Can I Use A Battery To Charge Another Battery?

You can charge up a discharged battery with the same kind of charged battery. You will not require any kind of conductor or charger between the two. You just need to connect them and the energy will start to flow on its own, red to red terminal and black to black. Note the voltage should be the same on each. The overall process is not very efficient.


12V to 12V battery charging

This process will work if the battery that has to be charged has its energy drained out is less than 10V and then it can be connected to a fully charged battery directly for the energy flow.

When it is fully charged a voltage of 13.8 to 14 V can be seen in the open circuit. The charging will continue till the batteries have equal energies. If the battery that has to be charged is of a very low capacity then the other one will get charged but not fully.

Now the alternate way to charge the battery is not that easy. If the leads on the cell are open just like the ones in old vehicles it takes place in two steps. First from 0 to 6V then from 6 to 12V. Due to the voltage difference the current circulated is quite high and has to constantly keep it in check.



12V to 24V battery charging

This combination is not possible. The charger that you use for the charging will be destroyed while doing so. 24 V is a very high voltage and may damage the capacitors present inside the charger. This can lead to a short circuit and may even cause fire during some situations.



How to charge a car battery

Car batteries draw their power from harnessing the extra power produced by the car’s engine. Some batteries can have a life of about five years. Following are the steps that you should follow to charge a car’s battery.



Prepare yourself to charge the battery – Wear the safety gear that are required during the charging process. Use protective eyewear to safeguard yourself from the fluids present in the battery. Wear rubber gloves to be careful of getting shocks. Keep children away from the car.



Find out the type of battery you have – If you want to charge your car battery first it is important to know the type of battery present in your car. You can find the type inscribed somewhere on the battery itself. If the battery due to some reason is missing you can check the manufacturer’s website to see the type.

You will also have to find out the voltage. The same can be done for finding the voltage it will be on the battery or the manual of the vehicle owner.



Get a battery charger – Find the charger compatible with your battery. A lot of new types of chargers have come into the market that have an auto-cut option when the battery gets fully charged to stop the overflow of energy. The old chargers do not have this option and have to be operated manually. There is a risk of overcharging in such kinds of chargers if you do not know how they function.



Charge the battery – After removing the battery from the car connect the charger. Start charging and be very cautious while doing so. Once the battery is charged, put it back in its place and your work is done. It can take 12 hours to be full.


The other ways you can use are jump-starting the battery with the help of some other car or using a trickle charger.



Lithium Battery vs other types

Lithium batteries are found in most cars and devices.

Let’s compare it with others. The lead-acid battery takes about ten hours to get charged while the lithium-ion battery gets charged in just three hours.

Hence it is more suited for times when you do not have time. This is because lithium can conduct current at a faster rate than lead.

The difference between lithium-ion and lithium batteries is that when a lithium battery is drained of its energy it can not be charged again but a lithium-ion battery can be charged over and over again.



Battery To Battery charging

Most of the battery banks out there have adopted this method of charging. All you require is a battery whose voltage is higher than the battery that has to be charged and also should be of a higher capacity that is in Ampere hours.

One interesting fact about the charging banks is that they mostly use Li-ion batteries to charge a Li-ion battery. The right way to do this is to have a DC-DC converter that can raise the voltage of 3.7V to a voltage of 5V.



How long to charge

The more the battery has discharged the longer it will take for it to be fully replenished or recharge. Normally it can take up to many hours to efficiently or fully charge the battery.

If a battery is fully discharged then the average time it is said to be fully recharged is about 12 hours. But then it also depends on the size and the purpose and the type of the battery.

Before proceeding to charge your battery measure it with a voltmeter and then you will know how much it needs to be charged and for what duration.


The information is generally written on the battery itself but if it is not available there due to some issue then you can search it on the net and get all the details about it. It is very important to know all the details about the battery to assure that no type of accident takes place.

You should know the type of battery it is, whether it is a lithium-based or a lead-based one. You should also know about the voltage of the battery.

The best way to charge is with a charger plugged into the wall outlet or cigarette plug. B to b is possible using matching voltages is slow and not efficient.


Instructions: How to Charge RV Battery with Generator



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