Newbie question

[Riskinator]

Hello,

I am researching as much as I can before I pull the trigger on ordering a new 25' RTB.

I am going to order the 400 watt solar upgrade and plunk two lithium batteries in the front box. Want to keep everything as much as "factory" as possible because I really don't have much knowledge with electrical matters! And quite honestly, I have enough on my mind I don't want to become an electrical expert.

Question: If I use my batteries in the evening for comfortable living while at Harvest Hosts, by example running evening lights, furnace, having a shower, etc. I've been told I'll have no problem with having two dual lithiums.

To charge them the next day I've wondering....

1. The solar panels should slowly recharge the batteries. But if its cloudy, under trees, etc. what are my options?

- I plan to carry a Honda 3200 generator. If I plug the trailer into the generator smart plug setup, how long would it take to charge up the batteries? Reasonable?

- If I drive, will the batteries charge from my truck? I've been told to look into a DC-DC converter. Is that true? Hard to install?

Thanks for any and all comments. I'm a newbie with all things electrical. Thanks!

[kscherzi]

My lead acid batteries would last three days under use like you describe without a charge. Two 100 amp hour lithiums ought to do the same or better. Unless you plan to camp for a week or more in a cave, your solar panels should be more than enough to keep them charged. They'll provide a charge even if its cloudy, just not as much as a bright sunny day. My thought is to take delivery of your trailer and try camping to evaluate what you have before spending a lot of money on a generator or DC to DC converter.

[Boondocker]

I have 400W on the roof and 400AH in lithium batteries. There is an off the cuff answer and the accurate one.

My experience last year. The 400W kept me close to fully charged every day. Most days before noon, the charger was showing 100%. BUT 100% on the monitor is a bit misleading as it isn't necessarily a full charge. The other thing I would say is this was in the summer through Oct. By Oct, the shortening days and lower angle of the sun was showing. That said, I am entirely comfortable going out without a generator. I might regret that at some point, but there it is.

[reginac]

Take the generator, especially in the winter. Just spent a month boondocking and had to top off the batteries daily due to the furnace running all night at 58 degrees. The winter sun is not enough to charge you up again in one day.

In summer sun the batteries are a non-issue. Could boondock every day and be fine.

I have 300 watts on roof and 3 lithium batteries. Already made appt to change out for 600 watts on roof.

[SallyForth]

Going with two 100ah lithium batteries will more than double your usable energy storage and lithium batteries have less internal resistance and will accept a charge more quickly.

When solar isn’t productive: The output of the standard WFCO converter / battery charger is 55 amps 12VDC (I believe it becomes 50 amps when it senses lithium batteries). The larger generator you mention may not be necessary unless you have plans to run heavier AC loads — microwave, A/C etc.

DC to DC charging is helpful — most helpful with a dedicate charge line to tow vehicle battery, but still helpful while underway when connected to the 10 AWG charge wire of the standard 7- pin wiring.

[Silvr_Bullet]

AGM (1) 100 amp. vs. Lithium (2) 100 amp.
AGM = 50% usable to preserve useful life
Lithium = Almost 100% useable.
2 Lithium will yield almost 4x the amount of usable power.
Weight of 2 Lithium = 1 AGM

[foobar]

The manual for the 2022 Airstream classic 30/33 states that the WFCO converter supplies 25 amps at 12v DC for charging the installed LiFePO4 batteries (two, 100ah batteries = 200ah battery bank).

The manual also states that the converter takes 8 hours to charge the 200ah battery bank, if the battery bank is fully discharged.

8 hours is rather impractical when trying to charge with a generator.

Will a larger generator speed this up? The answer is 'no' as the charge time is limited by the amount of current provided by the charger.

A 3200watt generator is much larger than you need. Recommend getting a cheap 2000w lightweight inverter based dual fuel propane/gasoline champion (or similar) and running it from your trailers external low pressure propane port.

25 amps at 12v DC translates to approximately 2.5amps at 120v AC. Given that a 2000w inverter generator can deliver 15amps @120v or so at peak and about 5amps at idle, you will save a lot of fuel (along with your aching back and pocketbook) by using a lightweight generator.

Can the charge time be improved? The answer is yes.

Lithium can accept much higher charging current for much longer than lead acid batteries.

You can replace the WFCO with a higher capacity charger that is optimized for lithium battery charging and can cut the charging time down significantly. You will need to check the battery data sheet to find out the maximum recommended charging rate vs the absolute maximum charging rate. Absolute maximum charge rate is ok for infrequent, short charging intervals, but can degrade the battery over time, so you will want to stick with the max recommended charging rate.

I just noticed that you were thinking of purchasing the Honda 3200. This is a good lightweight inverter based generator but is very expensive right now. The Honda Eu2200i is still expensive, but is much cheaper than the Honda 3200 at the moment. With the Airstream WFCO charger and a EasyStart installed on your a/c, the 2200i can run the smaller of your two a/c's and 'should' be able to charge your 200ah lithium bank at the same time. The 3200 will definitely be able to do both at the same time.

Recommend purchasing a Genconnex EU2200i. They have seamless propane converted Honda generators. They are the only propane conversions authorized by Honda and their conversion does not impact the Honda warranty. In addition, Genconnex offers a 4 year warranty on the converted generators. I don't know if they offer converted Honda 3200 generators yet.

[SallyForth]

Originally Posted by foobar

The manual for the 2022 Airstream classic 30/33 states that the WFCO converter supplies 25 amps at 12v DC for charging the installed LiFePO4 batteries (two, 100ah batteries = 200ah battery bank).

The manual also states that the converter takes 8 hours to charge the 200ah battery bank, if the battery bank is fully discharged.

8 hours is rather impractical when trying to charge with a generator.

Will a larger generator speed this up? The answer is 'no' as the charge time is limited by the amount of current provided by the charger.

A 3200watt generator is much larger than you need. Recommend getting a cheap 2000w lightweight inverter based dual fuel propane/gasoline champion (or similar) and running it from your trailers external low pressure propane port.

25 amps at 12v DC translates to approximately 2.5amps at 120v AC. Given that a 2000w inverter generator can deliver 15amps @120v or so at peak and about 5amps at idle, you will save a lot of fuel (along with your aching back and pocketbook) by using a lightweight generator.

Can the charge time be improved? The answer is yes.

Lithium can accept much higher charging current for much longer than lead acid batteries.

You can replace the WFCO with a higher capacity charger that is optimized for lithium battery charging and can cut the charging time down significantly.

Odd. Our 2023 International FB Twin came with an auto-detecting WFCO converter rated at 55 / 50 amps — lead acid / lithium.

[SuperTrouper]

Hi Riskinator,

I've converted in the past few years to 400W of solar coupled with 300AH of lithium for many of the reasons mentioned above. Namely, almost 90% use of available AH and ability to charge much faster than lead. I recently made two boondocking trips and recorded real world power use in another thread, Take a look here:https://www.airforums.com/forums/f38...ml#post2652538

I purchased a DC-DC converter but have not yet installed it. I plan to add 110W more solar where the TV antenna is currently.

Happy camping!

Brad

[Wazbro]

Originally Posted by SallyForth

Odd. Our 2023 International FB Twin came with an auto-detecting WFCO converter rated at 55 / 50 amps — lead acid / lithium.

Yes it is odd, although people have reported real world shunt measured charging with that same converter of only 20-25amps with lithium batteries more then 50% discharged.
Here is a thread with complaints of not getting that much.
https://www.airforums.com/forums/f44...ml#post2658599

[thiel]

I have two lead acid group 27 batteries and 400w of solar on my 25fb. It has never even occurred to me that I could run out of power on a simple overnight. The only time I worry is if I need to camp below freezing.

[SallyForth]

Originally Posted by Wazbro

Yes it is odd, although people have reported real world shunt measured charging with that same converter of only 20-25amps with lithium batteries more then 50% discharged.
Here is a thread with complaints of not getting that much.
https://www.airforums.com/forums/f44...ml#post2658599

While I did upgrade to 400ah of lithium, I never used the WFCO charger. Instead I installed a Victron MultiPlus 12/3000/120 Inverter Charger. The MultiPlus was throttled down to charge at a max of 80 amps given the size of our battery bank. It delivers a full 80 amps as set up.

[s1000pre]

As others noted, you don’t need the large generator. I have a Honda 2,200 converted to propane. You can run one A/C unit from the 2,200.
Propane: less fumes when running, no need to transport gas, you always have propane.
Honda it’s reliable, it always starts, even after sitting 6 months.
Cheat: (While running AC off the generator) Trip the breakers to the converter & inverted circuits, this allows you to run more items off the batteries without overloading the generator. Just remember to reset the breakers.
Solar When needed, I rarely see more than half of total performance from my 4 Zamp Obsidian panels. trees, sun low in the sky, clouds, etc. However, you’re talking about Harvest Hosting. The next day you’re traveling, travel days are my highest performing days. Less obstructions (weather permitting)
Charging Furnace, two TV’s, Apple TV’s, Router, Wife and 2 kids, we use our share of power. With clear sky's, my 4 90watt panels and tow vehicle have always recharged the batteries to nearly 100% while traveling. See image (6 days ago) 5 hour trip from Ft. Clark Springs, TX-Terlingua, TX.

[foobar]

Originally Posted by s1000pre

As others noted, you don’t need the large generator. I have a Honda 2,200 converted to propane. You can run one A/C unit from the 2,200.

Propane: less fumes when running, no need to transport gas, you always have propane.

Honda it’s reliable, it always starts, even after sitting 6 months.

Cheat: (While running AC off the generator) Trip the breakers to the converter & inverted circuits, this allows you to run more items off the batteries without overloading the generator. Just remember to reset the breakers.

Solar When needed, I rarely see more than half of total performance from my 4 Zamp Obsidian panels. trees, sun low in the sky, clouds, etc. However, you’re talking about Harvest Hosting. The next day you’re traveling, travel days are my highest performing days. Less obstructions (weather permitting)

Charging Furnace, two TV’s, Apple TV’s, Router, Wife and 2 kids, we use our share of power. With clear sky's, my 4 90watt panels and tow vehicle have always recharged the batteries to nearly 100% while traveling. See image (6 days ago) 5 hour trip from Ft. Clark Springs, TX-Terlingua, TX.

Nice graph. How do you access that information? I get something a bit cruder from the victron VRM portal.

[s1000pre]

Originally Posted by foobar

Nice graph. How do you access that information? I get something a bit cruder from the victron VRM portal.

Click here

[foobar]

Originally Posted by s1000pre

Click here

Gotcha, so you connect to the solar controller directly via bluetooth and then hit the history tab?

Is there any way to get to the same point remotely via the VRM?

Thanks for taking the time to respond.

[Wazbro]

Originally Posted by SallyForth

While I did upgrade to 400ah of lithium, I never used the WFCO charger. Instead I installed a Victron MultiPlus 12/3000/120 Inverter Charger. The MultiPlus was throttled down to charge at a max of 80 amps given the size of our battery bank. It delivers a full 80 amps as set up.

That does explain why you didn't see poor performance (compared to rating) from the WFCO. Other converters seem to actually get close to rated output unless deliberately throttled like yours is.

[SallyForth]

Originally Posted by Wazbro

That does explain why you didn't see poor performance (compared to rating) from the WFCO. Other converters seem to actually get close to rated output unless deliberately throttled like yours is.

The Victron MultiPlus 12/3000/120 can be customized, which I could have done myself, however it would have required buying an Mk3-USB (VE BUS to USB) interface device.

I purchased my Victron devices from Battle Born along with 400ah of their batteries. They set the charge limit on the MultiPlus at 80 amps based on the size of the battery bank.

Also, I rewired the inverter AC input / output circuit so this inverter now powers the entire AC panel, not just a three outlet branch circuit.

[richard5933]

In your example of spending the night at a Harvest Host running off batteries all night, using a generator to charge the batteries to recharge in the morning means either staying put till they're charged or leaving with partially charged batteries.

On clear days your solar should be able to recharge just fine, but in my experience the times you rely most on the batteries are the times that are overcast or raining.

Having a DC-DC charger means that you have options and can recharge while under way regardless of the weather, arriving at your next Harvest Host with charged batteries for another comfortable night dry camping. Redundancy is good.

Take this opportunity while you are installing to put a DC-DC charger and dedicated supply line from the tow vehicle.

[Hans627]

Originally Posted by richard5933

In your example of spending the night at a Harvest Host running off batteries all night, using a generator to charge the batteries to recharge in the morning means either staying put till they're charged or leaving with partially charged batteries.

On clear days your solar should be able to recharge just fine, but in my experience the times you rely most on the batteries are the times that are overcast or raining.

Having a DC-DC charger means that you have options and can recharge while under way regardless of the weather, arriving at your next Harvest Host with charged batteries for another comfortable night dry camping. Redundancy is good.

Take this opportunity while you are installing to put a DC-DC charger and dedicated supply line from the tow vehicle.

Based on my experience this is excellent advice.