How Do You Charge A Lithium Battery With A Generator?


Lithium batteries have actually become a popular option for their high energy density and long life-span. Nevertheless, it can be challenging to charge them when you’re far from standard source of power. Luckily, an extremely creative method to prevent this problem exists that includes a generator.

The generator is a crucial part of your automobile. While driving, it transforms power into electrical energy. This energy charges the starter battery and powers your automobile’s electrical system.

In this short article, we talk about whatever you require to understand to efficiently charge your lithium battery with a generator. In addition, we stroll you through the procedure detailed and highlight the threats included with this practice.


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Can you charge a lithium battery with a generator? Yes, you can charge your lithium battery with a generator. There are 3 methods you can link a generator to your lithium battery:

Parallel connection.

DC-DC battery charger.

External voltage regulator.

  • Despite the technique you pick, it is very important that you work out care.
  • Unlike standard lead-acid batteries, lithium batteries need a particular charging profile, so you need to utilize a battery charger that compares well with lithium batteries.
  • In addition, you need to make sure that the charging voltage and present are within the battery maker’s suggested variety and keep an eye on the battery’s temperature level throughout charging.

Keep in mind to our readers

: Although any air conditioner electrical generator can be technically called a generator, we’re utilizing the term generator to describe automobile or marine generators.

What is a generator?

A generator charges your car’s battery and materials power to its electrical system while it’s running. Source:

A car’s generator is a necessary part of its electrical system, accountable for creating electrical power to charge the battery and power the car’s electrical systems.

An alternator charges your vehicle's battery and supplies power to its electrical system while it’s running.
The generator transforms power from the engine’s turning crankshaft into electrical energy. It does this through a rotor and stator system, where the rotor spins inside the stator, developing an electromagnetic field that causes an electrical present in the stator windings.
A voltage regulator controls the electrical power produced by the generator to make sure that the battery and electrical system do not catch extreme voltage or present.

Basically, the generator is accountable for keeping the battery charged and offering electrical power to your car’s electrical system while the engine runs.

A generator’s elements

Generator’s main elements.

Source: Autocar-inspection.

A generator consists of the following elements:

Alternator's primary components.
Real Estate:
Typically made from aluminum, provided its light-weight and


  • homes. Rotor: A turning magnetic aspect made from a wire coil covered around a magnet (2 iron “claws”). Stator
  • : A fixed part that houses 3 sets of copper wire coil windings. It’s repaired to the shell of the generator. Voltage regulator:
  • Restricts the generator’s voltage, guaranteeing it remains in the suitable variety (12V to 14V). Rectifier:
  • Transforms the rotating present (AIR CONDITIONING) to direct present (DC). Pulley-block:
  • Links the engine to the rotor shaft through a drive belt. Its function is to turn the rotor as the engine runs. Bearings:
  • Assistance the rotor shaft, enabling the rotor to turn easily. How does a generator work?
  • A generator works according to Faraday’s Law of Induction

Simply put, this law mentions that any modification in the electromagnetic field of a coil of wire will cause a voltage in the coil.

As formerly pointed out, the generator is linked to the engine through a drive belt. This belt links the generator’s wheel to the engine’s crankshaft. An example of a system where a drive belt links the crankshaft from the engine to the generator’s wheel. Source:

For That Reason, when you switch on your automobile’s engine, its crankshaft starts turning. Therefore, the generator’s wheel (linked to the rotor shaft) likewise turns.

An example of a system where a drive belt connects the crankshaft from the engine to the alternator's pulley.
The starter battery at first offers a percentage of electrical power to the rotor’s coil. This electrical power travelling through the coil produces an electro-magnetic field.
2 iron “claws” (the electromagnet) improve this electromagnetic field. One is the magnet’s south pole, and the other is the north pole.

As the engine turns the shaft (turning the magnet), the altering electromagnetic field causes a present circulation in a set of coils (the stator), as forecasted by Faraday’s Law.

Since the electromagnetic field on the rotor rotates polarity (north/south), the instructions of the circulation of present caused in the coil likewise


lot of times per second. Therefore,

a generator produces rotating present (AIR CONDITIONING), thus the name “generator.” Considering that the automobile battery and its electrical gadgets require direct present (DC), every generator has a rectifier. The rectifier transforms the rotating present (AIR CONDITIONING) created by the generator into direct present (DC). Here’s an excellent video discussing how automobile generators work if you’re more of a visual individual:

How do you charge a lithium battery with a generator?

Now let’s get to the “hands-on” part of adjusting your generator to charge your lithium battery bank.

With a couple of tweaks occasionally, you can utilize the very same generator that charges the automobile battery and powers the automobile's electrical system to charge your off-grid lithium battery bank (your "home" batteries).

Some contemporary Recreational vehicles are currently established to do this. If you

link it with a 7-way adaptor

, it must have the ability to offer a present to charge your auxiliary 12V batteries (home batteries) while you drive.

Here’s a comprehensive diagram of a 7-way adaptor: Notification that input number 4 is for charging auxiliary 12V batteries, such as lithium batteries. Source:

Nevertheless, since this energy likewise powers all the Recreational vehicles gadgets (like displayed in the image above), the present that reaches your home batteries is reasonably low (normally less than 5A). For that reason, this is not the most effective method to charge your lithium battery with a generator.

7 way adaptor diagram.
To effectively charge your lithium battery with a generator, you need to ensure modifications to your car’s electrical system.
Numerous possible setups exist for charging a lithium battery with a generator. Some usage

battery isolators

, and some utilize a

split-charge relay In this short article, we talk about 3 setups. 3 various methods to link your generator to your lithium battery 1. Parallel connection

In this setup, you link the generator directly to the starter battery and after that position the lithium battery in parallel with the starter battery, thus:

Source: Climatebiz

This setup is simple to set up, and you do not require any unique devices.

Nevertheless, the significant drawback is that this setup will adversely affect your battery’s life and your generator. In addition, the charging speed will not be optimum since the voltage offered by the generator will be utilized to charge both batteries (starter battery and solar battery).

Charging a lithium battery with an alternator in parallel.
Additionally, it’ll charge both batteries with the very same voltage (single-stage charging)– this is far from perfect, particularly when charging various battery chemistries.

2. Utilizing a DC-DC battery charger

You can link your generator to your starter battery and after that connect your starter battery to your lithium battery through a DC-to-DC battery charger. An easy electrical wiring plan for this setup is revealed listed below:

Source: Climatebiz

This setup beats the very first one. Why? Since the DC-DC restricts the quantity of present entering into your lithium battery. In this manner, it does not harm your generator by continuously drawing a big quantity of present– it just draws a safe quantity of amperage.

You can likewise change the DC-DC battery charger to offer the appropriate

charging lithium battery using dc to dc charger
lithium battery charging


The issue with this setup is that it draws present from the starter battery, which can significantly slow the charging procedure of the lithium battery. 3. Utilizing an external voltage regulator With this setup, you utilize an external voltage regulator to link the generator to the lithium battery. Then, you utilize a DC-to-DC battery charger to link the lithium battery to the starter battery, as displayed in the image listed below:

Source: Climatebiz

This setup provides lots of benefits:

It enhances the generator, enabling quick charging for your lithium battery bank and starter battery.

charge lithium battery using external voltage regulator an alternator
It offers the appropriate charging profile, as needed by the lithium batteries.

The DC-DC battery charger likewise makes sure the starter battery is charged properly with the appropriate charging settings.

  • Disadvantages
  • Nevertheless, substantial disadvantages of this setup consist of high extra expenses (particularly with the external regulator), a fairly big system (with 2 additional gadgets), and increased setup intricacy.
  • For that reason, thinking about effectiveness and expenses,

the most suggested setup would be number 2– linking your generator to your starter battery and after that connecting your starter battery to your lithium battery through a DC-DC battery charger.

In truth, if you look for guide videos online on how to charge a lithium battery with a generator, you’ll discover that setup number 2 is the most extensively utilized.

Utilizing a DC-DC battery charger to charge a lithium battery with a generator Think About a DC-DC battery charger as a smart battery charger that utilizes DC power– from your generator (utilizing an external voltage regulator) or another battery, for example– as a source to charge your house/solar batteries.

In addition, you can set it as much as offer the appropriate charging profile for lithium batteries and

AGM & & Gel

, and so on. Its main function is to regulate/limit the present entering into the lithium battery. This avoids damage to both the DC source of power and the lithium battery.

Without a DC-DC battery charger, charging lithium batteries utilizing another DC source of power would adversely affect the life span of both gadgets. It’s time to get your hands unclean Apart from vital tools (like pliers and so on), here’s what you’ll require:

DC-DC battery charger (with a ranked amperage suitable with your generator’s size).

Linking wires (with the appropriate gauge/length).


  • Lug terminals (for the linking wires).
  • Change (optional– just if you wish to cut off the supply to the DC-DC battery charger by hand).
  • When you have all the necessary products– and presuming the generator is currently properly linked to the starter battery– you’ll require to follow these actions:
  • Link the starter battery to the DC to the DC battery charger’s input.
  • Link the lithium battery (in this case, called “home” or “auxiliary” battery) to the DC-DC battery charger’s output.

Ensure to link the “ignition wire” to your car’s electrical system so that the DC to DC just begins charging the lithium battery when the engine is running (so you do not unintentionally drain your starter battery).

  1. Pretty uncomplicated, ideal? Here’s a streamlined plan for this system, as offered by
  2. Victron Energy
  3. :

Source: After linking all the parts of this system properly, you’ll be prepared to charge your lithium battery with a generator effectively. It is very important to keep in mind that this is simply among the lots of possible setups for this system.

Simple scheme on how to charge dc to dc charger with alternator
You can change this setup according to your requirements and choices. Whatever the case, take preventive steps to prevent harmful your generator and/or lithium battery bank.

Just how much current does a generator produce?

According to an

speculative research study on the result of generator speed on the automobile charging system

, the power that a generator can produce is identified by the generator’s score, and it can vary from 40 Amps as much as 120 Amps.

DC-DC battery chargers are likewise ranked in regards to just how much charging present they can offer. The most typical commercially offered DC-DC battery chargers offer 20 Amps, 40 Amps, or 60 Amps. This 12V DC to DC battery charger from Renogy is ranked at 60A. Source:

The quantity of charging present entering into your battery will identify its charging time. The greater the present, the much faster it charges. Nevertheless, each battery has a limitation to the charging present.

Charge lithium battery with alternator using dc to dc charger
Discussing this limitation might harm the battery or not charge at all if the
battery management system (BMS)

begins to secure the battery from this overcurrent.

For That Reason, it is very important to think about the ideal present for your battery to pick the suitable DC-DC battery charger. What are the threats of charging with a generator? There are a couple of obstacles connected to charging lithium batteries with a generator.

If you neglect the essential preventative measures, this charging setup can show ineffective and unsafe in severe cases.

Here are a couple of issues that can emerge when going with this charging system and how to prevent such concerns:

Overheating your generator Since lithium batteries provide a low internal resistance when their state of charge is low (around 40% to 50%), they can draw a big quantity of present from the generator.

This high amperage output can be excessive for the generator to deal with. In such cases, the generator will strain, creating significant internal heat, which will not have the ability to dissipate correctly.

For That Reason, it’s vital to utilize a DC-to-DC battery charger to restrict the quantity of present drawn from the generator.

Additionally, the amperage from your DC to DC battery charger need to match the optimum amperage output of your generator.

In this manner, it will not draw more present than the generator can securely offer, avoiding early damage to your generator.

Here’s a video from Victron Energy revealing what can take place to your generator:

Overcharging the lithium battery

Although a lot of lithium batteries have integrated

battery management systems

, you must constantly beware not to overcharge them.

Since the quantity of present created by the generator depends upon the rotation speed of its rotor (therefore, the engine speed), it will not regularly provide the very same amperage. The faster it spins, the greater the amperage output. For that reason, utilizing a DC-to-DC battery charger safeguards the battery from a risky high charging present. Utilizing incorrect wires: thickness/gauge and length

Utilizing the appropriate wire (thickness/gauge and length) is vital to avoid it from overheating, igniting, or “taking off.”

Why? A wire offering excessive resistance to the circulation of electrons will create a great deal of heat, perhaps leading to a totally harmed, burned wire.

However how is the wire’s resistance impacted by its density and length?

Resistance and wire length are proportional: The resistance in a wire increases as the length of a wire boosts. Resistance and wire density are inversely proportional

  • : The wire’s resistance increases as the wire’s density reduces. Think About it in this manner: when electrons stream through a wire, they hit ions along the method. The longer the wire, the more crashes, and the more crashes, the higher the resistance.
  • Alternatively, a thin wire has less electrons to bring the present, whereas a thick wire has more electrons to move through it. In this manner, a thicker wire offers a lower resistance than a thinner wire.” W

hy is this essential?

If you utilize a wire too thin for the quantity of present provided by the generator to the battery, you’ll run the risk of overheating the wires. The increased resistance to the system can likewise, in time, adversely affect your generator and/or battery. Likewise, if you utilize a wire too long (if the lithium battery bank lies reasonably far from the generator), the very same thing can take place– there will be excessive resistance, and the system will not work. To prevent these concerns, ensure to

pick the appropriate wire

to match the amperage of your charging system. Likewise, think about the range in between the generator to the lithium battery.

Draining your starter battery The generator just produces power when the engine is running. For That Reason, when you link the generator to the starter battery and the starter battery to the lithium battery (through a DC-DC battery charger), you need to make sure that this system just works when the engine is running.

Otherwise, you run the risk of draining your starter battery by charging your lithium battery (an awful concept) when the engine isn’t running, which indicates the generator isn’t charging the starter battery.

DC to DC battery chargers include an ignition wire input to prevent this issue. In this manner, the DC-DC battery charger just begins charging the lithium battery when the engine is running.

In this manner, you’re not risking of unintentionally draining your starter battery.

Last ideas

So there you have it! You understand that you can tailor your car’s charging system to charge your lithium battery with a generator.

This works since the generator transforms power from the engine into electrical energy (when the engine is running). This energy is then utilized to charge the starter battery.

Nevertheless, with a couple of modifications, you can likewise utilize this electrical system to charge your lithium battery bank while driving your car.

This is an excellent method to pump some additional juice into your lithium battery throughout a long drive or when your photovoltaic panels can’t produce sufficient power to charge your lithium batteries (on rainy/cloudy days).

Utilizing a DC-DC battery charger for this charging system is vital, being ideal for double battery systems in cars and boats.

Renogy, Victron Energy, Sterling, and Redarc are a couple of examples of brand names that use top quality DC-DC battery chargers.

Although utilizing a generator is an efficient and inexpensive method to charge a lithium battery, the system must be thoroughly prepared and set up. In this manner, you’ll prevent any possible issues with this charging setup, like too soon harming your generator or lithium battery.


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