Solar and Li-ion - Fiberglass RV


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 07-25-2017, 12:52 PM   #1
Junior Member
 
Name: William
Trailer: Trillium
New York
Posts: 14
Solar and Li-ion

Folks,
Because we have a 12V-only (50W) Dometic fridge and live in the NE where it *is not* sunny 365 days of the year, I want to upgrade the 2014 Trillium (1-100W solar panel and a cheapo G24 lead/acid deep-cycle battery). From the very handy ervsolar calculator (ervsolar.com/sizing-your-system/) I determined that we need ~110W of solar (1 portable to add to the rooftop fixed) and 530Wh of battery. Before we dive in and get these, has anyone done this? Success stories? Horror stories?
Thanks!
__________________

Bill Lindenfelser is offline   Reply With Quote
Old 07-25-2017, 01:05 PM   #2
Senior Member
 
Name: Ken
Trailer: No Trailer Yet
US
Posts: 1,577
Someone posted these former RV'ers info. Maybe it will help you crunch the numbers.
Basic intro to Lithium VS AGM
https://youtu.be/J-kND4PaZm8
__________________

Ken C is offline   Reply With Quote
Old 07-25-2017, 03:24 PM   #3
Senior Member
 
John in Michigan's Avatar
 
Name: John
Trailer: 1978 Trillium 4500, 1979 Boler 1700
Michigan
Posts: 1,402
Registry
With your 50W (approx 4 amp) Dometic fridge, at a 50% duty cycle (running 50% of the time), the fridge will consume 600 watt hours (50 amp hours) per day. A 110W solar panel will produce maybe 500 watt hours per day using a PWM charge controller on a good day. So the 110W solar panel will not keep up with the fridge power consumption.

Is there a second solar panel?

Concerning the battery, with an electric fridge and other accessories typically a 200 amp hour (2400 watt hour) battery is used to keep the everything running on overcast days. For your fridge, the 200 amp hour battery would run down to 50% charge in two days.
John in Michigan is offline   Reply With Quote
Old 07-25-2017, 03:30 PM   #4
Senior Member
 
John in Michigan's Avatar
 
Name: John
Trailer: 1978 Trillium 4500, 1979 Boler 1700
Michigan
Posts: 1,402
Registry
OK I missed that you actually will have two solar panels, a 100 watt and a 110 watt. That should be sufficient for running the fridge and other accessories (lights, water pump, etc). As I mentioned, typically a 200 amp hour battery is needed to carry you for 2 days of overcast.

Disclaimer: I have a solar setup, but its only 100W panel, and I'm not running an electric fridge. I have met two people on the road that run small electric fridges and accessories with the 2 100 watt panels and 200 amp hour battery setup. That seems to be the typical starting point.
'
John in Michigan is offline   Reply With Quote
Old 07-25-2017, 04:06 PM   #5
Senior Member
 
John in Michigan's Avatar
 
Name: John
Trailer: 1978 Trillium 4500, 1979 Boler 1700
Michigan
Posts: 1,402
Registry
more thoughts

Re batteries, my above analysis assumes AGM or wet lead acid deep cycle batteries with a max depth of discharge of 50%. With a lithium-iron-phosphate battery, the max depth of discharge is 20% so you can get by with a smaller battery. In my 2-days-of-overcast example, a 120 amp hour (1440 watt hour) battery might be sufficient.

In my analysis, it appears I might have been overly optimistic in assuming the fridge "and accessories" could be run for 2 days of overcast. As you can see, you really have to have a realistic estimate of how much power will be used. More or larger solar panels may be needed if you want to run more accessories. More or larger batteries may be needed if you need to handle more days without sun.
John in Michigan is offline   Reply With Quote
Old 07-25-2017, 04:20 PM   #6
Senior Member
 
John in Michigan's Avatar
 
Name: John
Trailer: 1978 Trillium 4500, 1979 Boler 1700
Michigan
Posts: 1,402
Registry
lithium battery solar charge controller? converter charger?

I'm not sure there are solar charge controllers available designed to charge lithium-iron-phosphate batteries or other lithium technology batteries. (anybody know?)

Also not sure whether any converter has a built in charger designed to charge lithium batteries.
John in Michigan is offline   Reply With Quote
Old 07-25-2017, 04:53 PM   #7
Senior Member
 
Name: Michael
Trailer: Li'l Hauley
Oklahoma
Posts: 5,892
You'd want a controller that has settable voltage for each stage.
Mike Magee is offline   Reply With Quote
Old 07-25-2017, 05:29 PM   #8
Junior Member
 
Name: William
Trailer: Trillium
New York
Posts: 14
John in Michigan,
Well, I obviously got you thinking about this.

I used a data logger on my current electrical system to see what the net flow of energy in/out of the battery is. I came up with a figure of 170Whr/day. (Sitting out in the sun in the back yard in Rochester, NY.) Just the fridge and a couple small things (USB charger--unloaded--and indicator LEDs, i.e., essentially just the fridge. The lighting is LEDs.) Conclusion: the avg duty cycle is about 170/(50*24)=0.14. I'm figuring on up to 3 no-charge days for a total storage requirement of 530Whr. (I've derated for temperature.) So a 12V, 50Ahr battery ought to be enough. I'm also assuming that in the case of lots of non-sun days we throttle back on listening to NPR since the car stereo is an amazing energy pig, much to my regret. No other big energy drains. Even the water pump makes a negligible load.

And yes, I'm concerned about the marriage of solar and Li-ion. I haven't done the research yet to find a suitable PV regulator. (The current one is geared to Pb-acid.) And I'll probably remove the built-in power center, which is also a Pb-acid charger. That also means coming up with a replacement for the incorporated fuse box, too.

My conversations with a couple of RV solar/battery vendors were unimpressive. They were not able to explain to me why they were choosing particular components. So I'm doing my own digging, and hoping to hear about real-life experiences.

Thanks for the link to the RVers-turned-sailors.

Regards,
Bill
Bill Lindenfelser is offline   Reply With Quote
Old 07-25-2017, 06:02 PM   #9
Senior Member
 
John in Michigan's Avatar
 
Name: John
Trailer: 1978 Trillium 4500, 1979 Boler 1700
Michigan
Posts: 1,402
Registry
Bill,

That's great that you've already done some testing/evaluation. 14% duty cycle fridge is great vs. the 50% that I assumed.

Good luck!
John
John in Michigan is offline   Reply With Quote
Old 07-25-2017, 06:12 PM   #10
Senior Member
 
John in Michigan's Avatar
 
Name: John
Trailer: 1978 Trillium 4500, 1979 Boler 1700
Michigan
Posts: 1,402
Registry
Bill,

Also I'm curious. Are you considering lithium iron phosphate (LiFePO4) or lithium cobalt oxide (LiCoO2) batteries?

-John
John in Michigan is offline   Reply With Quote
Old 07-25-2017, 06:17 PM   #11
Senior Member
 
John in Michigan's Avatar
 
Name: John
Trailer: 1978 Trillium 4500, 1979 Boler 1700
Michigan
Posts: 1,402
Registry
my solar setup

Bill, I bought my 100W solar panel and 30 amp charge controller at amazon. So far used it for 17 days of continuous boondocking in TX in January and it worked great. The load was: 8 1156 led bulbs, LP detector, charging of tablets and phones...

EDIT: and a little Optima 38 amp hour AGM battery
John in Michigan is offline   Reply With Quote
Old 07-26-2017, 12:26 PM   #12
Junior Member
 
Name: Cathi
Trailer: Scamp 13'
Nova Scotia
Posts: 22
Gel cell batteries

Haven't seen anyone mention gel cell batteries. I used one that was purchased second hand...found it on Kijiji for 40$...group 27...removed from a backup system for a provincial telephone company, i believe. Worked well and felt "safer" in terms of off-gassing considerations.
Tillie and Tyler is offline   Reply With Quote
Old 08-07-2017, 01:29 AM   #13
Senior Member
 
Name: Elliott
Trailer: Bigfoot
Everywhere
Posts: 249
Honestly, for only 530Wh of capacity (~44Ah), Lithium is probably a waste of money. You can get something like a 90Ah lead-acid battery (so you don't have to worry about discharging below 50%) for a fraction of the price, and not have to worry about voltage settings (or, more importantly, a desulfation mode) on your charge controller(s). If you want a bit of extra margin, something like a pair of Trojan T105 batteries will get you 225Ah (though at that point, I'd up the solar capacity to match so you can fill them up most days)
Defenestrator is offline   Reply With Quote
Old 08-28-2017, 12:57 PM   #14
Junior Member
 
Name: William
Trailer: Trillium
New York
Posts: 14
Folks,
My apologies for not keeping up with the replies to my post.

Given what I know now, the direction re batteries is a Lithionics 52Ah (12V, 624Wh) battery (available this Fall, ~$650). Since this thing contains its own charge/discharge controller (or Battery Management System--BMS--gotta love the lingo) I believe that a simple, no-nonsense AC2DC charger would suffice. Lithionics claims the advantages at http://lithionicsbattery.com/wp-cont...g2017final.pdf, p3. It's expensive, but with 6-8X the number of charge/discharge cycles, the overall cost of ownership (and the maintenance) should be less.

The solar controller is another question: the controllers I have seen so far are geared to Pb-acid, i.e., their maximum output voltages conform to Pb-acid requirements. For sure, I don't want to burn out anything else in the Trillium, so I have to look into what the fridge, car radio, lights, etc, can handle. The current electrical system is a common 12V bus--everything connects to that.

I'll update this as I learn more.

Thanks to all,
Bill
Bill Lindenfelser is offline   Reply With Quote
Old 09-06-2017, 11:21 AM   #15
Senior Member
 
Buggeee's Avatar
 
Name: Buggeee
Trailer: Playpac
OH
Posts: 327
Check out Missouri Wind and Solar, he might have a programmable solar charger, or be able to program one for you... He's got lots of neato applications for solar and wind energy managment. Here's his link:

https://mwands.com/

I have ditched my 6v flooded golf cart batteries and just re-upped with AGM 12v deep cycle batts for my bank. I held off on lithium for now because of the charge controller puzzle you are unwinding. If you solve the rubic's cube here I'd love to know the solution because lithium is where I'd like to be.

Also, for those of us using inverters for 120v appliances (not like Bill who posted this thread, as he is using 12v from 12v) the inverters usually have a low-voltage cutoff that is suited for serving lead acid batteries so you'll want a programmable inverter too. In other words, the off-the shelf low-voltage cutoff point on the inverter might not allow you to pull out the bottom end of those lithium batteries even if they can take the hit.

If its useful at all to anybody, this weekend I ran a 3.5 cubic foot chest freezer with a refrigerator thermostat (120v off a pure sine inverter) for 3 full days on a 200 amp hour bank (two 100 amp hour AGM batts). I also ran a Maxx Air fan at a crawl intermittently, LED interior lights, recharged my phone three times, recharged a set of four AA batteries and filled the equivalent of five inflatable beds. The bank measured exactly 12.0 volts when I pulled out of the site so I still had a taste left if needed. No solar panels yet, just brought the fully charged bank with me to see if it would make it on its own, and it did.

I'll be adding another battery or two but that's how 200 amp hours fared for the Holiday Weekend (in NY - beautiful State Bill).
Buggeee is offline   Reply With Quote
Old 09-30-2017, 05:27 AM   #16
Senior Member
 
Buggeee's Avatar
 
Name: Buggeee
Trailer: Playpac
OH
Posts: 327
I was browsing Progressive Dynamics site, for other reasons, and noticed they have a new line of controllers rolling out specifically for lithium. I'll litter you thread with it in the event you, or any onlooker, finds it useful. Here you go:

https://www.progressivedyn.com/lithi...tery-chargers/

Also, another dude has a thread going about a monster lithium battery that he stole from some RV dealer for a song. He has a Zapp solar panel with a controller that has a lithium setting. Here is a link to his thread if you want to ask him about that:

http://www.fiberglassrv.com/forums/f...tml#post663908

It figures. Yesterday I just ordered the 4th and final battery to complete my new bank - replacing flooded lead acid golf cart batteries with deep cycle SLA (valve regulated absorbed glass mat). Today I stumble on the converter AND solar charger solutions that would have made my lithium dreams come true. Oh well. I still have the dream - and these SLAs won't last forever.
Buggeee is offline   Reply With Quote
Old 10-24-2017, 05:34 PM   #17
Senior Member
 
Name: Mike
Trailer: 1996 16' Casita SD
Louisiana
Posts: 547
Registry
Lithium-Ion sticker shock going on right now.....

I'll stick with gel cell or agm for now.

Right now, I have one 100AH AGM and 150 watt of solar. I'm not running a fridge...yet. I do watch a movie at night and have all led's and a 12v pump at the sink.
No problems so far.

I had an Engle 43 qt. fridge in my '74VW Westfalia with only 100watt solar. Camped for a week in Nov with very little sun. No problems (movie every night).
If I remember right, it used 2.6A on 12V when running. Of course, it doesn't run much in Nov.
itlives is offline   Reply With Quote
Old 05-14-2018, 02:42 PM   #18
Junior Member
 
Name: William
Trailer: Trillium
New York
Posts: 14
A further update.

We put in a Battle Born 100Ahr LiFePO4 battery and added a portable 160W Zamp solar panel. In addition, we upped the solar controller to a 30A Zamp. On a 6-week tour of the Southwest just concluded, we never had to plug in.

The key component seems to have been the battery. It was rare for the system to drop below 13V. Out in the sun all day, there was no need for the portable solar panel. That was pulled out when we happened to be camped at high altitudes, with a lot of big ponderosa pines overhead.

The fridge kept my beers cold.

The real test will be in coming weeks, when camping in the Northeast and the days of cloudy weather. I'll provide a further update after those trips.

Thanks to Joe at Back Country Solar for the advice and the great service.

Regards,
Bill
Bill Lindenfelser is offline   Reply With Quote
Old 05-15-2018, 02:55 AM   #19
Junior Member
 
Name: William
Trailer: Trillium
New York
Posts: 14
A further update.

We put in a Battle Born 100Ahr LiFePO4 battery and added a portable 160W Zamp solar panel. In addition, we upped the solar controller to a 30A Zamp. On a 6-week tour of the Southwest just concluded, we never had to plug in.

The key component seems to have been the battery. It was rare for the system to drop below 13V. Out in the sun all day, there was no need for the portable solar panel. That was pulled out when we happened to be camped at high altitudes, with a lot of big ponderosa pines overhead.

The fridge kept my beers cold.

The real test will be in coming weeks, when camping in the Northeast and the days of cloudy weather. I'll provide a further update after those trips.

Thanks to Joe at Back Country Solar for the advice and the great service.

Regards,
Bill
Bill Lindenfelser is offline   Reply With Quote
Old 05-15-2018, 03:28 AM   #20
Senior Member
 
Borrego Dave's Avatar
 
Name: Dave
Trailer: Casita SD17 2006 "Missing Link"
California
Posts: 3,739
Bill, sounds like you've got it squared away. If it keeps the beer cold every thing else is cake .
__________________

Borrego Dave is offline   Reply With Quote
Reply

Tags
solar


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
ENERWATT SOLAR EWC-30 Solar Controller Robert50 Electrical | Charging, Systems, Solar and Generators 7 09-14-2014 04:00 PM
Lithium Ion batteries Daniel V. General Chat 3 03-13-2009 06:10 AM
Trials and Tribulations: Dry campng with our Solar Panel peterh General Chat 52 11-09-2008 06:56 PM
Solar Charger and Panels Frederick L. Simson Modifications, Alterations and Updates 109 08-11-2008 10:41 PM

» Upcoming Events
No events scheduled in
the next 465 days.
» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 11:45 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
×