How To Charge a Battery Without a Charger

Few things ruin your morning like only getting a few empty cranks when you turn the key to your car. Your battery is dead. The good news is there are multiple options for recharging the battery. Read on to learn how to charge a car battery without a charger so you can get back on the road.

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How to charge a car battery without a charger

Charging a car battery without a charger can be difficult. The standard battery recharge process involves some kind of charging device, usually a trickle charger. That’s the case here, too, using existing products over something cobbled together out of a paperclip, potato and duct tape. That said, you do have several different options to get the job done. Here’s how to charge a car battery at home without a charger, ranked from super easy to really annoying.

Portable jump starter

Portable jump starters are the cool new tech of the last decade or so. They’re similar to the popular portable battery banks used to charge mobile devices. But they’re designed with a much larger battery capacity and car battery specific alligator clips. If you have a portable jump starter, just connect the clips to the battery terminals, power the machine on and start your ride. If you’re in the market, look for a portable jump starter with enough cranking amps to start your engine.

Pros

• Fast
• Portable
• Can be used on your own, with no help
• Can charge other devices and often have other features, like a built-in air compressor

Cons

• Costly
• Must be charged beforehand

Get a jump from another car

Jumper cables are a quick, easy and cheap way to recharge a dead battery. The idea is to use another (good) battery to start your engine, then let your alternator recharge your battery as you drive.

Just connect a red clip to the dead battery and the other red to the good battery. Then connect the black ground on the good car and the last ground on the disabled car. Start the working vehicle, give it a few minutes to charge your battery, then try to start the disabled car. While cheap and easy, the downside is this method requires another vehicle.

Pros

• Cheap
• Relatively easy to use
• No prior charging needed

Cons

• Not as intuitive as a portable charger
• Requires another car

Use a solar charger

Got some time on your hands or just looking to do the job in the most eco-friendly way? While most cheap car battery chargers only keep the battery topped up, a larger and more expensive solar charging system spanning several square feet can charge a car battery from empty. Keep in mind, even with a 300-watt solar charger, charging takes five to eight hours. Place the panels facing the sun, turn the charger on and wait. You’ll solve your problem, but you aren’t going anywhere for a while.

Pros

• Can be inexpensive
• Can be portable
• No external electricity needed

Cons

• Not really designed to charge a completely dead battery
• Chargers large enough to be effective can be expensive
• Not a fast solution

Charge it in a donor car

Back when car electrical systems weren’t as complicated (i.e., prior to the mid-90s or so), backyard mechanics could perform a neat trick: Take two cars with identical batteries, one dead and one healthy. Start the working car and, with the engine running, remove the battery. Replace it with the dead battery and kick back while the car’s alternator charges it. This was also a good way to determine whether the battery or alternator was responsible for your car’s electrical problems.

Unfortunately, you should not try this on a modern car with a sophisticated ECU. Mechanics say pulling the battery on a running modern car could overwhelm the electrical system, resulting in a more expensive repair. However, if you still have two cars that use the same batteries, you can always swap the working battery for the dead one if you don’t have jumper cables and are dead-set on driving the car with the dead battery. Find a way to charge the dead one at a later date, or recycle it and get a new one.

Pros

• Requires no special equipment

Cons

• Can only be done in very old cars
• Does not actually charge the battery when done with newer cars
• Not any easier than using jumper cables.

Battery isolator

If you have an RV, you’re likely familiar with these. A dual battery isolator kit is essentially a relay that allows you to charge two batteries off of one alternator. While battery isolators are useful in an RV for recharging deep-cycle batteries that run accessories, it’s unlikely that you already have this system in your car or SUV.

It is possible to add a battery isolator to your vehicle and then drive and recharge like normal, but it’s not a go-to solution if your sole vehicle won’t start.

Pros

• Effective
• RV owners probably already have one

Cons

• Most people are not RV owners
• Expensive compared to other options
• Still requires a car that can start

UPS/inverter

Nope, this doesn’t convert FedEx deliveries to UPS. UPS stands for Uninterruptible Power Supply. An inverter is what changes direct current to alternating current or vice versa. Together, they form a neat device that kicks on backup power the instant a power loss is detected. You can find them in hospitals and data centers, and you may find them in newer houses, usually located near the breaker box.

The UPS has a 12-volt battery that can power your critical systems, such as Wi-Fi, after the inverter converts the electricity to AC suitable for the devices. Without the inverter, the 12-volt UPS battery might be a direct fit to your 12-volt DC car battery. Obviously, this solution requires you to have a UPS nearby, one that is designed to discharge DC, and the appropriate cables to connect to your vehicle. If you have all that, get to it and get back on the road.

Pros

• Always ready to go once installed

Cons

• Expensive
• Requires extra equipment
• Not yet common in residential settings

Push-starting

If you have a manual transmission and at least one friend handy, you may be able to force the engine to start. Also known as “popping the clutch,” the process goes something like this: With the key in the “on” position and the clutch depressed, shift the car into second gear. Your friend (or friends) pushes the car along flat or (very) slightly inclined ground until it’s going at least 5 MPH. At that point, you release the clutch. The idea is that engaging the transmission while the car is in motion will force the engine to turn over, starting it. Then you wait for the alternator to charge the battery.

The risks of this method should be obvious. It can only work on manual transmissions. Until the engine starts, you’ll have no power braking or steering. This makes steering or stopping the car almost impossible. If you try this on an incline that’s just slightly too steep and it doesn’t work, you’ll be forced to rely on the parking brake to stop the car.

Pros

• Requires no equipment or second car
• Fairly reliable if a dead battery is the only electrical problem

Cons

• Requires at least one other person
• Only works on manual transmissions
• Requires an open flat or inclined space
• Driver may not be able to control the car until the engine starts

Conclusion

While there are several methods to recharge a dead battery, it’s something you usually don’t need to do if you perform the right maintenance. Watch for the warning signs of a failing battery or worn-out alternator. Keep a portable jump starter or jumper cables in your vehicle, and be ready to play Good Samaritan if another driver needs help.