I recently made a DIY solar car battery charger.
The circuit has an automatic shut-off to avoid overcharging the battery. And you can use any size solar panels depending on whether you want to charge fast or slow.
I did it that way:
Videos step by step
- 12V car battery– or just a pattern12V lead acid battery
- Renogy Wanderer 10A Charging rules- or anycheaper pwm charging rules
- Paint Solar 12V— I used onePaintel Solar 5W 12Vfor trickle charge. I would use onePaintel Solar 20W 12Vor larger for faster charging.
- cables, plugs and fuses— I used themNOCO GC018 12V-Adapter, which comes with ring terminals. If you need barrel clamps, use thoseNOCO GC017.
- MC4-Adapterkabel— Required if your solar panel has MC4 connectors. They are not required for the 5W and 20W panels linked above.
- NOCO Battery Cabinets(Optional)
Step 1: Connect the car battery to the solar charge controller
I used the NOCO GC018 to make it super easy to connect my 12v battery to my solar charge controller. (GC018 is a 12V plug adapter that comes with an in-line fuse and ring terminals.)
First I cut through the 12V socket with my pliers. snap snap!
Then I stripped the wires and stripped them with my wire strippers.
That's it, my “battery cables” are done. Now I can connect the charge controller and the battery.
To do this, I connected the positive and negative ring terminals to the respective battery terminals. Red on red, black on black! (I also changed the in-line fuse to the correct fuse size given the wattage of my solar array.)
I then connected the bare wire ends to the battery terminals on my solar charge controller.
My solar charge controller turned on and indicated it was properly connected to the battery.
Consult your charge controller manual at this point to see if you need to program it for your battery chemistry. Mine uses sealed lead acid by default, that's the type I used.
Step 2: Connect the solar panel to the solar charge controller
Connect the solar panel wires to the solar panel (PV) terminals on your charge controller.
Monitoring:If your solar panel has MC4 connectors, you will need to use MC4 adapter cables to connect it to your charge controller.
Now the solar panel is connected to the 12V battery via the solar charge controller.
See how mine turned out:
This means that my car battery solar chargerIt's complete! 😲
Yes, that's all.
Time to test and see if it works...
Step 3: Test your solar car battery charger
To test my solar car charger, I simply took the solar charger outside and placed the panel in direct sunlight.
Then I looked at the PV current display of my charge controller. It read 0.2 amps which means my solar panel was actually charging my 12v battery.
It works out!
Technically, my solar car battery charger is complete. I can leave the panel in the sun and the charge controller will stop charging when the battery is full.
That's right - this 12V solar battery charger has a built-in auto shut-off.Very cool. 🇧🇷
If I want to use solar to charge the battery in the car, I just place the solar panel and charge controller on the hood of the car.
But I decided to go one step further...
Step 4: Make your solar car charger look good (optional)
I took a NOCO battery box and put my 12v battery in it.
I then used a drill and the mounting screws that came with my charge controller to mount the controller to the top of the battery case.
See how it turned out:
I then drilled some holes in the top of the case to feed the battery cables through.
Tip:Drill the holes at slightly spaced angles so the wires don't touch as they go through the lid. You don't want to short out the battery!
Then I reconnected everything...
...and finally done:
I'm happy with the result. The case makes the whole system more portable and reduces cable clutter. It also looks cooler. 🇧🇷
DIY solar car battery charger circuit diagram
Here is the wiring diagram for a 12V solar car battery charger with auto shut off.
And this is how it looks structured:
Some things to note:
- Best safety practice is to place a fuse between the charge controller and the battery and solar array
- With most charge controllers, you connect the battery first and then the solar panel. Consult your controller manual for the manufacturer's recommended connection sequence.
- Make sure to get a 12v solar panel and 12v charge controller for your 12v car or lead-acid battery
- I recommend a PWM charge controller because it's a lot cheaper
Tip:This solar charging schematic would work for any battery chemistry and voltage as long as you have a compatible charge controller and solar panel.
How long does it take to charge a car battery with solar energy?
A typical car battery is a 12V lead-acid battery with a capacity of about 50 ampere hours (Ah).
Knowing this, we can use oursSolar battery charging calculatorestimate how long it would take to fully charge a dead car battery with a PWM charge controller.
Here are estimated charge times for 5 common solar panel sizes:
- 5W Solarpanel:107.3 hours of peak sun
- 10W solar panel:54.1 hours of peak sun
- 20W Solarpanel:27.6 hours of peak sun
- 50W Solarpanel:11.6 hours of peak sun
- 100 W Solarpanel:6.3 hours of peak sun
A 5W or 10W solar panel is a good size for a slow charge. Some people use these sizes to keep their car, trailer, or RV battery charged when not in use.
Do you want to charge your car battery with solar energy in a week or less? Go with a 50W or 100W solar panel.
You can also make your charger faster by changing aPWM charge controller to an MPPT charge controller🇧🇷 MPPT charge controllers are much more efficient.
See my post at for more helpSizing a solar panel to charge a 12V battery.
Add-Ons und Updates
Here are some ideas to make your car battery solar charger even better:
- Add suction cups to mount the solar panel in the windshield:I would recommend doing this with a 10w panel. Solar modules work behind glass, but with reduced performance. A 5W panel behind a windshield may not produce a high enough voltage to charge the battery.
- Add a 12V plug to charge the battery from the 12V socket:Some car batteries can be charged from the 12V socket in the car. Instead of connecting the solar charge controller directly to the battery, you can connect it to a 12V "lighter" plug and then plug the plug into the 12V socket. Connect the charge controller to the solar panel until you connect it to the battery.
2 more homemade solar chargers you can build right now
Do you know how to charge a car battery with solar energy?
...why not try to build solar chargers for the other batteries and electronics in your life?
Here are two more solar charging project ideas for you:
1.Solar charger for electric bikes
You can upgrade the 12V solar charging system you just converted into a solar bike charger simply by adding an inverter. An inverter converts direct current into alternating current, so you can plug in your e-bike charger like a socket.
2.USB solar charger for phones
Here is a portable solar charger for charging 5V portable electronics such as phone, tablet, kindle and USB battery pack. You will need a soldering iron for this project!
If a battery is completely drained, a panel can typically charge the battery within five to eight hours. The total charging time will vary depending on the state of a battery. If a battery is totally drained, a solar panel can energize the cells within five to eight hours.How many amps do I need to charge a 12-volt battery? ›
The safest amp to charge car batteries is from 4 to 7.5 amps. Charging within this range ensures the vehicle battery won't overcharge, overheat, or be damaged in the process. Yes, you can safely charge a minimum voltage 12-volt battery with this amp rating, though it will be pretty slow.How fast will a 200 watt solar panel charge a 12-volt battery? ›
An average 200-watt solar panel will charge a typical 12-volt car battery in 5-8 hours.Can you overcharge a 12 volt battery with a solar panel? ›
Higher charging voltage from the solar panels leads to higher Ah being delivered to the battery and ultimately leading to overcharging. The easiest way to control over charging of the batteries is to control the output voltage of the solar panel.What should a 12 volt solar battery read when fully charged? ›
12.6V volts or above - Your battery is healthy and fully charged.Is it better to charge a battery at 2 amps or 6 amps? ›
It is best to slow charge the battery. Slow charging rates vary depending on the battery's type and capacity. However, when charging an automotive battery, 10 amps or less is considered a slow charge, while 20 amps or above is generally considered a fast charge.What amp is best for car battery charger? ›
A charger like a trickle or solar charger are the chargers we recommend for maintaining your battery. A heavy duty charger, fully automatic - either 15, 20 or 30 amp - is what we recommend to charge your battery fully.How many volts does it take to start a car? ›
The standard volts needed to crank up a car is 12.6volts. This figure is between 13.7v-14.7v at the time of operation. The least volts you need to start your car is 11.8v, but you can still activate your vehicle at 10.8 volts.How long does it take for a 100 watt solar panel to charge a 12-volt battery? ›
How long does it take to charge a 12V battery with 100-watt solar panels? Here's the short (and generalized) answer: It can take anywhere from 22.8 minutes to 76.8 hours. It's useful to know when the batteries are fully charged to 100%. That's how you know when to stop charging them.How do I know when my solar battery is fully charged? ›
Using a hydrometer is still the quickest and simplest way to determine the state of charge of the flooded lead-acid batteries in your solar battery system. One of the advantages of a flooded lead-acid battery is the ability to quickly determine the battery's state of charge.
A typical 12-volt car battery has a capacity of 48 amp-hours.How to make a simple solar battery charger? ›
- Step 1: Prep the Fabric. ...
- Step 2: Wire the Solar Panels in Parallel. ...
- Step 3: Solder the Leads to the Panels. ...
- Step 4: Solder the Buck Converter to the Leads. ...
- Step 5: Glue the Charger to the Fabric. ...
- Step 6: Install the Eyelets (Optional) ...
- Step 7: Test Your DIY Solar Charger.
The simplest possible solar battery charging circuit is just to connect the positive wire from a solar panel to the positive battery terminal, and the negative solar panel wire to the negative battery terminal. This was the main practice back in the day, and will quite happily charge a battery!Can I charge my car directly from solar panels? ›
Yes, you can fully charge an electric car with solar energy. You'll need to put up a domestic Solar Photovoltaic System (Solar PV), along with the solar charger for the car battery. Solar panels and electric vehicles are a match made in heaven, on your roof.What happens to solar power when batteries are full? ›
Should the battery bank become full, it will stop absorbing power from the solar system. The solar panels will continue to generate voltage, but that voltage will not be used or stored until there is available energy demand, or battery space.What happens if you charge a 12v battery too long? ›
Overcharging a battery causes excessive gassing — the electrolyte gets hot and both hydrogen and oxygen gas are generated. On older vented batteries, the electrolyte could cook away, leaving the plates exposed and ruining them. On sealed batteries, the buildup of gases could cause the battery to burst.Can I just connect a solar panel directly to battery? ›
Don't connect a solar panel directly to a battery.
Doing so can damage the battery. Instead, connect both battery and solar panel to a solar charge controller.
An average car battery has a capacity of around 48 amp hours which means that, fully charged, it delivers 1 amp for 48 hours, 2 amps for 24 hours, 8 amps for 6 hours and so on.What voltage is a 12V car battery full charge? ›
With the engine off, the fully charged car battery voltage will measure 12.6 volts. This is known as “resting voltage.” When the engine is running, battery voltage will typically rise to 13.5 to 14.5 volts. The battery is boosted to these higher levels by the alternator.What is best battery voltage for solar system? ›
- < 1000W then 12V is Good.
- > 1000W and < 2000W then 24V is Better.
- > 2000W then 48V is Best.
1 Most people think of electricity in terms of voltage, or they might note wattage (e.g., a 60-watt light bulb). However, when considering amperage vs. voltage, amperage is what you need to be concerned with when it comes to electrical shock.What is more important volts or amps for charging? ›
“Ultimately, it's really the amperage that determines how fast a charger will supply power to your device. If you want quicker charging, look for a wall or car charger that delivers 2100 mA of current at 5 volts (or whatever voltage the device you're trying to charge is specced at).”How many amps does a car battery need to start? ›
That being said, a small to a medium-sized car would take around 200-400 amps to start the engine. Similarly, a large-sized automobile would probably need close to 1000 amps. However, a large truck would require about 1500-2000 amps to start.What are the 4 stages of battery charging? ›
- The bulk charge.
- The absorption charge.
- The float charge.
- The equalization stage.
The higher the number, the faster they will recharge. A 5 amp charger will re-charge mid-range batteries fully in 10-12 hours and should be fine for most fishermen. But if you need lightning fast recharges, or if you have batteries that are 120 amp hours or higher, we recommend purchasing a 10 or 15 amp charger.Should I use 2 or 10 amp car battery charger? ›
You would use 10 amperes on a car battery and 2 ampere on whatever small batteries you might want to charge that still use the same voltage. For example, a motorcycle battery could use the 2 ampere charging option.How many volts is lethal? ›
A good rule of thumb is that when a shock is at or above 2,700 volts, the person often dies or experiences severe injury. At over 11,000 volts, the victim will usually pass away.How many volts is too much for a car battery? ›
If your battery has a charge between 12.4V and 12.7V, your battery is fully charged and ready to run. If your voltage is below 12.2V, it needs to be recharged. Take a 30-minute drive on the highway or pick up a charger to bring the voltage back up. If your voltage is higher than 12.9V, the battery is overcharged.How many volts is a dead car battery? ›
A reading of 12.65-12.77 volts means your battery has a full charge. 12.45-12.54 volts means you have a 75% charge, 12.24-12.29 is 50% charged, and 11.99-12.06 volts is 25% charged. 11.75-11.89 volts means your battery is dead.How many amps does a 12 volt 100 watt solar panel produce? ›
A 100 watt panel produces an average of about 6 amps per peak sun hour, or about 30 amp-hours per day.
Here's a quick equation that should help: A 100AH battery charged on a 10 amp charger would take around 10 hours to charge up.How long will a 50 watt solar panel take to charge a 12V battery? ›
20W and 50W solar panels are good for fast charging small 12V batteries. For example, a 20W solar panel can charge a 20Ah 12V battery in around 17 hours of direct sunlight. A 50W panel can do it in around 8 hours.What are 3 stages of battery charging? ›
3- Stage Charging: Bulk Charge, Absorption Charge, and Maintenance Charge.What voltage is a full charge on a solar battery? ›
Most photovoltaic panels that are 12v will produce around 16 to 20 volts, and most deep cycle batteries will only need about 14 to 15 volts to be fully charged. As we touched on above, a solar charge controller is used to ensure a battery does not get overcharged.Do solar batteries charge when turned off? ›
Switch off and leave to charge for 72 hours
Many solar powered lights will still charge if they are not turned on, and by turning them off you actually allow the battery to get a full charge over several days of sunlight.
Most car batteries nowadays are 12-volt 105 AH batteries, which can deliver 12 x 105, or 1260 Watt-hours (1.26 kWh).How much watts is 1 amp? ›
That means that 1 amp = 120 watts.How many years does a 12v battery last? ›
THREE TO FIVE, WITH GOOD BEHAVIOR. Battery manufacturers suggest the average lifespan of an auto battery falls anywhere between three and five years — and for good reason.How long does it take a solar charger to charge a car battery? ›
The short answer is that a 200-watt solar panel that generates 1 amp of current takes between 5 to 8 hours to completely charge a 12-volt car battery.How can I charge my solar charger without a sun? ›
Solar panels can charge with other forms of visible light besides sunlight. Artificial lights such as incandescent fluorescent bulbs can be used to charge solar cells, provided the light is strong enough.
Charging your battery at 12 volts and 20 amps will take five hours to charge a 100 amp hour battery. By multiplying 20 amps by 12 volts, 240 watts is how big of a panel you would need, so we'd recommend using a 300w solar panel or 3 100 watt solar panels.How long does it take to charge a 12 volt battery with a solar panel? ›
For example, a 20W solar panel can charge a 20Ah 12V battery in around 17 hours of direct sunlight. A 50W panel can do it in around 8 hours. 80W and 100W solar panels are good for fast charging large 12V and car batteries. If it's a 50Ah battery, they can fully charge it in around 12 hours or less of direct sunlight.How many solar panels would it take to charge a car battery? ›
And until there's as many charging stations as there are gas stations, solar panels with a home charger are the best option for charging your car battery. Based on current technology, you'll find that anywhere from 6-12 solar panels will produce enough power to support your vehicle's daily needs.How fast will a 50 watt solar panel charge a 12-volt battery? ›
20W and 50W solar panels are good for fast charging small 12V batteries. For example, a 20W solar panel can charge a 20Ah 12V battery in around 17 hours of direct sunlight. A 50W panel can do it in around 8 hours.How fast will a 25 watt solar panel charge a 12-volt battery? ›
How long it takes for a 25-watt panel to charge a 12 V battery depends on the battery capacity. As a 25-watt panel produces 25 watts at 12 V, this translates to around 2 Amps of power to store. With 6 hours of sunlight, it takes that amount of time for your panel to charge a 12 V, 12 Amps battery.How fast will a 100 watt solar panel charge a battery? ›
So, to charge a 100Ah 12V battery, it would take 100Ah/7.08A, which equals about 14 hours. While this may sound like a long time, it is important to remember that this is just a single solar panel and it assumes that the battery you are charging has been fully discharged.Can you run a solar panel straight to a 12-volt battery? ›
But if you are serious and want a good and efficient way, a Solar Charge controller is a must for charging batteries with your trusty solar panel. To wrap it up: Yes, Solar panels can be directly connected to a battery.