How is this for a power system? Solar vs battery balance?

[LosAngeles]

How is this for a power system? Solar vs battery balance?

Hi all

Have owned a couple RVs, and now designing (with Hallmark) a 9.5’ Everest pop up truck camper.

How is this for the balance of 200 watts of solar and 200 amp hours of (probably Lithium) batteries?

I’m aware that the Lithium are very expensive, but they can be run down to 90% depleted without any damage….. plus they last many times longer than wet cells, so in the really long run, probably (hopefully) no more expensive. The Battleborn batteries (likely get these) have a built in battery management system that makes sure the battery can be used (or discharged) at temperatures as low as -4°F. However, the battery will not accept a charge below 25°F. The BMS also makes sure they dont over charge or under charge.

Planned system:

Propane for stove…. and Truma Combi. (hot water and air.)
(of course 12v needed to run the Truma Combi too)

7.2 CU side by side. 2 way compressor. Novacool RFS7501 fridge.

Maxx fan.

Interior LED lights.

Solar System: 2 X 100 Watt Soft Panels on roof.

Xantrex 817-2080 Freedom XC 2000, 2000 Watt Pure Sine Wave 12 Volt Inverter/Charger

Victron BMV 712 Battery Monitor w/ Bluetooth Lifepo4 Ready

2 (two) x Battleborn 100 amp hour (each) Lithium

Other occasional loads:
Small microwave. Blender. computer maybe.

We camp 4 seasons…. sometimes below freezing. Sometimes higher altitudes. Sometimes in cloudy Pacific NorthWest. So the ability to discharge the Lithuim 90% with smaller bulk and weight has advantages.

We mostly boondock. We prefer the quiet.
Occasionally we stay someplace for 2 nights, but often drive around a bit, to explore, each day (so the F350 would also help charge up the batteries)

Thanks for any and all thoughts.

J.

[Grit_dog]

^ The lengths you appear to try to go through for some things do seem strange to me, so I'll offer this. Once you figure it out, you can winterize the fresh water system and sewer tanks literally in minutes. (aside from the time it takes to drain the fresh water tank unless the drain valve is alot bigger than I've seen) And, no, you don't need to add antifreeze to the fresh water system if you do it right.

That is far better insurance than a temperature monitor and heating the camper all winter. I, and I'm sure most others with RV experience could help explain the lack of practicality of keeping a pop up TC, or most any RV that is stored outside and daily driven in sub zero weather, "wet" throughout the winter.

" I'll have 120v where it is stored." Maybe I mis understood. Thought you were clear that the camper was staying on the truck 24/7/365 and a daily driver. So stored means parked at the house?
Even easier to winterize as frequently as necessary.

[LosAngeles]

Grit dog wrote:
That's livin on the edge, trusting your heater to keep from needing to Winterize in the Midwest when you're not actively using the camper.
Just sayin.......

I think i'll invest the $149 on this well reviewed temperature monitor... so just in case the heater fails... this will tell me

https://www.amazon.com/gp/product/B01M1OPOZB

and also I could also put a small heater, on low (that has a thermostat) in it as well. I'll have 120v where it is stored, and also wifi for the monitor.

🙂

[brholt]

It sounds like a pretty good plan. The only thing I will add to the discussion is that we have dry camped many times in the PNW (west side of Cascades) and we get almost nothing from our 150 watt solar cell. Between the trees, the short amount of daylight, and the clouds there isn't a lot of radiation there.

[jimh406]

I prefer starting my builtin generator for short duration use instead of running on an inverter. I do like inverters for low draw appliances like tv, chargers, etc. As much as some of the batteries cost, it’s almost like buying a generator but without the ability to charge. If I regularly used that much power, I could see it. As is, I can get buy several days without generator, and if I run my generator, I run it just long enough to charge the batteries which usually only takes 30 minutes to an hour.

[srschang]

Oops, after reading another post on using starter batteries for high demand / short duration loads like a coffee maker or microwave, I remembered why I bought two Battle Born 100aH batteries. The wife's hairdryer draws ~ 140 amps on high. Can't draw that much power from one battery - Battle Born lithium batteries are rated c=1, meaning that you can continually draw the amp hour rating of the battery, in this case, 100 amps. So I needed two batteries to draw 140 amps. Keurig draws ~80 amps, so that would have been OK on one battery.

[Grit_dog]

That's livin on the edge, trusting your heater to keep from needing to Winterize in the Midwest when you're not actively using the camper.
Just sayin.
Interested to see how the batteries work though. Cool stuff.

[srschang]

I don't think I use power the way you're planning to, but I now have lots of experience with 4 100W solar panels and 2 Battle Born 100aH batteries. I also have a compressor fridge (Isotherm 4.6 cuft) and a Xantrex 2000 watt inverter. I do not have the camper hooked to the 12v feed from the truck.

My wife and I just got back from 5 weeks on the road to Alaska from Buffalo, NY. Although we stayed in campgrounds every night, about half the nights we were in a non electric sight or chose not to plug in because we didn't need to run the A/C and the batteries were fully charged.
We now run everything but the A/C on the inverter, or directly from the batteries for twelve volt items like the fridge.

The biggest battery hog by far is a 12" fan Merry bought at Walmart to run all night off the inverter. Can't sleep without the noise & air movement. Between that and the fridge, the batteries dropped from 100% to 76% overnight. Then running the Keurig for 4 cups of coffee, Merry drying her hair, and then flat ironing her hair, the batteries dropped from 76% to 68% (136aH of the 200aH left). If we microwaved something for dinner the night before, it may have dropped a few more AH, but not much. Although the wave uses a lot of watts, it only runs for a few minutes, so not a lot of AH.

We found that if the batteries were at 68% in the morning, and it was sunny, the 400 watts of solar would charge the batteries (provide 64aH of charge) back to 100% by noon or 1:00. If it was cloudy, it would take all day to recharge the batteries, or maybe even only get them back to 95%. Still very acceptable for the way we use the camper.

I guess I really didn't need to spend the extra $1000 for the second Battle Born battery, as one battery would have met our needs. But a single battery would have been very close to depleted most mornings. I console myself by thinking the extra Battle Born battery ensures that I have lots of juice available if we want to brew more coffee sometime. (Though that's some pretty expensive coffee!)

[LosAngeles]

toddb wrote:
I have 1 lithium battery, compressor fridge and 300w solar. If I was trying to charge 2 batteries I agree 600w+ would be better.
My fridge will consume 25-30 a/h a night with lows in the mid 70s. I have been able to get a full charge with a good day of sun.

Very good info - many thanks.

I believe my bigger fridge will consume more than most.

I am now leaning towards 720 watts solar. It will be very nice to be OK in a partially shaded campsite. Or short overcast cold days.

🙂

[time2roll]

Sounds great to me. Very well thought out.

Looking forward to the first trip report. Mostly interested to hear how 200 amp/hr lithium holds up and the % of battery used on a typical day.

[toddb]

I have 1 lithium battery, compressor fridge and 300w solar. If I was trying to charge 2 batteries I agree 600w+ would be better.
My fridge will consume 25-30 a/h a night with lows in the mid 70s. I have been able to get a full charge with a good day of sun.

[LosAngeles]

Grit dog wrote:
LA, based on your other posts, location, cold weather use, I'd think real hard about dropping the coin for Lifepo4 batteries.
Aren't they going to struggle big time with the cold?
Have never used a lithium battery in the cold except for cell phones, which the lack of performance in the cold is evident.
I'll have an into this year with a snomachine with a lithium battery. Will see how it works since it typically is not extremely cold where I ride.
I'll have a fresh jump start pack in my bag for sure!

Very good thought to be concerned about Lithium charge / discharge with Lithium batteries... the onboard Battery Management System on BattleBorn batteries (and most other lithum batteries) prevent charge / discharge at damaging temperatures (lower than you might think)

but when I asked this exact same question to Hallmark - given that I'm using the super efficient propane + 110v Truma Combi Plus - and it will have hot air ducts to various places in the camper, including a hot air duct to the battery compartment, and the fresh water tank inside the cabinet....
- and it is slow and steady heat.... i'll keep the heater on almost all the time (not when driving) so the camper batteries will be kept warm by the heater when i need the batteries.

The Truma heater also has a 50 F "keep from freezing" mode and when parked at home I'll keep it plugged into 120v so i hope to get away with not winterizing it.... as weather is good and bad in midwest... so the camper would be ready to go at a moments notice, all winter. (whenever i want to go out) Cool, eh? No pun intended. 🙂

[Grit_dog]

LA, based on your other posts, location, cold weather use, I'd think real hard about dropping the coin for Lifepo4 batteries.
Aren't they going to steuggle big time with the cold?
Have never used a lithium battery in the cold except for cell phones, which the lack of performance in the cold is evident.
I'll have an into this year with a snomachine with a lithium battery. Will see how it works since it typically is not extremely cold where I ride.
I'll have a fresh jump start pack in my bag for sure!

[pianotuna]

Hi,

I'd add the extra panel.

[LosAngeles]

Hi all again - 7 months later. 🙂

So we are finally about to place our order for our 9.5 foot long Hallmark pop up truck camper.

How is this for a (revised) power system?

* * in terms of amount of solar panel WATTS specifically. * *

I want to make sure i have enough solar panel power. The fridge will be the biggest draw, by far. (plus the Truma Combi running much of the night, in fall / winter / spring / subzero…… midwest.

Plan below has 540 watts solar, but for an extra $400 or so I could have a 4th 180 watt panel added - so that would make it 720 watts solar total.

Planned system:

200 amp-hours of Battleborn Lithium batteries. (2 x 100 amp hour batteries)

Propane for stove…. and Truma Combi. (hot water and air.)?(of course 12v needed to run the Truma Combi too)

7.2 CU side by side. 2 way compressor. Novacool RFS7501 fridge.

Maxx fan.

Interior LED lights.

Solar System: 3 X 180 “Grape” solar panels on roof = 540 watts

(or maybe 4 panels? = 720 watts)

“(each panel) Produces on average 45 Amp-hours/540-Watt-hours per day, EACH” (so 135 amp-hours a day for 3, on average, when the sun is out i suppose)

Power Converter 60A Mini Lithium Ion Power Center Black PM4060LIK

Victron 100/30 SmartSolar charge controller MPPT Solar Charger w/ Bluetooth Lifepo4 Ready

Xantrex 817-2080 Freedom XC 2000, 2000 Watt Pure Sine Wave 12 Volt Inverter/Charger

Victron BMV 712 Battery Monitor w/ Bluetooth Lifepo4 Ready

2 (two) x Battleborn 100 amp hour (each) Lithium

Other occasional loads:?Small microwave. Blender. computer maybe.

4 season camping. Yes there will be some rain and short grey days…. sometimes below freezing. Sometimes higher altitudes. Sometimes in cloudy Pacific NorthWest.

So the ability to discharge the Lithuim 90% with smaller bulk and weight has advantages.

We mostly boondock. We prefer the quiet.
?Occasionally we stay someplace for 2 nights, but often drive around a bit, to explore, each day (so the F-350 would also help a bit charge up the batteries)

Thanks for any and all thoughts.
J.