200 W of Solar
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Forum Name: Podmods, Maintenance, Tips and Tricks
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URL: http://www.rpod-owners.com/forum_posts.asp?TID=14608
Printed Date: 29 Apr 2024 at 4:55am
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Topic: 200 W of Solar
Posted By: SailorDude
Subject: 200 W of Solar
Date Posted: 02 May 2021 at 11:07pm
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Is this a good deal for charging 2 6 volt Golf Cart batteries?
https://www.renogy.com/200-watt-12-volt-monocrystalline-foldable-solar-suitcase/?gclid=CjwKCAjwm7mEBhBsEiwA_of-TFz7kre-WQPMBiXmYHgW4XN8BU1-u3Ft2VtXm-rGGSqJSkpyWkElhhoCpiAQAvD_BwE
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SailorDude
2018 RP176
F-250 Superduty XL
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Replies:
Posted By: offgrid
Date Posted: 03 May 2021 at 5:55am
Depends what you want to do for mounting (portable vs roof) and how many amphours you are taking out of you batteries daily. Get a voltmeter and starting with a fully charged battery, use power normally until the voltage (with everything off for half an hour or so) is around 12 or 12.1 volts. That is about 50% state of charge or roughly 100 amphours out of your golf cart batteries.
Divide by the number of days (and partial days) you've been camping. That is the number of amp hours per day you're using.
Next, multiply your daily amp hours by 4.5. That is roughly how many watts of solar you'll need to maintain battery charge under average 3 season conditions with an unshaded solar system. Many folks find 100 watts is sufficient, others need more, it depends on what you are running in the trailer.
Renogy stuff works fine but it's not exactly inexpensive. If you do decide you need a 200+ watt portable solar system, the most bang for the buck is to get a standard 60 cell residential (250-300 watts) module. These are often available left over from installations for 50 cents a watt or less. Try CL.
You will also need an MPPT charge controller, 30-40 amp, which you can get on the 'zon pretty cheap now. Some 10 gauge cable, a fuse and fuse holder, and back leg materials to tilt the module and fold up when not in use and that's it.
If you don't want to lug around a few hundred watts of PV and want to roof mount it instead, consider getting an 72 cell commercial module (350-400 watts) and roof mounting that. Those modules are the standard for commercial solar installations so are the least expensive per watt. The length of those big modules is almost the same as the width of the narrow rpods so if you get the right one it will extend side to side so you don't have to put holes in the rpod roof.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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Posted By: Colt
Date Posted: 04 May 2021 at 2:03pm
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I think you could do it a little cheaper, but Renogy is supposed to be a good company and there is a lot of convenience there.
I'd ask for an MPPT controller and run the panels in series (24V). That will give you a little more generation at the ends of a day and in rainy/overcast days. The higher voltage could also let you run longer wires from the panels to the controller (So your trailer can be shaded and the panels get full sun).
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John
'16 R-Pod 180
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Posted By: offgrid
Date Posted: 04 May 2021 at 6:25pm
If you run two modules in series then both of them need to be completely unshaded. All the cells in both will be series connected so shading any cell will take out both modules.
If you run two modules in parallel then shading on one doesn't effect the other. However, since MPPT controllers step the voltage down, you don't have enough voltage on nominal 12v modules (36 cells) to use one.
Thats why I prefer a PWM controller for portable applications subject to shading with 12v modules. Cheaper too. If you go with the 60 cell or higher modules then you need to use an MPPT.
Not sure what the convenience is with the Renogy kit? You can get a Renogy controller if you like that and still get a residential 60 cell module as the power source, and be ahead a couple hundred dollars with more power.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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Posted By: nasi
Date Posted: 10 May 2021 at 10:47am
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Hello offgrid. What is a CL? I also am looking for a 200w system. And, how long will a regular battery last without shore power if you are using only the water pump and lights? I have a 2020 R180.
Thanks ahead of time
Steve
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Posted By: offgrid
Date Posted: 10 May 2021 at 11:15am
craigslist. You could also try EBay but watch the shipping costs.
You should last several days if you're just using lights and the water pump. The pump has a very low duty cycle (% on time) and the lights are LED so very efficient. Just turn off the lights if you're not actually using that area. The fans (furnace and bathroom vent) use more if the weather gets hot or cold. I'd say 200 watts solar would probably be overkill in your situation. No harm in it though, the controller will prevent battery overcharging.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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Posted By: nasi
Date Posted: 10 May 2021 at 11:58am
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Thanks offgrid. So, do you think a 100w panel with a 20A PWM charge controller would be adequate to keep lights, water pump and furnace fan going, assuming enough sun?
Thanks again,
Steve
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Posted By: offgrid
Date Posted: 10 May 2021 at 12:45pm
Maybe not the furnace, that fan uses a lot. Especially in the late fall when it's both cold and solar irradiance is low. Spring is better because we have longer sunnier days.
But do consider what your options are if you run into a string of cloudy days, as we frequently do in the East and Midwest, it doesn't matter how much solar you have, it will be producing very little, about 10% if it's heavily overcast.
For confidence you wont run out of power I'd suggest you consider a dual battery configuration to get through some cloudy days, and a small generator for backup. You can run the genny from your propane if you don't want to carry gasoline. Nice and clean that way.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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Posted By: nasi
Date Posted: 10 May 2021 at 12:51pm
Sorry but I am a lame electrician. I have been thinking about a second battery, but not sure if parallel or series hookup is the right way. What do you think?
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Posted By: offgrid
Date Posted: 10 May 2021 at 2:22pm
Not lame, that's a good question.
If your current battery is a year or more old now (sounds like it might be) then I'd go with two new 6v golf cart batteries in series. Case size GC2. Very common battery in the golf cart world so can be had for a good price. Those are the largest size that will fit, are true deep cycle so can tolerate deep discharging, and everything else being equal series is better because both batteries always get the same charge and discharge current. When they're in parallel they don't, one will always have a little lower internal resistance than the other so will take and provide more current.
If OTOH your existing 12V battery is near new then it makes better economic sense to keep it if you can buy another battery same model and same manufacturer. If you do that connect them in parallel but pull your positive take off from one battery and your negative from the other, that will help keep them balanced.
One other word of warning, dual batteries are going to add about 60+ lbs to your tongue weight, be sure your tow vehicle can handle it.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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Posted By: Ben Herman
Date Posted: 15 May 2021 at 10:25pm
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We use a 100w Renogy system with a single 12 v battery and its more than adequate, but we live in sunny Colorado and rarely have cloudy days. Also, I added a 25 ft cable to the panels so that I can move it around to capture the sun during the day. We run out of water and blackwater tank space long before power.
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Posted By: nasi
Date Posted: 15 May 2021 at 10:42pm
Thanks Ben. I have been looking at the 100w Renogy system. Good to know. I see you are from Grand Junction. My parents used to live in Montrose and I know that area pretty well. I wish I was there many times in about February here in Wisconsin.
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Posted By: fwunder
Date Posted: 16 May 2021 at 8:42am
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I have that system. And a separate 100 watt HQST panel I carry on top of my TV. Dual 6 volt Duracells and 1500 watt VertaMax inverter. I use Voyager PWM controllers. All works very well.
Be advised the Renogy 200 watt suitcase uses very unique cell design. You cannot hook the two panels in series.
http://www.rpod-owners.com/forum_posts.asp?TID=13938&KW=renogy&PID=135651&title=setting-up-solar#135651 - http://www.rpod-owners.com/forum_posts.asp?TID=13938&KW=renogy&PID=135651&title=setting-up-solar#135651
fred
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2014 RPod 178 => https://goo.gl/CV446f - MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6
Yes, those are wild ponies dining on grass while dumping tanks!
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Posted By: StephenH
Date Posted: 16 May 2021 at 9:01am
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If you really need to save weight and have the budget for it, I would recommend converting to an LiFePO4 battery. I have a 100A one. I am considering whether to change to a 200A model. Two GC2 6V batteries weigh about 120 lbs. The 100W LiFePO4 battery weighs less than 30 lbs. It also can be mounted inside since it does not produce flamable hydrogen gas. You can see my write-up in my mods.
It isn't cheap to change to an LiFePO4 battery, but it also has a much longer expected lifespan than Pb-Acid batteries. It also can be discharged to a much greater depth than Pb-Acid batteries without damaging the battery. It does require other changes which you can read about in my mods. If you are going solar, then an LiFePO4 battery makes a lot of sense also.
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StephenH
Happy is the man that findeth wisdom,...
http://www.rpod-owners.com/forum_posts.asp?TID=7712 - ouR escaPOD mods
Former RPod 179
Current Cherokee Grey Wolf 24 JS
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Posted By: Ricktoon
Date Posted: 15 Jun 2021 at 11:29pm
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Anyone know if there is a fuse inline on the solar power cables running from the roof of a 2021 196 to the batteries. Putting a panel on top and charge controller inside and understand I should have a 20 or 30 amp fuse on the positive wire close to the battery. Wonder if the wiring already has one installed.
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Rick and Ellen B
2019 Chevy Colorado
2021 Rpod 196
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Posted By: offgrid
Date Posted: 16 Jun 2021 at 6:17am
Don't think so. Besides, it should be right at the battery. Just get a bolt on or inline fuse and install it at the pos batt terminal.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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Posted By: Ricktoon
Date Posted: 16 Jun 2021 at 3:37pm
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That is what I thought as well. Will install inline fuse on solar positive wire.
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Rick and Ellen B
2019 Chevy Colorado
2021 Rpod 196
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