Battery SOC, battery options, strategies, etc.

[ROBERT CROSS]

^
MacGyver did a complete 360w portable system for $3.6k.

You can get a very capable system for a lot less than the inflated $10k mentioned.

Bob
🇺🇸

[Sport 16 STL]

From what I understand is mixing solar controllers can be a problem. I don't believe mixing solar panels into a single controller is an issue.
Can anyone confirm?

[ROBERT CROSS]

https://www.youtube.com/watch?v=rSj6-JSxoD4

FWIW...both our panels have the same controller, and one will shut down before the other when approaching full charge.



Bob
🇺🇸

[TouringDan]

Based on the way you are camping, I would add a portable suitcase and just go camping. We have 400 watts on our truck bed cap but some of the time we carry kayaks on top. You just can’t beat the flexibility of portable panels.

We have lithiums and love them (along with an inverter), but you certainly don’t need them.

Dan

[Gulliver72]

In an effort at succinctness:
Our set up; 400W on the roof, 400AHr lithium under the beds, 2k hybrid inverter, internal surge protector, lots of monitors.
With all this, the best thing I did was add a Renogy 40A DC/DC charger, heavy gauge wiring from TV battery w/ Anderson plugs at hitch end. We move a lot. Getting as much as 900w input while driving. Lithium’s will suck up everything you send them. Go from 20% SOC to 100% in 4 or 5 hrs. We carry a 2500W generator that we haven’t used in the last 3 trips. Will be leaving it behind. BTW we boondock 60% of the time, using HP, furnace, and electric heaters.
BTW, IMHO, the Victron Hybrid inverter/charger is worth EVERY PENNY!

[RJKSr]

They key to successful boon docking is to know what your expected usage is in a 24 hour day. Once you know that, you can plan what you need and what to expect. Our needs are fairly modest. We don't need to power appliances, just occasional lites and water pump, along with loads for the refrigerator propane control, and hidden loads like the propane/monoxide detector. We found that we used around 35-40 amp hours a day. If you do a lot of cold weather camping, that could go up quite a lot if using the propane heater.

We found after two days, the two 75AH lead acid batteries that came with it were pretty much done without charging. We had a Renogy suitcase solar that was OK if you want to follow the sun with it and had the room to do so. We had JC add 240 watts of solar on the roof and that helped, but if we had more than a couple cloudy days or a shady site, it was still a problem. We already have a Honda 2000, and that helps in campsites that allow limited generator use, but not all do. After two failed sets of Interstates, we moved to heavy duty 6V golf cart batteries with 240AH capacity, which gave us 120 usable amp hours and extended us a few more days.

In the end, our goal is to go with lithium iron batteries under the front sofa. But that is quite a project and not inexpensive. Keep in mind that most factory converter/chargers cannot adequately charge lithium iron batteries. So that would likely need replacement as well.

[smsasf]

Originally Posted by Dennis C

I'm wondering if a bigger Goal Zero unit might work better in that regard...

After thinking about this thread and talking with my wife, I'm leaning at this point towards buying the Zamp 230 W briefcase portable solar panel and trying that out next year. It's rare that we need anything like the microwave or the television when we camp, and our use of the air conditioning is fairly rare also. If I can keep my AGMs topped up with a portable solar panel, that might be enough for now.

Dennis, I just finished a 52 days trip out west from NC that included your home state and various dispersed camping, as well as Fed and State parks and private pay. I have a 2020 Bambi 20’ purchased in June which came with Zamp 90W on roof. I added an additional Zamp 90W to the roof as changed out the Atkinson charge controller to a Victron 100/30 and also added the Victron Smart Battery Sensor to the battery box. Both are Bluetooth and have smartphone apps so you can set and monitor. I originally purchased a Zamp 230W portable but at 50 lbs and given its large area size imfound it too difficult to move around. Returned it and purchased the Zamp 180W portable at 35 lbs. My camping lifestyle seems similar to yours. If weather is nice I am mostly outside hiking and doing things, not sitting in trailer watch TV or laying around. So during the day little power is being used except for the refridge cycling on for cooling (mine is battery or electric, not propane). Other than fridge, only the propane sensor, the clock on radio, clock on microwave and converter are drawing any power. And sometimes the roof vent fans if hot. I turn off water pump when out.

My own experience has shown that if the trailer is in the sun so that both of the two Zamp 90W are exposed and I am away for a few hours then the two 80AH Lifeline AGM batteries are always in float at about 13.2V when I return. At one dry camp in NF down the road from Bryce Canyon I had parked AS along side of tall pine tree so that from around 11:00 am to 3:00 pm the solar panels were mostly receicing partial light. Batteries may have been around 13.0 V and in bulk stage. I pulled out the Zamp 180W portable and placed in direct sun light, hooked it to A-frame port (which is wired directly to the battery) and within minutes it was generating 14.4V and shoving amps to the battery. Within 30-60 minutes batteries were in float. The Zamp portable has its own charge controller and as to question of tehther that and the Victron work together, all I can say is that it seemed the Zamp portable took control of the charge directly, but the Victron saw what was going on and reported the float status.

So as long as I had sun, rooftop or portable, my batteries were at 13.0-13.2 when sun went down. In the evening with lights and maybe a fan running while cooking and water pump while washing dishes or showering and during night when refridge would come on for about 5 minutes every 15-20 minutes seems I did not draw down batteries too much. They would typically be at 12.7-12.8V in morning. Now, if I turned on furnace before bed and pushed temps up to 75 inside (because it was scheduled to be down in 40’s) the fan would draw down batteries a bit. I turned off. But sometimes in morning, around 5:30 am I would turn on furnace again for 10-20 minutes and watch battery voltage on Victron app. The furnace fan running could draw down batteries to around 12.5V or sometimes 12.4V, but the draw down would occur at onset fairly quickly and then kinda sit there during the 10-20 minutes. After shutting off furnace the voltage would creep back up to 12.6-12.7V. So at least in my case based on my life style I have been able to get by with 2 Zamp 90W on roof and the Zamp 180W portable suitcase. Also, on the transit stops in the Walmarts (Casper, Butte, Beaumont) I left the TV umbilical plugged in (my set up does not allow TV battery to be drained) and in early hours when it was cold I remote started the truck from my phone app and started the furnace and let it run longer since the TV was charging battery.

Other folks have mentioned high end more expensive upgrades but I would suggest you step into any upgrades after learning more about your needs. You can overkill it. Oh, one last point, I do have a portable Champion 2000W inverter generator (propane or gas) that weighs 47pounds. It is quiet and I have used it time to time, especially if I decide in advance I want to use microwave.

Also, if you look at Lifeline AGM document they show a SOC chart. Starts with around 12.78V at 100%. But they say that is for used battery and for new battery use around 13.0V for 100%.

Hope my own recent experience helps. Kind Regards, Stephen

[Dennis C]

Thanks for that Stephen. I appreciate your comments.

[smsasf]

Dennis, one last comment. When I have been in trailer in day for some reason and both Zamp 90 W roof top panels were in full sunlight, with batteries already in float, and I tested the balance of battery drain versus solar recharge by turning on multiple lights, TV, both roof vent fans, while refridge was in run/cooling cycle I think the most watts output noted on combined roof 180W panels was maybe 120W. Monitored this from the Victron 100/30 charge controller app on my iPhone.

[Dennis C]

I’m thinking my current setup might be okay - I just haven’t had enough sun exposure on my panels. The portable unit may solve that.

We’ve already booked our first two trips for the spring of 2021. Both of them have electrical hookups, so no need to rush into this yet.