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

[john.]

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.

[John Perz]

My understanding is that with regular lead acid batteries, you usually need a mult-battery bank to run a microwave. With only one or two batteries, a microwave pulls so many amps that the battery voltage drops to the point that the low-voltage cutoff on the inverter shuts it down before cooking is complete.

So if you want a small microwave, you need to find out how many amps it will pull at 120 volts, then multiply that by 10 to see how many amps it will need at 12 volts.

For example, a microwave that uses 8 amps when plugged into the wall will need 80 amps from a 12 volt system for the same power.

Then you need to research whether your lithium batteries can supply that many amps and if so, what kind of voltage it can maintain while doing so. The manual for your Xantex Inverter will tell you what the low voltage cut-off is on that particular unit.

Maybe the Lithiums will work fine for that particular application, I really don’t know. Of course, if you only run the microwave while the sun is shining, it’s possible the solar panels will add enough power for it to work.

Regards
John
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[john.]

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.

[Anonymous]

I have a Xantrex ProSine 2.0, 430w of solar (two systems, one 300w MPPT, one 130w PWM – both in full parallel) two WC 6v GCs, and a Panasonic 850w (gross) MW, and to keep track of energy usage a Xantrex LinkLite meter with shunt…I only have space for two batts due mostly to venting issues.

I started out with 200w of solar, but the problem you’ll soon find out about solar is that you just can’t get enough, and will want to be liberated from the genny – lol!!…Its all about the 4-5 hrs of typical harvest time (varies per season and latitude), so you’ll be in a true ‘race against the sun’ to achieve a full (or hopefully near full) recovery, and you’ll likely never achieve full rated panel watts during winter months… Thus, in my humble opinion 300w would be a far better ‘minimum’…Having said that, I believe the recovery times with lithium may be a bit faster than with WC’s, as is the case with AGM’s…I would assume that one advantage to lithium might be that the voltage output stays relatively constant up until they just plain quit, a good thing if you were running something like a 12v furnace or refer designed with a low voltage shutdown.

I also swapped out the factory installed 1500w (gross) MW, for a far more practical 850w (also ordered an online SS trim kit to fill the cabinet gap).
Inverter has no problem whatsoever powering this oven…Another point is to make sure your cable runs from batts to inverter are as short and as robust as possible, else with a heavier load your inverter may expreience a bottleneck and nagging low voltage alarms – be sure to adhere to Mfg’s recommendations …I eventually increased size to 0004 AWG with round-trip cable length at about 7’.

So even though I’m running only two GC’s, this system has proved quite optimal for our extended camping needs, even down to zero degrees, and even powering the 11k btu AC unit for short roadside lunch stops via the inverter (system is passively cascaded for shore, genny or inverter)… I carry a Honda 2200i as a SHTF back-up, but seldom ‘if ever’ need to use it, unless running the AC unit.

Having said all this, if I ever do another system, I would at least explore a 24v series two battery set-up, with something like a Xantrex Echo charger to recharge each 12v battery sequentially – just a bit of random thinking here – lol!

[Tom MacCallum]

I’m also going to convert to Li batteries. It would be interesting if there was a review of BB vs Trojan batteries. Even though they are mfrd in the US, I read that BB use chinese cells. I wonder if Trojan uses the same? There’s probably no way to avoid the use of chinese components in just about anything these days. Look at Cummins engine blocks.

[john.]

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.

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 charge up the batteries)

Thanks for any and all thoughts.
J.

[Anonymous]

I recently gained a bit of Lithium hands on experience by helping my neighbor convert his new 8×12 V nose cargo trailer into a camper…

His set-up includes one 100a LiFePo4 battery, a 2500w pure sine inverter charger, a 7.5 cf dc only refer (with a 12v danfoss compressor), a PD 40a Li converter charger, two 200w solar panels with PWM controller (soon to be replaced with a MPPT), Victron SOC meter (and shunt), a sub-panel (for air and house plugs), and a 11k btu Mach 1 P.S. air cold…

What’s so interesting is just how high the charge acceptance rate of the Lithium battery is (meaning a uber fast harvest!) and that the voltage stays nearly constant throughout the entire discharge…

He can run the air cond for about an hour (comp cycling) via the inverter and single battery (this, prior to adding solar…), and he inadvertently once allowed the battery to discharge all the way down to 6% SOC – this, with the air still running!!…Luckily no damage to anything, he was only alerted to the low SOC situation via the sounding from the Victron SOC meter alarm…

He wanted to be able to run the air cond (without struggling with the genny) for brief periods during a short roadside stop…It works perfectly!

Now with solar added, 12v refer is easily self-sustaining until the sun sets then consumes thru the night only about 25-30% battery capacity by sun up, with battery then fully restored by about 11:30am in the month of July…

Starting out with nothing but an idea, it was a fun project (lots of planning and wiring on my part) to see thru to the end, and even better because EVERYTHING worked out!!

To answer your question, 400w should work out perfectly (due to the uber high receptivity rate of Li), though (depending on low solar winter harvest and one’s energy consumption) I wouldn’t be afraid of having two batts, though I don’t see it as a requirement – in net terms, his one Li is easily equivalent to my two 6v golf cart batts which have never let me down …Just saying

Phil

[john.]

thanks so much for the great info! 🙂

i am currently thinking of Mach8 Plus HVAC, 720 watts solar, and 200 amp hours Lithium.

perhaps in full sun, i wonder how long i could run the HVAC off solar? with battery buffer. That would be wild.

Anonymous wrote:

I recently gained a bit of Lithium hands on experience by helping my neighbor convert his new 8×12 V nose cargo trailer into a camper…
His set-up includes one 100a LiFePo4 battery, a 2500w pure sine inverter charger, a 7.5 cf dc only refer (with a 12v danfoss compressor), a PD 40a Li converter charger, two 200w solar panels with PWM controller (soon to be replaced with a MPPT), Victron SOC meter (and shunt), a sub-panel (for air and house plugs), and a 11k btu Mach 1 P.S. air cold…
What’s so interesting is just how high the charge acceptance rate of the Lithium battery is (meaning a uber fast harvest!) and that the voltage stays nearly constant throughout the entire discharge…
He can run the air cond for about an hour (comp cycling) via the inverter and single battery (this, prior to adding solar…), and he inadvertently once allowed the battery to discharge all the way down to 6% SOC – this, with the air still running!!…Luckily no damage to anything, he was only alerted to the low SOC situation via the sounding from the Victron SOC meter alarm…
He wanted to be able to run the air cond (without struggling with the genny) for brief periods during a short roadside stop…It works perfectly!
Now with solar added, 12v refer is easily self-sustaining until the sun sets then consumes thru the night only about 25-30% battery capacity by sun up, with battery then fully restored by about 11:30am in the month of July…
Starting out with nothing but an idea, it was a fun project (lots of planning and wiring on my part) to see thru to the end, and even better because EVERYTHING worked out!!
To answer your question, 400w should work out perfectly (due to the uber high receptivity rate of Li), though (depending on low solar winter harvest and one’s energy consumption) I wouldn’t be afraid of having two batts, though I don’t see it as a requirement – in net terms, his one Li is easily equivalent to my two 6v golf cart batts which have never let me down …Just saying
Phil

[Anonymous]

John, I would have concerns about the Mach 8 (I assume you mean the cub 9,200 btu) from the inverter you’ve selected, in fact I seriously doubt that it would work or even last too long under such an extreme published LRA (Locked Rotor Amps) load… Compressor motors are highly reactive (think, counter-EMF inductive), so component selection is uber important…So you should weigh the cost and benefit ratio if wanting to run the Mach 8 Cub via an inverter…For example, here is found the specs on the Mach 8 9200 Cub, and notice the LRA and running amps:

*****************
Mach 8 cub

Below is all of the specs for the Coleman Mach 8 Cub.

Cooling/Heating Capacity: 9,200 BTU. Electric Heat Strip Capacity (sold separately): 6,000 BTU.
Electrical Rating: 115 VAC, 60 HZ, 1 Phase.
Cooling AMP’S: 11.2 (low fan speed) 11.7 (high fan speed)
Compressor: 8.9.
Indoor Motor High/Low: 1.2 / 0.7.
Outdoor Motor: 1.6.
Running Watts @ A.R.I. Standard: 1270.
Running Watts @ Desert Condition: 1550.
Running Watts-Electric Heat Strip: 1748.
Compressor Locked Rotor Amps: 58.4.
Metering Device: Bi-Flow Restrictor.
Refrigerant Charge – R-410A: 14.75 oz.
Evaporator Air Delivery (CFM): 300 – High Speed
NOTE: electric heat strip is not included, refer to part # 62763 if needed.
*****************

This is exactly why I chose the more efficient 11kbtu Mach 1 p.s. because the LRA is only 41.5amps (6.6a comp- 2.7a fan, 9.3a total). This also means a much lesser load on the inverter.

Having said that, Consider that IF running an air cond (a highly inductive load) via an inverter is your desire then I wouldn’t select that particular inverter (a HF switcher type…) because it lack sufficient head room (4-5 times LRA needed) and the surge rating is only marginal at best…

This is why when sourcing any inverter, it is important to consider the worse case load scenario application because the advertising wattage rating is only about 1/3 of the real performance story, with surge and duration the remaining 2/3rds…Thus, not all inverters having the exact same watts ratings measure up the same because of the way different inverters ‘see’ (respond to) a given load…For the Mach 8 the minimum inverter I would consider would be 3000w (preferably transformer based), nor would I chose the Freedom X for the more efficient 11k btu Mach 1…As I stated, component selection can get a bit dicey when powering an air cond…JMO

Phil

[john.]

Thanks so much Phil for the amazing info. Much appreciated. 🙂

I will speak with Matt at Hallmark to find the best solutions.

thanks again,

John

Anonymous wrote:

John, I would have concerns about the Mach 8 (I assume you mean the cub 9,200 btu) from the inverter you’ve selected, in fact I seriously doubt that it would work or even last too long under such an extreme published LRA (Locked Rotor Amps) load… Compressor motors are highly reactive (think, counter-EMF inductive), so component selection is uber important…So you should weigh the cost and benefit ratio if wanting to run the Mach 8 Cub via an inverter…For example, here is found the specs on the Mach 8 9200 Cub, and notice the LRA and running amps:
*****************
Mach 8 cub
Below is all of the specs for the Coleman Mach 8 Cub.
Cooling/Heating Capacity: 9,200 BTU. Electric Heat Strip Capacity (sold separately): 6,000 BTU.
Electrical Rating: 115 VAC, 60 HZ, 1 Phase.
Cooling AMP’S: 11.2 (low fan speed) 11.7 (high fan speed)
Compressor: 8.9.
Indoor Motor High/Low: 1.2 / 0.7.
Outdoor Motor: 1.6.
Running Watts @ A.R.I. Standard: 1270.
Running Watts @ Desert Condition: 1550.
Running Watts-Electric Heat Strip: 1748.
Compressor Locked Rotor Amps: 58.4.
Metering Device: Bi-Flow Restrictor.
Refrigerant Charge – R-410A: 14.75 oz.
Evaporator Air Delivery (CFM): 300 – High Speed
NOTE: electric heat strip is not included, refer to part # 62763 if needed.
*****************
This is exactly why I chose the more efficient 11kbtu Mach 1 p.s. because the LRA is only 41.5amps (6.6a comp- 2.7a fan, 9.3a total). This also means a much lesser load on the inverter.
Having said that, Consider that IF running an air cond (a highly inductive load) via an inverter is your desire then I wouldn’t select that particular inverter (a HF switcher type…) because it lack sufficient head room (4-5 times LRA needed) and the surge rating is only marginal at best…
This is why when sourcing any inverter, it is important to consider the worse case load scenario application because the advertising wattage rating is only about 1/3 of the real performance story, with surge and duration the remaining 2/3rds…Thus, not all inverters having the exact same watts ratings measure up the same because of the way different inverters ‘see’ (respond to) a given load…For the Mach 8 the minimum inverter I would consider would be 3000w (preferably transformer based), nor would I chose the Freedom X for the more efficient 11k btu Mach 1…As I stated, component selection can get a bit dicey when powering an air cond…JMO
Phil

[Anonymous]

John, to clarify, the Freedom x 2000w should do well for all the needs which you originally stated – in this scheme I would simply run the air cond from the generator…JMO

Matt should also be sure to design your system so that when the inverter is active, the onboard converter-charger is de-energized to avoid a ‘round robin’ effect…

Note also that (as I recall..), the Freedom X may be had either with or without a built-in ATS switch…

Happy to help,

Phil

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