Ready for Lithium and Solar - advice?

[pwlldvd]

Airmiles,

I can't argue that cost-wise AGM golf batteries have a big advantage. My problem, I think, would be charging from solar. From what I've read, and what I saw with the AGM's on my SOB, the bulk charge phase will take around 6 hours to go from 20% to 70% charge. 70% to 100% takes even longer. So the most I can expect from solar is to charge from 20% to 70% or maybe 80% on a good day. That would be 138ah. Using 100ah a day that will work, unless the sun doesn't shine in which case I have to run the generator several hours a day to keep up.

With Lithium I should be able to store at least twice that much on a good day, giving me two or three days of use, without further sun.

Am I wrong about this?

To me, I think it is worth the additional cost.

[lewster]

Hi Gang,

rmkrum is correct about the spelling on my last name!

pwlidvd,

The charge rate of the AGMs and lithium is basically correct with one exception. You should never bring AGMs to 20% of capacity, as this will definitely start to kill them, as 50% is the usual norm. It's not a great idea to use lithiums to this level either, as the more you leave in a lithium, the faster it will re-charge and the more amp hours you will receive.

That said, you solar capacity in terms of watts is easily calculated, but does vary with the seasons. You can bring either type of battery up to full (although you really only want to bring lithiums up to 90-95% or so on a regular basis) with the proper amount of panels that are designed to compliment your battery bank.

Originally Posted by pwlldvd

Airmiles,

I can't argue that cost-wise AGM golf batteries have a big advantage. My problem, I think, would be charging from solar. From what I've read, and what I saw with the AGM's on my SOB, the bulk charge phase will take around 6 hours to go from 20% to 70% charge. 70% to 100% takes even longer. So the most I can expect from solar is to charge from 20% to 70% or maybe 80% on a good day. That would be 138ah. Using 100ah a day that will work, unless the sun doesn't shine in which case I have to run the generator several hours a day to keep up.

With Lithium I should be able to store at least twice that much on a good day, giving me two or three days of use, without further sun.

Am I wrong about this?

To me, I think it is worth the additional cost.

[Njg]

Originally Posted by afk314

I originally installed 300Ah of lithium and 500w of solar on my 25'.


-Adam

Adam, where did you put the 500w on the roof? I have 400w on a 25’ now wired in series/parallel and see the space up there for the extra 100w, but I haven’t been sure how to wire it into the existing system for max efficiency. I’m using a victron MPPT charge controller (100/30).

Also, where did you put all of the batteries?

[AirMiles]

Originally Posted by pwlldvd

Airmiles,

I can't argue that cost-wise AGM golf batteries have a big advantage. My problem, I think, would be charging from solar. From what I've read, and what I saw with the AGM's on my SOB, the bulk charge phase will take around 6 hours to go from 20% to 70% charge. 70% to 100% takes even longer. So the most I can expect from solar is to charge from 20% to 70% or maybe 80% on a good day. That would be 138ah. Using 100ah a day that will work, unless the sun doesn't shine in which case I have to run the generator several hours a day to keep up.

With Lithium I should be able to store at least twice that much on a good day, giving me two or three days of use, without further sun.

Am I wrong about this?

To me, I think it is worth the additional cost.

My thoughts, with a $10K budget, would be to self-install 600W of solar with wet cells now for $3k and then to add a professionally installed Multiplus and large Lithium bank later (for $7-10K). You will have the solar right away and have a 95% solution, needing your generator for hairdryer, microwave, A/C, and multiple shady days. Maybe you will find the 95% solution will suffice and will not need to spend the additional $7-10K for the Multiplus and large Lithium bank. To do this in two steps only wastes $250 of 6V golf cart wet cell batteries and an hour to install them. You could do AGMs, but why spend extra on AGMs if you will likely scrap them for Lithiums in the near future?

I believe you will get WAY more than 138AH per day from 600W of solar, even with the less efficient wet cells. You can get 45A during peak sun. 4 hours x 45AH = 180AH. Then you will get more AHs during the shoulder hours. My links to my past history are with 400W of solar. My production is also limited by my usage and a 230AH wet cell battery bank. Here are some quick links to some of my history:

Summer 10 days with a 1.65kWh peak day from my 400W of solar: http://www.airforums.com/forums/f448...ml#post2110788

Summer (July) 30 days with a 1.53kWh peak day from my 400W of solar:
http://www.airforums.com/forums/f448...ml#post2133206

Winter (November) 30 days with 1.21kWh peak day from my 400W of solar:
http://www.airforums.com/forums/f448...ml#post2177241

Here is a Wulfraat post stating that he got 407AH in one day from 800W of solar and Lithium batteries: http://www.airforums.com/forums/f448...ml#post2129077

Maybe get a quote for a professional install of a Multiplus and large Lithium battery bank. Add $3,000 for self installing 600W of solar. Maybe it will come in within your $10k budget and you can have your desired large system now.

[AirMiles]

Originally Posted by Njg

Adam, where did you put the 500w on the roof? I have 400w on a 25’ now wired in series/parallel and see the space up there for the extra 100w, but I haven’t been sure how to wire it into the existing system for max efficiency. I’m using a victron MPPT charge controller (100/30).

Also, where did you put all of the batteries?

First, with series/parallel you need to keep an even number of panels. Two 100s, four 100s or six 100s. You would need to reconfigure to parallel for five 100s. I think you could put five 100s on a 25' if you go over one of the bathroom fans like Wulfraat did on his install to get eight 100W panels on a 30'. Second, with a Victron 100/30, four panels maxes out the controller's 30 Amp limit. You would need a 100/50 for five or six 100W panels.

[TouringDan]

Just to put some numbers on the hairdryer and microwave use, 10 minutes @ 1,400 watts is 20 AH and 10 minutes @ 1,000 watts is 14 AH.

Dan

[afk314]

Njg-


I have 4 Renogy Eclipses and 1 Zamp panel (that came with the trailer). I put three Renogy panels on the street side of the trailer. I have another Renogy panel just behind the batwing antenna. The older Zamp panel is behind the AC. Everything is parallel, wired with 6awg to the Victron controller.


I put the batteries near the electrical mess under the dinette bench seat on the street side. I've ended up cannibalizing a fair bit of the fore outdoor hatch storage. Moving the batteries was a pain and something that will likely need to be changed if you start with wet cells and move to lithium. Here is one finished pic of where the batteries were put.



Good luck,
Adam

Originally Posted by Njg

Adam, where did you put the 500w on the roof? I have 400w on a 25’ now wired in series/parallel and see the space up there for the extra 100w, but I haven’t been sure how to wire it into the existing system for max efficiency. I’m using a victron MPPT charge controller (100/30).

Also, where did you put all of the batteries?

[TouringDan]

David

Since you are designing your system to run your furnace a lot, I assume you will be camping in winter with low sun angles. In this case portable panels will work much better than panels on the roof. I have two 100 watt portable panels and I get about 50 AH on a good day in the winter.

I have two BB lithium batteries and I love them. Even when they are discharged 80% with a discharge of 40 amps per battery the voltage is still 12.4. So never any problems with the inverter turning off due to low voltage. My 2000 watt inverter works great and operates my microwave and all other stuff. I have a thread titled Battleborn golfcart Battery & 2,000 watt inverter installation.

Dan

[AirMiles]

Originally Posted by TouringDan

David

Since you are designing your system to run your furnace a lot, I assume you will be camping in winter with low sun angles. In this case portable panels will work much better than panels on the roof. I have two 100 watt portable panels and I get about 50 AH on a good day in the winter.

I have two BB lithium batteries and I love them. Even when they are discharged 80% with a discharge of 40 amps per battery the voltage is still 12.4. So never any problems with the inverter turning off due to low voltage. My 2000 watt inverter works great and operates my microwave and all other stuff. I have a thread titled Battleborn golfcart Battery & 2,000 watt inverter installation.

Dan

I agree with Dan that I would want lithium batteries for a 2000W, or above, inverter. The high Amp draw from these large inverters will drain a lead-acid battery really quickly, both AGM and Wet-Cell. When I turn my wife's hairdryer on low heat and low fan, using about 750W through my 1000W inverter, my wet-cell lead-acid batteries drop immediately to 12.1V. There is no way my batteries could handle the draw of a 2000W inverter. Lead acid batteries prefer to be discharged at a 20 hour rate. For my 230AH battery bank, that would be about an 11 Amp draw. The hairdryer drawing 750W at 12.0V is a 62.5A draw, well beyond the design of my batteries. 2000W at 12V is 166A! That would deplete my batteries in minutes.

On the portable vs. fixed panels, I'm not sure that 50AH from 200W on a good day is great. Last weekend, on a bad overcast day, my 400W fixed system did 830W by 3:45pm. 830W/13.5V=61.5AH. My prior documentation shows 1.25kWh on many November days, that's about 100AH per day from my flat panels, and most of those days were challenging with overcast conditions. http://www.airforums.com/forums/f448...ml#post2177241 It is difficult to access the capabilities of solar panels due to the how batteries charge. Maybe you only needed 50AH to return your batteries to full charged. I know those November days where my system produced 1.25kWh were when my batteries were well drained by using heat all day and night plus normal boondocking loads. But as evidenced by the above data, my solar and 230AH wet-cell battery bank has no problems keeping up with the furnace while boondocking in November with challenging overcast conditions.

[TouringDan]

Originally Posted by AirMiles

On the portable vs. fixed panels, I'm not sure that 50AH from 200W on a good day is great.

AirMiles

I agree that 50 AH isn’t great performance, especially compared to the performance of your panels on a fixed roof. I only know that my panels were perpendicular to the sun, and the performance would have been substantially less had they been installed on the roof.

Dan

[CarterKraft]

Originally Posted by pwlldvd

When it's cold, the fan on the furnace takes so much battery, we have to recharge daily.

Are you opposed to running a different style heater? It seems half your draw is furnace alone, that would make me wonder if a different style heater would solve 32AH per night?

A catalytic style perhaps?

[JohnSn]

You 2 are a little confused on your math. A one day gain of 50Ah out of a 200W panel is better performance than 61Ah out of a 400W bank. Inclining panels is a big advantage on a winter day.
In general, I highly prefer portable panels due to that fact. Also, I like to park in the shade in the summer.

[AirMiles]

Originally Posted by JohnSn

You 2 are a little confused on your math. A one day gain of 50Ah out of a 200W panel is better performance than 61Ah out of a 400W bank. Inclining panels is a big advantage on a winter day.
In general, I highly prefer portable panels due to that fact. Also, I like to park in the shade in the summer.

No, we are not confused, we are doing a comparison that is not very comparable. A great day to a bad day, sun aligned portables to flat mounted roof panels, different wattage arrays and different battery types. Dan and I are very familiar with each other's installations. I just felt Dan would have gotten more output from his 200W on a great day in the winter while charging his Lithium batteries.

But comparing solar output is difficult. A lot depends on the state of charge of the batteries. Maybe his batteries only needed 50AH that day and that was why the solar array only produced that much. I have wet-cell batteries. When my batteries go into absorption mode, I leave a lot of AH on the table. Even if you had two identical configurations with the same panels, wattage, and batteries, a side-by-side comparison would not produce equal wattage because the state of charge of the batteries would cause great differences.

Its fun to try to analyze and compare each other's systems. What matters most is that your system meets your needs. Dan and I are both very satisfied with our installations because they each work well for our needs. We try to share information so others can learn from our experience. i'm always trying to decipher how Lithium batteries charge and Dan provides me with data to analyze.

[TouringDan]

Originally Posted by AirMiles

No, we are not confused, we are doing a comparison that is not very comparable. A great day to a bad day, sun aligned portables to flat mounted roof panels, different wattage arrays and different battery types. Dan and I are very familiar with each other's installations. I just felt Dan would have gotten more output from his 200W on a great day in the winter while charging his Lithium batteries.

But comparing solar output is difficult. A lot depends on the state of charge of the batteries. Maybe his batteries only needed 50AH that day and that was why the solar array only produced that much. I have wet-cell batteries. When my batteries go into absorption mode, I leave a lot of AH on the table. Even if you had two identical configurations with the same panels, wattage, and batteries, a side-by-side comparison would not produce equal wattage because the state of charge of the batteries would cause great differences.

Its fun to try to analyze and compare each other's systems. What matters most is that your system meets your needs. Dan and I are both very satisfied with our installations because they each work well for our needs. We try to share information so others can learn from our experience. i'm always trying to decipher how Lithium batteries charge and Dan provides me with data to analyze.

AirMiles

I agree that I thought that I would have gotten more than 50 AH on that good day. My batteries were not fully charged, so that was not the reason. Sometimes I will look at the sun and try to estimate the charging rate. I am really not very good at it. For example, the other day I looked at the sun and my panels and estimated my 200 watt panels were putting out 125 watts. Then I look at the SC and the rate was only 50 watts. Still so much to learn about solar and lithium, but it is fun.

You are correct. Comparisons are difficult.

So glad to have you around to lead the effort.

Dan

[pwlldvd]

Thanks everybody for the advice! Really good to get different options and opinions, which makes me look at my assumptions and solution.

As for alternate heaters, it would be great if we could avoid that 30ah suck at night, but we are not comfortable sleeping with a propane heater inside the trailer. I know they have all sorts of alarms and shutoff, and the trailer has a co alarm as well. Even so, we wouldn't dare without leaving a couple of windows cracked for ventilation, and one of us (won't mention who) doesn't sleep well with a draft.

I'm going to go pretty much full on, knowing it will cost near $10K and take weeks to install. My plan is 4 solar panels on the roof, and probably 400ah lithium, but I may back off to 200ah and add more if it's not enough.


My overall plan is as follows:

I have a diagram drawn up and overall plan worked out, but before proceeding I will contact some of the vendors and of course post here.

Most of the new equipment will go under the bed, at the front of the trailer. This includes the multiplus, solar controller, batteries, and DC-DC converter for trailer wiring.

Add a sub-panel by the main AC panel (or replace with split panel). Subpanel will be for the inverter powered circuits. This way I can just move the appropriate breakers from the old panel to the subpanel without running lots of wires around the trailer.

Put the Multiplus and batteries under the bed. This will require (correct me if I'm wrong) a new pair of AC circuits between the multiplus and the AC panels which are midships under the pantry. One from the main AC panel to the multiplus, the other from the multiplus to the new subpanel. I'm not re-using the existing inverter wiring for this because I'm not sure the wire size is sufficient for the new loads.

Now that the existing inverter is removed, I can patch the old wiring together so that the old inverter-powered items are run off the old inverter circuit, which will be moved to the new sub-panel..

If possible, move the fridge AC to a new breaker on the main panel so I can run the existing circuit off the inverter. If not possible install a switch to disconnect the fridge or just unplug the fridge and forget about running it on AC.

Use existing Airstream pre-wire for solar panels. The pre-wire comes out under the bed where the batteries will be, so install the MPPT there.

There is existing 6ga wiring that runs between the batteries on the tongue and the charger/DC panel under the pantry. It will now run from the multiplus to the DC panel. Of course there will be new cables between new batteries and multiplus.

Breakers and/or fuses where appropriate, and of course lots of smaller tasks including control panels and I'm not sure what all yet.

I still have a lot of questions about wiring and breaker sizes, but have a sort of a design drawn out.

Diagram to follow.

[AirMiles]

Originally Posted by pwlldvd

Thanks everybody for the advice! Really good to get different options and opinions, which makes me look at my assumptions and solution.

As for alternate heaters, it would be great if we could avoid that 30ah suck at night, but we are not comfortable sleeping with a propane heater inside the trailer. I know they have all sorts of alarms and shutoff, and the trailer has a co alarm as well. Even so, we wouldn't dare without leaving a couple of windows cracked for ventilation, and one of us (won't mention who) doesn't sleep well with a draft.

I'm going to go pretty much full on, knowing it will cost near $10K and take weeks to install. My plan is 4 solar panels on the roof, and probably 400ah lithium, but I may back off to 200ah and add more if it's not enough.


My overall plan is as follows:

I have a diagram drawn up and overall plan worked out, but before proceeding I will contact some of the vendors and of course post here.

Most of the new equipment will go under the bed, at the front of the trailer. This includes the multiplus, solar controller, batteries, and DC-DC converter for trailer wiring.

Add a sub-panel by the main AC panel (or replace with split panel). Subpanel will be for the inverter powered circuits. This way I can just move the appropriate breakers from the old panel to the subpanel without running lots of wires around the trailer.

Put the Multiplus and batteries under the bed. This will require (correct me if I'm wrong) a new pair of AC circuits between the multiplus and the AC panels which are midships under the pantry. One from the main AC panel to the multiplus, the other from the multiplus to the new subpanel. I'm not re-using the existing inverter wiring for this because I'm not sure the wire size is sufficient for the new loads.

Now that the existing inverter is removed, I can patch the old wiring together so that the old inverter-powered items are run off the old inverter circuit, which will be moved to the new sub-panel..

If possible, move the fridge AC to a new breaker on the main panel so I can run the existing circuit off the inverter. If not possible install a switch to disconnect the fridge or just unplug the fridge and forget about running it on AC.

Use existing Airstream pre-wire for solar panels. The pre-wire comes out under the bed where the batteries will be, so install the MPPT there.

There is existing 6ga wiring that runs between the batteries on the tongue and the charger/DC panel under the pantry. It will now run from the multiplus to the DC panel. Of course there will be new cables between new batteries and multiplus.

Breakers and/or fuses where appropriate, and of course lots of smaller tasks including control panels and I'm not sure what all yet.

I still have a lot of questions about wiring and breaker sizes, but have a sort of a design drawn out.

Diagram to follow.

I like your plan and how you are approaching this upgrade. I'm not an expert on Lithium systems, so others will have to guide you through that complexity. But if a DC-to-DC converter is just needed for charging from your tow vehicle, I think that complexity could be eliminated by just disconnecting the tow vehicle charge wire.

I get very little charging from my vehicle and am sure I don't need any. I also disconnect my PD4655's battery charging capability while on shore power by flipping the breaker off. I only use my PD4655's charging capability with my generator on extremely dark rain days or complete tree canopy.

I'm sure others have skipped the DC-to-DC device and chose to disconnect their tow vehicle charging capability with Lithium installations. I'm sure they will be helpful with your system design and installation.

[pwlldvd]

Yes, I’ve seen reports of just disconnecting the tv charge wire. The panels should charge well enough when we’re on the road. I think brakes and lights are on a different wire.

If I decide later it is needed, It should be easy enough to hook back up.

[JohnSn]

When you mentioned the heater power usage, it got me thinking.
I’ve got 2 golf cart batteries. I put them in as soon as I bought the trailer. The trailer is good for 3 days in cold weather running the heater, lights, tv etc. No solar, no hair dryer. I figure a 100W panel will allow us to stay a week which is roughly when the black water tank is full.
My better half is fine skipping on a hair dryer. If she changes her mind, I’ll buy a honda generator.
I’m wondering if there’s an issue with your heater drawing too much power?

[AirMiles]

I've done some Amp load testing on my 2017 FC25FB.

Single loads:
0.39A with store/use switch on use and no other loads
1.82A with only one Fantastic Fan on
3.12A with both Fantastic Fans on
1.12A with only refrigerator on
7.50A with only furnace running

Combined loads:
3.72A with refrigerator and two Fantastic Fans on
8.30A with above plus inverter and TV
8.40A with above plus one pendant light
9.40A above with living room lights 1/2 bright
10.4A above with living room lights full bright

How long the batteries will last depends greatly on how many hours the furnace "runs" at 7.5A plus how long the TV is on at 5.18A. The refrigerator alone takes 27AH per day. If both fantastic fans are on, they use 75AH per day. It doesn't take much to draw down a pair of wet cell batteries in a day.

If its hot, I always have both Fantastic fans and the refrigerator on for 24 hours per day. That's 89AH in one day right there. If its cold, I have the furnace on. If the furnace runs 25% of the time for 24 hours, plus the refrigerator, those add up to 72AH. On top of these loads I will have some lights, water pump and cellphone charging. Therefore, I pretty much have to recharge my 230AH golf cart batteries every day with heat or fan use. My usage history shows that I use about 100AH per day and therefore need battery charging daily with my 230AH golf cart battery bank.

[pteck]

Originally Posted by AirMiles

I've done some Amp load testing on my 2017 FC25FB.

Single loads:
0.39A with store/use switch on use and no other loads
1.82A with only one Fantastic Fan on
3.12A with both Fantastic Fans on
1.12A with only refrigerator on
7.50A with only furnace running

Combined loads:
3.72A with refrigerator and two Fantastic Fans on
8.30A with above plus inverter and TV
8.40A with above plus one pendant light
9.40A above with living room lights 1/2 bright
10.4A above with living room lights full bright

How long the batteries will last depends greatly on how many hours the furnace "runs" at 7.5A plus how long the TV is on at 5.18A. The refrigerator alone takes 27AH per day. If both fantastic fans are on, they use 75AH per day. It doesn't take much to draw down a pair of wet cell batteries in a day.

If its hot, I always have both Fantastic fans and the refrigerator on for 24 hours per day. That's 89AH in one day right there. If its cold, I have the furnace on. If the furnace runs 25% of the time for 24 hours, plus the refrigerator, those add up to 72AH. On top of these loads I will have some lights, water pump and cellphone charging. Therefore, I pretty much have to recharge my 230AH golf cart batteries every day with heat or fan use. My usage history shows that I use about 100AH per day and therefore need battery charging daily with my 230AH golf cart battery bank.

Awesome data. Thanks for putting this information together. It's helpful to understand how and where the power goes.

I likewise run golf car batts. To your point that it's easy to run down "wet cell" batts. I think it's more fair to say it's easy to run down batteries, period.

Using reasonable depths of discharge per battery types:
A 230Ah golf car battery pair is about 160Ah usable.
A pair of lithium 100Ah batts rated for 200Ah is also about 160Ah usable.

That doesn't seem to be a meaningful different to me. Certainly not enough value to warrant chasing a technology that is an order of magnitude more expensive.