Costco 100W 18V solar blanket: which controller to use?

[profdant139]

Costco has a hundred watt foldable solar panel that supposedly puts out 18V. On a dollars per watt basis, it is not a great deal, but it is very easy to store and deploy, so I am willing to put up with the cost. (I already have a 120 W suitcase panel -- this new panel is for emergency use at home, as well as extra juice while camping.)

My question, of course, is that I want to use this panel to charge a 12V battery. There has to be an after-market controller that will do the job. Given the specs of the panel (see link below), which controller do you recommend? Thanks in advance for your wisdom.



Costco panel

[pianotuna]

BFL13 wrote:
Apparently nobody watched the video I linked back when.

Hi BFL13,

I watched it.

[BFL13]

Apparently nobody watched the video I linked back when.

[pianotuna]

profdant139,

A good decision.

[profdant139]

Well, after all that, I am going to return the panel to Costco. All of the connectors are dinky little metal tubes, the kind you'd use for powering a boom box. (I'm showing my age here.)

So the way I figure it, if the manufacturer of this panel thought that this unit could charge a real 12v battery, they would have included some hardware (maybe alligator clips??) that would attach to the battery terminals. But they didn't.

Bottom line -- I might (or might not) be able to get it to work with enough add-on hardware, but it is not worth the "sunk costs" of the hardware. I can easily return the panel to Costco -- but it is not so easy to return the hardware for a full refund.

[pianotuna]

profdant139 pwm controllers do not drop the voltage. They operate at what ever the battery voltage is. As the battery gets fuller the control "pulses" the power, with shorter "on" time and greater "off" time. PWM does include a one way diode to prevent the panels from drawing power from the battery bank.

110 amp-hour battery flooded? Then with this panel under PERFECT conditions 5.5 amps are going into the battery. But that only happens around solar noon.

I would be comfortable doing direct connection to the battery with an on/off switch between the panel and the bank.

[2oldman]

I can't find specific specs like with 'normal' solar panels. Open circuit voltage is normally 18v or higher, but when hooked to a load like a battery that voltage comes down. But, I can't say for sure if 18v is open circuit.

[BFL13]

How do you connect that 18v power wire to the 31 battery? or even to a solar controller that then connects to the battery?

You might have a power station that you charge up with that like in the video, and then use a battery charger plugged into the power station, but that seems a bit much.

[profdant139]

Very useful comments -- thanks! If I decide to keep this panel, I would use it to charge a group 31 deep cycle battery, with 110 amp/hour capacity.

My existing 120 watt panel fully recharges my battery every day -- we carry a spare battery but never need it! (And yes, we carry a generator, also never run it.)

So this new 100 watt panel (if it works with a 12 volt battery) would just add to my existing charging options.

And yes, it is clearly too expensive on a "per watt" basis -- but it folds easily, it is very light, and it is easy to store. Those are important considerations, especially since our trailer is so small.

[pianotuna]

Hi,

How large is the battery bank?

[BFL13]

It works with a power station, as seen in this video. It is not a "normal" solar panel.

https://sterlingwong.com/2022/02/05/review-costco-massimo-100-watt-solar-blanket-folding-solar-panel...

[vermilye]

I used a DOKIO 300 watt folding panel over the winter in Quartzsite. Made a 3/4"PVC frame to keep it tiled in the correct angle. It came with a controller, although I didn't use it - tied it in with the rooftop solar panels.

[Boon_Docker]

Have you checked DOKIO solar on Amazon. Reasonable in price and good reviews.

[Gdetrailer]

You would have to have a seriously tiny battery to get "cooked" by that panel, 18V at 100 watts is 5.5A. Any substantially RV usable 12V battery would laugh at getting 5.5A charge for the absolute max of 4-5 peak charging hrs you would get per day.

But to get that 18V you must use the "port" on that panel which looks like a small "barrel" connector (take a good look at the cable and universal connectors in the pictures).. That "port' most likely accounts for one of the three "outlets" and most likely has two 5V USB outlets..

That advertiser mentions plugging in laptops to it, I personally would not trust plugging any laptop into a unregulated solar panel unless you really want to take a chance that it won't go up in smoke in full sunlight..

It must have some sort of voltage regulation in order to allow one to plug a laptop into it.. Not all laptops accept 18V, some are 17V, some are 18V, some are 18.5V, some are 19.5V.. That is the reason for all of those little adapter plugs, those plugs tell the regulator what to set the voltage to..

But for your purpose, even if that panel offers 18V (standard for most "12V" panels) it is going to be 5A or less which unless you have it hooked to a small motorcycle battery, most likely won't harm your RV battery unless you leave it hooked up for months at a time.. Battery of 200 Ahr or greater, 5A for a few hrs per day is a bit above trickle charging..

But personally, that is one horribly expensive panel for the small amount of wattage..

[Boon_Docker]

If it had a charge controller it would say two 12 volt outputs not 18 volt outputs.