Insufficient Solar?!

[RingTheAlarm]

Originally Posted by B350

Ha! I’m glad to be on the positive end of a problem!

The lack of sun in the PNW definitely contributed to the low state of charge the batteries are at now. It seems that with the dwindling overhead sun trying to get these batteries fully charged again will be nearly impossible.

Unfortunately, the rooftop space is right with the existing 2 panels, a Maxx Air fan and Yakima storage box on the ass end. I measured about 15” of usable space but that’s far off the 21” needed for anothe 100W panel. Another panel would mean needing a new 40A MPPT controller too...

I actually don’t know what max amperage the panels have produced. I just know that before we left home in August the charge state was always around 14+V.

I happen to have a pic of the readout from June. And the second pic is from tonight after a good day of sun on the Oregon coast.

You could always buy one of those flexible panels and attach it to the Yakima box if you don't have enough room.

[arctictraveller]

I think shuttlepilot hit the nail directly on the head. The first 80% or so of recharge (amp hours) are pretty easy to stuff back into the batttery, but the remaining 20% takes far longer, probably longer than the sun is up or that we run the motor. In the long run, I think most folks never see a full charge until they plug into shore power or remove most of the loads for a couple days of solar recharging. The result of the lack of full recharge means that battery life is reduced somewhat. How much is the result of several factors includiing how deeply discharged they become on a regular basis, and how fully they are recharged. In my case, since I don't have an amp hour counter I can only guess, but judging by voltage alone, I'm over 50% discharged in the morning and about 85% recharged by sundown. Does this bother me? Not a bit, sure I know I'm reducing the life of my batteries, but they seem to last about 3 to 4 years and they are inexpensive to replace (2 x $80ea). I have a similar situation in my boat with a couple exceptions. I have 12 house batterys (6v lead acid, same as the van) that never reach full recharge until I plug in to shore power. On a one week cruise, they charge off a 100A alternator during the day, and get a bit of a boost the following morning with a couple hours of generator time powering a 120amp inverter/charger. After anchor down in the evening, they run everything from lights, the TV, stereo, freezer, pumps, the entire house load till morning when the biggest load hits, the electric coffee pot. I looked at them yesterday, and was kinda amazed to discover they are now 9 years old and still doing their job. So, despite being abused and having a reduced capacity, they are serviceable, just like the ones in the van. Rather than worrying too much about killing my batterys, I simply enjoy the silent power and buy new ones every few years.

[Flux]

Yeah, everything you guys have told me and what I have read indicates that the float charge really is the sensitive issue when getting full capacity out of your batteries. No alternator is gonna do that for you and you need to make darn sure your solar controller or shore charger is gonna do that right.

Big reason I went with Bogart Engineering is the simple fact that it's a 2 or 3 stage charger and has a built in charging profile for the lifeline batteries. I also went as far as to be able to isolate my solar and battery from the alternator and house loads when driving so the solar can float the batteries if they are bulked charged.

Of course, all of this is just dialing in your efficiencies any way possible and really does not solve the capacity issue.

[B350]

Wow! Thanks for all the input guys! Talking about a load...

After reading all your input and going down the internet wormhole here is what I think I’ve learned and the conclusions drawn.

The biggest factor leading to what I feel is insufficient charging and a low battery state of charge was the weather we encountered in the last 3 weeks. Thinking back, we were in shaded forests and then weather that included rain, snow and clouded skies- everything but sun. Even with those adverse conditions the battery bank showed 12.1 to 12.3V which, as far as I understand, is anywhere from a 30 to 45% discharge (still totally acceptable).

But, the “rebound” to a higher charge state has been slow and seemingly lacking a proper absorption charge. Like Scalf77 mentioned, the bulk charging is being done during peak sunlight with nothing left for an absorption charge to bring the batteries up to 13+V.

I say 13V only because I referenced a SOC (state of charge) chart for AGM batteries indicating 13V as 100% charged while it shows that 12.75V is already 10% discharged with 90% charge remaining. Does that sound accurate? Picture 1 below.

I had a peak reading of 12.9V today which is now at 12.7V again after wrapping up the day sitting here with a headlamp and nothing drawing power. Pictures 3 and 4 where at about noon. Picture 5 is now (midnight).

As the Renogy charge controller does not measure Ah in/out to the battery bank I don’t know how many amps are truly being used. My rough calculation is that we only use about 20A per day. The biggest draw, like arctictraveller mentioned, is our electric kettle. Running the inverter to power the 1000W kettle (93A) for about 5 minutes is 7.75A. Tomorrow we’re going to see how pulling it out of the equation may help being we can just boil water on the stove. Hopefully the sun comes out again to at least have a somewhat constant input again.

Neither the fan or Yakima box cast a shadow on the panels so that’s not an issue. But, I now better understand how shade greatly reduces theses panels’ output, especially when wired in series.

Splitting batteries to alternately charge and discharge one at a time just doesn’t sound appealing considering the extra switches and wiring to make it a convenient setup.

Angling the panels makes a lot of sense though. Does anyone have good examples of how it’s neatly and easily done? Getting up to the roof would be the biggest problem though.

I think what I may end up doing is to ditch the Yakima box in favor of something much smaller and the add 2 100W Renogy Eclipse panels, still in series. This way I can stick with the same 14awg wire (I think) that came with the original installation kit, and go to the 40A Renogy Commander MPPT charge controller.
Thoughts or ideas on that verdict?

And if that is what I should end up doing, it will be asap. But, we are traveling full time... Is there anyone around the NorCal that would be willing to offer a place or even a hand to do the install? We’re just about to head to the Redwoods from Oregon in the next couple days and make our way to Sacramento by the second week of November.

Thanks again for the great input!

[boywonder]

Adding a couple of Eclipse 100W panels sounds like a great idea to me...since you are adding two you can even consider series-parallel wiring them...not sure that would do much but worth a thought. Trading shade sensitivity for more current (and a little more wire voltage drop) through the wires from the panels.

Since you have no idea on AH in or out of your batteries consider a battery monitor. I picked up a Xantrex Linkpro from another member here and at first didn't know how much utility it would have. After using it for a year+ I'm wondering how I lived without it. Xantrex also makes a "lighter" version called the linklite.

There are a few other monitors out there as well, Bogart is one...trimetric...

Battery Chargers | LinkPRO Battery Monitor | Xantrex

http://www.xantrex.com/power-product...y-monitor.aspx

TriMetric Model Descriptions - Bogart Engineering

Alternatively you could find an MPPT controller that has additional functionality for battery monitoring. The Midnite Solar Kid has loads of bells and whistles, not sure how much battery monitoring capability but perhaps worth a look. Member 1der has one in his van.

[Scalf77]

That sounds like a plan.

I agree with boywonder, might be time to look at battery monitor. I would add

Victron Energy BMV 712 Smart Battery Monitor with Bluetooth It has built in Bluetooth and can connect to phone app.

If not interested in Bluetooth then

Victron Energy BMV 702 Precision Battery


Adjustable Solar Panel Mount Mounting Brackets Folding Tilt Legs, I generally agree that this would be a pane in the arse, but if I was stationary a lot.

I would change the wire from 14 to 8 gauge, even with the panels in series, 14 gauge voltage drop is probably close to 2 1/2 % , If you went with 8 this would put your in series drop below 1% , plus give you the ability to go all parallel or a parallel - series combo. MC4 connectors make this pretty easy.
Once you stay with 14 your committed to series, if your making the change.

Also have you thought of longer panel. A 58 1/2 x 26 1/2 panel can give you 180 watts , a lot of that additional surface area is in unusable with your current 100 amp panels.

[IMG][/IMG]

-greg

[Flux]

For days when you can step out of the van and boil water:

https://www.amazon.com/GS-3900P-Port...ne+stove&psc=1

Uses 8oz Butane or 16 oz Propane. I have used a ton of different stoves from white gas to propane to Isobutane. This stove is the fastest boiling I have ever used. Has OK simmering as well. I would buy and carry a second one of these over a 2 burner just to keep the great output.

[arctictraveller]

Tilting our panels can make a significant difference in output. With our GTRV top, they are easy to tilt in one direction, so I just have to make sure the van is parked with the rear facing South for maximum charging. with the top up. When I read that your voltage had gotten as low as 12.1 I thought you had lead acid. 12.1 is darn near dead with L/A, but not quite as bad with AGM, but still pretty low. Remember too that when determining the state of charge by voltage, it's resting voltage, not charging voltage, so unless it's dark, your not getting a true picture of the state of charge by voltage alone.

[arctictraveller]

Originally Posted by Flux

For days when you can step out of the van and boil water:

https://www.amazon.com/GS-3900P-Portable-Convenient-Carrying-Powerful/dp/B01N1RO9WG/ref=sr_1_2_sspa?ie=UTF8&qid=1509116553&sr=8-2-spons&keywords=gas+one+butane+stove&psc=1.

I agree, those are great stoves, I used one for years on work boats, they boil water quickly and use little gas. They are light weight, small, and inexpensive. I never had a problem using it inside the pilot house either, just crack a window.

[B350]

A battery monitor sounds like the way to go in gauging accurate usage and SOC.

The complexity and cost of this little upgrade is quickly adding up... It wouldn’t be so bad with the right tools and a little disposable income but neither one is in the bag when you’re living out of your van. :/

Correct me if I’m wrong, do you have to stay with the same sized panels when adding to existing panels? In this case, with 2 100W panels any additional panels should also be 100W. Adding say a 150W panel would just limit it to 100W like the others is that right?

If that’s the case I’d obviously keep the 2 100W panels I currently have and add 2 more of the same even though I’m not maxing out the roof width. It just makes more sense from an economic standpoint.

I cringe at having to do anymore wiring or even up-sizing the existing wires coming from the current panels due to not having anything but a simple crimp/wire cutter and other basic tools. Doing a hack job just goes against my morals! But, I definitely see how a larger gauge wire coming from the panels would be advantageous.

Titling panels... I like the concept and see the benefits. I just have to come up with a simple solution to potentially make that happen with the additional panels.

I’m going to make a call to Renogy and go from there.

Tacos and beer for anyone that can lend a hand!

Thanks again for all the great info. Much appreciated!