Critique proposed solar battery upgrade

phemens wrote:
is there enough of a reason to switch from FLA to AGM given what I'm doing? Right now, my biggest worry is watching the inverter bottom out at 11.4 when running the coffee maker, and it bugs me... strange, I know, but different strokes for different.

I've had both and I don't think AGMs handle large loads appreciably better. I've found 6 handles the big stuff better than 4, but boy does that get heavy.

Thanks for all the replies so far!
Running the fridge during the day would be the cherry on top, but isn't a deciding factor. Not ready to make the leap to residential fridge, as we do at least 2x trips a year where we'll leave the trailer at a nearby campground for a month on an unserviced site and do weekends - that's when LP is really nice, no issues with the fridge in the past few years.
Lithium Ion is a nice idea, but would at this stage completely obliterate any 'business case' justification even I could come up with, and I've made some whoppers over the years to convince the boss that I really need what I really don't need ;)
I guess the bottom line question after all this great input is, is there enough of a reason to switch from FLA to AGM given what I'm doing? Right now, my biggest worry is watching the inverter bottom out at 11.4 when running the coffee maker, and it bugs me... strange, I know, but different strokes for different folks. I have a 2k Yamaha genny, just don't like running it if I can avoid it.

Some tips...

Down here where an LPG fill is a major undertaking and expense, perhaps electric absorbsion refrigerator operation can be justified. Careful consideration to dusk to dawn ampere hour cycling wear and tear on the batteries comes into play. Daytime PV use and switch to LPG at sundown may be an alternative.

Again this is limited to "down here", but if I was considering cost/benefit of lithium batteries + RV parking nightly, the idea of abandoning RV use in favor of getting a nice, downtown hotel room comes into play. Let someone else do the housework, do the cooking and dishwashing is mighty attractive.

time2roll wrote:
Lithium is going to seem like a leap. However half your solar is going to be wasted on absorption time with the amps tapering off to nothing with the AGMs....lithium will absorb all the solar you can produce right up to the point of full.

Also as you get into the 1 kW solar zone consider going 24 volts on the main battery and inverter.

x2.

Li's are great, but will dent your wallet something fierce. If you can handle the $1000/battery you won't look back. Zero maintenance and much less weight than lead batteries. And way less voltage drop on high-draw appliances.

24 volts or higher is a great idea. You don't need cables the size of your thumb. I'm running 48vdc. Small converter for the coach's 12v supply.

Running higher voltage solar is what I also recommend. Again, smaller wire size and more efficiency. Of course you'll need a controller to handle the input voltage.

OP, the advice on the fridge is spot on they are power hogs. I'm running with lithium and do what you want to do of running the fridge during the day on solar and switch to lp at night but with the lithiums being topped off isn't an issue like fla/ agm batteries. It takes alot of solar to feed the fridge/ misc and charge the batteries.
As for the inverter leaving on all the time I do that also and it can consume a small amount of power to just be on during the night, mine (magnum 3000w) uses roughly 2ah while you sleep.

OP, you're Canadian and East Coast. Is that where you boondock?

Although we actively search for sunny sites, we're often shaded or partially shaded out East. So rarely do we get "excess" sun when boondocking, our batteries are routinely partially charged and our solar charger usually stays in bulk/mppt mode all day. So, I too wonder about your "excess" solar.

A generator would help but I don't like them and some places we camp do not allow them. So I would like to have some portable panels, in addition to those on the roof, that can be moved to the sunny spots.

And batteries that survive PSOC would be helpful. Unfortunately, while our FLA batts can be heavily equalized after boondocking, most AGMs cannot. Some have switched to LiFePO4, but I worry about their issues with charging in freezing temperatures (and cost).

There are other possibilities like Firefly's Carbon Foam AGM, and lead acids with a carbon "secret sauce" that are supposed to handle PSOC better (AGM: Outback "Nano-Carbon"; FLA: Trojan T105RE "smart Carbon"). The Outback AGM is my current favourite.

With the sealed AGMs you can put them in a heated interior spot and preserve 20-30% of their capacity when it's cold outside.

And if you're a Snowbird and travel frequently between boondocking sites, you can gain a lot by upgrading your vehicle's charging system. I recently added a 1000W 120VAC inverter in the truck and ran an extension cord back to the charger in the trailer. Big help.

We recently converted to a 24V battery bank and with a 2000W 24V Kisae inverter. It essentially reduces all necessary wire sizes and solar charger Amperage by 1/2. But you've already got your 12V inverter, so maybe not.

i like everything EXCEPT fridge on solar during the day
that 300+ watts is a lot of drain
you might find you don't always have that much 'excess'
imo better off with the fridge on LP and any excess? will be put to use when you use the MW, both while cooking to reduce battery drain, then after cooking to replace used ampHrs
if you want to use elect for fridge, replace the fridge, with either a residential fridge or a DC compressor fridge with a dan Foss style compressor
either one will use less electric energy (amp hrs) than the RV fridge,
1/3 the power or even less

i'm sure PianoTuna will be along and elaborate on power use of an RV fridge on solar and batteries

For that size system I will suggest a residential fridge and lithium batteries.

Running an absorption fridge on electric is a huge power hog and 3x the electric power of a residential.

Lithium is going to seem like a leap. However half your solar is going to be wasted on absorption time with the amps tapering off to nothing with the AGMs. Ok they are somewhat better than the flooded cells. However lithium will absorb all the solar you can produce right up to the point of full.

Also as you get into the 1 kW solar zone consider going 24 volts on the main battery and inverter. This cuts amps in half and lets everything run more efficient. Small DC/DC converter will supply 12v power to the accessories and controls.

That is a bit of a leap in several areas... think about it.

I'm no expert to be sure, but this blog seems to be pretty good regarding solar:
https://handybobsolar.wordpress.com/

He is big on heavy conductors from the panels to the controller so you don't lose what you've caught from the sun, and having the charge controller close to the batteries so it rreads battery voltage not panel voltage (negates drop in the wires)

I have about 200 watts of panels feeding 4 FLA 6v250 Ahr batteries through a 30 amp controller. I ran a 1500 watt inverter power the fridge in my garage for a month with no shore power at all. Last June while camping in Ocracoke NC (no hook ups) it ran lights, small 110v fridge in my popup a keurig coffe maker 6-10 cups of coffee a day, and charged our electronics (2 phones, 2 tablets, and a laptop)
I want to add the panels to my new rig when I get it, but I am afraid of drilling holes into a brand new roof... is there any trick way to mount them without drilling holes?