Can You Overcharge an RC Battery (LiPo and NiMH)

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Batteries are critical in the optimal operation of RC vehicles when they’re in good shape. But when they are overcharged, their performances can be impacted, and they can even become damaged. As an RC hobbyist, you must know what to do to prevent your battery from overcharging to maintain its top efficiency level. 

That said, there are two major types of RC batteries: LiPo and NiMH batteries.
LiPo and NiMH batteries are similar because both battery types can store a certain amount of energy based on their various capacities. 

However, a significant variance exists between them. The difference between LiPo (Lithium Polymer) and NiMH (Nickel-metal hybrid) lies in the chemical properties that enable the charging of the batteries. Put differently, LiPo uses lithium-ion technology, whereas NiMH batteries utilize nickel-based technology.

The big question that follows is, can you overcharge your RC Battery? The best answer to the preceding question is in the famous saying, ‘too much of anything is bad. 

Can RC batteries overcharged?

Of course, RC batteries can become overcharged, just like any battery, when they’re being charged for too long.

There’s no denying that batteries can become overcharged when charged for too long. Hence, it becomes necessary that we should know the normal charging for both LiPo and NiMH batteries for the efficiency and longevity of our RC batteries. 

Besides, an overcharged battery can die; however, this is not the most dangerous side-effect. In rare cases, an overcharged battery can explode, sending plastic and lead shrapnel flying around plus spraying caustic sulphuric acid, which is dangerous to human safety.

Can you overcharge LiPo batteries?

Using LiPo batteries for RC vehicles offers numerous benefits, including high working voltage, high energy density, long cycle life, low self-discharge rate, and no memory effect.
However, to get the most out of these LiPo batteries, you should be wary of not overcharging them. 

Your LiPo batteries can become overcharged when they charge for too long. When LiPo batteries are excessively charged, the batteries can become severely damaged, performance can be lost, and the life span of the batteries can be dramatically reduced. 

 Can you overcharge NiMH batteries?

As we said earlier, NiMH is an abbreviation for Nickel-Metal Hydride.
Nevertheless, just like LiPo batteries, NiMH can also become overcharged when you fail to unplug them when they are fully charged.
You should monitor your NiMH batteries while charging to avoid overcharging. 

Plus, experts recommend using trickle charging to charge your NiMH batteries. This method is the safest means of ensuring your battery is not overcharged while charging. However, while using this method, ensure you’re charging your battery at the lowest possible rate that will keep your charge time below 20 hours, and remove the battery at that point.

Trickle charging is the safest method for charging NiMH batteries. It essentially ensures that your battery charges at a rate that will not get overcharged but keeps it topped up.

What happens when you overcharge the RC battery?

When RC batteries are overcharged, your RC’s battery voltage becomes too high. In addition, if you overcharge your RC battery, it will begin to heat up very quickly and could easily damage the battery or the electronics in the charger.

Knowing the proper method to charge your battery is necessary to maintain the optimal operation of your car. For instance, If your RC batteries gets hot when it is charging, it means that it’s fully charged and will need to take off the charger. 

What can happen if you overcharge an RC battery?

Perhaps, you’re wondering what could go wrong internally when your battery becomes overcharged. 

When RC batteries are overcharged, it creates an unstable condition inside the batteries, increasing pressure and causing thermal runaway. In addition, overcharging of batteries can lead to chemical and electrochemical reactions between battery components, gas release, and rapid increase in temperature.

Furthermore, batteries become overheated and can even explode and catch fire when they are overcharged. Plus, a slight overcharging decreases the cell’s discharge capacity. 

Is it ok to leave your RC batteries charging overnight?

Depending on your RC batteries capacity and the type of battery used in charging them, you can charge your batteries overnight, provided that they don’t suffer from overheating. However, it’s advisable to err on the side of caution and implement all the necessary safety measures. For example, you can use the method of trickle charging which permits a low charging rate. Taking safety precautions ensures that your RC batteries operate at the highest efficiency level.

Can RC chargers prevent overcharging

RC Battery charges are designed to send a constant voltage to the batteries until they’re turned off. In other words, you have to check the batteries to make sure you disconnect the charge when the battery reaches the point of a full charge.  

However, with a maintenance charger, you can leave your battery connected indefinitely without the risk of damage to the battery. 

Battery maintenance chargers completely stop the current output to allow the battery to settle. And when the battery voltage reduces to a certain point, the charge will automatically turn back on to top off the battery.

When is your RC battery ‘full’? 

Knowing the specific point when your battery becomes fully charged is essential to maintaining its top efficiency. Below is the recommended voltage for both LiPo and NiMH batteries. 

  • LiPo 

LiPo batteries are fully charged when they attain 4.2v/cell.

  • NiMH

Your voltmeter should show a voltage anywhere between 1.3-1.5 volts.

  • Should you charge your RC battery to 100%?

There’s no harm in charging your RC battery to 100%, provided you don’t overcharge the battery. Always keep tabs on your RC battery to maintain a healthy charging that fosters efficient battery performance.

Conclusion

Proper battery charging ensures that your battery is kept in good shape. It’s imperative you know the most effective means to charge your battery to keep it in high-level performance. Avoid mistakes many battery owners make  to ensure the longevity and utmost performance capacity of your battery. 

Sources used for this article

Naval Research Laboratory – Performance Loss of Lithium Ion Polymer Batteries Subjected to Overcharge and Overdischarge Abuse – Read it here