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.

[brholt]

A few thoughts.

We live in Washington and camp year round primarily on the westerm side. If you are dry camping out here in winter I don’t believe you can make a system without a generator work, especially with a compression fridge. It’s just to dark, to cloudy, and too many trees. Our experience in winter is that our solar does little or nothing.

The other thing I would worry about is the temperature limitations for charging the Lithium cells. It can get cold here especially if you have an altitude and, depending on where the batteries are located in the camper and how much heat they get, could be a big problem.

Finally, the Truma systems are pretty neat but they do seem to be slow heating. We tend to sleep with the heat turned way down under a pile of comforters. Besides liking sleeping warm with cold noses it saves a lot of propane and power. It is nice when the furnace kicks in and then heats the camper back up in the morning. The Truma may take a while to do that.

[pianotuna]

Hi,

Some exceptions to LI being the right choice. One is cold weather use. The other is Li are NOT forgiving in any sense of the word. I'd hate to ruin 200 amp-hours of LI (I think 300 would be safer). The other is connecting Li in parallel.

The Li absolutely need a battery management system. One that monitors the charge on each and every cell would be my choice.

There is one Li chemistry that can be used and charged in extreme cold, but I've not been able to find it in a high amp-hour configuration.

Camper_Jeff_&_Kelli wrote:
I have seen the cost calculated between lithium vs AGM, lead acid and in the long run, the lithium costs less. It's that big up front cost you have to get passed.

[Camper_Jeff___K]

Having recently finished a month on the road in winter conditions, I would go with a couple 170 watt Go Power or similar solar panels for a total of 340 watts with an MPPT controller. I would also have 300 AH of batteries or the most you can fit. I have 210 AH of AGM batteries effectively 105 AH battery power. Not enough for running the furnace, laptop, lighting, printer, inverter, water pump, phone charging, and other intermittent uses. The 4 gauge wire off the alternator never charges higher than about 13.7 volts. The solar charges to 14.5-6 volts on a sunny day. A lithium battery will give you better performance, more AH in a given space. Whichever battery you choose, 200 AH of usable power is the target at least for my use. I have seen the cost calculated between lithium vs AGM, lead acid and in the long run, the lithium costs less. It's that big up front cost you have to get passed.

[dave17352]

Those trojan Li batteries look to be superior to Battleborn. With constant 300 amp discharge and I think 100 amp charge rate. I think Battleborn are 50 amp charge rate and 100 amp discharge. That huge discharge rate could be handy with the high surge rate of the micro and the truma. I really like the battery status indicator. I wonder how that works and how accurate it is. Driving down the road with that 100 amp charge rate you would charge your batteries in no time. JMHO

[DWeikert]

jplante4 wrote:

LosAngeles wrote:
Click

I didn't see anything about capacity in that article. Any clue?

www.trojanbattery.com/trillium/

Two 12v sizes, 110 and 92 AH, and a 25 AH 24v

[terryrey]

I forgot to add that we spend 8 to 9 weeks a travel season, and have done so for the last 10 years, using the camper, tripping all over the West, so the electrical system in our Outfitter gets a good work out. Terry

[terryrey]

We have an Outfitter Apex 8 with the NovaKool 7.5 CF compressor fridge, two 6 Volt 230AH golf cart batteries (last summer was their 11th season and still going strong!), 375 watts solar, tv / dvd, radio, LED lighting, 1700 watt inverter, and the usual other stuff like AC, propane heat, stove, etc. We also carry a Honda 2000. The one electrical upgrade I made that really made a huge difference in keeping the camper batteries charged was installing a high amp direct charging circuit from the truck directly to the camper batteries! The factory charging circuit may deliver 10 to 12 amps - maybe, because of the small gauge wire. I use 1-0 welding cable and can deliver over 100 amps. Of course the batteries can only accept around 25 amps, but still this allows the batteries to come to a full state of charge in much less time than with the factory charge circuit. If it is sunny 5 or 6 hours a day, while parked, we never run out of battery because the solar keeps up, even with the electrical draw of the compressor fridge, furnace, etc. If it is cloudy or rainy, and we don't run the truck, but do run all of the electrical systems, including furnace (the largest single power draw), we have battery for less than two days. Since we mostly travel where it is sunny (we live in Utah) our economical Interstate battery installation along with solar and high amp charge circuit means that we don't use the generator and always have power to spare. Clouds and/or rain (no sun), however, means that we have to get the generator out by the end of day two, if we stay in one place for several days and don't drive the truck. Terry
PS. Be sure to get the aux cooling fan on your NovaKool.

[jplante4]

LosAngeles wrote:
Click

I didn't see anything about capacity in that article. Any clue?

[LosAngeles]

some new info - I did not know that these new models existed from Trojan.

https://www.solarpowerworldonline.com/2018/10/trojan-battery-company-releasing-trillium-battery-line/

just a bit more than Battleborn, about $1,000 Trojan vs about $900 for the (i think) similar one from Battleborn.... Trojan may well be worth the extra $.

J.

[pianotuna]

Li batteries do not wish to be topped off, nor trickle charged. More solar (400 to 600 watts) and a charge controller designed for Li would be my choice.

Victron has a 2000 watt inverter that is cheaper and better than the Xantrex. The biggest difference is, that after warranty runs out, the Victron can be repaired. Xantrex won't sell the parts.

I suggest staying with one "family" for components--so go Victron for the solar charge controller, too!

600 watts may obviate the need for a generator, except for running the roof air.

Battleborn has some "packages". I suggest following their recommendations.

[crosscheck]

We dry camped with a compressor fridge for 5 years. 7.5 cuft NovaKool, great unit but we found 200w solar, 200AH batteries just for the fridge was required for 100% dry camping. The rest of our electrical needs were minor. Good luck.

Dave

[Geewizard]

2 100W solar panels on the roof won't get you much charging current except in the summer with the sun overhead.

I suggest you consider two things:

-portable solar panels you can orient towards the sun for maximum charge current.

-A MPPT solar controller.

I realize using portable panels more work (set up, storage, cable, etc).

I use one 110W panel on the roof and one portable 110W panel that I can move with the sun, and especially, put OUT in the sun when the TC is parked in the shade.....and a Morningstar MPPT solar controller. Yes, the MPPT controllers get more out of the solar panel than conventional controllers.

If it were me, I'd put my money into solar panels and an MPPT charger than LiFePo batteries. And definitely NOT flexible panels.

https://www.amazon.com/Renogy-Watts-Volts-Monocrystalline-Solar/dp/B009Z6CW7O

https://www.morningstarcorp.com/products/tristar-mppt/

Hope this helps.

[kohldad]

Can't really answer your question without knowing more about the Truma system. Can't find any power consumption specs nor BTU output. Only info I could find is that it runs about $1500.

Other thing I would need to know is how much aux power you need for computers, tv, etc. If you are light on those (say 1hr/day) and assuming the Truma consumes the same power as a regular furnace, you should be able to get two possibly three days of boondocking in clear weather with that system before you need alt source.

Usual rule of thumb is 100 watts solar per 100 amps of storage for short term. Idea is that 100 watts will average about 60A/hrs per day while a battery drained to 50% will require 50A/hr. However, those numbers assume you don't have a large requirement during the day. With the compressor fridge, you should consider a 3rd solar panel so it will provide the necessary power for the fridge during the day which is usually it's highesst demand period since that is when it's the warmest. With the lithium batteries which you may drain deeper than a standard battery, it will also help recovery. Of course, this assume you are in a sunny environment.

In regards to the batteries, since you are going lithium, make sure you put them inside where they are in the climate controlled space for better performance along with one less leak and insulation hole in the outside wall.

Edit: Finally found a few specs for the Truma 4E version but they should all be about the same. While the power consumption is less, the heat output is less so it's going to run longer than a standard furnace. The assumption to use the same power consumption above as a standard furnace is valid and on the safe side.

[Tom_M1]

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

If by 'Soft Panels' you mean the flexible type, I would not recommend these for a permanent install. I have one 180 watt flexible panel that I use as a portable. The plastic has fogged and it is cupped in several spots. As others have mentioned, you need more solar. The compressor fridge is quite economical but will draw a lot more power than a propane one.

[HadEnough]

You need a lot more solar.

Why spend all that money on the batteries and have a weak charging system?

You should have more like a single 350 watt or a pair of 350 watt panels.

The charge acceptance is pretty high on those lithium batteries. Find out the charge acceptance rate on them in amps per hour and size the panels to match that output.