Critique my battery/solar setup before I purchase!

[Esus]

Hey everyone. Just equipped my Chevy Colorado with a 2015 FWC Fleet. I’m not an electrical pro, but I’m also not a rookie having built a camper van from scratch in the past. I have a system designed but thought I’d bounce it off you guys before I purchased the gear. Chime in if you have any thoughts!

I calculated my daily amp hour requirements and built a little cushion into the numbers. Looks like at the most I’ll require 110 ah.

In my hunt for batteries, I decided to shell out the cash and do it right. I’m planning on buying two Lifeline 6 volt, 220 ah AGM deep cycles and wiring them in series of course. Not only are these great batteries with a 5 year warranty, but it’s the most amp hours I can get when I consider the battery size vs fitting two of them in the actual FWC battery compartment. Also, the compartment doesn’t have ventilation and I don’t want to add it, so I opted out of flooded cells.

I’m mostly off grid camping and would like to go indefinitely. The plan is to buy two flexible 120 watt panels (so cheap these days!) and mount them in parallel to the roof with a good controller (12v/20-25ah). I was looking at this controller: http://shop.pkys.com/Victron-Energy-MPPT-10030-Solar-Charge-Controller_p_3666.html and these panels: https://www.solarblvd.com/products/solar-cynergy-flexible-bendable-120-watt-12-volt-solar-panel/

I like the Victron controller because I can get this dongle for it http://shop.pkys.com/Victron-VEDirect-Bluetooth-Smart-dongle_p_3796.html and get excellent monitoring and control info directly on my smartphone.

I had 230 ah capacity and 200 watts solar on my old rig and could go indefinitely off grid without driving. I think with 220 ah capacity and 240 watts solar I should be fine?? The batteries are better and the solar is more efficient in this setup too. I’m counting on the solar to do most of the heavy lifting! The Chevy Colorado has a Regulated Voltage Control (RVC) system that cuts the voltage way down from the alternator when in Fuel Economy Mode (and I like the fuel economy mode – avg 15mpg on a shakedown run to WY over the weekend). Between that and the 10awg wire FWC ran, I’m not counting on getting much recharge from driving – especially with the fridge running.

The FWC comes with a Sure Power isolator. I don’t know a ton about it, but I’m guessing it simply senses 13.8/14+ volts and opens the circuit? I wonder if that’s bi directional and the solar on the house batteries will open the circuit and send power to the engine battery. Not sure if there’s any issue there I need to be concerned with? In my old rig I had a voltage sensitive relay and configured it to only charge from engine to house unless I manually overrode to go the other direction.

Feel free to critique. This is my dream camper/truck setup so I don’t want to cut any corners or mess anything up. My last rig was purpose built to be disposable and only go one way and it most likely is still sitting in Argentina somewhere!

Cheers,
Eric

 

[RC Pilot Jim]

Looks good Eric

You will average less than 5 amps per hour draw. 220 watts should give you around 8 amps in on December 22nd and over 10 June 22nd..if you can't tilt the panel into the sun.

I don't recall if you have a battery monitor. If not buy something like a Trimetric 2030RV to show your amps in and out and percentage of full.

I didn't have good luck with the flexibles going back to a 150 watt rigid for our application.

 

[Esus]

Looks good Eric

You will average less than 5 amps per hour draw. 220 watts should give you around 8 amps in on December 22nd and over 10 June 22nd..if you can't tilt the panel into the sun.

I don't recall if you have a battery monitor. If not buy something like a Trimetric 2030RV to show your amps in and out and percentage of full.

I didn't have good luck with the flexibles going back to a 150 watt rigid for our application.

Thanks Jim, those are the same numbers I was getting with respect to daily use and solar generation. I'm wondering if the solar dongle will monitor the battery as well, otherwise I'll need to add that.

We're you having bad luck with flexibles in general or specifically the ones I linked? I'd hate to end up with lame panels.

 

[Happyjax]

Esus,

Vic Harder did a great write up on his solar install using Victron MPPT.

http://www.wanderthewest.com/forum/topic/13230-i-need-more-power-scotty/page-12

 

[rando]

This looks like a good plan - however I think you are over estimating your power needs. For instance, it is unlikely you would run your furnace for 4 hours a day and your fan on medium for 8 hours a day and have your fridge running that much. I have essentially the same setup as you (fleet flatbed on a Tacoma, albeit with an Isotherm fridge as opposed to the less efficient Dometic) and do just fine with the stock 70Ah battery and a 150W roof mounted solar panel. With your fridge you may want to go with a 90Ah battery, but no need for 220Ah. Weight is going to be your enemy and 220Ah of batteries is HEAVY. It is a better idea to save some weight and occasionally draw your batteries down to 30% SOC. Don't forget that when you fridge will need to run the most (middle of the day in the sun) your solar system will also produce the most power. Maybe start with a single 12V battery and if you end up running low, add a second battery.

A couple of other comments:
- I would be a little cautious of roof mounting the flexible solar panels. While their weight is very attractive, there have been so many problems with them. You would hate to hard mount the panel and have it fail within a year. I use a rigid panel on the roof, and a solar blvd 120W flexible as a portable.

- I would definitely want to add a battery monitor to your system so you can watch and learn about your batteries. 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).

 

[Vic Harder]

Indeed, it looks like you are off to a great start. Thinking about your needs first is the right way to do it. I agree with Rando that you are likely overestimating your draw. The other thing to keep in mind is that you need to account for not being able to charge every day. If you want to be out for 2 or even 3 days without charging, then you may want to take Rando's comments about not needing that much battery (probably true) and ponder what that means if you can't charge the next day.

I second the comments about getting a Victron BMW70x. Nice gear. And if you are using that MPPT controller, consider wiring the panels in series instead, using those as portables and/or getting a big 265W or more panel for the roof.

 

[Esus]

This looks like a good plan - however I think you are over estimating your power needs.

The other thing to keep in mind is that you need to account for not being able to charge every day.

Thanks for the feedback guys. Much appreciated. I did a lot of thinking on this but that by no means should point to my having got it right

I definitely padded several of the numbers. I figure in the desert the fridge will run a lot and my wife and I like to crank the fantastic fan the entire time we're asleep. But like Rando mentioned, there's a lot of sun in this scenario. But what if I'm camping on a ski trip and it's a full on blizzard for 2-3 days? Then I'm running the furnace a lot but getting little from solar.

So say I want to run at 60 ah a day average, but go at least 2 days in a good storm with little to no sun keeping in mind I don't ever want to drain my expensive AGMs past 50%? Wouldn't 110 ah usable be about right? I definitely don't want to over-engineer it, but that would always be preferable to under-engineering it.

Also, Rando, the extra battery is just a little over 60lbs. Not the end of the world, but not light.

If I can purchase one battery and a single panel... well that saves me a lot of money. Assuming I don't have to add later.

 

[Esus]

I would be a little cautious of roof mounting the flexible solar panels. While their weight is very attractive, there have been so many problems with them. You would hate to hard mount the panel and have it fail within a year. I use a rigid panel on the roof, and a solar blvd 120W flexible as a portable.

I was unaware of the problems with them having only used a rigid panel on my previous rig, but you're the second (out of 3 total people so far) on this short thread to mention it - that's alarming. Are they pretty notorious? In what way do they tend to fail?

 

[Esus]

I second the comments about getting a Victron BMW70x. Nice gear. And if you are using that MPPT controller, consider wiring the panels in series instead, using those as portables and/or getting a big 265W or more panel for the roof.

I had wondered if parallel or series would be better with the panels. Thanks for the thought.

 

[Vic Harder]

I had wondered if parallel or series would be better with the panels. Thanks for the thought.

The MPPT controller really only has advantages if the Voltage is high enough for it to play with. Plus the higher voltage drops your power losses over skinny wires

Also, I think what folks are referring to regarding the flexi panels is that if you mount them to the roof without air space under them, they get hot, and heat is the enemy of photo-voltaic power generation. Even without that, I have tested two separate portable arrays, and the power output from my big heavy panels was way higher than from the flexi panels. Bummer is I have no room for the thicker and better panels.

 

[Esus]

Esus,

Vic Harder did a great write up on his solar install using Victron MPPT.

http://www.wanderthewest.com/forum/topic/13230-i-need-more-power-scotty/page-12

Thanks for pointing me to this thread. Besides the loads of awesome info Vic researched, I especially appreciated Rando's Expected Lifecycles graph. Hitting 30% on the AGMs occasionally isn't such a big deal after all compared to 50%. Perhaps I am overestimating my power needs.

 

[Esus]

The MPPT controller really only has advantages if the Voltage is high enough for it to play with. Plus the higher voltage drops your power losses over skinny wires

Also, I think what folks are referring to regarding the flexi panels is that if you mount them to the roof without air space under them, they get hot, and heat is the enemy of photo-voltaic power generation. Even without that, I have tested two separate portable arrays, and the power output from my big heavy panels was way higher than from the flexi panels. Bummer is I have no room for the thicker and better panels.

My last setup used a 200 watt 30 volt house panel with an MPPT. It worked great. The point about the skinny wires is good too. I saw your mention of not wanting to rewire the FWC in your thread that happyjax linked. Maybe I need to scale down to one battery and get a higher voltage rigid panel. I definitely don't want a heat issue with the flexibles. It'll reduce capacity but it's unlikely I'll be in many sun blocking, multi-day storms, plus the panel will perform better. But I don't want to rely on alternator charging with the Chevy's RVC and the skinny wire... can't scale down too much.

 

[Vic Harder]

re the RVC: That sounds strange, BUT if there is a second battery wanting juice, won't the alternator assume the truck battery is where the draw is coming from and just keep charging? ARE you going to be driving every day? If so, you want to explore this more, as it is "free power" if you can access it.

The default separator you have sucks with skinny wires. It perceives the voltage drop and disconnects too soon. Consider a manual override, and/or a good separator like the Blue Sea ML ACR series.

Even over skinny wires, it should be able to manage the absorb and float levels of your house battery charging needs. It would be interesting to run the numbers using a voltage drop calculator for your setup.

The occasional 30% SOC is certainly tolerable. I just would not size my system to PLAN to have that happen. 60AH day for two days with NO charging at all means you do need about 120AH at your desired 50% SOC, so 240AH. That is a lot of battery.... and about what I have in my Hawk. Mind you, that is sitting on a 3/4 2500HD. Not a small truck.

 

[rando]

Thanks for the feedback guys. Much appreciated. I did a lot of thinking on this but that by no means should point to my having got it right

I definitely padded several of the numbers. I figure in the desert the fridge will run a lot and my wife and I like to crank the fantastic fan the entire time we're asleep. But like Rando mentioned, there's a lot of sun in this scenario. But what if I'm camping on a ski trip and it's a full on blizzard for 2-3 days? Then I'm running the furnace a lot but getting little from solar.

So say I want to run at 60 ah a day average, but go at least 2 days in a good storm with little to no sun keeping in mind I don't ever want to drain my expensive AGMs past 50%? Wouldn't 110 ah usable be about right? I definitely don't want to over-engineer it, but that would always be preferable to under-engineering it.

Also, Rando, the extra battery is just a little over 60lbs. Not the end of the world, but not light.

If I can purchase one battery and a single panel... well that saves me a lot of money. Assuming I don't have to add later.

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.

 

[PaulT]

On trips where solar input hasn't provided sufficient power to keep a comfortable reserve of battery charge, we have learned to find a campground with electric hookup, showers, &, usually, shopping nearby to replenish battery charge, food supplies, & hygiene in a single night.

Sometimes Mother Nature doesn't provide in a timely manner so we take evasive action so we can continue our trip. Be flexible and take advantage of opportunities to keep your trip going forward.

Paul

 

[abqbw]

This looks like a good plan - however I think you are over estimating your power needs. For instance, it is unlikely you would run your furnace for 4 hours a day and your fan on medium for 8 hours a day and have your fridge running that much. I have essentially the same setup as you (fleet flatbed on a Tacoma, albeit with an Isotherm fridge as opposed to the less efficient Dometic) and do just fine with the stock 70Ah battery and a 150W roof mounted solar panel. With your fridge you may want to go with a 90Ah battery, but no need for 220Ah. Weight is going to be your enemy and 220Ah of batteries is HEAVY. It is a better idea to save some weight and occasionally draw your batteries down to 30% SOC. Don't forget that when you fridge will need to run the most (middle of the day in the sun) your solar system will also produce the most power. Maybe start with a single 12V battery and if you end up running low, add a second battery.

A couple of other comments:
- I would be a little cautious of roof mounting the flexible solar panels. While their weight is very attractive, there have been so many problems with them. You would hate to hard mount the panel and have it fail within a year. I use a rigid panel on the roof, and a solar blvd 120W flexible as a portable.

- I would definitely want to add a battery monitor to your system so you can watch and learn about your batteries. 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).

Rando,

The 120 watt flexible for a portable seems like a good idea. I have a renogy 100 watt for a portable it works fine but it's a lunker. How do you store and handle the flexible panel. I guess I'm asking how flexible is it. Can you just tuck up on the bed or something and take it out and prop it up or does it need to be attached to a board or something?

 

[rando]

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.

 

[Esus]

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.

The one I was looking at claims to be 2" thick, so 5 times thicker than what you're talking about.

 

[Esus]

re the RVC: That sounds strange, BUT if there is a second battery wanting juice, won't the alternator assume the truck battery is where the draw is coming from and just keep charging? ARE you going to be driving every day? If so, you want to explore this more, as it is "free power" if you can access it.

The default separator you have sucks with skinny wires. It perceives the voltage drop and disconnects too soon. Consider a manual override, and/or a good separator like the Blue Sea ML ACR series.

Even over skinny wires, it should be able to manage the absorb and float levels of your house battery charging needs. It would be interesting to run the numbers using a voltage drop calculator for your setup.

The occasional 30% SOC is certainly tolerable. I just would not size my system to PLAN to have that happen. 60AH day for two days with NO charging at all means you do need about 120AH at your desired 50% SOC, so 240AH. That is a lot of battery.... and about what I have in my Hawk. Mind you, that is sitting on a 3/4 2500HD. Not a small truck.

The language is a little odd. It states in the first paragraph that The generator may exit "Fuel Economy Mode" if additional voltage is required and will fluctuate between 12-14 volts but then states that tow/haul mode can be enabled to override the RVC system so it will stay in "Charge Mode" and the targeted generator output voltage will be 13.9-15.5 volts.

So I can definitely put it in tow mode and theoretically charge at up to 15.5 volts, but my experience has been that the truck drives a lot better when not in that mode. It changes the RPM to shift ratio so I end up driving with much higher RPMs than seems necessary which hurt my fuel efficiency quite a bit. I think the tow/haul mode would be better when pulling significantly more weight.

And then there's the small wire and the low quality separator. With all of those different variables I was hoping to just go 100% solar and eliminate the problems entirely. Especially because I frequently camp in the same spot, off grid, without driving for extended periods of time.

I suppose with that victron battery monitor I'll be able to determine if solar isn't doing it and can then engage tow mode just to charge over the skinny wire for a bit.

I included the Chevy language below in case anyone is reading this in the future looking for Colorado specific info.

Voltmeter Fluctuation Condition
Some customers may comment that the voltmeter is fluctuating between 12 and 14 volts on their full size pickup or utility vehicle. Starting with the 2005 model year, light duty full size pickups and utilities are equipped with a Regulated Voltage Control (RVC) system. This system reduces the targeted output of the generator to 12.6-13.1 volts when in "Fuel Economy Mode" to improve fuel economy. The generator may exit "Fuel Economy Mode" if additional voltage is required. This will cause the voltmeter to fluctuate between 12 and 14 volts as opposed to non-regulated systems that usually maintain a more consistent reading of 14 volts. This fluctuation with the RVC system is normal system operation and NO repairs should be attempted.

Camper/Trailer Battery Charging Concerns
Some customers may comment that when towing or hauling a camper/trailer, the auxiliary battery for the camper/trailer will not stay charged. In most cases, this concern is blamed on the new RVC system. While the RVC system does reduce the generator's targeted output voltage to 12.6-13.1 volts when in "Fuel Economy Mode", this feature is bypassed if the tow/haul feature is enabled. With the tow/haul feature enabled, the RVC system will stay in "Charge Mode" and the targeted generator output voltage will be 13.9-15.5 volts, depending on the battery state of charge and the estimated battery temperature.

 

[rando]

The one I was looking at claims to be 2" thick, so 5 times thicker than what you're talking about.

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.