Solar panel upgrade

[BlueGekko]

My ‘19 Navion has two 100w solar panels. We’re half way through a 3 month road trip out west. We generally dry camp for two days and FHU the third. When dry camping the battery voltage drops to around 12 overnight from a daytime high of 14.4. I understand that dropping below 12 wears on the battery and, if done very often, shortens the life of the battery and the battery fails to fully charge. It stands to reason that if I add another solar panel, the batteries should remain fuller longer. However, I’m not an electrician so I don’t know if this is a reasonable assumption. Also, if I add another 100w panel, do I have to similarly upgrade any other gizmo/gadget? Hoping for knowledgeable advice.

[BobC]

1. The common perception is to not go below 50% or about 12.1 volts (depending on what chart you use. However, based on what I've recently been reading, most manufacturers say that 80% or about 11.7 volts is the maximum safe discharge. The key factor is how often you do it. 50% is a good rule of thumb for routine discharge but an occasional 80% discharge shouldn't be a problem assuming your equipment will run on the lower voltage. If you have conventional lead acid batteries, you need to keep your fluid levels up. Here's a link with some good battery information:

https://www.trojanbattery.com/tech-s...y-maintenance/

2. Adding more batteries are always a good idea, especially if you're adding more solar. More solar can be wasted if there isn't enough battery capacity to absorb the charge. You should have at least 200 to 225 Amp Hours of battery capacity. The type of batteries is also something to consider. True deep cycle batteries are preferable to the typical Marine/RV dual purpose batteries typically found in RVs. Many of us install two, 6V deep cycle, golf cart batteries connected in series (+ to -) for 12V. If a battery has CCA (cold cranking amps) in its specs, it's not a true deep cycle battery even if it has deep cycle in its name. There are also Lithium Iron Phosphate Batteries aka LiFePO4 but they're very expensive and should only be considered after you educate yourself about them.

3. Before adding another panel, you'll need to check out the capacity of your current solar controller to see if it can handle the additional wattage. You should also confirm that your wiring adequate, generally 10 gauge wire is adequate for most installations.

[BlueGekko]

Ahhh, I knew it couldn’t be as simple as adding another panel. Fortunately, when we get home we have a nearby Winnie dealer who enjoys cashing my checks so I’ll hold off fiddling with stuff I know nothing about until then. Thanks for the info.

[BobC]

Originally Posted by BlueGekko

Ahhh, I knew it couldn’t be as simple as adding another panel. Fortunately, when we get home we have a nearby Winnie dealer who enjoys cashing my checks so I’ll hold off fiddling with stuff I know nothing about until then. Thanks for the info.

You may have a great dealer, but, in most cases dealers aren't the best option for projects like this. Your best bet is to read all you can about solar on Winnieowners before doing anything so you're in a position to critique any estimate.

I don't know if you have any DIY skills or are even interested but, adding a panel, a battery and swapping out a controller is pretty straight forward. Your wiring is likely to be OK but even that isn't too difficult.

At the very least, get estimates from a couple of independents to compare with your dealer's quote. I've seen posts where dealers have estimated thousands of dollars for what should cost under a thousand dollars. In terms of equipment cost, an additional 100W panel will be $100 - $150, a new controller $200 or so and, depending on what you do battery wise, maybe $200 - $400. If you give us more information as to your controller make/model and your existing battery of batteries, we can be more specific.

I suggest augmenting your battery power first and take it from there, I think you'll see a difference. We camped for years with 200W and two 6V golf cart batteries. A lot will depend on how much room you have in your battery "box".
It's not too difficult if you pay attention to your power usage and think "camping" not RVing.

[creativepart]

BG, Let's talk about your batteries and your solar panels.

First, when you say that your batteries start at 14+ volts... that's a lie. You're not lying, your voltage battery meter is lying to you. A fully charged battery is 12.7 to 12.8v. And it can not be any higher than that. When your battery is at 12.7v it's FULL.

What your voltage battery meter is telling you is that you have a charger connected to your batteries and it is putting out 14+ volts. Because that's what battery chargers do. And, you say, "What charger we're dry camping?" Your solar panels are connected to a solar charge controller which is, as the name suggests, a battery charger.

If you had no sun and your battery was resting - and had been resting for a couple of hours THEN you could look at your battery meter's voltage reading and see an accurate representation of your battery bank's actual state of charge.

Here's another thing about that 14+ volts showing on the meter. If you start up your Navion's engine or generator you'll see 14+ volts from those charging sources, too.

Making it ever more difficult... charging adds a surface charge to the batteries so that even when you stop all charging your meter still will read above 12.7v. It takes an hour or more to for that surface charge to dissipate. And, if you put a heavy load on that battery it would sag the voltage down and even after the load was stopped it would take it an hour or so for the battery meter to show the REAL voltage of the battery.

What have we learned here? That your battery voltage meter is just about worthless at figuring out your battery's state of charge when you are dry camping.

Let's go back to your original post (OP). You said you start the day at 14+v and end the day at 12v. But that info is from your lying battery meter. The truth is you don't know what your starting voltage is. It could be 12.4v but because of the charge or surface charge it's reading 14+ volts on your meter.

Your ending voltage could be wrong, too but probably by a much less margin of error.

So, here's what I would suggest.

Don't buy anything BUT a shunt-based battery monitor. It's a funny looking device that connects between your battery bank's negative terminal and all the other negative loads. This device measure AMPs not volts and it tallies up every amp that goes in and out of your battery bank. Then the shunt is connected to a read out OR to a cell phone app and it tells you in percentages how charged or discharged your battery bank is. No resting required. Even if you are charging at the moment you look at the monitor's reading it will tell you the actual, real, honest state of charge on your batteries... morning, noon or night.

These cost anywhere from $40 to $210 and you can get a real nice bluetooth model that works with your cell phone for $120.

They are easy to self install, but you have to be a bit of a DIYer and not afraid of working with your batteries. But a tech could install one for you for not much money because of how easy they are to install.

Back to your OP... if you had this "BMK" Battery Monitor Kit installed then you'd know if you are really seeing your solar panels fully charging your batteries. If they are... you don't need more solar panels. If they are not maybe you do.

Also, at the end of the day you'd know if you are really at 50% or 40% or even 30% state of charge and this would tell you that you need more battery storage capacity - more or bigger batteries.

If you don't like to dry camp, or boondock, you may not need a BMK. But if you do, even a little, and it sounds like you do, buying and installing one of these is probably the only next step to take.

[backtrack15]

I agree with the battery monitor being an easy and appropriate next step. It’s scheduled to be my next acquisition. I have 200W of solar and two 6V batteries. Watching the battery voltage isn’t telling me what I want to know.

[BlueGekko]

Thanks for the above and for confirming that I need to talk to my Winnie dealer friend about whether I really need another panel or just better gear to handle the panels I have. Or just sell my Navion and stick with gear I know and can fix myself. Bicycles, boots, etc.

[Sparky19053]

Creativepart, Good information on the shunt batter meter, I'm looking in to one now. I have to look for one with a panel display. Last thing I want to look at is my phone when on the road.

BlueGekko I have the 2021 Navion and also thinking about adding a third solar panel, So far I have been good going three days without starting the gen. Zamp offers a 170 watt kit. The good news is your rig should have a third port on the roof so adding a panel should be plug and play.

[BlueGekko]

Mreuth, by plug and play you mean just plug another 100w panel in to the junction box on the roof, scotch tape it to the roof and my battery will charge quicker and last longer?

[Sparky19053]

Blegekko, Yes you SHOULD have a three port collector box on the roof of your RV, Two ports are used, one for each of the 100 watt panels that Winnie installed and third open port. The recommended plug and play panel for those with ZAMP solar is https://www.amazon.com/dp/B07GNL9KCY...v_ov_lig_dp_it

Please check for an available port before purchasing anything. And give the post from Creativepart some real consideration. He makes a lot of sense.

However while I feel I have to have this I'm not sold on the need to have it yet. Considering the cost and that Zamp was just sold or traded hands I'm exploring other more economical options. If you do add the third panel I would to like to hear your thoughts on how it helped keeping up with your power needs.

[Elkman]

If you have the Zamp kit with the 3-port roof cap and the Zamp charge controller then both are rated for 510 Watts from the panels. With the two 100W panels you can add a third 100W panel and a 190W panel to the roof and only need to connect in with the existing panels.

I changed out the wires for the two factory installed Zamp panels to both shorten the wire runs and to combine them into one DC input with the 3-port roof cap. That left one port for the third 100W panel and one port for the 190W panel.


I bought a 100W Renogy panel from Home Depot costr $115 and a 190W Grape panel from newegg.com for $218 and they were shipped for free to my house. I bought the mounting feet from AmSolar which sells ones for panels of different frame dimensions (35mm or 40mm).

Only trick part is that Zamp uses SAE connectors and reverses the normal polarity with their wiring connectors. You can buy polarity reversing adapters or have all the panels reversed for the connection into the 3-port roof cap.

The bad thing about the cheap Zamp roof cap is that there is no way to add a cut-off switch so you need to cover all the panels (existing and new ones) so they do not produce power while you are making the wiring connections.

I did find that my 490W panel array was much faster at charging my new lithium-phosphate batteries than the factory lead acid batteries. The lithium can charge 3 times as fast and so fewer hours of sunlight are needed to bring them back after a discharge overnight.

[BlueGekko]

Thanks, Elkman. As I understand your post, I can add another 100w or 190w panel by just plugging it in (and mounting brackets) without adding any other electronic gizmos and in doing so will not overload my stock coach batteries. Really, the only reason I want to add another panel is to prevent the batts from discharging too far below 12v overnight. We don’t use the inverter when we’re dry camping - in fact have never used it and don’t know if it works - so it seems like the additional panel will fit the bill. And thanks to CreativePart for the comprehensive explanation. However, CP, I learned many years ago from Dirty Harry that “A man’s got to know his limitations”. I’m pretty familiar with mine so I’ll be helping my local Winnie dealer put his kid through college when we get home in another six weeks or so. It’s just money. ��

[Elkman]

That is correct as the Zamp charge controller and the 3-port roof cap can handle 510 Watts from the panels. It is close to plug and play except for the reverse polarity SAE connectors and wiring of the existing Zamp 100W panels.

You can buy SAE cable wiring and also SAE reverse polarity adapters on Amazon. Sources for panel mounting feet include Amsolar and RVsolarstore.com and be sure that the feet which are in 35mm and 40mm sizes are the correct ones for the panel frames.

I thought is easiest to wire the two existing panels in parallel and then run separate wires from the two new panels to the roof cap.

Good idea to use heat shrink exterior use butt cable connectors to be sure the connections are weather tight.

[BlueGekko]

Thanks, Elkman. Sorry for the delay. We’re on the road and wifi enabled campgrounds are not easy to find. Following your example, will be adding panels to my 24D when we get home in August. Thanks for the info.