Solar Show and Tell

[uncle_bob]

Hi

Turns out there's room on the factory pre-wire box on the roof to drill it and put on another socket for a fourth panel. Inside the box you can wire the panels whichever way you wish.

Mine are wired in parallel, simply because that's the way the factory wanted to do it. I'd do it another way, but I don't like crawling around on the roof.

Bob

[Changing Itinerary]

Love this thread! Learning a lot on here!

We launched our 6-month travel plan a few days late on June 9th running from the 100 degree plus heat of Phoenix to ~7000 feet of elevation and cooler temps not too far away in Flagstaff, AZ.

So far: Solar is great! Lion Energy LiFePO 4 Batteries are great!

The last two days our Zamp 230 Watt portable solar panel kit added 102 Ah and 110 Ah to our battery bank. This morning I decided to put the panels out early at 6:30 am and increase the tilt toward the rising sun with a high-tech arrangement of an amazon box. We pulled in 17 Ah before I finished my morning coffee at 8 am. Below is a picture of the high tilt including the coffee cup. If I manage the angle to the sun well I can pull an average 13 Amps per hour.

On a sad note: our 2019 FC is not charging our batteries from shore power at all. We return to Airstream of Scottsdale Monday morning at 7 am to have them diagnose and repair. In addition to solar charging, the batteries charge from the 7-pin going down the road. The factory WFCO converter/charger checks out fine as do all accessible fuses. Connections in the battery box are tight. If anyone has encountered this before or has any ideas please let me know!

[Fair_Enough]

If your WFCO is like the ones I’ve owned, it is probably not making a high enough voltage for the charge to be realized. Mine would never enter what they call boost mode and float is too low. It is easy to be sure whether it is or isn’t making something. Disconnect all other charging sources and read battery voltage with and then without converter powered up. Charging it should be higher if only slightly. Also you could disconnect batteries and SCC and see if the converter powers 12 volt loads such as interior lights. You mentioned charging from the 7 pin and tow vehicle. Don’t expect to see any useful charging that way. Wiring run is too long and gauge too small. Plus the TV is “concerned” about its chassis battery only. Different charging profiles between the starting battery and Li.

[uncle_bob]

Hi

+1

The typical stock converter "likes" to run at 13.2V. That's not enough to properly charge lithium batteries.

Quick check:

In the evening ( = no solar) and when on shore power, turn off the breaker to the converter. Let the batteries "run down" a bit (like to below 13.2V). Check the voltage at the converter with a multimeter. Say it's 13.1V.

Now flip the breaker back on. Check the same voltage at the output of the converter. It should be up above 13.2V. If it is, the converter is working.

In a similar fashion you can check the voltages at various points in the system to see what's going on. The use/store relay (and how it's wired) is one thing to dive into.

Bob

[SilverHouseDreams]

Originally Posted by Changing Itinerary

On a sad note: our 2019 FC is not charging our batteries from shore power at all. We return to Airstream of Scottsdale Monday morning at 7 am to have them diagnose and repair. In addition to solar charging, the batteries charge from the 7-pin going down the road. The factory WFCO converter/charger checks out fine as do all accessible fuses. Connections in the battery box are tight. If anyone has encountered this before or has any ideas please let me know!

Fact is that “plug and play” lithium isn’t exactly reality. Ditch the WFCO and replace it with a new converter that supports lithium, otherwise you are going to add a lot of extra cycles and never be able to predict when/if you will be at 100%. I have a lot of posts on this subject.

[Fair_Enough]

I didn’t mention the solution. Like SHDs said, replace the WFCO. Best Converters sells a Progressive made to their specs that works with LFP and FLA. when optioned (jumper change) for Li, it puts out 14.6 volts 24/7. I have this in my 2012 23FB. Frankly I am not sure it is “best”. It might not be optimal. Renogy, for example, recommends 14.4 vdc +\- 0.2 vdc. What I’m not crazy about is when the build-in BMS correctly stops the cells from charging, loads continue to see 14.6 vdc. Plus, I’m not sure it’s good to keep LFP at a near 100% full all the time. I’ve read that it is not. What I don’t like is what’s going on in the BMS is a mystery. By their nature, voltage level mean little. Although a good battery status monitor (I.e.TM-2030 RV) can be setup for realistic information.
Clint

[uncle_bob]

Hi

Like it or not, Lithium's are a new thing. The charging recommendations are all over the map. Marketing departments *really* want to sell you something even if it is not quite a perfect fit. That's true both on the battery side *and* on the charger side.

The chemistry of lead acid has given us a set of terms and a bunch of ideas about chargers. The chemistry of lithium is different. On top of that, anything you buy these days isn't a Lithium battery. It's a battery *plus* a built in BMS. You aren't supplying power to the battery. You supply it to the BMS. The BMS then wanders off and charges the battery. There are some *very* good reasons they do it this way. The early generation of non-BMS batteries had significant issues ....

Right now, it seems that you want to charge up to about 14.6V (but not over 14.6) for most lithiums. You then want to drop off to about 13.4V ( = below 13.5) and stick there pretty much forever (like weeks). You can go right up to the 14.6V point with full amps out of the charger. Your batteries will charge the quickest if you do. There does not seem to be any downside to doing this.

Can you do it other ways? Sure it will work. Will you get the full life out of your very expensive lithiums? Maybe yes, likely no. For many of us, charge cycles are what killed our lead acids. Lithiums last for a lot more charge cycles. Doing the math just based on charge cycles gives you crazy lifetime numbers. It is likely that something like charging issues will be what gets your batteries ....

What's going on inside the battery? Well, when you run up to 14.x V, the BMS goes into "balancing mode". It plays games to move current around to get all the cells in the pack happy. While doing this it plays games dumping power here and there. The normal assumption is that it will do this once and a while. Who knows what happens when you are at 14.x V all the time ... does it run forever and ever? Maybe it does. I'd bet that's not a good thing.

You could just kick back and hang on to your 10 year warranty. The simple fact that they are willing to put a 10 year warranty on a battery suggests that it should last for quite a while. Personally, my experience with warranties has been ....errr .... mixed. I'd very much *not* want to depend on that replacing my batteries a decade from now.

Bob

[AirMiles]

Today is one of those lousy days for solar. I’ve been out for five weeks under all different levels of shade, tree canopy and cloudiness and have gotten plenty of solar to keep my batteries happy in all conditions. But occasionally there is one day where solar is just not effective.

I’m dry camping on the North Shore of Lake Michigan off US-2. There is a fog advisory for the area. It’s been raining and drizzling all day. The furnace has been running since last evening as it’s been in the mid-50’s. We have made only 170Wh of solar through 2 pm with a max Wattage of only 60W from my 400W solar array. I’m hoping to avoid running the generator to boost charge the batteries, but it’s going to be close.

I tell everyone how well Solar works under most conditions, but you must have a backup plan for lousy solar production days. That backup plan may be a larger battery bank with multiple days of reserve Amphours or a generator. I’m hopeful that my 230AH battery bank consisting of two Duracell EGC2 batteries gets me through until the sun returns again like yesterday. Yesterday’s solar production was over 1KWh in the same location. What a difference a day makes.

[uncle_bob]

Originally Posted by AirMiles

Today is one of those lousy days for solar. I’ve been out for five weeks under all different levels of shade, tree canopy and cloudiness and have gotten plenty of solar to keep my batteries happy in all conditions. But occasionally there is one day where solar is just not effective.

I’m dry camping on the North Shore of Lake Michigan off US-2. There is a fog advisory for the area. It’s been raining and drizzling all day. The furnace has been running since last evening as it’s been in the mid-50’s. We have made only 170Wh of solar through 2 pm with a max Wattage of only 60W from my 400W solar array. I’m hoping to avoid running the generator to boost charge the batteries, but it’s going to be close.

I tell everyone how well Solar works under most conditions, but you must have a backup plan for lousy solar production days. That backup plan may be a larger battery bank with multiple days of reserve Amphours or a generator. I’m hopeful that my 230AH battery bank consisting of two Duracell EGC2 batteries gets me through until the sun returns again like yesterday. Yesterday’s solar production was over 1KWh in the same location. What a difference a day makes.

Hi

Welcome to pretty much exactly the situation that convinced me we needed 400AH (usable) of battery on board. You may not ever run into bad weather out west. You most certainly do in the north east.

If you look at the maps of "solar hours per day" there is a big blob of low hours over the Great Lakes region. More or less what they are saying is your risk of having a run of bad solar luck is fairly high camping out there.

My "guess" was that a 100AH usage per day was about right for our trailer and pattern of use. The heat in ours is pretty low power usage so it's not a big factor in the number. We still stay roughly "in budget" on nights with it turned on.( = lows in the 50's or high 40's).

As you have noted, generally you start to fall behind budget over a couple of days. It's not a "the sun just goes away" sort of thing. Three to five days of this and that .... you are at half capacity. Along comes a day where the sun really does not come out and you are well behind and starting to wonder about the next day.

Our answer is to pull up after a week of that sort of nonsense and book some place next that *does* have power. The converter will thunder along using up their juice for a good solid 5 hours or so "filling" 400AH. That's still comfortably inside a one day stay someplace.

So far, in the year since we put in the Lithium's, they have not gone much below 50%. We doubled up the solar back in April so most of the data is with only two panels on the roof. We did not try for "a couple of weeks" with just two panels. With them, even after a week or two off grid, rarely below 80%. All of that in the eastern part of the country.

Lots of fun !!!

Bob

[AirstreamCSH]

Even with our 450w on the roof and 120w on the ground filling our 220-AmpHr batteries, we still feel the need to have a single 2000 watt propane generator to fill-in for those days which @uncle_bob describes so well above. Solar is a great way to extend your boondocking time and high ampHR batteries extend that even further but until there are significant improvements in cost/life/AmpHr of RV coach batteries, keeping that small generator around tides you over without having to find shore power when the sun hides for a while.

[pteck]

Originally Posted by AirstreamCSH

Even with our 450w on the roof and 120w on the ground filling our 220-AmpHr batteries, we still feel the need to have a single 2000 watt propane generator to fill-in for those days which @uncle_bob describes so well above. Solar is a great way to extend your boondocking time and high ampHR batteries extend that even further but until there are significant improvements in cost/life/AmpHr of RV coach batteries, keeping that small generator around tides you over without having to find shore power when the sun hides for a while.

I agree.

As I live in the southwest, I also have a need to power my A/C on occasion for those hot weather summer road trips to various national parks. Temperatures regularly exceed 90, and well into the 100s.

No amount of solar or batteries will power the A/C for any significant duration without completely depleting the stores, at which point one needs to figure out how to recharge anyways. No different from those rare long dreary or tree covered spells for which one will want the same contingency.

The Honda eu2200i is almost custom tailored for this task. Small, light, powerful. Takes up no extra room or attention in my setup, hiding behind the propane tank on the tongue.

[Wconley]

Originally Posted by uncle_bob

Hi

Like it or not, Lithium's are a new thing. The charging recommendations are all over the map. Marketing departments *really* want to sell you something even if it is not quite a perfect fit. That's true both on the battery side *and* on the charger side.

The chemistry of lead acid has given us a set of terms and a bunch of ideas about chargers. The chemistry of lithium is different. On top of that, anything you buy these days isn't a Lithium battery. It's a battery *plus* a built in BMS. You aren't supplying power to the battery. You supply it to the BMS. The BMS then wanders off and charges the battery. There are some *very* good reasons they do it this way. The early generation of non-BMS batteries had significant issues ....

Right now, it seems that you want to charge up to about 14.6V (but not over 14.6) for most lithiums. You then want to drop off to about 13.4V ( = below 13.5) and stick there pretty much forever (like weeks). You can go right up to the 14.6V point with full amps out of the charger. Your batteries will charge the quickest if you do. There does not seem to be any downside to doing this.

Can you do it other ways? Sure it will work. Will you get the full life out of your very expensive lithiums? Maybe yes, likely no. For many of us, charge cycles are what killed our lead acids. Lithiums last for a lot more charge cycles. Doing the math just based on charge cycles gives you crazy lifetime numbers. It is likely that something like charging issues will be what gets your batteries ....

What's going on inside the battery? Well, when you run up to 14.x V, the BMS goes into "balancing mode". It plays games to move current around to get all the cells in the pack happy. While doing this it plays games dumping power here and there. The normal assumption is that it will do this once and a while. Who knows what happens when you are at 14.x V all the time ... does it run forever and ever? Maybe it does. I'd bet that's not a good thing.

You could just kick back and hang on to your 10 year warranty. The simple fact that they are willing to put a 10 year warranty on a battery suggests that it should last for quite a while. Personally, my experience with warranties has been ....errr .... mixed. I'd very much *not* want to depend on that replacing my batteries a decade from now.

Bob

I’ve noticed unexpected voltage levels sometimes while hooked to power and I think it’s exactly this, the BMS doing what it does. Like seeing 90% charge after being hooked up for a couple of days, etc. It works so well I stopped worrying about it. The other big change I found with our Lithium batteries is that they charge much, much quicker. When needed, I used to have the generator going for hours and hours to get the Lead Acid batteries topped off. Last winter when I did this, the batteries were back to 100% in about an hour!

[AirMiles]

I did squeak by without using the generator. Luckily we got a little brighter fog/overcast conditions later in the day and sunny skies today. I have very little excess battery power. I typically use close to 100Ah per day from a 230AH battery bank. I carry a generator to boost charge the batteries when I don’t get enough sun. The days where I needed to use the generator in the past only produced about 100Wh of solar. Yesterday I got 390Wh and got through without needing the generator even though the furnace was running for the whole two days. Lowest voltage recorded was 12.18V and that reading would have been under the load of the furnace.

[pteck]

Originally Posted by AirMiles

I did squeak by without using the generator. Luckily we got a little brighter fog/overcast conditions later in the day and sunny skies today. I have very little excess battery power. I typically use close to 100Ah per day from a 230AH battery bank. I carry a generator to boost charge the batteries when I don’t get enough sun. The days where I needed to use the generator in the past only produced about 100Wh of solar. Yesterday I got 390Wh and got through without needing the generator even though the furnace was running for the whole two days. Lowest voltage recorded was 12.18V and that reading would have been under the load of the furnace.

I'd say you did better than squeak by, with still some good battery reserve to spare.

As you have 6V batteries, they can stand up to greater depths of discharge without harm. I'm wholly comfortable running them down to 80% DoD, or ~11.7V on the rare occasion.

Having significant solar already means the batts live an easy life. As solar does the heavy lifting, the batts are cycled more gently in both C-rate and DoD on the typical day. Asking them to give back a bit won't hurt them in the least and will still prove to have a long long healthy life.

[uncle_bob]

Originally Posted by pteck

I'd say you did better than squeak by, with still some good battery reserve to spare.

As you have 6V batteries, they can stand up to greater depths of discharge without harm. I'm wholly comfortable running them down to 80% DoD, or ~11.7V on the rare occasion.

Having significant solar already means the batts live an easy life. As solar does the heavy lifting, the batts are cycled more gently in both C-rate and DoD on the typical day. Asking them to give back a bit won't hurt them in the least and will still prove to have a long long healthy life.

Hi

Be very careful there.

Absolutely nothing at all about 6V batteries makes them able to withstand a greater depth of discharge. 6V is simply a number on the side of the battery. It tells you nothing about how the battery is built or what it was designed to do. It might be built the same way / same specs as the worst 12V battery you have ever seen.

Indeed there *are* 6V batteries that do pretty well. You have to be very specific about exactly which batteries those are. For me, the list has one entry on it - Trojan T105 .....

======

The BMS will not do much to impact charge percentage as shown on your BMV-712 (or equivalent). The charger ramping up to do the 14.x V stuff will get it a bit confused from time to time. It's the same thing, but from a different source.

Bob

[pteck]

Originally Posted by uncle_bob

Hi

Be very careful there.

Absolutely nothing at all about 6V batteries makes them able to withstand a greater depth of discharge. 6V is simply a number on the side of the battery. It tells you nothing about how the battery is built or what it was designed to do. It might be built the same way / same specs as the worst 12V battery you have ever seen.

Indeed there *are* 6V batteries that do pretty well. You have to be very specific about exactly which batteries those are. For me, the list has one entry on it - Trojan T105 .....

======

The BMS will not do much to impact charge percentage as shown on your BMV-712 (or equivalent). The charger ramping up to do the 14.x V stuff will get it a bit confused from time to time. It's the same thing, but from a different source.

Bob

You must think I like to live on the edge?

Actually, 6V as a format is indeed more capable than the typical 12V battery type. They are built for deep cycle use cases (golf cart), versus typical hybrid/deep cycle in name only 12V formats. This is because they have better geometries and features like deeper wells and thicker plates that enable this type of use. It's why many of us use them - to enable more usable reserves, while still maintaining more overall durability and usable life.

Sure you're talking about specific quality among a battery brands. I'll leave that for you to figure out. Yet that doesn't dismiss that 6V again as a format, is generally built far better than a comparable 12V.

Any battery supported by significant solar is living a pampered life. It's like buying a hot rod and letting her sit in the garage. I'm going to drive and enjoy the capability I paid for.

[AirMiles]

- Lead acid batteries with thick lead-antimony plates, Golf Cart Batteries, are designed to be deeply discharged to 80% repeatably.

- Lead acid batteries with thin lead-calcium plates, like Marine/RV Deep Cycle & Automotive Starting Batteries, are designed to be discharged to 50% without severely shortening their lives.

Source: https://www.solar-electric.com/learn...ttery-faq.html

The Duracell EGC2 (Deka GC15) batteries use thick lead-antimony plates: http://www.ieeco.net/Documents/Batte...kaSolarC&L.pdf

Trojan T105 batteries use thick lead-antimony plates: https://ressupply.com/batteries-and-...looded-battery

Interstate GC2 batteries state they have a "lead-antimony grid - Works in conjunction with the high-density paste to reduce corrosion and improve battery performance".
Source: https://www.interstatebatteries.com/...ts/gc2-ecl-utl



It appears Interstate GC2 batteries use lead-antimony and therefore should share the deep cycle capabilities of the Trojan T105 and Deka GC15. I could not find the manufacturer which I'm sure changes to the lowest bidder occasionally. But I agree with Uncle_Bob, "Since they are "free batteries" what's not to like? If I was spending money on batteries, they aren't the way I would go."

Link to original comment with working links

http://www.airforums.com/forums/f449...ml#post2239704

I’m in a poor cellphone service area and cannot easily fix the links. Also working from a cellphone also makes it difficult so this is the best reply I can provide. But many 6V golf cart batteries are definitely built better to allow deep 80% cycling. I’m willing to risk my $230 investment in batteries with deep discharges and will just replace them when they wear out. I’m closing in on 200 deep cycles and they still test and perform like new as evidenced by how well they held up with the furnace running on a low solar production day. And the attached hydrometer reading I just took:

[uncle_bob]

Originally Posted by pteck

You must think I like to live on the edge?

Actually, 6V as a format is indeed more capable than the typical 12V battery type. They are built for deep cycle use cases (golf cart), versus typical hybrid/deep cycle in name only 12V formats. This is because they have better geometries and features like deeper wells and thicker plates that enable this type of use. It's why many of us use them - to enable more usable reserves, while still maintaining more overall durability and usable life.

Sure you're talking about specific quality among a battery brands. I'll leave that for you to figure out. Yet that doesn't dismiss that 6V again as a format, is generally built far better than a comparable 12V.

Any battery supported by significant solar is living a pampered life. It's like buying a hot rod and letting her sit in the garage. I'm going to drive and enjoy the capability I paid for.

Hi

Simply not so. I can go down to Wallmart and buy a 20AH 6V battery and it's *not* going to do me much good at all. Even in the "golf cart" format, some outfits make utter junk batteries. There is no guarantee that you are getting something special just because it says 6V on it.

Bob

[pteck]

Originally Posted by uncle_bob

Hi

Simply not so. I can go down to Wallmart and buy a 20AH 6V battery and it's *not* going to do me much good at all. Even in the "golf cart" format, some outfits make utter junk batteries. There is no guarantee that you are getting something special just because it says 6V on it.

Bob

Bob, I'll let you continue to run in circles by yourself. Your point is a distinct and separate point from mine. You can focus on your detail and let the rest of us move forward on the bigger picture.

[Fair_Enough]

7 years ago I bought 2 6v 230 Ah Duracell’s $200 each for the toyhauler I had. A year later I bought 2 more of same brand and size to give me 460 Ah and headed out West. They are East Penn / Deka. 2 of them are in the 23FB now, 2 in the garage. I swap them occasionally to make sure they stay charged. As far as I can tell, they are still at or near original performance. I maintain them properly. Sure Crown is better, but why did I need better when good was good enough. Now proven. My recent foray into LFP in the cargo conversion was overkill but I needed a sealed or AGM and figured what the heck. I trust these Deka’s... the new Renogy’s not so much.