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What 100w flexible panel and controller for starter battery trickle?

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cj3waker

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Joined
Mar 25, 2024
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I seem to be pretty great at letting truck batteries die. I'm gonna throw a 100w flex panel on the roof of my truck and use it to trickle charge my battery. BougeRV and Renogy both offer a few different types of flexible panels

Bouge fancy flex
renogy standard flex
renogy fancy flex

and cigs

Just wondering if you guys had any input. Also what charge controller would you pair it with?
 
I would prefer not to replace it in a few years. Do they all really die that quickly? If they don't overheat or have impacts/physical wear is there any info on what kills them? Do they just get brittle and crack?

Cigs might be a better option then?
 
cj3waker said:
I would prefer not to replace it in a few years. Do they all really die that quickly? If they don't overheat or have impacts/physical wear is there any info on what kills them? Do they just get brittle and crack?

Cigs might be a better option then?
Click to expand...

Flexible suck.

Either the ETFE one or the CIGS have the best chances of survival. Best to install with an airgap comparable to a rigid panel to prevent them from overheating/degrading.
 
Cracking the solar elements or the wires from flexing, or delaminating and letting water in which then corrodes everything.

Note that if they are installed with a gap underneath, then they can flex in the wind. This makes mounting them flush to a surface tempting, but such mountings can overheat the panel or the underbacking, and when the wires crack (which they will eventually do) they can start a fire if the underbacking is flammable. There's a youtube video of RVers who had a flexible panel start a fire on their RV roof. (It didn't destroy their RV, but it could have.)

Will P's guidance is that "all flexible panels are garbage". You might also consider a small rigid panel. You don't need much power just to keep batteries topped up. Maybe a 50 W or even 20 W panel would work, around the size of a cafeteria tray.
 
Last edited:
I was able to Source a Renogy 100 watt flexible panel For cheap because someone had already Cracked it. It's still put out good Watts though voltage was fine and short circuit amperage was fine. This panel is velcro to the roof of my truck, because I don't believe the panel will last forever and will likely die sooner rather than later. I have wires running down the side of my windshield on the frame, a 10/ 2 jacketed cable, super glued to the frame. This cable runs under the hood where it doesn't get pinched and into a Morning Star sunsaver 10 amp solid state pwm charge controller. This charge controller is velcroed onto a convenience spot near the battery. I also have a couple 10 gauge wires going from the battery to the charge controller, the positive lead from the battery to the charge controller has an inline fuse fused at 15 amps I think. 10 gauge is good for 30 amps more or less. I've been super happy with this setup it cost me around $200 All In. It always keeps my battery charged, and I can take my truck down to the river and play music all day long and not have to worry about the battery getting drained to the point where it won't start my engine. I also have a small power plug station in the cabin with a couple USB ports and an integrated voltmeter so I can keep an eye on the battery itself. I didn't fuse the solar panel wires because the panel can only put out about 5 amps and I'm using 10 gauge wire rated for 30 amps to connect the panel to the charge controller. It's not the prettiest set up in the world but it gets the job done.
 
cj3waker said:
I seem to be pretty great at letting truck batteries die. I'm gonna throw a 100w flex panel on the roof of my truck and use it to trickle charge my battery. BougeRV and Renogy both offer a few different types of flexible panels

Bouge fancy flex
renogy standard flex
renogy fancy flex

and cigs

Just wondering if you guys had any input. Also what charge controller would you pair it with?
Click to expand...

Wy 100 watts?

I use a 25watt panel on my boat to charge my starter battery in the winter , summer .
With over price dual charger pwm from Victron
It charge about 1.5a with the pwm controller .
2x100Ah agm battery .(Not parallel connect)

I understand that trucks in the usa are 12volts systeems ?
In my country those are 24volts and than you can not use a 25watts 18-20volts panel.
Than you need 2X25 Watts in series to use

Its a small panel .
42,1L x 32B x 1,7H centimeter

 
Suijkerbuijk said:
Wy 100 watts?

I use a 25watt panel on my boat to charge my starter battery in the winter , summer .
With over price dual charger pwm from Victron
It charge about 1.5a with the pwm controller .
2x100Ah agm battery .(Not parallel connect)

I understand that trucks in the usa are 12volts systeems ?
In my country those are 24volts and than you can not use a 25watts 18-20volts panel.
Than you need 2X25 Watts in series to use

Its a small panel .
42,1L x 32B x 1,7H centimeter

Click to expand...
I chose a 100 watt panel for a couple reasons. One was that because I was using the pwm charger I needed to make sure that even when the panel voltage was dragged down to battery voltage, I was putting a decent amount of power into the battery. The panel is rated at about 20 volts VOC, but after being dragged down to battery voltage I imagine I'm only getting about half of the rated 100 Watts out of the panel. The other reason was because I wanted to not only trickle charge the battery but have enough access to power that I didn't have to worry about running auxiliary stuff like my stereo or charging a battery pack for my phone's or my phone's directly and over discharging the battery. 5 amps at 12 volts is about 60 watts. I've measured 5 amps coming off the panel but I haven't measured the voltage coming off the panel so I'm not entirely sure exactly how much power is going into the battery. I forgot to mention I used industrial Velcro that is 6 in wide and comes on a spool that's 20 yards long or something like that. It has an adhesive backing and I've had absolutely no trouble with the velcro or adhesive on the roof of my truck, with speeds exceeding 80 mph. The velcro is placed specifically to prevent air from getting under the panel. I have a big strip across the front of the panel, Airstream facing, and then several strips oriented parallel the trucks direction of travel, one at each edge of the panel and one down the center of the panel. This prevents air from getting under the panel and flapping it. I chose a flexible panel because I felt it would be more resilient to the vibrations it would encounter in driving then a rigid panel, and it also offered a lower profile for wind resistance. It's also a little stealthier but if you're looking you can definitely see it.
 
The top of my F350 has some ribs, I had planned on running it across the top of the ribs which would give it an airgap in the areas between the ribs, I was going to tape the front and both sides. The main reason I wanted to do flex was a normal panel on my roof is gonna have a really annoying whistle

It makes sense that the flex in the unsupported airgap portion could ripple in the wind and cause damage
 
My suburban has three 100W glass panels. I have them bolted to aluminum angle, that is bolted to ly luggage rack.
I have the front side taped to keep air at speed from lifting the panels.
There is no noticable noise from the panels.
 
cj3waker said:
The top of my F350 has some ribs, I had planned on running it across the top of the ribs which would give it an airgap in the areas between the ribs, I was going to tape the front and both sides. The main reason I wanted to do flex was a normal panel on my roof is gonna have a really annoying whistle

It makes sense that the flex in the unsupported airgap portion could ripple in the wind and cause damage
Click to expand...
Oke but wy your battery go dead .
U use it without engine running ?
More explain wy u you go that way will be nice to know.
If its only to have a fully battery for the reason you do not use a lot the truck .
And the battery go down.
Or u use the car radio for music and fridge and kill the battery that way.
 
cj3waker said:
I would prefer not to replace it in a few years. Do they all really die that quickly?
Click to expand...
yea the plastics won't hold up very long
cj3waker said:
If they don't overheat or have impacts/physical wear is there any info on what kills them? Do they just get brittle and crack?
Click to expand...
that is unfortunately the nature of solar panels. The crystals are reflecting light but need light to produce energy so we have to make everything dark so it absorbs light and thus gets hot as fuck
 
Supervstech said:
My suburban has three 100W glass panels. I have them bolted to aluminum angle, that is bolted to ly luggage rack.
I have the front side taped to keep air at speed from lifting the panels.
There is no noticable noise from the panels.
Click to expand...
It was on a jeep, but the crossbars for a ski rack drove me nuts. I've never had anything on the roof of the f350, but I figured it would be a similar experience
 
Alrighty well amazon was having a sale on this ecoworthy kit
100w compactish panel, a controller that can also do lithium batteries (think I'm gonna replace the starter battery with lithium) and quite literally the perfect amount of wire. It was $79. I also bought some vhb tape, some wire holders and a no drill mounting kit, I'm into the whole thing sub $150 with tax and everything. I still need some loom and RV tape for the front edge

panel mounted
gvRfUiY.jpeg


9T812Qu.jpeg


panel was producing ~21v, battery was getting 14.4
SVc3KoH.jpeg


started charging around 3 amps
oDltMZP.jpeg


it ramped amperage down pretty quickly which I thought was cool
UzXPVMu.jpeg
 
sunshine_eggo said:
Normally, I'd tell you to send me your money, and I'll set it on fire for you, but that's not a bad deal, and it looks like it's working for you.
Click to expand...

I hear ya lol. $150 is worth me not dealing with dead batteries all the time. Obviously that shouldn't be an issue....but it is
 
cj3waker said:
It was on a jeep, but the crossbars for a ski rack drove me nuts. I've never had anything on the roof of the f350, but I figured it would be a similar experience
Click to expand...
When i carry a new extension ladder it will HOWL going down the road.
I fill the rungs with sprayfoam and the noise is gone.
 
Pwm has its place, not sure why a single panel for keeping an automotive battery topped needs mppt. I have several smaller panels with waterproof Pwm controllers that keep various mowers, atvs etc topped up for parts of the year.


gotbeans said:
$75 for a 100 watt panel wtf
Click to expand...
I'm not sure wtf when it's a ruggedized etfe flexible panel from a generally reputable company that is competitive with other flexible panels. Other ruggedized panels can be $90 for 30w.

Ecoflow is 200, renogy is 150, overland is 300, sungold is 170, etc

Being able to bend 360deg allows it to be used by people packing it with their adventure gear and also be able to handle some abuse.

These panels are great for pulling out for temporary setups where lighter weight and durability are needed .

Their grommets allow quick deployment in areas aluminum and glass panels can't easily be mounted.
 
HarryN said:
Consider to just put a 10 watt panel inside of your dash board.
Click to expand...
Yeah, 10 w panels inside wont charge well enough.
MAYBE if it is outside in direct sunlight 10W would work.
I mount 100 or 200W panels to maintain.
 
sunshine_eggo said:
I tried this a long time ago with a panel marketed to keep batteries topped off.

It drained my battery :P
Click to expand...

Interesting. I put one in a customer's van and it worked just fine, but it had a very low loss charger.

It was also a panel designed for that specific use. ( amorphous Si )
 
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