Except for the "clean and quiet" aspects, is Solar really justified anymore?

[rickst29]

The "Voltage Booster" with MPPT Controller assembly (pretty exhaustively described here (http://www.trailmanorowners.com/forum/showthread.php?t=16761)), allows you to exceed the charging capability of 200W Solar panels under any conditions - including clouds, winter days, and even night time driving.

Except for the noise and stink of running the TV "24VDC generator" in camp, and running a long extension cord to reach the TM in some campsites - I don't see a lot of justification anymore. (Although my preference is to camp in QUIET, without stinking up the CG with car exhaust - so my own panels aren't going anywhere.)

Comments?

[klpauba]

I have a limited understanding of the finer aspects of charging a lead acid battery, but it seems to me during the boost and float stages, running a booster from the TV would be pretty inefficient (due to the lower current requirements), no? Wouldn't solar be much better to get the last bit of energy to get to 100% SOC?

[rickst29]

I have a limited understanding of the finer aspects of charging a lead acid battery, but it seems to me during the boost and float stages, running a booster from the TV would be pretty inefficient (due to the lower current requirements), no? Wouldn't solar be much better to get the last bit of energy to get to 100% SOC?
In camp, this particular charger will run only two stages: "Boost" and "Float". Boost starts out with really high current, which declines as the differential between charging voltage and "native battery voltage" begins to decrease - the batteries just won't take a lot of current when that differential is small. Think of current "acceptance", rather than current "requirements". ;)

Unless you customize your "Float stage" charging parameters, you probably can't reach more than 90% SOC under any circumstances. The "phantom loads" increase in camp, because accessories like the gas detector are turned on by raising the shells.And most good controllers impose both a lower Voltage setting (typically 13.8V) and an amperage limit (typically 2.0A) when running "Float". If the "Float Stage is current-limited, the batteries might actually be loosing ground over time - leading to a resumption of "Boost" stage. (Hint: in this particular controller, the Float Current Limit is set by adjusting the total "AH Size" of the battery string. When "phantom loads" are high, in camp, you could increase Float max current by pretending to have 300AH of batteries.)

Running the TV engine to create mere "Float Voltage" is definitely a bad idea. And actually, the last few minutes of "Boost" might also be pushing a "too-small" amount of current and power - relative to the gasoline consumption. Running the TV is a great choice for moving from 50% SOC to 85-90% SOC, but it is too inefficient for long, slow transfer of energy to safely go above 95%.

Within storage, you can approach 100% charge - as a result of continuous Float, plus (perhaps) an Occasional 'Equalize'. (This depends on the capabilities of your Converter, or separate battery maintenance charger.)

My suggestion is for camping use, not long-term battery maintenance. And in camping, a quick recharge from 50% to 85-90% should be sufficient to handle the needs for the next 24 hours. Oversized panels, with lots of time to run a float stage after completing "Boost", might do a good job of adding another 5-10% (It depends on the Controller capabilities - this one can do that, especially if you modify the charge Voltages and battery configuration "size".) It doesn't sound like much - but, since you probably shouldn't use more than about 50% of the energy stored in the batteries to begin with, that might actually be 10-20% of your daily allowance.

[rickst29]

I have solar on my class A and on my popup, I would not have a trailer without solar. Keeps my batteries topped off always. Plus not just for quiet cg, but for cleaner air, cost less once purchased, and ease of use, not having to haul or lug around a genny or tie up to a tree etc... Solar is your friend.
I like neighbors like you (and me). :D For us, the "TV as battery charger" applies only to days with bad sun, and (for people with smaller panel configs) time driving down the road.

[BrucePerens]

Your scheme replaces the generator, at least some of the time.

One of the main differences is how much you cycle your battery. With sufficient solar, the battery is probably not being drained during much of the day. With TV or generator charging, you have a deeper charge-discharge cycle.

My loads aren't like everyone else's. I bought the Dometic compressor refrigerator. I expect to do a lot of ham and computer stuff in the trailer. I figure the generator will have to be on when I use the 1.3 kilowatt linear amplifier (http://www.expertampsusa.com/1-3k-fa/). But hopefully not otherwise.

[klpauba]

This option will suit me well. I can spend another year researching my solar requirements yet still spend some time boondocking with my DW. I will then be able to better assess her real interest in that type of camping and better understand what equipment we will need. My plans are to add this mod along with a battery monitor before we head out in the spring.

[scrubjaysnest]

We took a slightly different approach a few decades ago, pre solar for us. Our method was and still is a dual battery charging system in the TV. Down side is the move the battery back and forth requirement so it is now just a back up. This is the primary reason we stayed with 12volt batteries rather then GC-2's.

Some CG's are generator free and we found out this means you cannot run your TV to charge the batteries also.

For us, as mainly dry campers solar is the way to go. This past summer we did extensive testing and SG testing agreed with the trimetric about 3 hours of sun on the panels per day had us back to 100% soc.

Some so called rules we followed:

1. conserve, use a Mr Heater or wave 3 instead of the furnace for heat. Change all lighting to LEDs. Disconnect all power to the radio and FM antenna.
2. deploy the portable panels while opening the camper up.
3. while around camp move the panels as needed.
4. The solar CC must have remote battery voltage sense and temperature probe on the battery. While in Flagstaff I added the temp probe and the data sucked off the CC showed a major difference in charge currents and voltages.

Not once from mid May to Mid Nov. did I have to resort to pulling a battery.


@Bruceperens take on the challenge of running barefoot instead of using the linear.

[Padgett]

Have said it before but with 200W solar, 2 GC2s, and a 1KW inverter. the generator is only needed for the AC.

I would be surprised to find a campground that didn't allow a quiet generator when the temp is over 90F.

Now I have seen areas in a campground that are restricted but not an entire campground. Must admit have not been out of Florida yet.

[Craigrrr]

Have said it before but with 200W solar, 2 GC2s, and a 1KW inverter. the generator is only needed for the AC.

I would be surprised to find a campground that didn't allow a quiet generator when the temp is over 90F.

Now I have seen areas in a campground that are restricted but not an entire campground. Must admit have not been out of Florida yet.

I use our Honda inverter gen at campgrounds at night never had a complaint yet and generally I hear the drunks around the campfires more than anyone would hear a honda genny.

[Padgett]

Agree, there are a number of gennys as quiet as the Honda and are the only ones I'll test.

The AC is louder particularly when inside.

[BrucePerens]

challenge of running barefoot instead of using the linear.

I have an Elecraft KX3 backpack setup for that.