Critique my battery/solar setup before I purchase!

[Esus]

The one you linked to (Solar Cynergy 120W semi flexible from solar blvd) is the one I have. It is claimed to be 2.5mm thick, which seems about right.

I see that now on the description tab. Thanks. When you click the additional details tab it states: 52 x 23 x 2 in

I'm curious, it the 52 X 23 part also mm? I was trying to get a feel for how much space it would take up on the roof. Though since this thread, I'm now contemplating a higher voltage/watt single rigid panel.

 

[Esus]

The problem with using the 6V batteries is that it is all or nothing - with 12v batteries you can start with one then add more in parallel for more capacity, which is why I would go that route.

I am not sure where you are located - but around here a 2 day storm with little to no solar (or driving to better weather) is a very rare event. It is more likely to happen in the winter, but in that case your fridge would almost never run and you wouldn't use the fan so you would probably be under 30Ah per day. Also, even when overcast you may still get 15% - 20% of your solar yield so it is not a 0 input. I guess my advice is to design for 90% of scenarios, and on the rare occasion that you are outside your spec, modify your behavior instead of way over designing your system for that once in a blue moon scenario.

I absolutely get what you're saying with respect to planning for majority of scenarios and adjusting behavior/needs in the rare situation. Here's my dilemma. You mentioned the ease with which a second 12v battery can be added if needed whereas a 6v solution pigeon holes me. I kind of see it the opposite way. If I go with the two 6v Lifelines, I can fit them both in my battery cabinet, will certainly have enough amp hours for all my needs, and will have a fixed weight of 132lbs. If I go with a single 12v 125 ah Lifeline and end up needing more amp hours, I will not be able to fit a second battery in my compartment and the batteries weigh even more than the 6 volt solution then.

To be honest, I like the single battery solution. Simplicity, cost savings, weight savings. I just need to be sure that it will truly power my off grid needs. The fridge is what it is. The fan will probably run all night if it's hot while we're sleeping. The heater will need to run to keep the family warm. I have seen several comments that 60ah a day seems to be a pretty fair average. And you have also said I'm coming in way too high at 110. So I'm thinking the 125 ah battery is a nice in between. Gives me 60 ah per day even before solar (and more if I go past 50% occasionally). Add a solid solar setup to power loads and recharge and that number is a lot higher. Grab a little off the alternator while driving. It seems reasonable. I'll be kicking myself if I undershoot though.

Just need to find the right panel and size it correctly I suppose. I can't be dragging a portable out that I don't have room for and messing with long cables. I'm out climbing and jumping off cliffs while the sun is out!

 

[Stalking Light]

If you will be doing any camping at all in hot humid conditions like the SE US don't underestimate your battery usage. I have an Eagle with a Dometic 65 and it runs almost constantly during the summer months, and the hazy air doesn't do much for solar efficiency. I have 300w solar on the roof and a 60w foldable panel and I still sometimes take a generator if I'm going to be camping a long time in cloudy weather. Even though I swapped out my Surepower for a BlueSea ACR I still don't rely on much charging from the truck. I don't like portable panels much due to the overhead deploying them and putting them away although I know they can be more efficient if you keep them oriented properly.

My roof solar is my original 100w Zamp and 2 100w GoPower flex panels attached with 5100C double sided acrylic foam tape.

 

[Esus]

If you will be doing any camping at all in hot humid conditions like the SE US don't underestimate your battery usage. I have an Eagle with a Dometic 65 and it runs almost constantly during the summer months, and the hazy air doesn't do much for solar efficiency. I have 300w solar on the roof and a 60w foldable panel and I still sometimes take a generator if I'm going to be camping a long time in cloudy weather. Even though I swapped out my Surepower for a BlueSea ACR I still don't rely on much charging from the truck. I don't like portable panels much due to the overhead deploying them and putting them away although I know they can be more efficient if you keep them oriented properly.

My roof solar is my original 100w Zamp and 2 100w GoPower flex panels attached with 5100C double sided acrylic foam tape.

I ran into the same thing when I was driving around Central America. I thought I would have the best solar there when in reality it was likely the worst because of the fridge's constant run and the humidity. Most of my time will be spent in CO/UT/WY but trips to humid places are certain to happen as well. I'll probably go with 240 or 260 watts for now and then add a panel if I plan on a big overland trip south again.

Just curious, how many amp hours are you packing in your battery/batteries?

Have you ran into any overheating issues with the flexible solar panels?

 

[Stalking Light]

I have 2 75ah agm batteries. I found that when I had added one of the flex panels the charging was adequate when I was in dry sunny climes so I added another to be on the safe side.

I've never run into any overheating with the panels, I think the double sided foam tape provides a bit of space between the roof and the panels plus the GoPower panels are designed for this type of mounting in a variety of applications.

 

[Esus]

I have 2 75ah agm batteries. I found that when I had added one of the flex panels the charging was adequate when I was in dry sunny climes so I added another to be on the safe side.

I've never run into any overheating with the panels, I think the double sided foam tape provides a bit of space between the roof and the panels plus the GoPower panels are designed for this type of mounting in a variety of applications.

Two 12v in parallel right? So a usable capacity of ~75ah at 50%? I'm still really struggling with my ah/weight-of-battery ratio. I don't want to oversize it, but I don't want to fridge to shut off if I don't get solar for a bit. Curious because you have the same fridge which is my primary load and concern.

 

[abqbw]

It depends on how you want to use the panel. They are pretty floppy (think sheet of thin cardboard), but if you plan to deploy it flat on the ground or leaning against your windshield, it would be fine as is. I wanted mine to be more rigid to use with a small stand so I stuck a piece of 10mm thick expanded PVC to the back (vycom celtec). This adds a couple of pounds to the panel, but makes it rigid enough to stand on edge. Double wall polycarbonate greenhouse panels were also suggested as a material to make it stiffer. I have a double cab truck without any seats in the back, so I store the panel there. It is only about 15mm thick so you could store it under the bed too.

Thank you for answering the question so thoroughly. Very helpful.

 

[Stalking Light]

Two 12v in parallel right? So a usable capacity of ~75ah at 50%? I'm still really struggling with my ah/weight-of-battery ratio. I don't want to oversize it, but I don't want to fridge to shut off if I don't get solar for a bit. Curious because you have the same fridge which is my primary load and concern.

Two in parallel is correct. I did add a second external fan to my fridge which has made it a bit more efficient but nothing magical.

 

[Boonie]

- I would personally avoid the commonly recommended trimetric. If you are already going with Victron for your solar, get the BMV-700, which is a far superior product that can also use your bluetooth adapter (see Vic's thread for details).

I missed this comment previously, so could someone give me reason to avoid the trimetric ( I assume the Bogart 2030)?

PS I do not have or use a "smartphone" or bluetooth.

 

[Vic Harder]

I missed this comment previously, so could someone give me reason to avoid the trimetric ( I assume the Bogart 2030)?

PS I do not have or use a "smartphone" or bluetooth.

Oh Boonie, this is almost like a Ford vs GM or Beer vs Wine question!

While I went VictronEnergy and MPPT myself, the Bogart/Trimetric stuff is very good and works well for many people and situations.

I went with the MPPT solution because:

- I wanted to minimize power loss by running higher voltage, less current, across skinny wires
- MPPT typically has better power production in the conditions I will be camping in (for example, cloudy and snowing here today and I am still getting 25w out of my 265 roof mounted panel)
- I don't mind the extra complexity of having multiple guages (battery and mppt gauges) vs the simple single TM2030.
- The Victron stuff looks snazzy
- It has my name in it!

 

[rando]

I made that comments originally. I understand the trimetric works well enough - but the user interface interface is poorly done, and the Trimetric is missing some minor (and one major) features that others (Victron, Xantrex etc) have, yet it costs more. But the thing that really bugs me about the Trimetric and Bogart is that they make a bunch of bogus claims as to why their product is actually superior to the competition because it lacks these features.

PS The minor features are peukert effect compensation and thermal compensation and the major feature is Maximum Power Point Tracking in their solar charge controller.

 

[Boonie]

Rando,
Thanks for the info. I don't want to hijack this thread, but without a smartphone/bluetooth which do you recommend?

 

[Vic Harder]

Boonie,

Rando and I are vastly in agreement on most electrical/solar questions. Even the Bogart/Victron one. Minor differences, and when I make a boo boo, Rando is kind enough to point it out. I really appreciate that!

You don't need a smartphone/bluetooth to use the Victron stuff. And it is very high quality indeed.

 

[rando]

Agreed on the Victron - that is what I have. Blue Sea Systems also makes one with an even snazzier OLED interface but it is quite new to the market.

 

[craig333]

The Trimetric does offer temperature compensation but you have to purchase it seperately.

 

[Boonie]

The Trimetric does offer temperature compensation but you have to purchase it seperately.

The Trimetric option re: temperature that I understood was "Battery temperature monitoring" not compensating. Did I miss something?

 

[Vic Harder]

Manual says Trimetric compensates, and measures temp directly off the +ve battery post. It is actually one of the things I thought the Bogart stuff did better than the Victron I have.

My Victron 75/15 does it indirectly, by measuring the temperature of the MPPT controller, not the battery. I DO have the BMV 702 with the temp measuring option, so I can read what the temp of the battery is, and my controller and batteries are in very close proximity.

 

[rando]

The Trimetric does offer temperature compensation but you have to purchase it seperately.

Only on the solar charger, not on the trimetric.

This is important if you camp in the winter:

 

[Boonie]

And I thought Vic and rando always agreed.


Rando, as for me I follow your concept of meeting 90% of anticipated then modifying my habits if I encounter the 10%. Which means "winter" camping is camping in Dec-Feb on a beach.

 

[PaulT]

Temperature of the batteries when they are being cycled regularly in winter is likely to be heavily influenced by the camper with the most desire to stay warm while camping. In my case, that would be my wife. That would put the capacity probably in the 90% and up on the above temperature/capacity chart because the batteries are in the heated area..

Temp compensation would seem to be most important for the charge controller. The battery monitor is tracking SOC by computing energy in and out and battery voltage so I guess I don't understand why its lack of reading the battery temperature sensor is that important. Victron apparently agrees as they apparently use the temp of their charge controller?

Anyway, both Victron & Bogart products have satisfied customers. As to MPPT vs, PWM, they each have ranges of system size where they excel with considerable overlap in the area where their ranges meet. In the overlap, you can pick like you choose gasoline over diesel, or Coke over Pepsi, or ATC over FWC, or ice cream over pie (both for me, thanks)

Paul