DIY Solar 12V Car Battery Charger: 4 Steps (w/ Video)
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I recently made a DIY solar car battery charger.
The circuit has auto cut-off to prevent overcharging the battery. And you can use whatever size solar panel you want depending on whether you want a fast charge or a slow trickle charge.
Here’s a 60-second video I made showing how I built this project. Check it out below and consider subscribing to my YouTube channel for more DIY solar videos like this!
- 12V car battery — or just a standard 12V lead acid battery
- Renogy Wanderer 10A charge controller — or any cheap PWM charge controller
- 12V solar panel — I used a 5W 12V solar panel for a slow trickle charge. I’d use a 20W 12V solar panel or greater for a faster charge.
- Wires, connectors, and fuses — I used the NOCO GC018 12V adapter, which comes with ring terminals. If you want battery clamps, use the NOCO GC017.
- MC4 adapter cables — Needed if your solar panel has MC4 connectors. These aren’t needed for the 5W and 20W panels linked above.
- NOCO battery box (optional)
- Wire cutter
- Wire stripper
- Drill (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. (the GC018 is a 12V plug adapter that comes with an inline fuse and ring terminals.)
First, I cut off the 12V plug socket with my wire cutters. Snip, snip!
Then I peeled the wires apart and stripped them with my wire strippers.
Just like that, my “battery cables” are ready. I can now connect charge controller and battery.
To do so, I connected the positive and negative ring terminals to their respective battery terminals. Red to red, black to black! (I also swapped out the inline fuse for the right fuse size given my solar panel wattage.)
Then I connected the stripped wire ends to the battery terminals on my solar charge controller.
My solar charge controller turned on, indicating it was properly connected to the battery.
At this point, consult your charge controller’s manual to see if you need to program it for your battery’s chemistry. Mine defaults to sealed lead acid, which is the type I was using.
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.
Note: If your solar panel has MC4 connectors, you’ll have to use MC4 adapter cables to be able to connect it to your charge controller.
Now the solar panel is connected to the 12V battery via the solar charge controller.
Here’s what mine looked like:
This means my solar car battery charger is complete!
Yep, that’s all there was to it.
Time to test it 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 put the panel in direct sunlight.
Then I looked at the PV current display on my charge controller. It read 0.2 amps, meaning my solar panel was in fact charging my 12V battery.
Technically my solar car battery charger is done. I can just leave the panel out in the sun and the charge controller will cut off the charging when the battery is full.
That’s right — this solar 12V battery charger has auto cut-off built right in. Pretty cool.
If I want to solar charge the battery while it’s in my car, I can just put the solar panel and charge controller on the hood of my car.
But I decided to take it one step further…
Step 4: Make Your Solar Car Charger Look Nice (Optional)
I picked up a NOCO battery box and plopped my 12V battery right inside.
Then I used a drill and the mounting screws included with my charge controller to mount the controller to the top of the battery box.
Next, I drilled some holes in the top of the box to feed the battery cables through.
Tip: Drill the holes angled slightly away from each other so the leads won’t touch when fed through the lid. You don’t want to short the battery!
Then I reconnected everything…
I’m happy with how it turned out. The box makes the whole system more portable and cuts down on cable clutter. It also looks nicer.
DIY Solar Car Battery Charger Circuit Diagram
Here’s the circuit diagram for a solar 12V car battery charger with auto cut-off.
And here’s what it looks like when built:
- Safety best practices are to place a fuse between the charge controller and both battery and solar panel
- For most charge controllers, you connect the battery first and then the solar panel. Consult your controller’s manual for the manufacturer’s recommended connection order.
- 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 circuit diagram would work for any battery chemistry and voltage as long as you got a compatible charge controller and solar panel.
How Long Does It Take to Solar Charge a Car Battery?
A typical car battery is a 12V lead acid battery with a capacity of around 50 amp hours (Ah).
Knowing this, we can use our solar battery charging calculator to estimate how long it’d take to fully charge a depleted car battery using a PWM charge controller.
Here are the estimated charge times for 5 common solar panel sizes:
- 5W solar panel: 107.3 peak sun hours
- 10W solar panel: 54.1 peak sun hours
- 20W solar panel: 27.6 peak sun hours
- 50W solar panel: 11.6 peak sun hours
- 100W solar panel: 6.3 peak sun hours
A 5W or 10W solar panel is a good size to pick for a slow, trickle charge. Some people use these sizes to keep their car, camper, or RV battery topped up when not in use.
Want to solar charge your car battery in a week or less? Go with a 50W or 100W solar panel.
You could also make your charger faster by swapping out a PWM charge controller for an MPPT charge controller. MPPT charge controllers are much more efficient.
Add-ons and Upgrades
Here are a couple ideas for making your car battery solar charger even nicer:
- Add suction cups for attaching the solar panel to inside to your windshield: I’d recommend doing this with a 10W panel. Solar panels work behind glass, but with a reduced output. A 5W panel behind a windshield might not output a high enough voltage to charge the battery.
- Add a 12V plug to charge the battery through the 12V socket: Some car batteries can be charged through the 12V socket inside the car. Instead of connecting the solar charge controller directly to the battery, you could connect it to a 12V “cigarette lighter” plug and then put the plug in the 12V socket. Just remember not to connect the charge controller to the solar panel until you’ve connected it to the battery.
DIY Solar Chargers You Can Build Now
You know how to solar charge a car battery…
…why not try building solar chargers for the other batteries and electronics in your life?
Here are two more solar charging project ideas for you:
Solar Electric Bike Charger
You can upgrade the 12V solar charging system you just made into a solar ebike charger simply by adding an inverter. An inverter converts DC to AC, letting you plug in your ebike charger like you would into a wall outlet.
Solar USB Phone Charger
Here’s a portable solar charger for charging handheld 5V electronics such as your phone, tablet, Kindle, and USB battery pack. You’ll need a soldering iron for this project!
Noco solar charger
UPC 046221130928 is associated with NOCO XGS9USB XGRID 9 Watt Foldable Solar Panel XGB3L Battery
UPC 046221130928 has following Product Name Variations:
- NOCO 9W FOLDABLE SOLAR PANEL W/XGB3L 11WH USB BATTERY PACK AND LED FLASHLIGHT
- NOCO XGS9 USB 9W Solar Panel USB Battery Pack LED Flashlight
- NOCO XGS9USB XGRID 9 Watt Foldable Solar Panel XGB3L Battery
- NOCO XGrid 9 Watt Portable Solar Panel and USB/LED Flashlight Kit
- NOCO XGrid XGS9USB 9W Portable Solar Panel and USB/LED Flashlight Kit
- 9W Portable Solar Panel USB/LED Flashlight Kit
- NOCO Xgrid 9W Portable Solar Panel USB/LED Flashlight Kit XGS9USB
- Noco Xgrid 9w Portable Solar Panel USB/led Flashlight Kit. 4000917. Power Ba
- Noco XGS 9-Watt Solar Panel With USB Led Flashlight Kit
- XGrid 9W Portable Solar Panel USB/LED Flashlight Kit
|UPC-A:||0 46221 13092 8|
|EAN-13:||0 046221 130928|
|Country of Registration:||United States|
|Product Dimension:||7.8 X 3.1 X 14.3 inches|
|Last Scanned:||2022-01-15 11:00:17|
Products with UPC 046221130928 were listed on the following websites. Product are accurate as of the date/time indicated and are subject to change. Disclosure: We may earn a commission when you use one of our links to make a purchase.
|NOCO 9W FOLDABLE SOLAR PANEL W/XGB3L 11WH USB BATTERY PACK AND LED FLASHLIGHT||77.32||2017-06-28 11:23:16|
|NOCO XGS9 USB 9W Solar Panel USB Battery Pack LED Flashlight||80.00||2022-01-15 11:00:17|
|NOCO XGS9USB XGRID 9 Watt Foldable Solar Panel XGB3L Battery||89.75||2018-11-23 21:28:27|
|NOCO XGS9USB XGRID 9 Watt Foldable Solar Panel XGB3L Battery||89.95||2017-06-19 10:59:07|
|NOCO XGrid 9 Watt Portable Solar Panel and USB/LED Flashlight Kit||89.95||2017-08-02 14:38:44|
|9W Portable Solar Panel USB/LED Flashlight Kit||102.80||2016-12-07 05:44:32|
|Noco Xgrid 9w Portable Solar Panel USB/led Flashlight Kit. 4000917. Power Ba||149.95||2017-01-31 12:26:00|
|Noco XGS 9-Watt Solar Panel With USB Led Flashlight Kit||149.99||2015-08-27 22:12:28|
|XGrid 9W Portable Solar Panel USB/LED Flashlight Kit||188.95||2016-12-07 11:22:45|
|NOCO XGS9USB XGRID 9 Watt Foldable Solar Panel XGB3L Battery||287.00||2020-03-25 21:15:08|
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The Best Jet Ski Battery Charger – Voltage, Amps, and Tips You Need
The best jet ski battery charger will be a 12-volt Smart charger that charges at a max of 2 amps.
You must not charge over 2 amps, and you need to use a Smart battery charger. There are also other little details you need to do that we’ll discuss below.
A battery charger sometimes goes by the names trickle charger and battery maintainer too.
Important: Just like a boat, it’s good practice to vent your jet ski for a few minutes before working on it or starting it, especially if it’s been sitting, or you just put gas in it.
NOCO GENIUS2, 2-Amp Fully-Automatic Smart Charger
My top pick for the best jet ski battery charger is the NOCO GENIUS2 2-Amp Fully-Automatic Smart Charger. Here are the reasons why it’s my top pick.
- 2 Amps – not too much and not too little of charging power, it’s just right.
- Smart charger – It turns on and off as the battery needs it.
- Has a built-in maintainer.
- Can detect sulfation and help restore a battery.
- One of the few Smart battery chargers that will try to bring back a dead battery.
- Small – It doesn’t take up much room.
- Its alligator clips are easy to use on jet ski batteries.
- Temperature compensation – Needed for hot days or cold days in storage.
Tip: These battery chargers are the same you find for car batteries. So yes, you can use a battery charger made for car batteries for your jet ski battery, so long as it’s 12-volt and meets the correct amps.
Battery Tender Plus 12V Battery Charger and Maintainer
My second place pick is the Battery Tender Plus 12V Battery Charger and Maintainer. Here is why I picked it.
- 1.25 amps – Just enough amps to charge a jet ski battery at a good speed.
- Super simple to use – Plug it in, connect to the battery and select 12 volts and let it go.
- Maintainer – Turns on and off as the battery needs it.
- Small – Stores away nicely when not in use.
Solar Battery Charger
A solar battery charger is the best option if you need to charge or maintain your jet ski battery without a power outlet.
This is what I use on my jet ski to help maintain the battery, and I go over the full details here.
How To Charge A Jet Ski Battery
But here is a short version…
- For best results, remove the battery from the jet ski.
- Connect the positive cable of the charger to the positive post of the battery.
- Connect the negative cable of the charger to the negative post of the battery.
- Plug the battery charger power cord into the correct wall outlet.
- Wait for the Smart charger lights to go on and let you know it’s charging.
When charging is done, remove the negative cable of the charger first and the positive cable next.
Battery Charger Is Not Charging Jet Ski Battery?
If the battery charger status lights don’t come on when you connect it to the battery, then make sure you have it hooked up right.
The positive cable of the charger goes to the positive of the battery, and the negative of the charger goes to the negative of the battery.
If the lights do come on, but the charger says the battery is bad, you need to get a new battery. The battery is too sulfated to recover.
If the battery charger says the battery is charged, but when you start the jet ski, it doesn’t start, then you only had a surface charge. There could be other reasons why your jet ski is not starting as talked about here.
A surface charge is not a full charge, and you’ll need to get a new battery no matter what the charger says about the battery charged status. Only a load tester can determine if the battery is good to start a jet ski and not the LED light on the charger. If you don’t have a load tester, many auto part stores will load test a battery for you, and a lot do it for free.
How Do I Know My Jet Ski Battery Is Bad?
What matters more than voltage is amps, and a load tester can only test this. Many auto parts stores will load test a battery for you.
The easiest way to tell if your jet ski battery is bad is by listening to the engine area when you start your jet ski.
A weak battery will struggle to turn over, especially in the water.
A super-weak battery will give you multiple clicking noises when you press the start button, as talked about here.
A completely dead battery may power on the gauges, but nothing happens after that.
The majority of starting issues you’ll run into with your jet ski will most often be a bad battery. So if your jet ski won’t start replacing the battery is often the first thing you should do, even if you think the battery is fine.
Can You Recharge A Jet Ski Battery and How Often?
Jet ski batteries are rechargeable, but they will die and won’t recharge if you don’t use your jet ski for 4 months.
It’s best to recharge your jet ski battery every 3 months that you don’t ride.
So if you don’t ride your jet ski in August and September you should charge your battery at least once in October.
Tip: If you’re not riding for a few months you should take the battery out and use the Smart chargers with a maintainer built-in to keep the battery good when in storage.
Does Your Jet Ski Need a Battery Switch?
No, your jet ski does not have a battery switch and does not need one either.
The reason why your jet ski battery dies is not that the jet ski is always pulling a little power, but instead, it’s because the lead-acid battery goes flat if it’s not being used regularly.
If you ride your jet ski all the time, the battery stays active and lasts for a long time because it’s being used. However, when you leave it to sit for too long, it goes flat, and adding a battery switch doesn’t fix this.
Instead of a battery switch, consider getting a solar charger. When you’re not riding, hook up the solar charger, and it will keep the battery active and lasting for longer. See how I have my solar charger set up on my jet ski.
What Amp To Charge Jet Ski Battery?
You want to charge your jet ski battery at a max of 2 amps. Lower amps like 0.75 to 2 amps are fine too.
Going over 2 amps charges the battery too fast for these small batteries, and you can end up cooking the battery, which is very bad.
When charging your jet ski battery, you need to have it ventilated as lead-acid batteries release a small amount of hydrogen and oxygen when charging. Leave the access panel, seat, or hood ajar when charging your jet ski battery or better yet, take it out of the jet ski. Also, keep the rain off your jet ski when you have an access panel, seat, or hood open, so you don’t flood your jet ski with rainwater.
How Long Does It Take To Charge A Jet Ski Battery?
It takes about 12 hours to charge an empty jet ski battery fully.
It can take longer or shorter depending on what the Smart charger considers is best for your battery. This is why we suggest using Smart chargers as they turn on and off as they’re needed.
You need to let your battery charge fully and slowly if you want the battery to last. It’s best to not rush these things.
When Should You Replace A Jet Ski Battery?
The most I’ve gone without replacing a jet ski battery is 5 years, but that is because I kept it on the solar charger when I was not using it.
Ideally, it would be best if you replaced your jet ski battery every 3 years.
If you’re replacing your jet ski battery every year, then it means you’re not riding it enough or charging it enough during the off-season. Lead-acid batteries go bad when they’re not used for months.
You can sometimes recover a dead battery that’s been sitting for a long time by charging it, but a good bit of them don’t recover.
Can You Jump Start A Jet Ski Instead Of Charging It?
No, do NOT jump-start a jet ski battery, especially from your car or truck. I explain why this is bad in this post.
What Battery Do I Need For My Jet Ski?
You need a 12-volt battery that ranges in sizes from 16, 20, to 30.
What type of jet ski battery you need and what is the best one to get can be found in this guide here.
Do You Need To Add Water To A Jet Ski Battery?
Adding water to jet ski batteries is not very common these days.
Most manufacturers are moving to sealed jet ski batteries, which makes adding water a thing of the past.
Even if you have a non-sealed battery, I would not add water to it and instead, get a new battery. The trouble you would have to go through to get the distilled water, get a hydrometer, and mess with dangerous sulphuric acid is not worth it if you ask me.
Will Riding My Jet Ski Charge It’s Battery?
No, riding your jet ski will not fully charge your jet ski battery. It may give it a surface charge but nothing lasting.
Jet skis use a stator and not an alternator like your car.
A stator only maintains a charge and does not fully charge as an alternator would.
8 thoughts on “The Best Jet Ski Battery Charger – Voltage, Amps, and Tips You Need”
Great advice on battery and charger. I am looking at purchasing our first jetski, Seadoo gti 130. This website has been invaluable to supply the information I need. Thanks very much Reply
Hi. Picked up the 2 amps NOCO charger and noticed the battery says charge at 1.8 amps. Will the extra charge amperage cause any issues? The same store also had a 1 amp NOCO available. Thanks. Reply
It’s fine. I’ve never seen a 12-volt lead acid battery be that specific about charging amps (except maybe for computer power supplies, but not automotive), they usually round up to 2 amps. The biggest thing is that you don’t want to go over 2 amps, so avoid the 2.5, 3, 4, etc. amp chargers. Also, make sure it’s a Smart charger, the ones that turn on and off as needed. Reply
Hey Steve I’ve just ordered a new GTX230 and will be keeping it on a Jetski Pod at a marina with a cover on it between rides, so no ability to have a Smart charger hooked up. A little confused by your battery charging advice in that; on the one hand you say the battery needs to be on a charger if you’re not riding the ski for more than 3 months (winter). So I’m guessing it will be fine if I’m riding the ski at least once a month year round, but then you go on to say that riding the ski won’t change it up because it runs on a stator not an alternator? So does this mean whether you ride it or not, it will still need to be charged up every three months? Maybe I’ve misunderstood you, can you please clarify. PS Yeah, we can ride year round in Oz no snow here. Our winters are just less hot than our summers Cheers Steve Reply
It’s more about keeping the battery active than charging it. When you ride your jet ski it’s keeping the battery active with the stator and so does putting it on a battery charger. A stator will charge a battery but it’s more of a side effect of maintaining the charge. If you’re not keeping the battery active the internal plates sulfate and cause it to die, this takes months to happen. Charging a dead lead acid battery will sometimes loosen the sulfation and allow the battery to charge again but if you ride it more or keep it on a Smart charger the plates won’t sulfate. If the sulfation is too much the battery won’t recover when using a battery charger. This is why I like the solar battery chargers as they supply just enough power to keep the battery active, they don’t even need to be in direct sunlight. So if you’re riding your jet ski often, once a month is fine, you don’t need to charge the battery as you’re keeping it active. But if you go the whole winter without running the jet ski or keeping the battery on charge you run the risk of the battery being dead because it sulfated too much and the battery charger might not be able to “smack it back to life”. Reply