Can You Charge a Battery With Another Battery?

If your battery dies, you can call a tow truck, but it may be more convenient to charge battery from another battery. However, there are a few factors to consider before charging it. Otherwise, it could put your car in danger and would incur severe damage. If you’re looking for ways to do it securely, this article is designed for you.

Can you charge a car battery with another battery?

Yes, you can charge your car battery with another battery. But before you start hooking up jumper cables to your neighbor’s old clunker, you should consider the kind of batteries used in the cars, voltage (e.g., 12-volt vs. 6-volt), and the possible hazards when done incorrectly.

One way is to connect one battery’s positive terminal (the red cable) to another’s negative terminal (black). Other methods include connecting two metal objects like an iron pipe and steel wool or hooking up jumper cables in reverse order.

How do you charge a 12-volt battery with a 12-volt battery?

You may think that two 12V batteries will charge each other if drained out to less than 10 volts, but this isn’t possible. If the first one has a higher voltage, it would damage your unit and causes it to get hot or explode since there are no differences in their electrical charges.

This means internal resistance starts rising too, which causes increased losses during current flow through wires, affecting power transfer rates even though efficiency might not seem affected at first glance.

Therefore, it’s best to recharge your 12V battery by using another similar-capacity 12V power supply. But, if you have access to a 24V source, it will be safer and more efficient to use instead of two 12Vs placed in series (i.e., one after the other). If this still doesn’t work for some reason, it would be best to have your 12V battery professionally recharged.

Can you charge a 12V battery with a car battery?

Yes, you can charge one large or deep cycle lead-acid battery with another smaller voltage capacity battery. It’s essential to charge them if both lithium-ion batteries have equal watt-hour ratings and are at full capacity.

Lead-acid batteries shouldn’t be charged this way. The  12-volt batteries typically have differing voltage ratings. Thus charging a 6-volt battery using a 12-volt battery may work for a minute, but it would overcharge because too much energy is transmitted between them. Lithium-ion batteries don’t use battery tolerance ratings. Watt-hours are used instead. It can only be cycled once each day. Thus they need more time to recover before being recharged.

To sum up, it’s possible to charge a battery with another battery as long as they have similar watt-hour ratings and are at the same state of discharge or full capacity. But remember that not all batteries are designed to be charged this way, so always consult your user manual before attempting to charge your batteries this way.

Can you fully charge a car battery with jumper cables?

Yes, you can charge a car battery with jumper cables, but it’s not always the best idea. If you have a battery charger, that’s the better way to go. Jumper cables are meant for jumpstarting a car, not charging it. Thus, charging a battery with jumper cables can damage your car’s electrical system and even start a fire.


In conclusion, the next time your car battery dies, don’t panic. You can charge a battery with another battery, but it isn’t safe or effective. Use a battery charger to charge your car battery instead. It is the better option and is much safer than using jumper cables. Follow the simple tips mentioned above, and you’ll be back on the road in no time. Nonetheless, if anything wrong happens, a tow truck waits for you.

About the author, Phil Borges

Phil Borges is a battery aficionado. He's written extensively about batteries, and he loves nothing more than discussing the latest innovations in the industry. He has a deep understanding of how batteries work, and he's always on the lookout for new ways to improve their performance.