An e-bike battery can typically take you up to 40+ miles on a single charge. However, one struggle you face as an e-bike owner is keeping your electric bicycle fully charged for longer distances or when you don’t have a charging outlet. Having your battery die in the middle of your ride can be not only inconvenient but dangerous.
One alternative charging option may be to use a car battery to charge your e-bike.
You can use a car battery to charge an e-bike battery safely, as long as you have the correct tools. You can charge your electric bike with an inverter and 12V car socket.
Let’s talk more about charging your e-bike and why an inverter and the right voltage are so important when using a car’s battery. Keep reading to learn of the dangers of electric bike battery charging using car batteries and how to do it safely.
Using an Inverter to Charge an E-Bike Battery is Vital
An inverter is vital for charging an e-bike with a car battery because it regulates the flow of electrical power from the car battery to the e-bike battery. The inverter will convert direct current electricity to alternating current electricity, allowing less voltage to pass through.
When you charge your e-bike with a car battery, it is important to understand that it has a lot more power than you need. The voltage produced is too high for the battery voltage of an e-bike.
Higher voltage can pose a huge risk to your electric bike’s battery.
Dangers of Too Much Voltage
There is a lot of risk with charging a battery using too much voltage.
In the case of using a car battery for your electric bicycle, it typically has too much voltage for the e-bike. This means that there would be too much voltage passing into the e-bike without an inverter, which can damage the charging cord or the battery of your e-bike.
The best-case scenario for using a battery with a voltage that is too high to charge your e-bike is that the cord may get fried. If this happens, you will need to replace the cord to charge your e-bike.
However, a fried cord certainly isn’t the worst thing that can happen. Using a car battery without an inverter can cause permanent damage to your electric bike battery (read how to repair and rebuild an e-bike battery). If the battery voltage is not identical, then it can affect the ability of your battery to charge.
It can also reduce battery life, causing your battery to die faster than normal as it can wear out the battery over time.
Overloading your battery with too much voltage or the incorrect amount can also completely fry the battery causing it to no longer work. This means that you would need to replace the battery or even your e-bike altogether.
So, using a pure sine wave inverter with the battery is very important for the upkeep and care of your electric bike battery.
The Inverter Controls the Voltage
The inverter helps control the flow of voltage from the car battery to your e-bike, so it won’t overload your e-bike but simply charge it and get you back to pedaling in no time.
Inverters work by converting direct current power to alternating current power. There are a few major differences between the two types, but we’ll focus on the difference it makes for your e-bike. Direct current doesn’t lose power except over long distances, while alternating current changes to higher or lower voltage.
So, the inverter is vital for this process because it allows the battery to only provide the amount of voltage necessary to charge your electric bicycle. This means that it can charge safely without worrying that it will fry the cord or the bike battery.
Charging Without an Inverter
If you don’t have an inverter, then you may still have hope yet. When you want to charge your e-bike and all you have is your car, you may be able to use an outlet available inside the car. These power outlets usually carry a smaller voltage to ensure that phones and other electronics are not overloaded with power and do not drain the car’s battery too much.
To ensure that your e-bike battery is safe, you will need to check the voltage on the electrical outlets in your car and how much power they give out. Any outlet that you choose should have 12 volts of power, which will ensure that your battery can charge safely.
If your car does not have any power outlets with the appropriate voltage, then make sure you do not use the plugs to charge your electric bicycle. If needed, you can consult with a mechanic to have 12-volt outlets put into your vehicle for charging convenience.
Otherwise, an inverter is your best bet for ensuring your battery charges safely. However, since even e-bike batteries are not universal or interchangeable, you should also consult with an electric bike technician and/or a professional experienced in how much power is required.
What Size Inverter Do I Need to Charge My E-Bike Battery?
Typically, you need an inverter with 1000W of power or more to charge your bike battery. Get an inverter with at least as much total wattage as your electric bike battery and preferably more.
Check your e-bike’s total Watt-hours (Volts multiplied by Amps). So, a bike with a 48V 14 Ah battery will have 672 Wh. Thus, a 1000W inverter will be powerful enough to charge it, while a 500W inverter will not.
Recommended Inverters
Here are the recommended inverters found on Amazon and their wattage and price comparison:
| Inverter | Watts | Price |
| Maxpart Power Inverter 12v | 1000W | $59+ |
| Ampeak Inverter with Dual AC Outlets | 1000W | $63+ |
| Ampeak Inverter 12V to 110V Power Inverter | 2000W | $159+ |
Inverters get more expensive with higher wattage. However, the price difference might be worth it because:
- You can use it for other things that might require a higher inverter wattage
- When your battery dies in the future (and you upgrade it), you’ll still be able to use the inverter without purchasing a new one
Can You Use a Car Battery for an Electric Bike?
Generally speaking, a car battery is too big and heavy to fit onto an e-bike frame, it’s built differently than a lithium-ion e-bike battery, and it has 12V of DC power, as opposed to varying AC wattage.
This discussion is different from the above where we were talking about using the car battery to charge your electric bike battery. Although you may be able to do that, you can not simply replace your bike battery with a car battery because:
- It won’t fit on a bicycle frame easily- A battery from a car is typically a different size and shape, not to mention much larger than e-bike batteries.
- Car batteries drain much more quickly- The car engine alternator charges a 12 V deep-cycle battery with the car’s engine to keep it running. This is why your battery drains quickly when you are not running the car but simply listening to music with the key in the ignition.
- Voltage does not match– E-Bike batteries are typically 36V to 48V and only charge while connected to a standard charger. Thus, you’ll be decreasing your range by using a car’s deep-cycle battery.
- E-bikes typically have li-ion batteries- They last longer and can be fully charged an average of 1000+ times, lasting you 5-7 years or more depending on your riding style (the more pedal assist or throttle you use, the greater the reduction in battery life).
How Do You Charge an E-Bike Off-Grid or While Camping?
If you intend to ride off-grid or take your e-bike camping, you may require an alternative charging station for your electric bicycle battery, as you won’t always have access to a power outlet. Fortunately, there are options for a different power supply, but they do require advanced planning. These include:
- Solar panels- Solar charging can be quite handy if there is lots of sun where you’ll be riding. And you can actually attach them to your e-bike! Find out more about using solar panels in this article.
- Generator- With the right generator power supply, charging with one can work great while camping or traveling. Learn more about using a generator to charge your e-bike here!
- Wind turbine- Although this can be done, setting up the right equipment can be costly. However, it is a green alternative.
- Inverter- Using a car battery with an inverter is a viable battery charging idea with the right equipment.
- Add a second battery in Parallel- Consider adding an additional battery to your bike so that your range is double what you’d have with one battery. Everything you want to know about adding a second battery in parallel can be found in this article.
How Can You Help Your E-Bike Battery Last?
You can help your e-bike battery last by not allowing it to die fully or letting it overcharge. Another way to ensure the battery lasts is to not store the bike in extreme hot or cold temperatures.
Let’s break down how you can help your e-bike battery last longer and what makes them each effective.
Not Allowing Battery To Die
It is important not to let your e-bike battery fully die. It was once a common belief that allowing your battery pack to die fully was good for it, which was the case when batteries were made of nickel.
However, this is not relevant anymore with the growth of lithium batteries.
Now that we use all lithium-ion batteries let’s talk about what works for them. It is not best to allow your electric bicycle battery to die completely as we thought it to be with nickel batteries. Instead, you should try to avoid that if possible.
Allowing your battery to fully die before recharging is actually not good for it.
This can be difficult at times since the traditional electric bike does not have a gauge within the charging station to let you know when the battery is getting low. The best way to ensure your e-bike fully charges is to measure how much you are using it.
Most e-bikes have a distance or amount of time that a new battery will last, so you’ll want to measure the number of miles you go to ensure it doesn’t die. Further, plug in the charger to a wall outlet to get a full charge before riding.
Don’t Overcharge
Another important part of caring for your e-bike battery is to ensure it does not overcharge. Leaving your e-bike battery on the power station for an extended period is not recommended as the battery can overheat and get damaged.
In fact, an overheated battery can harm your e-bike entirely, so you may be stuck replacing the whole thing.
Overheating is the main concern when it comes to overcharging as it may cause damage, but overcharging can also make your battery begin to wear out faster than it normally would. Don’t leave your e-bike battery charging for too long as it can be bad for your battery.
Extreme Temperatures
Storing your battery in extreme hot or cold weather can be bad for the battery as well. Even though your battery will not be running, extreme low or high temperatures are not good for it. In fact, extreme temperatures can affect the chemistry of your battery, making it die faster.
So make sure you are storing it somewhere dry with temperatures that don’t get too high or low.
Final Thoughts
Overall, it is safe to use a car battery to charge your e-bike as long as you have an inverter and a 12V power outlet. However, there are a lot of considerations, as discussed in this article, so prepare ahead of time.
Most importantly, don’t use the battery from a car without an inverter, as it can cause damage to your electric bike battery.
Read more on electric bike batteries here:
