Solar Necessary for Boondocking w/ 12V Fridge?

[Mark_K5LXP]

I think we have reached the point where Lithium has became cheaper than Lead Acid, over the average life expectancy of the battery when not abused.

All other things being equal maybe we are there. Then the performance advantages become icing on the cake. There'd still be the factors of running them to expiration and refit cost but even those margins diminish as cost continues to go down. Another factor I can see is increasing cost or decreasing availability to replace lead, which may make some of the economic issues moot.

Mark B.
Albuquerque, NM

 

[PSnartland]

Thanks, everyone, for all your input. My big concern is that it is winter now, and we are planning our first big trip (1 month or more in duration) in the new camper in April, shortly after taking it out of storage. I am concerned about finding ourselves running out of battery during the night and our food going bad or my wife getting cold. Maybe I'm being paranoid, but I can envision having to run the generator nearly constantly to keep the batteries topped up for the overnight. You're right, in that I certainly don't have all the answers needed to give accurate answers, and budget is certainly a consideration. Thanks again for all your help.

 

[Viajeros]

Thanks, everyone, for all your input. My big concern is that it is winter now, and we are planning our first big trip (1 month or more in duration) in the new camper in April, shortly after taking it out of storage. I am concerned about finding ourselves running out of battery during the night and our food going bad or my wife getting cold. Maybe I'm being paranoid, but I can envision having to run the generator nearly constantly to keep the batteries topped up for the overnight. You're right, in that I certainly don't have all the answers needed to give accurate answers, and budget is certainly a consideration. Thanks again for all your help.

Glad you found help on this forum. We have some pretty informed people here. And Mark is a great resource for all of us.

 

[Alontheway]

since buying my coach a bit over 5 years ago, in that time I have went through 2 sets of batteries, rather it is close to time to replace my second set,

2 sets in 5 years. I want advise on batteries from you and only you... lol.

Other topic:
There is a guy that I already ignore that everyone seems to disagree with. You don't have to reply to every post. There will always be people who say crazy things

 

[Isaac-1]

Well I did know I was abusing them at the time (by deep discharging), but a pair of lead acid batteries was cheaper than hiring a welder to fabricate a larger battery tray

 

[Alontheway]

yes, you did that math, that worked for you. I still won't be asking for battery advice... no offense.
There are battery trays that hook on a vehicle frame (p/u trucks) but could work the same on a trailer frame, no welding necessary. It is permanent and won't wear out in 5 years either.

 

[Isaac-1]

I have a class A motorhome, not a trailer, finding a ventilated place to mount lead acid batteries other than the factory battery tray without custom fabrication would not be an easy task.

 

[Alontheway]

Use your internet search and look at the images on the search result:
"frame mount battery tray"
The yellow one was the one I had in mind. All of them look workable.
It will work for your motor home the same as it would on a trailer. I think more are for motorhomes than trailers, but the frames on either are similar all around. The battery ends up sitting next to the frame. Probably not the most fun job checking water levels so an AGM battery would be more ideal than a flooded batt, but the point is to hold the battery.
I can weld, so I just make my own custom parts, but I did consider making something like this.

 

[Isaac-1]

The problem is lack of any open space along the frame where such a tray could be mounted, as most available space along the frame has cargo compartments, the generator, or the propane tank mounted to it. About the only open space large enough to fit another pair of batteries would be next to hitch bracket between the rear frame, under the back bumper, which would be a very bad place to add a couple of hundred pounds worth of batteries. About the only place where one could add batteries is by removing the factory tray and building a tray that would hold 4 batteries perpendicular to the frame like: |||| vs the 2 that are mounted like:-- There are even dimensional plans for such a tray available on the Trek owners forum.

 

[Mark_K5LXP]

we are planning our first big trip (1 month or more in duration) ... I am concerned about finding ourselves running out of battery during the night and our food going bad or my wife getting cold.

It would seem if it's cold out, the refrigeration question is a self solving problem. If you can figure out a way to keep critters out, the outside world is your refrigerator.

Power consumption and energy storage are all solvable beforehand if you like. Comes down to assessing the anticipated loads and running some basic calculations. From there you can compare to any given battery capacity and performance and also do estimated generator runtime or solar input calculations. I use a spreadsheet which makes managing the variables and constants easy, and allows easy comparisons of different operating scenarios. Depending on the precision and accuracy you need it doesn't need to be terribly complex or involved to estimate.

Mark B.
Albuquerque, NM

 

[Robert K]

200 watts in the shade recharge my two gc's back fully. I do not know how many amps the panels give in the shade, all I see is their 18 volts, but they do work in the shade. Full sun pointed directly at the sun is idea, and more panels will make up for shade. By shade I do not mean inside a garage, but under trees. Always some daylight coming through and usually short periods where there is direct sun. They work in the shade.

raining cloudy southern Georgia
3 - 180 watt panels in series
we are plugged in at state park

attachment didn't work
the panels are showing 25 to 30 volts
full sun normal around 67 volts

 

[Alontheway]

Roberk gets about half the power from his solar when it rains, so it takes a little over twice as long to charge the batteries? big deal. 2 hours in full sun, 4 in the rain? The solar works without your being there, so what if it takes all day as long as it charges?

i have 200 watts of solar and the batts seem to get fully charged in the rain or in the shade by the time the sun sets.

 

[Rob&Deryl]

Roberk gets about half the power from his solar when it rains, so it takes a little over twice as long to charge the batteries? big deal. 2 hours in full sun, 4 in the rain? The solar works without your being there, so what if it takes all day as long as it charges?

i have 200 watts of solar and the batts seem to get fully charged in the rain or in the shade by the time the sun sets.

Which 200w system do you have? I am going to buy a portable next month.

 

[Alontheway]

Don't buy a system unless you have $5,000 to throw away or want to stimulate the economy.
You build your own. There is nothing special about a system other than you get it in one box.
On eBay buy some 12 volt panels. the panels put out 18 volts or sometimes 20 volts, but is what a 12 volt system uses, so don't be confused by the difference in numbers.
Buy a charge controller. MPPT is what I prefer as do most people. You need one big enough amp-wise for the panels. Add the amps from each panel in your system to come up with a max amp output and get a bigger controller.
You will need wire and a "blister" to get the wire through the roof without leaking.
You already have the batteries.
That's it!

I suggest running at least two panels in "series" so you have a higher voltage - 36 volts instead of 18. You can use thinner wire when you have higher voltage.
If you get two 150 watt panels, then run them in series then down to the controller which is inside yet near the batteries. You run a wire from the controller's negative post up to the negative on a panel, then out that panel's positive to the other panels negative then out the positive and back down to your controller's positive post.
Hooking up the controller to the battery will be self-explainatory (positive to positive, negative to negative).

You can do any panel configuration you want -
all panels running into the controller individually or in series, or have one set in series paired with an identical set in series and run the two sets parallel (this to keep amps where you want them).
You can run high amps, like 4 panels in series, 80 amps, and some controllers can convert that down to 12-14 volts needed for your batteries, but this is less common on RVs.

 

[steveblonde]

Roberk gets about half the power from his solar when it rains, so it takes a little over twice as long to charge the batteries? big deal. 2 hours in full sun, 4 in the rain? The solar works without your being there, so what if it takes all day as long as it charges?

i have 200 watts of solar and the batts seem to get fully charged in the rain or in the shade by the time the sun sets.

now you are betting on staying in one spot. if your traveling through like we often do, we stop at sites along our route sometimes we pull in at 2pm sometimes 6pm and we leave again 8-9 am with a solar system you wouldn't get much "grid" time so to speak.

 

[Alontheway]

yep, if you drive long every day then the vehicle will be enough to charge the batteries, you're overnight parking it sounds like more than boondocking.

 

[quadna71]

now you are betting on staying in one spot. if your traveling through like we often do, we stop at sites along our route sometimes we pull in at 2pm sometimes 6pm and we leave again 8-9 am with a solar system you wouldn't get much "grid" time so to speak.

In this situation, will your solar panels still charge the system while you drive down the road? Or is the system built so that the solar power is blocked and only the juice from the TV is making it through as you drive?

 

[creativepart]

now you are betting on staying in one spot. if your traveling through like we often do, we stop at sites along our route sometimes we pull in at 2pm sometimes 6pm and we leave again 8-9 am with a solar system you wouldn't get much "grid" time so to speak.

Errrr... the sun continues to shine while you drive and so does the charging. Drive all day and charge all day via the tow vehicle AND via the solar panels.

 

[quadna71]

This thread really hits for me. I’m at the crossroads of increasing my battery bank either through lead acid or lithium. There are pros and cons for each direction and quite honestly it seems like either direction is a good move. I don’t see solar going on the roof at this time (personal decision) and I only have the same 100w Renogy suitcase kit that lots of folks buy as their first foray into solar.

The backstory is our 2020 travel trailer came with a marine dual purpose battery that was the bare minimum for a trailer that has a 12v residential refrigerator. It’s a 24 group lead acid with only 450cca and weighs 37lbs - probably the smallest marine battery I’ve seen. I didn’t know enough at the time to challenge the dealer when we bought it as I think they were supposed to supply a larger group. And then they had the camper for warranty work for more than 4 months out of our 1st year of ownership and they neglected to take care of the battery. Didn’t disconnect the leads nor did they remove the disconnect lever. So the battery was at 0% for an extended period and is now already shot.

So. Do I double up with better lead acids or do I go with a lithium? Even a single good true deep cycle will be better than our OEM battery so buying a pair of new ones will be a very good and simple upgrade. But then again even a single 100ah lithium will likely give us equal or maybe slightly more power than the two lead acids due to the inability to discharge lead acid past 50% without damaging like our current one. Yes, I’d have to upgrade the charger/converter to one that works with lithium but the one I priced to work with my power system will auto detect either of the 3 most common battery options…sort of future/past proofs it.

A good set of 100ah deep cycle lead acid batteries that I’m looking at are $172 each, a locking dual-battery box at $125 since I can’t just buy a second single box as they are both larger than my current battery box , and a simple cable kit to connecting the second battery is $45. That lands me at $514 to have a solid 200ah lead acid system of which I can typically use 50% of without causing any long term damage to the batteries.

A good charger/converter to handle lithium batteries that works well with my camper is $130, a 206ah lithium battery with both high and low temp protection built into the BMS will run me $929, and the brackets for bolting it under my bed are already on a shelf in my garage - just simple aluminum L brackets with straps. So I can land on a lithium system for $1059 that will have me at nearly double the capacity of amp hours considering I can discharge them to nearly 0% will no ill effects. Even if I go with a 100ah version of the same battery for $520, I’m still only $136 more than the lead acids and with the lithium I can drain it all the way down.

Having the lead acids on the tongue - that’s a con. Sure my truck can handle it fine, but I already have things balanced pretty well…no need to add close to another 100# of hitch weight (new batteries are considerable heavier than current battery plus cables). Relocating the lithium battery to under the bed - that’s a con. Sure it is a pro once it is mounted, but a pain to gain access through the underbelly protection. I‘ve measure the cables and the length is good so no big deal there.

Regardless of which route I go, I’m considering a Victron Smartshunt so that I can better manage the batteries and not get myself into a situation where I don’t have a good solid idea of my battery capacity.

Sorry for the different directions than the original poster, but I feel that some of these points can also be valid details for what everyone has been discussing.

 

[MoInEd]

I tell everyone who wants to buy a new trailer to stay away from 12V fridges manufacturers are now putting in new trailers to save cost.

FYI HAD two 120ah lead batteries in my previous trailer with 3x100w solar on the roof. For the new one we got I am putting same solar on the roof and 200ah lithium batteries and ditch the lead battery.
If you put solar you don't need new converter to charge your batteries.