the batteries and the camper internals (I mean inside the frame; NOT the 2/0 gauge that connects to the batteries).

4. Same question with LiFePO4. I see I could get 3 x Lion Safari UT from COSTCO for about the same price as 2 x Battle Born, giving me more amp hours. Would my wiring support three batteries if I went that route?

Thanks all.

[IchLiebeBier]

Ok, so I think I was able to find the answer about the wiring. Since parallel setup doesn't increase voltage, total amps don't change either. The storage capacity does (amp hours), but that doesn't equate to an increase in amp output.

I hope that's right. Please tell me if that is right or not.

Thanks.

[Flybob]

Since there is really no one size fits all due to the varying parameters I suggest when you dewinterize in the spring, you go to a campground with electric hook ups ( or your driveway if possible) and measure your actual usage and replenishment capability via a good usage monitor. This way you have actual numbers and shore power for backup if you need it. Do not forget to take into account you may get 2-3 cloudy/rainy days in a row.

[aircommuter]

Amp output is dependant on load.
For example if you parallel 4 solar panels at 100 watts each at 12 volts. You now have 400 watts available at 12 volts. If the charge controller needs all of that because the batteries are low then the wiring will attempt to carry that 400 watts (assuming best panel orientation). If you put them in series you have 48 volts but only the same 100 watts available, then the wiring only has to carry 100 watts if the charge controller needs it all.
You need to have a charge controller that accepts that voltage or various voltages. Or you need to have a matching 48 volt inverter and battery setup.
The limitation that also can come up is the insulation rating of the wiring.

For batteries the same thing applies, if you parallel the batteries you stay with the voltage of one battery, if there is no load then the wiring does not have to do anything. You have a greater amperage available which could mean the wiring is too small if a higher amperage is called for.

[Flybob]

I think you are referring to amps and not watts. Four 100W 12V panels connected in parallel will produce about 20A of current in the lines between the panels and the charge controller. The same four panels connected in series will produce approx 48V at approx 5A of current in the lines. The total power is the same in both cases you simply have lower line loss in the series setup.

Originally Posted by aircommuter

Amp output is dependant on load.
For example if you parallel 4 solar panels at 100 watts each at 12 volts. You now have 400 watts available at 12 volts. If the charge controller needs all of that because the batteries are low then the wiring will attempt to carry that 400 watts (assuming best panel orientation). If you put them in series you have 48 volts but only the same 100 watts available, then the wiring only has to carry 100 watts if the charge controller needs it all.
You need to have a charge controller that accepts that voltage or various voltages. Or you need to have a matching 48 volt inverter and battery setup.
The limitation that also can come up is the insulation rating of the wiring.

For batteries the same thing applies, if you parallel the batteries you stay with the voltage of one battery, if there is no load then the wiring does not have to do anything. You have a greater amperage available which could mean the wiring is too small if a higher amperage is called for.

[IchLiebeBier]

Geesh...clearly I don't get this at all. I'd probably flip a switch and my trailer would take the park out like Bikini Atoll.

I'd probably need to be safe and take it to an installer and cough up the money.

I am clueless when it comes to electricity. Clearly.