Solar question

[1handyhubby]

Do solar panels require a controller. The PO of our camper made this solar briefcase and said he used it to charge the camper batteries, laptop, phone etc. I've never used solar panels but I thought you needed a controller so you don't over charge your batteries. I'd appreciate any insights y'all have to offer. Thanks

[Almot]

KD4UPL wrote:
But, a charge controller is always a good idea and can be had for less than $50 so why not?

Yep, ~$40 for a decent 5A controller.

On short trips I wouldn't bother with 30W solar. If laptop/cellphone addiction is an issue, a fully charged external battery will triple or quadruple the life.

[KD4UPL]

You provided no information on the panels but from the looks of things I'd guess they are too small to NEED a controller if hooked to a moderate size battery.
A general rule of thumb is that if the amperage of the panel is less than 1% of the AH rating of the battery then no controller is need.
I'll guess those are 15 watt panels so about 1 amp each. If you've got at least 200 AH of battery I wouldn't bother.
But, a charge controller is always a good idea and can be had for less than $50 so why not?

[Almot]

1handyhubby wrote:
he used it to charge the camper batteries, laptop, phone etc.

Yes, laptop and phone. You don't just "charge" these items with solar - you hook solar up to battery and it's running these small chargers, plus putting some charge in camper battery, plus running pumps etc. All processes can go at the same time but the more loads you use, the less will be left to put in camper battery.

"Charge the camper batteries"?
Yes, if you don't use anything other than listed above AND it's perfectly sunny. Otherwise it will put none or very little charge in. If camper battery was substantially discharged the previous day, it won't fully charge with this small solar. If you used loads listed above but it's less than perfect weather, it won't fully charge again.

the size pictured can be anywhere from 30 to 120W total wattage. If 15W each panel, 30W total - yes, controller would nice though not absolutely necessary.

IMO, 30 W solar is a useless thing other than for maintaining battery in storage. It won't help you on a trip unless it's a tent-style living - laptop, cell phone, no 12V draw of fridge, no lights after sunset.

[Ski_Pro_3]

No. You do not need a controller. However, you will need to remove the solar at the end of each day and check the charge on the battery. You can use one of those voltage testers that plug into a cigarette lighter to monitor battery voltage. There is an excellent one on Amazon;

https://www.amazon.com/INNOVA-Battery-Charging-System-Monitor/dp/B000EVWDU0/ref=bit_abba_def_ff_us_t...

[webrx]

Buy a cheap controller off Amazon, better to have and not need then need and not have.

This is the one I use for 100-200 Watts of Solar - mine has a digital display of volts and amps:
Sunforce 60032 30 Amp Solar Charge Controller - $80

this can be used for up to 120 watts of solar
Sunforce 60031 10 Amp Digital Charge Controller - $30

For you setup, you can probably get away with something like this:
Sunforce 7 Amp Charge Controller - $16

or this:
10A 12V/24V Solar Charge Controller Solar Panel Battery Regulator Safe Protection - $9

for the difference in price I would get the $30 at a minimum one for a basic portable setup. Not a FT setup, but good for a portable one at around 100 watts.

Watts / volts - AMPS so 100 Watt panel / 12 v = 8 amps in theory
In reality you might see 6 amps at best.

if those are HF 15W panels you will at best see around 2 amps of charge so a little controller is fine. I used a 40w portable panel for a long time and if you are stingy with battery usage it is enough to keep thinks charged up and let you top off each day.

Dave

[Darryl_Rita]

Look like Harbor Freight 15w panels. I wouldn't worry too much about a controller, unless it's left on the battery in high summer sun with no loads connected.

[MrWizard]

Are there any numbers on that that tell you the volts , watts, amps
A 15v panel could be connected directly without a controller and removed when the batteries were charged
A couple of small panels, connected along with normal daily loads water pump, fridge etc..
Will probably be OK

[time2roll]

Over about 10 or 15 watts per RV battery needs a controller.
If the panels have no blocking diode you need a controller to prevent discharge at night.

[Fire_Instructor]

All but the very simple 12v output panels do. My 300W of panels output at 34.4v, so that needs to be converted to 13V+/- by the controller.