Solar panel hookup

[KeithB]

I can't imagine it would be this simple, but before I dig into things I thought I would ask. On my 2018, 2108 DS travel trailer, there is a hook up on the outside labeled solar. I'm not looking to do anything extravagant. Can I get a solar panel and simply plug into that to enhance the charge on my battery while boondocking?

[creativepart]

If the portable solar panel you connect has a built in charge controller then yes. That's all it would take.

If you don't get one with a built in charge controller OR you add a solar panel to the roof then you'll need to add a solar charge controller between the connection on the travel trailer and the battery.

Many (most?) "suitcase" portable solar panels would have a basic charge controller. Most, roof mount panels would not.

[KeithB]

Perfect. Thanks! So if I can go one step further, I now have a standard marine RV battery that needs replaced soon. Can I get one more season out of it with a basic solar panel? Or would you go ahead and invest in a good AGM battery? I can’t afford both at the same time. I would like to be able to Boondock three or four days at a time.

[Marine359]

You should first check inside curbside pass thru. If there is a small patch on the forward bulkhead, there will be wires behind it that lead up to the roof. Then check on the roof just aft of the forward vent to see the f there is a mc4 gland there. If there is a gland, you can just connect a solar panel thru it and secure the panel to the roof. There are dozens of you tubes to show you how.

If the “hook up” you’re referring to has a cover and is on the sidewall of the trailer, it’s likely either a Furion or a Zamp port. Great for portable panels, but they have a 10amp limit. I always advise against roof or portable panels with built-in charge controllers. First is because they limit the distance that the panel can be from the batteries, and second because most are cheap pwm controllers which do not take full advantage of your panel(s). If you want efficient solar, advise installing an mppt controller as close as possible to your batteries. Even a small mppt can handle 2 or more panels. $130 gets you a quality mppt.

[creativepart]

There is no easy one size fits all answer to your question.

I will add though - for off-grid camping you need in order of importance:

1. As much battery storage as you can afford/accommodate
2. A back up portable generator to charge batteries and run AC appliances
3. As much solar charging capability as you can afford/accommodate

I can't tell you what YOU need. I wouldn't go out without a minimum of 2-12v Deep Cycle batteries of at least 80 - 100 amp hours capacity each. (Alternately, 2-6v Golf Cart batteries with 160 to 220 amp hours capacity combined when wired in serial configuration.). And a 2000w portable generator.

Solar, is really great but it wouldn't be first on my list. 2-batteries would be top of my list. And, a generator would be second.

You get to decide what's on your list.

[Marine359]

Originally Posted by KeithB

Perfect. Thanks! So if I can go one step further, I now have a standard marine RV battery that needs replaced soon. Can I get one more season out of it with a basic solar panel? Or would you go ahead and invest in a good AGM battery? I can’t afford both at the same time. I would like to be able to Boondock three or four days at a time.

No. You’ll be wasting your money buying solar with your current battery.

[KeithB]

Originally Posted by Marine359

You should first check inside curbside pass thru. If there is a small patch on the forward bulkhead, there will be wires behind it that lead up to the roof. Then check on the roof just aft of the forward vent to see the f there is a mc4 gland there. If there is a gland, you can just connect a solar panel thru it and secure the panel to the roof. There are dozens of you tubes to show you how.

If the “hook up” you’re referring to has a cover and is on the sidewall of the trailer, it’s likely either a Furion or a Zamp port. Great for portable panels, but they have a 10amp limit. I always advise against roof or portable panels with built-in charge controllers. First is because they limit the distance that the panel can be from the batteries, and second because most are cheap pwm controllers which do not take full advantage of your panel(s). If you want efficient solar, advise installing an mppt controller as close as possible to your batteries. Even a small mppt can handle 2 or more panels. $130 gets you a quality mppt.

Thanks for the quick explanation. With the fact that the wife and I will probably only Boondock a couple times a year, I’m wondering why I want to lug around a suitcase panel. Can I get four days of basic electricity out of a 100ah AGM battery?

[creativepart]

Originally Posted by KeithB

Can I get four days of basic electricity out of a 100ah AGM battery?

If you don't use any 12v power you can get by for 3-weeks or more.

See the difficulty? There is no way for anyone to tell you how long your batteries will support your needs because no one knows what your needs will be.

This is why I said first on the list is as much battery storage capacity as you can accommodate or afford.

Then you go out camping. If you run out of battery power in 3-days then the answer is no. If you still have over 50% of your battery capacity at the end of 4-days then the answer is yes.

That's where that No. 2 on the list generator comes in... when you run out of battery earlier than expected you start up the generator and recharge your batteries.

[Marine359]

Bite the bullet and buy 2 x 100ah AGM. If you don’t watch tv, use laptops, cpap or other power hogs, it will give you 3 days. I use 40-42ah per day, but I have a compressor fridge and cpap. If you are truly camping, and using propane for my st of your needs, you can be comfortable on 30ah per day. So 200ah would give you comfort for 3 days without taking the batteries down to a deep discharge.

Just estimating based on what you stated. Actual mileage may vary.

[Marine359]

Agree with Creative.
The priority for you at this time is batteries. You may never need a generator or solar until you get out there with better batteries.

[KeithB]

Excellent. Thanks for the comments and feedback.

[BobC]

Originally Posted by Marine359

Bite the bullet and buy 2 x 100ah AGM. If you don’t watch tv, use laptops, cpap or other power hogs, it will give you 3 days. I use 40-42ah per day, but I have a compressor fridge and cpap. If you are truly camping, and using propane for my st of your needs, you can be comfortable on 30ah per day. So 200ah would give you comfort for 3 days without taking the batteries down to a deep discharge.

Just estimating based on what you stated. Actual mileage may vary.

Expanding on Marine359's comments, you should be looking for AGM "true deep cycle" batteries. Any battery with CCA (Cold Cranking Amps) in its specs is either a starting or dual purpose deep cycle/starting battery (often labeled Marine/RV), not a true deep cycle battery. Many dual purpose batteries are labeled "deep cycle", so read the specs. Here's an example of a 110AH AGM deep cycle battery (you'll need two for 220AH):

https://www.amazon.com/Interstate-Ba...dDbGljaz10cnVl

Note that these are more expensive than flooded, 6V golf cart batteries which are available at Costco or Sam's Club for under $90 - $100 each. With these you still have to monitor your fluid levels, which can be simplified by the addition of one of these:

https://www.amazon.com/Flow-Rite-RV2...e%2C244&sr=8-2

Golf cart batteries are taller than the typical 12V battery so measure carefully. You'll need two Sam's Club $90 215AH 6V golf cart batteries for 215AH at 12V.

[RocknRoll]

Note that 6V GC batteries are extremely heavy (as are AGM) and two of them can add up to an additional 120 lbs. to the tongue weight.

Save your money and buy a LiFePO4. The advantages make it a no brainer.

[Marine359]

As I understand, OP is on a tight budget. LiFePo4 right for you and me, but not if you’re trying to keep cost to min, so maybe not a good fit for OP. With AGM, OP can keep his existing charger. He can find other ways to economize on weight.

[DavidM]

Originally Posted by KeithB

Can I get four days of basic electricity out of a 100ah AGM battery?

Yes, probably. In my previous simple T/T I could go three days on a single Group 24 battery that has something like 65 amp hours of capacity. If yours is simple (no fancy electronic displays and remote relay node like mine for example then your parasitic loads (those that you don't know what they are and can't turn off) should be low and you should be able to go 4 days on 100 Ahs even if you have to dip beyond the magic 50%. Occasionally going down to 80% discharged on an AGM battery won't materially affect its life.

I suspect my new MH uses more energy for its parasitic loads than yours uses for real loads.

David

[BobC]

Originally Posted by RocknRoll

Note that 6V GC batteries are extremely heavy (as are AGM) and two of them can add up to an additional 120 lbs. to the tongue weight.

Save your money and buy a LiFePO4. The advantages make it a no brainer.

Not 120 additional pounds AH to AH. Two golf cart batteries weigh approximately 140 lbs, two 12V AGM batteries weigh about 90 lbs, for 50 additional pounds.

LiFePO4 batteries are aren't exactly a no-brainer. They have their advantages over the long haul, particularly if you use your RV a lot and boondock or dry camp a lot. There is definitely a weight advantage. But you must be able to afford the high upfront cost.

[KeithB]

Originally Posted by Marine359

Bite the bullet and buy 2 x 100ah AGM. If you don’t watch tv, use laptops, cpap or other power hogs, it will give you 3 days. I use 40-42ah per day, but I have a compressor fridge and cpap. If you are truly camping, and using propane for my st of your needs, you can be comfortable on 30ah per day. So 200ah would give you comfort for 3 days without taking the batteries down to a deep discharge.

Just estimating based on what you stated. Actual mileage may vary.

After considering some great comments, I believe upgrading my current battery is the way to go at this point. Question: I am reading that the depth of discharge for an AGM sealed lead acid battery is 80%. Do you agree? Or is this a marketing exaggeration? If so, wouldn't this give me an additional day of dry camping over my lead acid battery which is at 50%?

[Marine359]

Discharging AGM to 20% SOC will not damage the battery, but it will shorten its life if done consistently. Maybe that doesn’t matter to you. Maybe you should try camping with a single AGM to see how long you can go. Then hook up and go somewhere you can plug-in. Your alternator will provide some charge current through the 7 pin, but not much. But enough to get your slide in or use your tongue jack if you let the motor run for a few minutes.

[Wyatt]

Originally Posted by Marine359

Discharging AGM to 20% SOC will not damage the battery, but it will shorten its life if done consistently.

Respectfully, why will it not damage the battery, yet shorten its life?
Perhaps we’re parsing words. If it’s shortening it’s life, then SOME damage is being done. Call it “wear and tear”, but it’s wearing it down prematurely.
It may be slow wear and tear, but it’s measurable in terms of the battery rebounding to 100% SOC. It won’t, IMHO.

[RocknRoll]

Originally Posted by Marine359

As I understand, OP is on a tight budget. LiFePo4 right for you and me, but not if you’re trying to keep cost to min, so maybe not a good fit for OP. With AGM, OP can keep his existing charger. He can find other ways to economize on weight.

Possibly! As I read it, he's interested in boondocking 3-4 days, replacing the 12V soon AND minimally utilizing solar which is quite the checklist. My suggestion was to save his money instead of buying something else that may be replaced later. If I'm not mistaken, the existing charger will work but it just wont get the DOC.

Stating from experience as far as weight, the previous owner of my TT had installed (2) GC batteries. My TW was at max without anything in my truck bed. Removing them and replacing with a single LiFePO4 relocated in the pass-thru saved 120 lbs. That alone was reason enough to upgrade.

Originally Posted by BobC

Not 120 additional pounds AH to AH. Two golf cart batteries weigh approximately 140 lbs, two 12V AGM batteries weigh about 90 lbs, for 50 additional pounds.

LiFePO4 batteries are aren't exactly a no-brainer. They have their advantages over the long haul, particularly if you use your RV a lot and boondock or dry camp a lot. There is definitely a weight advantage. But you must be able to afford the high upfront cost.

I apologize Bob, I should have clarified. As stated above, the 120 lb. savings was going from (2) GC to a single LiFePO4 AH to AH.

As far as upfront cost, prices for LiFePO4 have come way down from even a year ago.

If my math is right, the cost for AGM runs about ~$2/AH whereas LiFePO4 is ~$4/AH ($3 in larger sizes). Roughly double, but taking into account that you can discharge LiFePO4 up to 90%, it works to be about the same. Not to mention you'll probably never have to replace a LiFePO4. IMO, there's not a single advantage to FLA/AGM.

Not to go too far off-topic, but I recently upgraded my "inherited" surge protector to an actual suppressor with EPO

https://www.amazon.com/Power-Watchdo...s%2C182&sr=8-4

Besides the obvious protection it offers, it's has a Bluetooth app that has power monitoring. I was surprised at the amount of parasitic draw which I believe was around 1.0A. When the battery disconnect was enabled, it ended up being ~.5A, most likely from the solar charge controller. That's approximately 12A over a 24 hr. period without turning anything on. Could this be right?