I have a 30 foot travel trailer with plenty of space on the roof and I want to do some remote camping. I'd like to be able to run the refrigerator, watch TV through-out the day, and be able to use laptop, and some other small electrical items.I was planning on getting two of the Grape 250 watt mono panels. I've heard others say the MC4 connectors don't work all that well so they cut the MC4 off and splice in 10 or 8 AWG. I know this likely voids the panel warranty. Either way, I would fish the two sets of wires down an existing vent (refrigerator vent likely). Down into the lower storage bay.There I planned on buying a decent charge controller, something I could use on another project down the road, the midnite classic 150. I would likely install a breaker/shut off box (as smkettners install). I am thinking I could get 8 six volt trojans (T-105) batteries with a 1500w or 2000w inverter. I was even thinking about installing a 30 amp transfer switch, wiring the inverter into the 'generator input' and taking the existing 30 amp shore power plug, wiring that into the 'shore input'. Then wiring the transfer switch output to the existing shore power input. That should give me power to the entire trailer??? I don't think I could run the microwave and everything, but that would allow me to use any receptacle. Does anyone have any suggestions?

renoman's compilation of Member's solar installations Thanks, Reno!The 30 amp direct connection with transfer switch has some merit as all receptacles are then powered. You could also use individual, smaller transfer switches (ala smkettner) to power select circuits. If all you are going to need is screen, laptops, and installed circuit boards, there are lesser systems that will allow that, i.e. you won't need 8 Trojans and 500w of solar charging with 2000w inverter. First step: Downloadable spreadsheet for use and solar calculationsBTW, MC4 connectors are purpose-built for solar application. They are available in 10AWG and you can't find much better.

daveyboy12 wrote:the midnite classic 150. I am thinking I could get 8 six volt trojans (T-105) batteries with a 1500w or 2000w inverter. That should give me power to the entire trailer??? Great controller..good choice. 8 wet batteries is very heavy and a lot of maintenance. If you can afford that controller, perhaps you'd prefer AGM batteries.It will. That's what I do.

Standard RV fridge will mostly run on propane and is not a huge 12v draw.The rest of the stuff can be run from a 300w inverter. Microwave needs 1800+ watts, electric coffee needs 800-1200 watts and other big stuff that can often be avoided.MC4 is excellent IMO. They are specifically designed for all conditions up on a roof for 20+ years.Midnight Classic 150 IIRC goes to 150v Voc so I have to recommend series panel connection with just two wires coming down. Due to the high voltage I do recommend an appropriate switch on the panel connection for ease of service and safety.8x T105 is a lot of battery. With a small inverter and LED lights you may only need two T105s and four would get you through a period of clouds/rain. If you go 2000w inverter then you do need four but I would wait and see if you need the second set of four. Could about go to a 24v system at this level.Whole house inverter connection is fine. I only recommend sine wave inverters.

RV absorption fridge ?leave it on propane Not on electricelectric uses way to much power around 300 watts to power the heating elementthats 24 amps , the avg total output from your solar panels'fridge control' uses very little power

daveyboy12 wrote: I've heard others say the MC4 connectors don't work all that well so they cut the MC4 off and splice in 10 or 8 AWG. This seems odd, why not open the box on the back of the panel and wire directly or open the box and add short MC4 versus cutting.

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JiminDenver
Explorer II
Oct 22, 2013
Toss around a 8-D a few times and you'll think those L16's are light. lol
mena661
Explorer
Oct 22, 2013
Almot wrote:

Trojan L16 weight: 125 lbs. I wouldn't try lifting it on my own.
Mine are 370Ah which are 100 lbs. Use your legs not your back. Besides, with a well designed battery tray these should only be lifted once and that's to get them into the tray. I really don't understand why lifting is a concern. Leave the batteries in the rig.
Almot
Explorer III
Oct 22, 2013
daveyboy12 wrote:
How do you best determine your battery level charge?

What 2oldman said. Keep in mind that those voltages are for RESTED battery, i.e. 24(?) hours after the end of charging and in absence of loads. Practically, it's close enough if you measure voltage in the morning, before solar kicks in and without high-draw devices running.

daveyboy12 wrote:
Do they make a battery charge level meter?

No. There are standalone meters like Trimetric, or sometimes there is capacity-measuring feature on solar controller display, they calculate capacity from the net AH flow, but you can't rely on them. High loads will screw the readings up, not to mention directly wired inverter. The only accurate measuring is specific gravity (not applicable to AGM), or voltage at rest.

And there is also an "idiot green light" :) - green indicator on solar controllers without display. It tells you when the battery is near full. God only knows exactly when it lights up - supposedly at ~90%. I prefer seeing the voltage.

Trojan L16 weight: 125 lbs. I wouldn't try lifting it on my own.
mena661
Explorer
Oct 22, 2013
daveyboy12 wrote:
How do you best determine your battery level charge? If I fully charge them, how would I know they are at 75% or 50%? Does the voltage drop to say 6 volts when they are 50% CHARGED? Do they make a battery charge level meter?
You would wire 4 6V's in series/parallel so that they'll still be 12V so you can use the 12V charge tables. Honestly, with 740 amp hours of batteries I only occasionally check my battery monitor just to either make sure everything is working ok or for nerd purposes. :) I pretty much use as much power as I like on a 3-4 day trip. I had these in my old 5th wheel too and with the extremely low parasitic draw in that rig, I never went below 80% SOC even on a 4 day trip.

Old rig - batteries in front storage compartment
mena661
Explorer
Oct 22, 2013
Almot wrote:
One little problem is that it takes two big guys to lift one L16.
I lift them by myself and I'm not big at all but it's just from the tray to the ground and vice versa. Once I get a reinforced tray and longer slides then I won't have to lift them at all.
CA_Traveler
Explorer III
Oct 21, 2013
Google Trimetric 2025 for a decent battery monitor.
time2roll
Nomad
Oct 21, 2013
The 12 Volt Side of Life
2oldman
Explorer II
Oct 21, 2013
From a google search of '6v battery charge table':

100% 6.3
75% 6.2
50% 6.1
25% 6.0
daveyboy12
Explorer
Oct 21, 2013
How do you best determine your battery level charge? If I fully charge them, how would I know they are at 75% or 50%? Does the voltage drop to say 6 volts when they are 50% CHARGED? Do they make a battery charge level meter?
ktmrfs
Explorer II
Oct 21, 2013
mena661 wrote:
Like others have said, unless you're running a MW, coffee maker or other high draw appliance, a 300W inverter and two GC's will be plenty. And I wouldn't even bother with more than a 200-250W panel either. IMO, if you want to pig out on power but not use the high draw stuff, get four 435Ah L16's instead of the 8 GC's. The L16's weigh less overall and take up less space. Yes, you'll lose some amp hours and they're taller than GC's but I have 4 of the 370Ah versions and have plenty of power. No solar either.

good advice. I have 160W of portable solar and I use 4 T-125GC with a 1000W inverter for the microwave etc. (Panasonic true inverter, so I can set it for max power of 800VA easily).

I'd have use L-16's but couldn't manage the height and they are heavy. But if you can fit them in by all means use L-16's instead of GC.

We are prudent, but not anal about power when we dry camp. microwave occasionally, DW uses hair dryer, use maxair vent fans when hot, furnace when cold and LED lights. use lights in the AM and evening. Even with all that we can go at least 8 days before the battery bank is down to 50%SOC with 4 GC with 6hours of solar/day. (Darn Trees and mountains, kill the # solar hours in the fall.)

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