Reader note: This post may be fascinating if you own an Alto; otherwise, consider it a possible answer to the insomnia that might be ailing you. And in either case, please remember that this is my experience of Alto power generation and usage, and your experience may (and probably will) vary!
Act I: In the Beginning
When I got my Alto, it had a voltmeter, which basically showed me how much energy was running through my system at that exact moment. It didn’t really tell me a lot, and so I used this chart to figure out how my battery was doing when I was boondocking (dry camping, so no electric hookup).
If the voltmeter showed 12.2 or lower in the morning, I would run the generator until it said 13.6 or so, and then figure, well, I guess the battery is all charged up. But, honestly, I had no idea. I had no data to prove or disprove that. Sometimes the battery lasted 24 hours more, and sometimes it dipped back down to 12.3 before nightfall and I’d run the generator a bit more, topping up the battery to last through the night, so that I could be sure the electric ignition and fan in the propane heater would work.
The week I stayed at Kalaloch up on the Olympic Peninsula, it was a totally shady spot and pretty darned cold, so I ran the generator every day. In the back of my mind, I wondered if I really needed to and I wanted to know more about what my battery was actually DOING with all that energy I was feeding it. As a full-timer, I really wanted to understand my power generation and usage. It was clear I needed better data.
Act II: Enter the Trimetric
At the end of December, a pair of generous friends installed a Trimetric battery monitor in my Alto. I provided the parts, they provided the “we do electrical stuff” labor.
I love my Trimetric. It shows me three really useful numbers:
- The current voltage of the system (could not resist that pun)
- The amount of amps going in and out of the battery storage system. Solar and shore power put energy in, and things like lights, heater, and water pump take it out.
- The percentage that the battery is charged up at any given moment.
This last one has been the most useful in helping me understand how much energy I actually have in my battery. And to explain that, I’ll back up a bit. I have a “group 27” battery, which means it can store 90-100 amp-hours of energy. And since it is a typical wet-cell deep cycle RV/marine battery, the best way to treat it is to not let it run down below 50% and that translates to about 45-50 amp-hours that I can use before the battery needs to be charged up, either by solar, electric hookup, or a generator.
Act III: Camping in Shade and Cold
I did some dry camping recently at Chiricahua National Monument, and while solar was OK, it was definitely a “partly shady” spot so the solar panels weren’t able to work to full capacity. Nerd that I am, I thought this would be a great opportunity to see how the battery handles 3-5 days of not much power input. I started with the battery at 100% after a day of driving and the solar panels being fully exposed to the Arizona sun.
Usage Habits
- Propane heater was set to 50F overnight (flannel bedding rocks in cold weather). I have the Truma Eco Combi Plus.
- 12v fridge was set to 2 during the day and turned off at night.
- I used solar lights in the evening rather than the built-in LED lights.
- I avoided draining the laptops, so charged Mac Book Air (MBA) only twice during my stay and did not charge the heftier Mac Book Pro (MBP) at all.
Trimetric Readings with Notes
Day 1 PM – 96% – overnight low 33F
Day 2 AM – 92% – overnight low 33F – Solar charged back up to 95%.
Day 2 PM – 95%
Day 3 AM – 87% – overnight low 35F
Day 3 PM – 92%
Day 4 AM – 80% – overnight low 32F (ouch!)
Day 4 PM – 85%
Day 5 AM – 76% – overnight low 35F
Day 5 PM – 71% – very overcast, virtually no solar charging
Day 6 AM – 65% – overnight low 34F
The Trimetric data showed that even though the overnight voltage reading was 12.1-12.3 (which would translate to the battery being 50%-60% charged (using the standard table below), the battery was actually way above that most of the time.
If I had been looking only at voltage using my original equipment, I would have run the generator every day because I would have thought the battery needed the boost. I didn’t run the generator at all because the battery was well above 50% the whole time. So it’s good to know that I can go 4-5 days without a generator or hookup boost to the battery if I watch my energy usage.
Act IV: Camping in Dry Heat
Camping at Big Bend National Park was an interesting test because the Alto was in full sun all day, every day, which the battery really liked because the solar panels were cranking out the energy. I generally charged my laptops in the AM, and then let the solar fill the battery the rest of the day. The two days the battery did not get to 100% were the two days the temperature was over 95F and the 12v fridge couldn’t handle it and ran all day long trying to keep things mildly cool.
Usage Habits
- Propane heater was set to 50F overnight (flannel bedding rocks in cold weather). I have the Truma Eco Combi Plus.
- 12v fridge was set to 2 during the day and turned off at night.
- I used solar lights in the evening rather than the built-in LED lights.
- I used the laptops a fair amount for writing, so charged the MBA most mornings for an hour and the MBP a few times during the week. (I would have used them more but there was zero connectivity so no posting or social media!)
Trimetric Readings with Notes
Day 1 PM – 96%
Day 2 AM – 92% – overnight low 40F
Day 2 PM – 93%
Day 3 AM – 87% – overnight low 40F
Day 3 PM – 87% – fan medium for 3 hours, fridge ran a lot (day temp 90F)
Day 4 AM – 82% – overnight low 43F
Day 4 PM – 83% – fan high for 4 hours, fridge ran all day (day temp 95F)
Day 5 AM – 79% – overnight low 49F
Day 5 PM – 87% – fan medium for 2 hours, charged laptops
Day 6 AM – 84% – overnight low 42F
Day 6 PM – 91% – fan high for 2 hours, fridge on 3 for 3-4 hours (day temp 88F)
Day 7 AM – 88% – overnight low 42F
So what did I learn here?
- Full sun makes for a very happy battery.
- Too much sun = very hot Alto = 12v fridge wasn’t happy.
How hot can an Alto get? Well, I left it locked up except for the fan vent remaining open and went for a day trip. When I got back, it was 114F inside the Alto. So, yeah, it’s a tin can of a trailer in full sun and high heat.
Act V: Sucking Up the Power
Now, let’s move to the question of what uses power in the Alto and how much does it use? To do this, I let the solar panels cool off after sunset for a few hours, until I could see that the Trimetric amps in/out feature was showing no input and just a tiny bit of output (we’ll call this the phantom output because everything else is turned off completely except the Trimetric monitor). From there, I turned on each item and watched the amps out reading until it had settled, then recorded that number. Some items have more than one setting (lights have a dimmer, fridge has several degrees of coldness, and the fan can go from low to high and anywhere in between), so in those cases, I recorded the two settings I use the most. And then I put it all into a spreadsheet and developed the two scenarios I have been using most: (1) cool day (cooler weather and/or shady spot) and (2) hot day, using half the electronics.
Now I know that I can run the lights all evening and not worry about it, which is great to know on long winter nights. And it confirms what I already guessed, that the 12v fridge is a big consumer; on hot days, it will use even more power because my estimate uses 15 minutes/hour but at Big Bend, I was seeing closer to 45 minutes/hour.
I haven’t done an energy audit on the Truma heater/water heater. It does take some battery power to fire up the propane and then run the fan (always set to Eco mode). It’s next on my list.
Epilogue: Thanks and Acknowledgements
- To Richard, for telling me what to order and then installing my beloved Trimetric (and thanks to Alissa for the installation support for Richard).
- To Karl, for answering a lot of newbie questions about fulltiming and battery usage.
- To Jim, whose blog on battery usage was my jumping off point for the Sucking Up the Power section above.
- To my cousin, John, for helping me figure out watts, amps, and solar power stuff.
- To my dad, who repeatedly said “turn off the lights” when I was growing up. He was right, as always.
I really appreciate your blog posts. I’m in the Seattle (Woodinville) area so relatively nearby. I’m sure my wife and I would both like to see a 1743 in person sometime!
I don’t own an Alto yet, but I’m hoping to be able to find an F1743 sometime during my remaing years on earth (hopefully in the next year or two) – used/new are okay.
Just a comment about one generator for those needing to top off their battery when the solar isn’t producing enough power. With my current trailer set-up (we want an Alto to lighten up and to get a smaller tow vehicle!) – I have 300W of solar on the roof, but – as you say – under trees and particularly in winter, the solar just doesn’t produce enough to keep up with my relatively modest power demands.
For those occasions, I carry a very small Honda EX350 generator (unfortunately, no longer manufactured – you’d have to buy used!) – about the size of a standard 12V deep cycle battery. The generator runs on 2-cycle mix, but is quiet, runs for a long time, with an output of 300W 120VAC (inverter) or 10A 12v to charge your battery. It is a great setup that you can leave running until the full tank (about a pint of fuel) runs out – to charge your deep cycle battery. I wish they still made these since they are perfect for topping off a 12V Deep Cycle battery!
We have avidly read this post trying to figure out what is draining our battery. We had to replace our 4 year old battery in Bryan, OH when it died after a HH overnight. The new Marine battery was fine boondocking for 3 nightsin full sun in Fort Collins, Colorado. We had electric most of the way to Kentucky, then boondocked 2 days in a row near Mammoth. We lost all power, including lights at one point. I spoke to Frederic at SC Friday, July 3 and we troubleshooted it down to it being aTV issue. Sure enough, we had a bad fuse in the harness. We were helped out by Central Kentucky RV who changed the fuse and charged our battery. Truly frightening to drive with no running lights. Thereafter, we have not been able to maintain a charge overnight without electric, despite the solar panels. Thank goodness we’re home now, but we are scrounging around to figure out what is happening. Thank you for all your guidance which is hopefully helping us unravel the mystery.
I hope you can figure it out. If your new battery was drained all the way down, it will never be the same and you might want to invest in (yet another) new one. Have you checked all the connections, from solar converter to battery and made sure they are all tight? I did at one point have very bad solar input and it was because the wires had worked themselves loose on the solar converter (which is very hard to reach, you have to take apart the front shelving under that long, narrow cushion). After I tightened those wires up, my solar started working fine.
Exceptional post, Annie! I’m looking forward to installing a BMS so I can have a little less battery anxiety. Hopefully we’ll get a lithium battery in there one day too.
Hi, Justin, and thanks for reading! Given your plans and the age of your Alto, I’d suggest looking into getting a lithium-ion battery, upgrade the solar controller as well, and put a Victron monitor on the whole thing. It makes my dry camping/boondocking experience a whole lot more fun, and way less anxiety about power!
Annie, Do you think cracking a window and running the fan during the day in Big Bend N.P. would have kept the interior a bit cooler? Maybe the power used by the fan would be offset by less power being used by the refrig. plus you would be returning to a slightly cooler trailer.
The fan didn’t really make much difference, it was 90F or higher outside the Alto during the day, so the diff between 90F outside and 110F inside was pretty nominal as far as comfort goes; both temps were miserable. I ended up bailing on the last two days of my reservation, and even the camp host admitted those temps were unseasonably hot for end February 🙁
Excellent post!
Annie,
Did you also install the matching solar panel controller along with the Trimetric monitor?
I didn’t add the solar controller.
A+ post, Annie! I have a much better understanding now and won’t have to bug you with so many questions and angst about the electrical “stuff.” 🙂 I especially appreciate the breakdowns in your spreadsheet, because I tend to practice similar usage routines dry camping in the ever changing temperature and solar availability scenarios.
Wow! We will be referring to this often when we finally get our 1743!!! Love your blog posts, ALL of them i cluding the “sciency stuff” as I call it. LOL
Annie you are a legend. Thank you for all the detail.
Thanks, Mal! I am happy it was useful to you, but I’m blushing at the legend comment 😉
I second Donna’s comment. I read your blog and Alyssa’s blog faithfully. Your experience and the information from Richard via Alyssa’s writings have been extremely useful! Jane and I pick up our R1723 on May 8th. So much to learn!!
Thank you, Daniel. I wrote it to help myself sort out what I was learning, and realized that Alto people might benefit too, since the learning curve can be challenging for batteries and power.
Annie, this is fantastic! I want to know what you know! Electricity, batteries, volts, amps, etc. are a black box to me. Thank you for shedding some light. Now I understand why the Trimetric or something like it are a must-have, especially for lengthy Alto stays. I’m keen to read anything else you care to share about this essential topic.
I learned it all in the last year, reading blogs and asking questions of people on Altoistes and in person. It wasn’t that hard once I committed to learn it, honestly. It was more trepidation before I started.
FWIW, when we had an RV, it had a propane refrigerator. I am not sure if those are more efficient or not, but it did mean not having to use juice on the fridge. And it did not seem to use a great deal of propane in comparison to the heater.
I went with 12v fridge because solar can usually power it, and it’s one less thing to use the propane. I don’t know if it’s more efficient, it might be!
FWIW, the table is fairly accurate, but the voltage it wants is open circuit voltage, so if anything is drawing current, the voltage will read lower and make it look like it is less charged. I assume the trimetric compensates for the current load to give a more accurate reading of the charge.