XPost: alt.home.repair, sci.electronics.repair
On this 16 Nov 2024 05:00:59 GMT, rbowman wrote:
Do you think this 10 Watt (claimed) solar panel can charge a car
battery?
https://www.amazon.com/dp/B0DG5J98YH
It (says it) supports 12 volts.
The goal is a DIY science project but it has to work to do the job.
I doubt it. It says it has a switch for 6, 9, or 12 volts which makes me think it has adjustable voltage regulator similar to
https://www.sparkfun.com/products/527
I've seen those simple potentiometer diagrams which show how to use that
LM137 as an adjustable power supply. My goal is to build a solar-powered
spa heater that slowly (or quickly - it doesn't matter the speed) pumps
water in the summer from the spa (which is roughly about four feet cubed) through a few hundred feet of black hose back to the (now warmer) spa.
I'm thinking of three major components might be needed to accomplish that.
1. 12VDC water-transfer pump (of some sort - I have an RV pump now)
2. 12VDC car battery (I have three old ones - which will work for now)
3. Black garden hose (I have a few hundred feet of Continental Rubber hose)
4. Some way of charging the battery using sunlight as the source
My first problem is how to figure out what solar wattage I'll need.
to be compatible with AAs, Ds, or whatever the game camera uses, A charged car battery is around 12.6V and the charging circuit is 14-14.5.
https://www.amazon.com/dp/B07N2PR267/
is designed to maintain car batteries and has some overcharge circuitry
but doesn't limit out at 12 V. It's similar to the plug in battery maintainers that I use to keep the bike batteries healthy over the winter.
Oooh. I like it!
The Amazon description says it's a SUNER POWER 10W 12V Solar Battery
Charger (Bulk, Absorption, Float) Maintainer, Built-in Smart MPPT Max Power Point Tracking Charge Controller, Adjustable Mount Bracket, Waterproof 10
Watt Solar Panel Kits for Car Automotive Boat Marine RV Trailer with a
floating charge voltage of 13.8VDC & an optimal-charge current of 0.56Amps
with a trickle-charge current of 0.2Amps & an overcharge-protection voltage
of 14.4VDC.
The connector type they show is what my RV pump uses. What's it called?
They called it an "SAE harness" in the picture on the Amazon listing.
https://www.amazon.com/dp/B07N2PR267/
I need to get one with alligator clamps to connect to the battery.
So I need to know the name.
In their diagram, the red is the female & the black is the male.
But on my pump, the red is the male and the black is the female.
Do you know what name to look up to get it with alligator clamps?
And what is the overcharge-protection voltage anyway?
Is that the highest that it will go before it limits its cutoff voltage?
Now for the bad news. How many watt-hours is your science project going to require, In other words how many watts does it require, and how long are
you going to run it per day?
Dunno. My friend dropped off a second RV pump for me to try.
1st RV pump:
https://www.amazon.com/dp/B0DF7B1VYD (4.6Amps, 8Amps max)
2nd RV pump:
https://www.amazon.com/dp/B0CBLYJX63 (9Amps, 18Amps max)
That makes the 1st pump about 55 Watts & the 2nd about double that.
The old "Interstate Batteries, All Seasons" battery sticker on the top says MT26, 625CCA, 655CA & RC85.
Do you think that car battery (let's assume if it was new) could run the smaller pump for about five hours during the hottest part of the day?
Using 50 Watts and 100 Watts for simpler math, I think that means the
battery needs five times that in watt hours, or 250 to 500 Watt hours.
Does my quick calculation above sound about right?
Then consider the solar panel. The 10W
rating assumes full sunlight. Even on a sunny day in southern AZ, unless
you have a tracker, if you graphed the output you'd get a nice curve
maxxing out when the panel is perpendicular to the sun, building up in the morning and declining in the afternoon. You won't see full output on overcast days and obviously nothing at night.
I'm trying to size the solar panel, where you're helping a lot, as I just realized only when I did the math above that I may need something like a 50 Watt panel for the smaller pump to run it real time.
But don't I need a smaller panel if it's running off the battery?
Unfortunately both battery & panel have to work together during the day but
the battery can be charged all day while the pump only needs to run during
the late morning and early afternoon to get the hottest sunlight, right?
https://www.radarsign.com/
Those are popular here and are on trailers so they can move them to
different locations, The trailer has a battery pack and a small solar
panel, I'd guess around 30W. It's been cloudy and rainy for the last few
days so the one I passed on my way home was barely functioning. If the weather forecast is correct it will be dead pretty soon.
They work well in the summer but with shorter, darker days they struggle. That's solar power in a nutshell. Without knowing further details of your project my guess is you won't be happy.
Thanks for helping me run the calculations.
Do you think the car battery can run the motor long enough for the hottest parts of the day? And do you think maybe a similar-sized 30 Watt solar
panel can charge it back if that solar panel charges for the entire day?
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