Class B Lithium Batteries and Solar for Off-Grid A/C Use

[scsmith63]

Newbie here....wife and I are looking at Noovo and Coachmen Beyond based on what we believe our use case will be with some boondocking/off grid use. Haven't decided on a particular model yet.

This will be our first purchase of an RV.

My question is around requiring a generator or going Lithium Battery with solar panels only. My concern is on cloudy days the Lithium Batteries may drain with heavy AC use on hot and humid days.

Noovo suggested doubling down on the Lithium batteries.

Curious about the real experiences on Lithium power consumption as it seems a 660ah battery may last 6-8 hours with heavy AC use. I read the 400 watt solar panel takes 4+ days to recharge the lithium battery.

 

[booster]

Your guess on the AC use and battery sound pretty close and you can't put enough solar on the roof of the van to recharge the batteries fast enough to run AC regularly, as even double the batteries gives two hot days and even longer to recharge from solar.

That leaves you with shore power, which you won't have if off grid, and engine charging which would take 4 hours or more of driving most days, or long periods of idling the van and fast idle.

If you want to stay offgrid for multiple days with driving, the only solution would a generator, IMO.

 

[Steve Biegler]

This is how we do it. Between the solar, driving, shore power and autostart/fast idle we have never run out of power.

 

[engnrsrule]

Booster is correct. Lithium is definitely a step up as the percent of useful power is much greater than lead acid. Roof AC is rarely useable thru an inverter on battery. What you may not realize is that most class Bs have a design feature where you can put the roof vent on med-low exhaust and crack the side windows by your bed and enjoy a lovely cooling breeze across the bed. This is the same concept as the old whole house fans common before AC.

I would generally prefer to have a generator and solar to expand boondocking flexibility. I had 300ah of lithium and 290w of solar. That could handle a few cloudy days without loosing ground, running chargers, TV, internet, compressor fridge, etc. on a 1500w inverter. To run the microwave or coffee pot, I just run the generator for a few minutes. Water heater stayed on propane if no shore power.

 

[ChristyCappello]

A friend & co camper has a class B with the Volta lithium system. With the Volta system you can run the A/C for 9 hrs without any hookups. I know travato & adventure vans makes them.
Check it out:

 

[booster]

A friend & co camper has a class B with the Volta lithium system. With the Volta system you can run the A/C for 9 hrs without any hookups. I know travato & adventure vans makes them.
Check it out:

Yep, you can do that with batteries, but for offgrid air conditioning how do you replace all that battery charge without a bunch of driving or idling?

 

[Hepstein45@gmail.com]

We have a 2020 Coachmen Beyond. We have a generator. We rarely use the A/C. When the original 600 AH AGM battery deteriorated we replaced it with a 460 AH Lithium battery. We added an additional 200 watts of solar panels for a total of 400 watts. We also added a 50 amp DC to DC charger from the alternator. We have the original 120Volt Coleman rooftop A/C. We cannot run the A/C from just the battery. We do not use the A/C when plugged in. We can run it when the generator is on but it s too loud. Even just the A/C is quite loud.
Both the solar charger and alternator charging are trickle charges. A day of driving in the sun may add 15 - 20 AH of charge. The generator will charge the battery from 40% back to 80% n 2 - 2 1/2 hours - we often do that while we are driving so the we don’t notice the noise. We have a 2000 watt inverter which will run the microwave but not a coffee maker at the same time.
So to summarize. 1) Perhaps a 12volt DC A/C will run from battery power? Perhaps it will be quieter? But a 120 Volt A/C unit needs shore or generator power and is noisy, especially while running the generator. Even a 3000 water inverter would not be big enough to run the A/C free m the batteries, regardless of size of batteries. 2) AGM batteries are really heavy and do not provide enough power to run the latest appliances such as water and room heater, They may not be enough to run an induction cooktop. Even if they have sufficient power they will not last long and it will be difficult to keep your AGM battery above the recommended 50% without being connected to shore power or running the generator. 3) our charging capability from the alternator is insufficient to recharge a battery. Perhaps newer models have better alternator charging. 4) Lithium batteries are definitely the way to go. You can easily upgrade AGM batteries to Lithium in a Coachmen Beyond. 5) A venerator makes boon docking possible- water is the limiting resource. A better alternator charging capability can negate the need for a generator.
Hope this helps.

 

[Hepstein45@gmail.com]

Correction. We do run the A/C when plugged in to shore power.

 

[booster]

We have a 2020 Coachmen Beyond. We have a generator. We rarely use the A/C. When the original 600 AH AGM battery deteriorated we replaced it with a 460 AH Lithium battery. We added an additional 200 watts of solar panels for a total of 400 watts. We also added a 50 amp DC to DC charger from the alternator. We have the original 120Volt Coleman rooftop A/C. We cannot run the A/C from just the battery. We do not use the A/C when plugged in. We can run it when the generator is on but it s too loud. Even just the A/C is quite loud.
Both the solar charger and alternator charging are trickle charges. A day of driving in the sun may add 15 - 20 AH of charge. The generator will charge the battery from 40% back to 80% n 2 - 2 1/2 hours - we often do that while we are driving so the we don’t notice the noise. We have a 2000 watt inverter which will run the microwave but not a coffee maker at the same time.
So to summarize. 1) Perhaps a 12volt DC A/C will run from battery power? Perhaps it will be quieter? But a 120 Volt A/C unit needs shore or generator power and is noisy, especially while running the generator. Even a 3000 water inverter would not be big enough to run the A/C free m the batteries, regardless of size of batteries. 2) AGM batteries are really heavy and do not provide enough power to run the latest appliances such as water and room heater, They may not be enough to run an induction cooktop. Even if they have sufficient power they will not last long and it will be difficult to keep your AGM battery above the recommended 50% without being connected to shore power or running the generator. 3) our charging capability from the alternator is insufficient to recharge a battery. Perhaps newer models have better alternator charging. 4) Lithium batteries are definitely the way to go. You can easily upgrade AGM batteries to Lithium in a Coachmen Beyond. 5) A venerator makes boon docking possible- water is the limiting resource. A better alternator charging capability can negate the need for a generator.
Hope this helps.

It appears you have some things that aren't working properly in your system based on the recharging results you state.

Both the solar charger and alternator charging are trickle charges. A day of driving in the sun may add 15 - 20 AH of charge. The generator will charge the battery from 40% back to 80% n 2 - 2 1/2 hours - we often do that while we are driving so the we don’t notice the noise.

The solar and alternator charging you list should be nowhere near only being trickle charging.

Using the the old standard estimate of average solar charging gain per 100 watt of solar in good sun, you should be able to get 120ah of recharging per day and see upwards of 20 amps charge rates, especially with lithium that doesn't taper off charging much as you get toward full.

You haven't defined how many hours a typical day of driving is for you, but a common in amount is maybe 4 hours so I will use that. You should be able to get 200 amp hours of recharge in that amount of time driving.

You are missing way more power than you are getting so it really looks like would be short of power compared to the size of the system.

Your generator and shore power charging both come from the same inverter/charger you probably have and appear to most likely be about a 100 amp charger that nets the 92 amps you need for the 40-80% recharge you get that way. This would indicate the batteries are functioning as they should.

With somewhat decent sun and moderate amount of driving you should be fine if using less that 100ah per day, which is likely when not using AC.

About the only way you can lose that much charging is by having very bad settings in the two power sources that are underperforming.

I would suggest starting a new thread on the topic so we can see what equipment and what the settings are to help with trying to get it all working like it should.

 

[Snowy]

You should add Panoramic RV to your list. They are reputed to be of very high quality, and have a five year warantee. i was thinking about a Coachman Beyond before i found Panoramic. The Panoramic just seems much better built. The Noovo seems well-built (and has a 3-year warantee), but you are restricted to a RAM or a Mercedes. I would never buy a Merc Sprinter, with all their emision-system problems. The Noovo also means you must get a cassette toilet, making every dump just disgusting. I prefer a black tank. Finally, Panoramic makes a model called the Perspective built on a ford transit which i think is the best chassis for Bs right now.

Good Luck

 

[Snowy]

Also - go to the facebook pages for the coachman beyond and for the panoramic and search around for actual experience people are having with the A/C and alternator charging. I don't think it takes 4 hours driving around to charge enough to get a significant amount of A/C runtime with either rig.

 

[booster]

Also - go to the facebook pages for the coachman beyond and for the panoramic and search around for actual experience people are having with the A/C and alternator charging. I don't think it takes 4 hours driving around to charge enough to get a significant amount of A/C runtime with either rig.

I don't know if you are talking about the Hepstein45 post, or what the RV was stock, but that is what I was referring to in my post, if that is what you are addressing. It is always good to quote the comment you are replying to so there is less confusion.

In Hepstein45's post it was stated that the power system was altered with a 50 amp B to B charger and that only 15-20ah of power is added in a day of undefined hours of time driving. If you want 6-8 hours of AC time it is going to need somewhere around 600ah or more of energy to do it for most AC systems. The 15-20ah is not going to do that.

My comments of a day of 4 hours netting out 200 amp hours of engine charging is based on the limit of 50 amps from the B to B charger, and even that is only a 2-3 hours of AC time.

If you are talking about the RV in stock condition, the RV had 600ah of AGM it was stated and to get that bank full to 80% at 50 amps would take nearly 10 hours with another 4 hours plus to get to 100%. It is possible the AGMs would only run the AC until about 50% SOC depending on their voltage drop under load.

Without knowing how big and how many alternators the RV had stock it is unknown how fast it would charge, but no second alternator was mentioned, nor was OEM alternator mentioned.

The original post was a query from a non owner, scsmith63 about charging time with and without a generator and using only solar so it is assumed that driving was not in the equation, and in that case there would be no real chance of getting enough charge to run AC much at all from 400 watts of solar.

 

[booster]

For reference here is a list of the options available on a current beyond show a maxed out lithium setup. Of interest is the massive 12600ah of lithium and a 280 amp second alternator on the charging side and a 3000 watt inverter on the use. It doesn't appear that a normal generator is available with the package so driving would be essential. The limited testing we have heard about says that the second alternator will net out somewhere around 165amps average output, but that may have changed if they used a different brand that doesn't have the heat issues of older ones. Even 165 amps plus 15-20 from the solar would give around 2 hours of AC run time per hour of driving time so much more possible. It appears that there may or may not be a standard 620ah of lithium to add the package to, or it may be an intermediate update you have to also order over possibly standard AGM batteries. It is unclear on that, but on the smaller bank a gas generator appears to be stated as available. Very cryptic sales jargon, I think.

• Extra 640AH Lithionics Lithium Battery /w Internal Heater (1260AH Total w/ Li Lithium Option) (Must Have Optional Li Lithium Battery System)
• Li Lithium Battery System includes 640AH Lithionics Lithium Battery, 2nd 280amp Under Hood Alternator, multi stage voltage regulator, BMS (Battery Management System), Victron 3000W Invertor/Charger (2.8KW Gas Generator Not Included w/ Li Lithium System)
• Truma Aventa 13,500 BTU 110V A/C
• Driver & passenger upgraded seat re-covers
• Grey tank heaters
• Cozy Wrap® upgraded insulation package
• Upgraded front window covers
• New Rover 148" Roof Rack
• New KO2 Upgraded Tires w/ Black Rims
• New Rover Ladder w/ Cargo Box
• New Pull Out Pantry Behind Drivers Seat (N/A 22R

 

[scsmith63]

Appreciate the feedback....we plan on going with the dryflush Modiwell unit instead of the cassette on the Noovo