Zamp 90 watt panels, lithium vs AGM, etc

[nickaroux]

Hello Forum-

We are new owners of a 2016 AS, 25' Int'l Serenity, 30 amp, trailer. It came with brand new AGM batteries. We would like to install solar and are wondering about a few things and would appreciate opinions. 1) Is this the time to go Lithium--obvious there is some cost differential, but..... 2) Considering Zamp rigid, long, 90 watt panels with Victron Blue Solar MPPT 100/30 controller. Thoughts on these? "In Series", or "In parallel"? Perforation of shell, or 3M adhesives for application? We would like to be able to boondock for 1-2 weeks, at times, and won't be dependent on AC. Is Lithium overdoing it? There are probably good, strong opinions here.

Thanks in advance for input!

Kindly,

Nick

[richard5933]

Lithium has many advantages over AGM, including quicker charging time and more useful capacity. Also, they don't require venting and weigh much less. Only real downside is cost.

There are less expensive alternatives to the Obsidian panels, like the Renogy. I just installed 400 watts of Renogy for about the same cost as one Obsidian panel.

[pteck]

Congrats on your new purchase.

What region are you out of and is sunlight a reliable resource? What's your electricity consumption?

AGMs can be great batteries, including the stock batteries. The installed capacity is okay and can be supplemented greatly with solar, or "live" batteries as I call it. Because ultimately, batteries are just a buffer. For long boondocking trips, a buffer is not enough, no matter how large, if you have a power generation deficiency.

At prices today for lithium, if you don't have reliable sunlight in your area, you'll need more buffer, and may just be better to expand that via lithium.

Either way, you should greatly invest in solar first. That expands the battery effectively as you'll use the power live as it's generated. Then the batteries will have the best change as they are topped off, and don't come into play until nightfall or overcast days.

Parallel, definitely parallel. That's how the professionals due it. Because solar on a moving trailer is unpredictable with shade. Series is a transmission optimization for fixed roofs, where shadows are known and well controlled. From a systems perspective, optimize for the largest variable first. That's shade, and not the minor tertiary transmission consideration.

[nickaroux]

Thanks Richard & Pteck--

Live in southern Oregon, so most travel will be PNW, mostly east of Cascades (lots of sun). Richard, which exact Renogy panels did you use? Did you apply with 3M product, or screws? I like the idea of optimizing for solar, first (already have the AGMs), and can move to lithium later. And thanks for the comment on 'parallel' vs 'in series'. A fellow at an Airstream affiliated institution in Portland recommends 'in series', so just wondered why he would do so.

Nick

[Dennis C]

Congrats on your new Airstream. As you’ve already seen, the world of solar panels and battery upgrades is a deep rabbit hole. It goes as deep as your wallet allows.

I’ve got four Zamp 90W panels on my roof, with a Zamp solar controller and two AGM batteries. I’ve thought about upgrading to Lithium on a few occasions. The biggest issue is cost, as mentioned above. However, there are other things to consider. For example, you’ll probably want to install a DC to DC charger on your tow vehicle as the standard 7-pin connector will likely be inadequate for lithium batteries. Additionally, lithium batteries won’t charge in freezing temperatures. Many people deal with that problem by relocating the batteries inside the trailer, often under the bed. This is very doable, but it adds more expense to the lithium conversion.

I find that 360W of rooftop solar, 2 AGM batteries, and a backup generator work very well for me. The generator means that electric power is not a problem, even for extended boondocking trips. Tank capacities are a much bigger issue, but there are ways to deal with that too.

Most of my boondocking trips are 2 - 4 days, so the cost/benefit of lithiums doesn’t make sense.

Good luck as you dive into the rabbit hole.

[richard5933]

Originally Posted by nickaroux

Thanks Richard & Pteck--

Live in southern Oregon, so most travel will be PNW, mostly east of Cascades (lots of sun). Richard, which exact Renogy panels did you use? Did you apply with 3M product, or screws? I like the idea of optimizing for solar, first (already have the AGMs), and can move to lithium later. And thanks for the comment on 'parallel' vs 'in series'. A fellow at an Airstream affiliated institution in Portland recommends 'in series', so just wondered why he would do so.

Nick

I have four of these: https://www.renogy.com/renogy-100-wa...e-solar-panel/

Got them when they were on sale last month for $109 each.

I was planning to attach via the 3M tape, but something about it didn't sit right. Even though hundreds of installs have been done with just the tape, I also used fasteners. Helps me sleep better at night. But, this is not the thread for debating that, so just take it as what I did and not as what's 'best'.

[pteck]

Originally Posted by nickaroux

Thanks Richard & Pteck--

Live in southern Oregon, so most travel will be PNW, mostly east of Cascades (lots of sun). Richard, which exact Renogy panels did you use? Did you apply with 3M product, or screws? I like the idea of optimizing for solar, first (already have the AGMs), and can move to lithium later. And thanks for the comment on 'parallel' vs 'in series'. A fellow at an Airstream affiliated institution in Portland recommends 'in series', so just wondered why he would do so.

Nick

Missed a couple questions... Don't penetrate the roof. With modern day adhesives - VHB and Sikaflex - there's no reason to. They bond incredibly strongly with only 4 standoff. I've had my system for 4 yrs and they're not going anywhere. And many others.

RE: parallel. Some very outspoken, but non-technical enthusiasts got in their head the idea that series is an optimization to strive for. And we all know the low bar by which social media strives for these days. It is an optimization, but it's a very minor one, on the order of 1% or less. Transmission optimizations are more relevant for very high voltage house installations, which panels are alignment optimally with controlled shading. It however trades parallel advantages for shading and uneven solar illumination on panels which is pretty much always for a trailer that has panels non-optimally aligned. Systems thinking is to optimize for first order principles for best performance.

The reason why parallel has advantages is that each panel can be a current source independently to the solar controller. Doesn't matter which or what is shaded as they will all produce current in an additive fashion to the controller, instantaneously. Series ties panels together in current. If one panel is shaded, it will be a current limiter. At which point an MPPT charge controller has to respond and seek the right voltage to optimize power for. That takes time, and it can result in much bigger losses (easily over 1%) as the controller has respond and find the max power point tracking.

In a good installation, both aspects can be optimized. Parallel config with larger wires, solving both sides of the coin.

This is why the professionals install in all parallel.

[MemphisRebel]

If you have not yet I would recommend spending some time on the amsolar website. They have quite a few videos and instructional articles. My unit came with two 90W Zamp panels from the factory and I added 2 more to bring me to 4. However, if I were starting from scratch with a blank canvas I'm not sure I would go with the 90W Zamp legacy panels. Renogy makes a 100W panel that fits on Airstreams. If you want 1-2 weeks of boondocking at a time you will probably want quite a bit of solar up there and the Zamps tend to leave some unused roof real estate, IMO. Also with that much boondocking I think the jump to lithium would be very much worth it.



AMSolar also sells some really nice quality panel mounting brackets with the 3M VHB tape already installed.

[cazual6]

I was in the same boat as you were with my 2018.

I upgraded to AGM in less than a year of getting my rig.

I purchased (4) 90w Zamp OBSIDIAN series for Airstream. I also got the Victron Solar Controller and Battery Monitor.

I recently upgraded to LiON after (4) years of upgrading to AGM.

[coasttocoast]

So what are you thinking in terms of amp hours and watts? Are you just going to turn on the lights, or use everything like the TV, furnace, fridge, freezer, hair dryer, coffee maker? Start with these numbers: 600 watts of solar and 600 amp hours of lithium. Then scale up or down. I have 400 watts on the roof, 500 amp hours of lithium plus 80 hours of AGM’s plus a DC to DC car charger for the lithium. I stayed at a campground in Alberta for the last 2 nights, and I didn’t bother to plug in. I’m at 78% this morning with lithium and 100% with AGM’s. I’m going to drive for about 5 hours today, so the lithium will be at 100% upon arrival. I’m mostly just using lights, the furnace, and a Keureg.

[pteck]

Couple more thoughts
- Not all panels are made and rated the same. Like stereo system watts, they're not necessarily all comparable. Zamp products in particular are highly under-rated. I'd easily put a 90W Zamp panel against a 100W Renogy. Not that Renogy's are bad (I have them)...but Zamp's will easily outperform an equivalent rated panel. As they should as they are easily multiple times more expensive.

A combination of roof-top and portable panels is preferred for mixed environments. Especially for somewhere like Oregon with lots of trees. Many times I find myself parking under shade, so the portable panels are a great way to get at direct sunlight and still reap solar benefits. Something like 400W on roof and 100-200W of portable will easily keep all the 12V systems humming, with excess to support 120V luxuries.

120V devices are the real power hog. If only supporting 12V devices, half of that in solar would be good.

[daleyocum]

Renogy Eclipse panels 100w panels are a bit smaller than their cheaper, less efficient line. That will let you get five on your roof if you like. See attached. The new Zamp thin panels are pretty cool and would look slightly sleeker than the thicker Renogy, or conventional Zamp, ones. You pay quite a price penalty for that sleekness.

I have 500AH of Lithium and would never go back. It is quite a rabbit hole because you’ll be upgrading most of the electrical system. To do it right, I installed 500w of solar on the roof, 100w on a ground panel, Multiplus 3000 hybrid inverter, 500ah of Battleborn lithium, and misc Victron gadgets. In the end it cost $10k with me doing all the labor.

Now, though, every outlet in the trailer is powered by the inverter, we can run pretty much any electrical appliance. We can run the AC for a few hours on super hot days to cool the trailer down in the evening. It transforms how you think about electricity.

As others have said, my panels are all in parallel. I used VHB, a sheet metal screw, and Silkaflex to attach them. I just felt better with the screw in there. Was it necessary? Probably not. Just clean the surface super well and get the recommended outdoor VHB tape.

[AlIslander]

Originally Posted by nickaroux

Hello Forum-
Is Lithium overdoing it? There are probably good, strong opinions here.

Hi, I don’t think lithium is overdoing it. I’m fairly new and at first look I saw everyone preaching about lithium and chalked it up to being just a bandwagon thing. But after spending time learning about them I think they’re the best way to go. One of my favorite things about the ones I have is that you don’t have to stress about discharging them below a certain percentage. If you take them all the way down to zero there isn’t anything bad that happens to the batteries unlike lead acid or AGM where you’ll kill them off by discharging them too much. I think they also charge faster than lead acid which is good because you’re being more efficient with your hours of sunlight or the time you’re making noise with a generator.

[daleyocum]

AlIslander: Cool to see you you were able to use the new, sleeker, Zamp panels and a mixture of panel sizes to get six panels on new 25’. Older trailers with a fridge vent can’t do that easily and are limited to five. Nice job!

[field & stream]

I don’t know exactly when Airstream switched from halogen bulbs, but if you don’t have LED’s you should upgrade. DIY easy and only about $10 per light. This will make a significant difference.

Similarly, some advice from one with lithium and solar, the best bang for the buck is conservation.

[jimdelane]

When it comes to capacity, long life, consistent voltage, discharge capacity, weight to energy ration and faster charging, AGM/lead acid batteries come in a far second to lithium batteries.

Compare AGMs to lithium on a usable energy basis. You can pay a premium for BattleBorn with low temp charge protection and a 10 year warranty or buy a cheap generic lithium battery without low temp protection and a 5 year warranty. AGM come with a 2-5 year warranty, usually prorated, depending on the manufacturer.

The cost of lithium batteries have dropped in price significantly.
A 100ah AGM will cost around $200-$400 or more. That gives about 50Ah usable capacity and weighs around 65-70lb each. So you need two batteries.
A cheaper 100ah lithium battery will cost $375-$500 and the BattleBorn 100ah is $800-$900 and weigh about 30lbs. The lithium battery will provide 12.8v throughout 80% of the discharge. The battery can be discharged 100% but it is no fun to have the lights go out.

So the question is do you want to load up with lead based AGMs which will likely be replaced in 5 years or less and save a couple of dollars or do you want to go with lithiums which are lighter, provides higher consistent voltage and spend a few dollars more. Often, folks want to fill out the battery bay which means more batteries, more capacity and more money.

A 100ah AGM should not be discharged more than 50% and should be brought up to 100% charge on a regular (preferably daily) basis if you want to get the expected cycle life. Folks that have AGMs last for 4 or more years, usually do not discharge more than 25% and bring them back to full charge regularly. Leaving an AGM partially discharged for extended periods leads to lead sulfate crystals building up on the plates and reduced capacity. Lithiums can be left in a partially discharged state indefinitely. This is an advantage for boondockers.

How important is low temp protection? If you plan to store the battery where the battery is subject to freezing (below 0F) and you plan to have the solar or shore power charging the battery, then it is important. Lithium cells can safely discharge in temps -4F but should not be charged below freezing. Lithiums have a low self discharge rate, so one option is to disconnect the battery when winterizing.

Lithium batteries also charge faster. AGMs charging profile reduces voltage and amps as the battery approaches a full charge which significantly extends full charge time. Lithiums take max voltage (14.5v) and max amps available to charge throughout the charge cycle. amps x volts = watts. Lithiums charge with max watts available whereas AGMs reduce charging watts relative to state of charge. Inversely, AGM battery voltage is a linear relationship relative to state of charge. Full charge is around 12.7v, 50% charge is 11.95-12.12v. Lithium batteries fully charge are 13.2-13.4v and 50% charge is 13.1v.

You can never have too much solar or too much battery capacity.
Due to sun angle, clouds, heat, etc., solar panels put out 50-80% of the manufacturers panel rating. The MPPT charge controllers are 99% efficient whereas PWM charge controllers are 70-75% efficient.
Boondockers have to balance energy usage with available energy. That means doing an energy audit. The Victron battery monitor will provide battery capacity, incoming/outgoing watts/amps which can be used to determine energy demands of appliances.

Good luck.

[pteck]

No argument that LiFePO4s are the way to go today, if any money is spent on batteries. (IMO, Battleborns are way overpriced by 40-60%) The OP already has AGMs. I wouldn't necessarily upgrade more AGM capacity, but they're not bad batteries and a pretty solid place to start. Doing this in phases, attacking solar first, and upgrade capacity with "live" batteries. See where it all lands, and upgrade batteries to lithium if needed.

The opinions on flooded lead acid (FLAs, including AGMs) draw downs are way way too conservative. AGMs are hearty high quality batteries and even regular draw down by 50-80% isn't going to hurt anything appreciably. That's like saying don't drive a car because there's minor wear and tear? FLAs sitting at low states of charge is a different thing. Which having significant solar always tending to batteries is a great way to extend the health and usable capacity of any FLA.

[nickaroux]

OP here. Thanks for ALL the comments and input--good for me, good for all readers.

I'm going to make a request--please be gentle and don't consider me too lazy!

I'm overwhelmed with options and need for specifics. I'd like to install a system myself, but I'd like opinions on total packages--either components hand-picked and arranged together, or packages that come as 'one'. I need details so I can simply purchase these parts online and do it. Here are my perceived needs:

1. No greater than 1 week of boon docking.

2. WILL use solar/batteries for refrig (though my 2016 AS has a frig which works with propane, as well), lights, minimal DVD/TV use. Will NOT use microwave, hair dryer, toaster, electric boiler, Vitamix, coffee machine or any other consumptive AC device I can think of. Have room, I think, for 400 watts of panels up top and am willing to buy a movable panel to capture sun when parked in shade. Will not use a generator (that is my plan, anyway).

3. Even though I have 2 new, unused AGM batteries, I'm willing sell then and go lithium.

4. Pulling trailer with a Tundra and have 4-pin and 7-pin connectors. Am willing to set up DC to DC charger.

I appreciate opinions, but please include details--top to bottom--of what I will need for the DIY. I'm not educated about the finer points of batteries/electricity/panels, but am reasonably smart and can follow directions/use tools.

Thank in advance for specific info for the final push!

Regards,

Nick

[Atwebs]

We have a 27' with solar and AGM batteries and we can boondock for a very long time with no power issues, but some of that depends on where...here in Northern CA, we have mostly sunny weather. Our AGMs are four years old and still going strong.

Lithium batteries do require heating if your area gets too cold (they are either installed inside or have a heated blanket to keep them warm) and I know they require some other specific parts for Lithium charging and such. We've looked into swapping to Lithium at some point but for now since everything is working perfectly we see no reason to do so.

[coasttocoast]

I’ve had my Sprinter and been on the Forum for over 6 years now. Everything you do with your Airstream will be, and is, a learning curve. I spent a lot of years in sales where the simplest of math formulas was used to calculate an order for a customer. Ninety-five percent of adults who called couldn’t navigate the formula, even though my seven year old nephew has it mastered.

Calculate how many amp hours each thing you will use consumes. My electric fridge (12v when boondocking) uses 2.2-4.4 amp hours per hour.

24 hours x 3 (approximate) amp hours = 72 amp hours

72 amp hours x 7 days = 504 amp hours

Now factor in lights, a water pump, a TV, a propane switch, a furnace fan, and whatever else you plan on using.

Now think that you won’t always have full sun, and solar doesn’t work at night. You will pick up some input when the sun comes up and in late afternoon and evening, but not like you will get during peak hours.

In my opinion, cover the roof with solar and take some portable panels. Get about 600 plus amp hours of lithium.

I’m in a Sprinter which has a 220 amp alternator. When the engine is running, I’m getting a significant input. Your rig is different. You will charge up before leaving home and then plan to be on lithium and solar. You will probably not run the tow vehicle to charge. I have a built in 2.5kw Onan which is noisy and barely ever gets used. I have a Honda 1000 for when all other options have expired. If you have a lot of lithium and solar, you can chill out and not fool around with trying to get things working while you are trying to chill out.

Life is short, spend some cash and get it working right the first time.