They solved my problem

[AJMike]

We just returned from a trip into the Gila mountains in southwest New Mexico. My wife likes to soak in mineral waters to relax and there is a campground near the Gila Cliff Dwellings that provide several mineral water pools in a beautiful natural setting next to the Gila River. The place had been closed due to the virus but opened a couple of weeks ago with State-mandated restrictions and we made some reservations. As I have mentioned in some other posts the campground is quite nice but also offers some challenges.

First, the spaces are small and the owners won't allow large RVs. Our Fuse is 24 feet and is probably about as large as someone could get in the space.

The campsite is surrounded by mountains and thus direct sunlight is limited to about 6 hours a day (about 9am to 3pm) and further limited by the heavy foliage. Our campsite had a small arc of sky without tree coverage and it seemed to me that we had perhaps 60 minutes of direct sun, perhaps a little more, and then the sun was again limited by the foliage. Since the sky is generally filled with clouds there is usually even less usable sunlight for the solar panels. And since the owners do not allow any generator use the sunlight is all you have to recharge the batteries. And, of course, there are no utilities. It is as close to boondocking as you can get in a prepared campsite.

Our Fuse has a compressor refrigerator and I have found that the RV typically uses a bit more than 5 amps per hour during the day with nothing but the refrigerator and other built-in electronics running, and perhaps 3-4 amps per hour at night, depending upon the ambient temperatures. Colder means lower power usage, warmer means higher, so my basic assumption has been that the RV consumes about 100-110 amps per day, (12 x 5.2) + (12 x 3.8).

On our previous trip with our 62AH AGM batteries we were so low on power the first morning that we had to close up the RV and drive somewhere to recharge the batteries. It was not wasted since we went to the Gila Cliff Dwellings and ran the generator while we hiked up and back down the trail at the site and were able to get our batteries back to 100%. The second morning we left very early because I was not sure we would have enough power to run anything since the batteries were seriously low.

This trip was very different. This is the place that I had in mind when we upgraded to the BB batteries. We had 2 batteries installed and although I was not very worried I was unsure how much power would be left in them after 2 days without driving around to recharge. I thought we night be down to 15-20% on the second morning but assumed it all depended upon how cloudy the day would be.

We arrived about 2:30 in the afternoon with full batteries from the drive but by 8pm or so were down to 91%. The night was cool and early in the morning we were down to 75%, and down to 71% by about 9am when the sun was high enough that the RV was no longer in shade.

From then until about 11:30 we got a small amount of sun through the foliage and then some direct sunlight until perhaps 12:30 or so when the sun again went behind the leaves. Fortunately for us the sky was clear and we were getting 17 AH or so of power with the direct sun. By the evening we were up to 92%.

That night was very cold (it was freezing in the morning) so the refrigerator did not consume very much power. In the morning when we left it was about 72%, so we were never really low on power. Here are the figures I came up with:

1) power consumed first day - 100% down to 71% = 29% = 58AH.
2) power consumed second day - 92% down to 72% = 20% = 40AH
3) net solar added first day - 71% up to 92% = 21% = 42AH

My assumption is that had we been using our old AGM batteries the 58AH usage the first day would have left us with 53% capacity left. Close to the safe minimum. The second day's solar input would have left us at about 84% and the second nights usage would have left us with about 51%. Again, perhaps OK, if barely so. More to the point if the second night had not been so cold and if we had used as much as we did the first night then we would have been down to 40% (58AH + 58AH loss, 42AH gain = net loss of 74AH) and I suspect that would have been a serious issue.

Alternately, as I said, the day was clear with no clouds. Had it been like the other times we were there I think we would have been lucky to get 60% of the solar power that we got, which would have given us 58AH used first day, 24AH added second day and 42AH used second night for a total loss of 76AH. That means that the batteries would have been at 39% and I don't know if that would have been enough to run anything. The same figures with out BB batteries would have left us with 62%, more than enough to spend 2 more days, so I am completely satisfied. It was not a cheap upgrade but the whole business cost me about $2600 for the 2 batteries, the DC-DC charger and the installation of both.

However it did leave me with a question. I was very surprised to find us back to 92% by sundown on the second day since I don't remember our AGM batteries charging so quickly even in direct sunlight. Do the Lithium batteries accept charge more quickly than wet cells? Or AGMs?

[Winterbagoal]

"However it did leave me with a question. I was very surprised to find us back to 92% by sundown on the second day since I don't remember our AGM batteries charging so quickly even in direct sunlight. Do the Lithium batteries accept charge more quickly than wet cells? Or AGMs?"

Rumor is, yes, they charge faster because they have less "internal resistance" and so can accept charge faster than FLA. Don't quote me on that, though.

Even on an overcast day, I can pull some amps in from the panels. That helps, too.

[AJMike]

Originally Posted by Winterbagoal

Rumor is, yes, they charge faster because they have less "internal resistance" and so can accept charge faster than FLA. Don't quote me on that, though.

Even on an overcast day, I can pull some amps in from the panels. That helps, too.

If true that would explain why I saw them recharge so quickly. I could not believe that with the little sunlight the batteries got back to 94% and if the AGMs would have charged more slowly then I assume I would have had an issue with them even with the second very cold night and the lower power usage.

[Winterbagoal]

Originally Posted by AJMike

If true that would explain why I saw them recharge so quickly. I could not believe that with the little sunlight the batteries got back to 94% and if the AGMs would have charged more slowly then I assume I would have had an issue with them even with the second very cold night and the lower power usage.

Your AGMs would have struggled. That's why I replaced mine. Inadequate and unreliable. The new 2020 View/Navion units have a GR31 AGM (standard batteries) or a lithium upgrade for around $5000. You and I have done it for a lot less than that. They also come with a 2000W inverter, which would have been a better option. I have the 1000W unit and sometimes wonder if I'll exceed it's ability making coffee or whatever. So far, it's worked fine, but with inverters, more is better. (for me)

[AJMike]

Originally Posted by Winterbagoal

They also come with a 2000W inverter, which would have been a better option. I have the 1000W unit and sometimes wonder if I'll exceed it's ability making coffee or whatever. So far, it's worked fine, but with inverters, more is better. (for me)

The added power in the LiFePO4 batteries made me wonder about the inverter as well. I almost connected my wife's electric hot water kettle to the inverter while camped since it is rated at only 700 watts, but don't know if the refrigerator runs off of the inverter as well and did not want to have to hunt around for the right fuse. Monday I should call Winnebago and ask how much of that 1000 watts is actually usable.

I thought about having the inverter upgraded to 2000 watts and even checked on prices on Amazon but I don't know what the installation cost would be since I assume the wiring would also have to be upgraded and I don't know how much of it would be involved.

As for the batteries, I don't know how to put a price on the peace of mind that I now have knowing that my batteries will be usable in the morning. Now I wish I had done it 9 months ago when I upgraded to AGMs.

[orangeminnie]

Lithium rocks!