Tell me how please

[Arbee]

Hi:

Allow me to express my goals--or at least what I think are my goals--in the hopes that those in the know (thank you in advance) can recommend products to accomplish this. Links are greatly appreciated.

I own a Jeep Wrangler that has a roof rack that's rarely used. It's got three equally sized metal panels (actually each 1/3 section has two panels, for total of six) of which I can install, at anytime, anywhere from zero to 3 of these pairs .

They look like this https://www.lodoffroad.com/products/jk-jl-destroyer-roof-rack-aluminum-floor-kit-2-panels-per-kit- and I am happy at your request to fill one or more of them with solar panels you recommend, flexible or rigid. I'm thinking that no one solar panel be more than 200 watts because that's a size, particularly with a rigid panel, that could fit on each roof panel pair--although I think when you hear me out you'll believe I don't need that many watts of power (maybe not.)

I live in a four season climate at 41 degrees latitude. Need I tell you that the solar panels in this application, unlike on a sloping home roof, sit parallel with ground to the extent that that, and cloudy days, and other factors, compromise their abilties at producing power. I park outside in some degree of shade in the warmer months when foliage is on my property's nearby trees.

I wish one or more solar panels to accomplish two independent tasks. One is to trickle charge the dual (we'll call them starter) batteries when the vehicle is parked, I have under my hood, which are connected in parallel:

https://www.fcpeuro.com/products/au...MIgNqsw7yIhAMVu2VHAR2xmAn9EAQYASABEgKAwfD_BwE

and

https://www.partsgeek.com/wbg7d53-j...MIi5yEgL2IhAMVjExHAR2_YwwSEAQYAiABEgK7bfD_BwE

as their amp hours and cold cranking amps I assume would be relevant to you to help me size this endeavor.

The second task I wish the solar panel(s) to accomplish, through an intermediary house battery of your size choosing--although I am leaning towards it being of AGM (absorbent glass mat) lead acid type given my exposure to freezing temperatures, is to power a dual dash camera while in standby mode, which according to its specs requires a mere 4.2 watts of power (at 12 volts.) I've read that they (AGM batteries) are safe in the cabin and don't off gas. Perhaps (educate me) a LiFePO4 battery might pack more power for size here, and some even have battery warming technology, but I have ample room in the cargo area of my Jeep to store an AGM battery that seems to only need to be relatively tiny for this one dash cam powering task.

When the vehicle's engine is cranked (assume) that dash camera will be powered by the starter batteries, themselves of course back filled with power by the vehicle's (smart) alternator.

I'm fine with solutions that include Renogy's DCC50S or DCC30S, or not.

https://www.renogy.com/dcc50s-12v-50a-dc-dc-on-board-battery-charger-with-mppt/ that combine this task into one, additionally trickle charging the starter batteries when the house battery is charged, or the house battery when the engine and alternator are functioning, or not. I'm fine for this to be a single or two systems.

I have no problem bringing the MP4 cables from solar panels into the cab.

I'd probably consider some Redarc stuff a bit pricey for my taste here, although "buy once cry once" I realize may apply. I'm fine spending the $ on MPPT charge controllers versus PWM ones.

Being able to monitor this with a Bluetooth TM app would be nice.

Tell me what else I'm missing that's relevant to share with you.

Again, thanks.

 

[HRTKD]

If temperatures below 32°F (0°C) are a concern, then LiFePO4 may not be an ideal battery for you. There are ways to work around the limitation of not charging under 32°F, but that adds expense to the solution. AGM is a good fit.

Consider using a single, large residential panel. Just one. It may be a lot easier to mount since it's just one.

The Renogy device you mentioned has some serious limitations (last time I looked). The voltage can't be very high, which would rule out a large solar panel. If the vehicle is running and providing a charge, then the DCCxxS will limit how much the PV can contribute, even if the vehicle provides 1 amp.

 

[Arbee]

If temperatures below 32°F (0°C) are a concern, then LiFePO4 may not be an ideal battery for you. There are ways to work around the limitation of not charging under 32°F, but that adds expense to the solution. AGM is a good fit.

Consider using a single, large residential panel. Just one. It may be a lot easier to mount since it's just one.

The Renogy device you mentioned has some serious limitations (last time I looked). The voltage can't be very high, which would rule out a large solar panel. If the vehicle is running and providing a charge, then the DCCxxS will limit how much the PV can contribute, even if the vehicle provides 1 amp.

Panel size in watts, flexible or not, recommended manufacturer, separate panels for trickle charge and dash camera, which MPPT controller(s)?

Thanks for your confirming thoughts on battery chemistry but I could really use some advise on which "tonka toys" to buy and hook together.

 

[HRTKD]

I would not use flexible panels. They haven't lived up to the hype.

You could put in separate panels for each "system". Or, you could put in one panel that goes to one of the batteries, then a DC-DC charger off of that.

I put in Victron Energy components. I'm happy with it, but Victron isn't inexpensive.

 

[Tomthumb62]

I used to have a lot of Renogy gear. Sold it all. It was problematic to use and poor efficiencies.

Victron has been great as replacements. They also lowered their prices last year on some of their products including MPPT units.

AGM is good for freezing conditions, but you need to size it right. I couldn’t get enough charging power with 2x100 panels trying to charge two 100Ah 12v AGM batteries. Because AGM requires more finicky charging than lithium. Result was my AGM batteries died an early death, twice, to the tune of a total of $800. Which could’ve bought a heated lithium battery! I didn’t know about the special charging requirements for AGM until it was too late. They also leaked even though they were supposedly sealed.

So if you do go AGM, get a smaller battery, perhaps 50Ah, but that will depend upon how watts of panels you can fit as well as how many hours a day you want the dash cam to operate. Unless you also plan to drive every day for 30 minutes of dcdc charging or more as well as solar. You also have to be more careful not to overcharge lead acid, so sizing your MPPT and DC-DC chargers are more critical. Lead acid doesn’t have a BMS to protect from over charging or over discharging.

Lithium is less picky on charging. But as mentioned, dealing with the cold costs money and energy for lithium. How cold does it get where you are? Below zero F?

 

[robbob2112]

Don't forget about the self-heating LiFePO4 batteries. LiTime puts out a few. The downside is the heater takes power, so depends on how much your solar panels put out verse how much it takes to heat them. The heating is temp sensitive so only on below a certain temperature.

 

[Dave in AZ]

@Arbee I just wanted to say, your question was one of the best written ones I've read, kudos to you for writing a smart question that lets folks actually help!

Say 5w for the camera. 24 hrs is 120Whrs, or 10Amp hrs. AGM can use down to 80% discharge say, so a smaller 50Ah AGM could give you 4 days camera.

41 N lattitude, around Ft Wayne, N Ohio etc, plenty of sunlight to charge things. If all you are looking to charge is trickle your dual starters, which should basically be full if you drive almost ever, and the camera.

120Wh keeps you level, 150 Wh a day will charge stuff back up. A 100 W panel should give you 20 to 30W, but...

From PVWatts, at 41 N in Ft Wayne, I had to guess since you chose not to tell where you are, a 1000W array with zero tilt gives about 1100kWh a year. That goes from daily averages of 1133Wh in Dec, to 4733Wh in Jun. Again, that is a 1000W solar array. So a 100W panel should give 113Wh in Dec, your low month, which is not enough. But a 200W panel gives 226 Wh, an excess of 100Wh, probably plenty. To recharge an 80% depleted AGM 50Ah, that is 40Ah x 12.8v is 512 Wh. So battery would recharge with 5 days sun. If you went 400W array, 2.5 days sun.

So, slap at least a 200 W panel up there, if 4 days is as long as you go without driving and zero sun then 50Ah AGM. If you think 8 days no sun, then go 100Ah.

 

[Browneye]

Perhaps I misunderstood, but all this for a dash cam while the vehicle is parked? You can’t just plug it in?

 

[Supervstech]

Perhaps I misunderstood, but all this for a dash cam while the vehicle is parked? You can’t just plug it in?

My suburban is parked for months without moving.
The dashcam, plugged in will drain the battery in a week...
I have 300W of solar on my cargo rack, and a pair of starter batteries under the hood, along with various house batteries, and powerstations in the back.
I plug the house batts into the vehicle power outlet while parked, and never worry about the accessories draining the starter batts.

 

[Browneye]

You have more in a suv that sits parked than I do in a Winnebago.
I’m not getting the dash-cam thing. Enlighten?
My cars park in the garage. [shrug]

 

[HRTKD]

Some dash cams are battery voltage sensitive and turn off at a certain battery voltage. It may depend on how you wire it up. It sounds like the OP wants his dash cam active all the time, so an external charge is needed to prevent the battery from getting drained to zero.

 

[Supervstech]

You have more in a suv that sits parked than I do in a Winnebago.
I’m not getting the dash-cam thing. Enlighten?
My cars park in the garage. [shrug]

Yeah… I wish I had gotten 400w… on trips, the refrigerator strains. I get funny looks when I head to the top floor of parking garages. I gotta get them photons!

 

[Arbee]

I would not use flexible panels. They haven't lived up to the hype.

You could put in separate panels for each "system". Or, you could put in one panel that goes to one of the batteries, then a DC-DC charger off of that.

I put in Victron Energy components. I'm happy with it, but Victron isn't inexpensive.

Thank you sir. I will definitely take close look at Victron's website and their product offerings/indications.

 

[Arbee]

Some dash cams are battery voltage sensitive and turn off at a certain battery voltage. It may depend on how you wire it up. It sounds like the OP wants his dash cam active all the time, so an external charge is needed to prevent the battery from getting drained to zero.

My dash camera can indeed be configured to shut off when in parking mode, based upon a programmable voltage setting of my choosing.

Such shut off options aren't, nor need be available when the dash camera is recording while the engine is cranked, as the camera's power in this circumstance is supplied from the starter batteries and alternator combination. "Batteries" is plural here as the vehicle comes equipped with two AGM batteries hooked up in parallel.

At the risk of conveying that already known, my dash camera has 3 wires that energize it. One is a common ground, one is designed to be hooked up to a 12V power source that is always energized (a "battery" connection), and one gets hooked up to a 12V power source that is only energized when the vehicle's engine is cranked (an "accessory" connection.)

When the dash camera "sees" power on the accessory wire it assumes the engine cranked and the vehicle is traveling. When the dash camera "sees" power only on the battery line it assumes that it needs to be in parking mode, "conscience" of its voltage cutoff, and, accoding to spec, using 4.2W of power.

I never wish the dash camera to be without some power source. Currently the "accessory" wire connects to places in the vehicle that are only energized. as mentioned, when the engine is cranked, and get their power from the starter batteries and vehicle's smart alternator combination. The battery wire I wish to connect to a "house" battery.

 

[HRTKD]

At the risk of conveying that already known, my dash camera has 3 wires that energize it. One is a common ground, one is designed to be hooked up to a 12V power source that is always energized (a "battery" connection), and one gets hooked up to a 12V power source that is only energized when the vehicle's engine is cranked (an "accessory" connection.)

This is how I have my dash cam connected.

Some brands have a dedicated battery that is available only to the dash cam that is used to keep the dash cam running when the engine is off. That may be a simpler solution than connecting PV to both house and starter batteries. It depends on how long you go between engine starts.

 

[Arbee]

You have more in a suv that sits parked than I do in a Winnebago.
I’m not getting the dash-cam thing. Enlighten?
My cars park in the garage. [shrug]

I think that you are questioning my motivation for a dash camera relative to that I and you have to lose. To be honest I am not certain.

Regardless, you certainly are within bounds to both question my motives and conclude differently.

The dash camera is mostly to record while in motion. I have little concern of theft while the vehicle is parked in my driveway, much that sometimes on trips, it's parked elsewhere and in places I would like to record.

The presence of a roof rack on my vehicle is a given (i.e, a place to hold solar panels,) as is the reality that its dual AGM starter battery setup, of two, by factory design, dissimilar size AGM batteries in parallel, with a frequent track record of the smaller engine start stop (ESS) battery cannabolizing the main battery, finds me cause to, in addition to seek solar power to indirectly run (via a house batery) the dash camera in parking mode, use some of this solar to trickle charge the two stater batteries.

Many owners of my vehicle model abandon this smaller battery and turn off the ESS system. To the extent that I can use solar to keep the stater batteries topped off with trickle charge, and use the engine start stop system to save gasoline and do my part to be somewhat green, allowing the ESS system to engage at stop lights, all while energizing my dash camera while in parking mode, all the better.

Again, I completely respect that YMMV, so to speak.

As far as the dash camera's use in driving mode: at times it has been indespensible. Nothing beats confronting a both wrong and hostile fellow motorist with the 5 words "I have a dash camera." On more than one occasion, the speed with which they shut up and get back into their vehicles is near priceless.

And nothing beats being able to send your insurance company motion pictures proving your innocense and the other driver's fault in matters of subrogating accident damage, much that the dash camera's power in this case is from the starter batteries and somewhat off topic for this forum.

 

[Arbee]

This is how I have my dash cam connected.

Some brands have a dedicated battery that is available only to the dash cam that is used to keep the dash cam running when the engine is off. That may be a simpler solution than connecting PV to both house and starter batteries. It depends on how long you go between engine starts.

Thank you sir. Allow me to add some additional factors that perhaps I should have included up front.

I wish a system that is not dependent on the frequency with which I crank the engine and use the vehicle. Many of these dash camera power packs you speak of are predicated on a frequency and duration of vehicle engine on time to replenish themselves via the vehicle's alternator, or shore power (which I do have available to me on my driveway.) I have tried to make a concerted effort to minimize my fossil fuel usage and may drive in a vehicle as infrequently as once a week.

Additionally, the better ones (battery packs that is) from my research are LiFePO4 based, but sans warming technology. I desire ability to function in below freezing temperatures.

 

[Arbee]

Perhaps I misunderstood, but all this for a dash cam while the vehicle is parked? You can’t just plug it in?

I do in fact have access to shore power while the vehcile is parked on my driveway. I wish to devise a system though that permits the functionality of my dash camera in parking mode, and the trickle charging of my starter batteries independent of where I park, as long as I park outside, and especially when I don't park on my own (safe) driveway, where of course shore power may not be available or even if so, compromised by someone pulling the cord prior to committing illegal acts.

And yes, sometimes I guy or gal has to park in long term parking in a garage at the airport where my wishes for a solar run dash camera go to hell in a hand basket.

 

[Arbee]

@Arbee I just wanted to say, your question was one of the best written ones I've read, kudos to you for writing a smart question that lets folks actually help!

Say 5w for the camera. 24 hrs is 120Whrs, or 10Amp hrs. AGM can use down to 80% discharge say, so a smaller 50Ah AGM could give you 4 days camera.

41 N lattitude, around Ft Wayne, N Ohio etc, plenty of sunlight to charge things. If all you are looking to charge is trickle your dual starters, which should basically be full if you drive almost ever, and the camera.

120Wh keeps you level, 150 Wh a day will charge stuff back up. A 100 W panel should give you 20 to 30W, but...

From PVWatts, at 41 N in Ft Wayne, I had to guess since you chose not to tell where you are, a 1000W array with zero tilt gives about 1100kWh a year. That goes from daily averages of 1133Wh in Dec, to 4733Wh in Jun. Again, that is a 1000W solar array. So a 100W panel should give 113Wh in Dec, your low month, which is not enough. But a 200W panel gives 226 Wh, an excess of 100Wh, probably plenty. To recharge an 80% depleted AGM 50Ah, that is 40Ah x 12.8v is 512 Wh. So battery would recharge with 5 days sun. If you went 400W array, 2.5 days sun.

So, slap at least a 200 W panel up there, if 4 days is as long as you go without driving and zero sun then 50Ah AGM. If you think 8 days no sun, then go 100Ah.

Thank you Dave for not simply your kind thoughts but the "math" I seek.

I hear you on all the losses of a system, from cloudy days, to winter's shorter days, to panel efficiency and loss of efficiency over time, to the smaller acceptable range of depth of discharge (DOD) of AGM battery chemistry over other batteries, to their loss of capacity with time, to heat's effect on solar efficiency, to my longitude and all else. I live North of NYC FWIW and since you asked.

That said, and at the risk of pointing out that we all know, the sun does indeed come up every day, not every four days (your projected longevity)--much that one could make the argument that what I say isn't the case after a heavy snow. I was hoping to go with a smaller AGM house battery, simply because I can tuck it away in a corner of my cargo area, and I was hoping to use no more than 1/3 of my roof space on a solar panel, which is about 70" X 26" give or take. Perhaps some 200W rigid panels well fit within that size.

Perhaps I should seek a small LiFePO4 with warming technology--as I am to understand that LiFePO4s can fit more "juice" in less space, much that I don't want to break the bank on this project.

Your additional thoughts are greatly appreciated. Perhaps your overengineering isn't that, but solid wisdom from the learned experience that I lack.

Again thanks.

 

[Arbee]

Don't forget about the self-heating LiFePO4 batteries. LiTime puts out a few. The downside is the heater takes power, so depends on how much your solar panels put out verse how much it takes to heat them. The heating is temp sensitive so only on below a certain temperature.

Thank you sir. Not only, from what I've readi, can LiFePO4 batteries pack more power in them for their size than lead acid ones like an AGM battery, important to me to free up cargo area space in my vehicle, but their cost, even for heated ones, when amortised over the life of a power project may turn out cheaper than replacing AGM batteries.

I've recently looked into Silicon Dioxide, a.k.a. Lead Crystal batteries for their large temperature range capabilities, given that there one so called limitation, that they tend to be larger and heavier for their power output, might be less of a concern for me running a mere 4.2W dash camera and starter battery trickle charger concurrently and requring but the smallest of house batteries.

With one firm (Azimuth Solar; who in no way do I wish to disparage) seeming to carry them, I'm not sure this battery chemistry may live fully up to that claimed of it.