Battery banks and RV windows, worth it?

luthj

Engineer In Residence
I have no issue running a 110L fridge, induction cooktop, fans, computers, lights, etc, from a 600W solar array and 500AH lead battery. Really a 400AH lead bank would work fine. It really dependson what you are cooking. My cooktop uses about the same as or less than the fridge in warm weather. A 200AH lithium pack would meet this need. In winter keeping lead batteries charged off the grid (including full charges to prevent rapid degradation) is challenging. Solar charging is greatly reduced due to angle and day length.

Meals range from 5-50AH depending on whats being cooked. Boiling water is the biggest user. I also have a compact toaster oven, which is great for a variety of meals, from pizza to roasting meat/veggies. WIth a bit of insulation, power consumption is about 50AH per hour.
 
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Ducstrom

Member
I have no issue running a 110L fridge, induction cooktop, fans, computers, lights, etc, from a 600W solar array and 500AH lead battery. Really a 400AH lead bank would work fine. It really dependson what you are cooking. My cooktop uses about the same as or less than the fridge in warm weather. A 200AH lithium pack would meet this need. In winter keeping lead batteries charged off the grid (including full charges to prevent rapid degradation) is challenging. Solar charging is greatly reduced due to angle and day length.

Meals range from 5-50AH depending on whats being cooked. Boiling water is the biggest user. I also have a compact toaster oven, which is great for a variety of meals, from pizza to roasting meat/veggies. WIth a bit of insulation, power consumption is about 50AH per hour.
Thanks! The usage information is really helpful. I am limited for space on my roof, 200watts easily, but more than that and things start getting crowded and shady. I am not really interested in buying and carrying a generator specifically to charge the batteries. Also, I don't really have anywhere left to put it and I don't want it in the truck or inside the camper. That's why I am trying to justify the lithium for their ability to charge faster from the 200watts of solar and I hopefully can make up the rest using the trucks alternator.

I am going to have a look at those motion windows everyone is mentioning. I am also thinking of ditching the roof hatch altogether as I can always climb up the outside to get on the roof.
 

dreadlocks

Well-known member
check this out for some performance comparisons to the good ole trusty GC2: https://battlebornbatteries.com/comparison-one-battle-born-lifepo4-battery-two-6v-gc2-batteries-series/

If your going to rely on Alternator charging as your anchor I think you should try to shoot for that 0.4C charge rate so you can get it empty to full in ~2h, or about an hour to put half the charge back in.. with 200AH of LFP thats 80A, probably gonna have to chain two 40A DC chargers together to get that level of performance but it would require minimal driving to keep up with even heavy demands..

When I tried to use Alternator as my charge anchor using lead batteries I ran into issues of not actually driving enough, with 8h to fully recharge the lead batteries that kind of journey is only something I'd do like once a week tops and the few hour hops between camps or scouting around barely put a dent in it.. since you can dump energy into a LFP so fast you can mitigate much of that.

I found my 'range anxiety' with these high charge rates basically vanished, since it takes so little effort and time to recharge now I dont really need the capacity to go a week w/out recharging.. Kinda like when my smart phone used to charge slow as crap it made me really want a long lasting battery.. but now my phone can fully charge in like an hour or two, if I wake up and my phone is dead.. I can get 30% charge back in it just on the drive to work and make it through the day comfortably.. instead of just getting 1-2% back in that short commute and having to leave my phone tethered all day at work.
 

luthj

Engineer In Residence
With a good sized lithium bank and alternator charging, you can get rates of 50A sustained without much effort. If you drive often, running an induction cooktop that way is doable. Just remember that you need to keep them warm if you want to charge in cold weather. A well designed and insulated batter box can do that pretty easily, with modest power requirements.
 

Alloy

Active member
Besides the great charge profile another advantage of Lithium is not having to vent (in winter) the batteries which makes a big difference if you go out in temps that fall below 34F.

I use (so my screw-ups don't cost as much) 8-6V FLA (lead acid) that are vented (top&bottom right of pic) battery box. The battery box sits inside a compartment insulated with 2" XPS that is heated with a 3" furnace duct.

20190512_100153.jpg

We have 4 fixed and 4 portable 330W solar panels. In winter more often than not there is no (see pic) direct sun. As the temperature drops bringing out the portable and tilting the rooftop panels has diminishing returns. To heat our 35' trailer at temps below 15F the furnace starts to consume (0.8Kw/day) more power than the 2600w of solar can supply so the generator (in snow cave to keep noise down) becomes a necessity. Below 0F the furnace will consume more than 1.0Kw/day.

20191230_130635a.jpg


This is a pic of the temperatures in the bottom of our trailer from our latest trip.
- CH 1 Water pumps - the compartment was opened that morning to pull gear out.
- CH 2 Water tanks - kept loosing the channel but the water kept running
- CH 3 Back of the battery/holding tank compartment . The drop at 12hr was after closing the 3" furnace duct too much then opening it up a little more.
- CH4 Front of the battery/holding tank compartment. The 3" heater duct cannot supply enough heat to the front of the battery/holding compartment and overcome the loss from the vented (-10F air) battery box.
- CH5 Outside
20200114_080612a.jpg
 

Ducstrom

Member
Besides the great charge profile another advantage of Lithium is not having to vent (in winter) the batteries which makes a big difference if you go out in temps that fall below 34F.

I use (so my screw-ups don't cost as much) 8-6V FLA (lead acid) that are vented (top&bottom right of pic) battery box. The battery box sits inside a compartment insulated with 2" XPS that is heated with a 3" furnace duct.

View attachment 561708

We have 4 fixed and 4 portable 330W solar panels. In winter more often than not there is no (see pic) direct sun. As the temperature drops bringing out the portable and tilting the rooftop panels has diminishing returns. To heat our 35' trailer at temps below 15F the furnace starts to consume (0.8Kw/day) more power than the 2600w of solar can supply so the generator (in snow cave to keep noise down) becomes a necessity. Below 0F the furnace will consume more than 1.0Kw/day.

View attachment 561709


This is a pic of the temperatures in the bottom of our trailer from our latest trip.
- CH 1 Water pumps - the compartment was opened that morning to pull gear out.
- CH 2 Water tanks - kept loosing the channel but the water kept running
- CH 3 Back of the battery/holding tank compartment . The drop at 12hr was after closing the 3" furnace duct too much then opening it up a little more.
- CH4 Front of the battery/holding tank compartment. The 3" heater duct cannot supply enough heat to the front of the battery/holding compartment and overcome the loss from the vented (-10F air) battery box.
- CH5 Outside
View attachment 561680
That temperature display is awesome, mind if I ask who makes that? Are the sensors wireless? The goal of the post was to save me money,not make me spend more!

I have designed the battery box size to hold 2 - 6v deep cycle batteries so as long as the lithiums fit the same foot print I'll be good. The box is inside and insulated with 1" foam. Currently there is no vent to the exterior cut into the battery box and that's the way it'll stay if I get the lithiums. Unfortunately routing the heater line into the battery box is not doable for my layout they are just too far apart with no logical way to route a heater line.
I'll see if I can find any type of DC electric heater with reasonable current draw that would be able to maintain an insulated 2 cubic foot box.
 

Joe917

Explorer
I would suggest double glazing is not worth the money when you consider the percentage of window to wall, as long as the wall is well built and you can live with some condensation on the windows. Citing Earthroamer's windows as high end is funny since until recently they were using European RV standard crappy Seitz acrylic windows. Lead acid will accept all large charge rates initially. The trick if you have low (lead acid) batteries is to run the generator early in the day and let the solar finish the charge. Lithium are still not worth the money unless weight is a deciding factor.
 

dentedvw

Wire twister
You could also look to the chinese sellers for windows. I have been considering it. In some cases there is a minimum purchase quantity, but not always.
Will they be Arctic Tern? Probably not. But they do seem to have very similar qualities and features.
I bought the Arctic Tern door, and don't regret it. I wish it had come with a cutting template however. And that the flange was wider, to help hide any oops spots that may or may not have happened. Thank goodness for good adhesives.

I got lucky and found one window and the fancy roof hatch at a discount damaged freight store. VERY lucky.
 

Victorian

Approved Vendor : Total Composites
You could also look to the chinese sellers for windows. I have been considering it. In some cases there is a minimum purchase quantity, but not always.
Will they be Arctic Tern? Probably not. But they do seem to have very similar qualities and features.
I bought the Arctic Tern door, and don't regret it. I wish it had come with a cutting template however. And that the flange was wider, to help hide any oops spots that may or may not have happened. Thank goodness for good adhesives.

I got lucky and found one window and the fancy roof hatch at a discount damaged freight store. VERY lucky.
as with many components the arctic tern windows are made in Europe and China! Our team in China discovered them, we brought them to North America and handed it over to tern overland. These windows are very nice. Not to compare with the dometic windows. There are countless other manufacturers in China for windows and doors. I have ordered from several others to compare quality. I’m not kidding if I say that nothing came close to the arctic tern. It’s like the same with everything else made in China, there is the junk and top notch products. Finding the good stuff is not easy! for example: our factory is running two production lines , one for China and one for total composites . The Chinese market composite panels are crap, the ones made for us are the same or better than what you get in Europe. Our factory is also on alibaba... if you order through that avenue, you get the Chinese stuff 😁 therefore be careful what you see and read.
 

Alloy

Active member
That temperature display is awesome, mind if I ask who makes that? Are the sensors wireless? The goal of the post was to save me money,not make me spend more!

I have designed the battery box size to hold 2 - 6v deep cycle batteries so as long as the lithiums fit the same foot print I'll be good. The box is inside and insulated with 1" foam. Currently there is no vent to the exterior cut into the battery box and that's the way it'll stay if I get the lithiums. Unfortunately routing the heater line into the battery box is not doable for my layout they are just too far apart with no logical way to route a heater line.
I'll see if I can find any type of DC electric heater with reasonable current draw that would be able to maintain an insulated 2 cubic foot box.
Here it is. It is 110VAC so we use a 600W (more $$ to spend) that only draws 0.5A of 12V on standby.

https://www.ambientweather.com/amws3000x5.html

All batteries suffer from the affects of cold and heat. While Lithium doesn't need venting (in winter) there is a good chance it will need cooling in summer. Our old battery box was next to the outside wall and would easily go over 100F which isn't good for Lithium or FLA.

If I was building a box for Lithium in the temp ( -15F) we use the trailer it would have 3" of XPS insulation (protecting the investment), be easy to access so the batteries can be removed when not in use, have 2 heating sources and ducting for cooling.

There are several threads on the Expo forum regarding heating Lithium with electricity.
 
This is a great thread. I know it scares some people but AliExpress can be an amazing resource if you are careful. I find the key is similar to eBay, trust the feedback, stick with products that have actual reviews and be patient with delivery. A communicative seller is a plus. Definitely some risky stuff out there, but I've also found Chinese suppliers are much more likely to employ innovative form factors and odd configurations. Forget about warranty and accept the risk and you can get some cool stuff that is straight up not available available in the USA. So aside from price, the rapid innovation can be really neat. I spend hours sometimes combing through Alibaba and AliExpress. Here is a 100ah 12v LifePo4 that I've been eyeballing has good reviews and some real user feedback from folks from the USA and is only a little more expensive than a good AGM. YMMV of course:

https://a.aliexpress.com/_rQUsoW
 
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Fadeagray

New member
During the renovation of my truck, I installed both Motion and Arctic Tern windows to replace Sietz and a combination of single pane glass windows. I can provide pros and cons for both Manufactures.

The Motion duel pane glass windows were custom ordered to fit openings that could not be resized to fit Arctic Tern windows. The folks at Motion are easy to work with, the custom sized windows fit the openings perfectly and installation was very easy. After 9 months of continual use they perform well. Condensation is minimal but, more so than the acrylic Arctic Terns. Cost was twice as high for smaller windows. I was glad to pay a higher price to find a duel pane window solution that fit. The motion windows come with a screen but, not with a shade. I had to source a marine shade for the two windows I installed.

Arctic Tern windows replaced Sietz windows. They came with screens and shades. Condensation is rare and not a problem, even in temperatures around 15* F. The screens / shades are fare better than Sietz and work very well. Pricing was better as well. Installation was easy even though I had to resize the openings due to a difference in radius at the corners.

Having had both single pane and now duel pane windows, I would never go back to single pane. Condensation and thermal transfer are no longer a problem.

Both Tern Overland and Motion are great people to work with and both companies strive to make their customers happy.
 

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