Avoid Excess Discharge of LiPo Batteries in RC Helicopters

Those who fly RC helicopters must have a greater understanding of the LiPo batteries. This is not just about the use, charging, and recharging of these batteries. The bigger RC helicopters are power-hungry devices. Some can go over 8000 Watts at the rotor shaft.

So, it’s absolutely necessary that you can keep your LiPo batteries happy and healthy in a big RC helicopter. If you can do so, you can keep them happy and healthy in almost anything. LiPo is short for Lithium Polymer battery. It is a type of battery that’s rechargeable and used especially for remote-controlled planes and helicopters.

It is because of this battery that electric flight became a viable option over models that use fuel. LiPo batteries have several advantages, which makes them an excellent choice for RC aircraft. They’re far more efficient than the conventional rechargeable NiMH or NiCad batteries.

The 3-volt threshold

To begin with, it is necessary to understand how excess discharge or over-discharge can severely damage a LiPo battery. It heats up quickly and can suffer irreversible damage if over-discharged under load. The extent of damage will depend on how larger the load is. Never allow these batteries to discharge below 3 volts per cell while in use.

This is the over-discharge threshold level that you need to remember. This also applies to a 60C pack that can only draw one quarter of that amount of power. If it goes down to 3 volts per cell under load, it can shorten the battery’s life substantially.

About ESC and LVC

ESC refers to electronic speed controls and LVC refers to low voltage cutoff. Most ESC have an LVC. The purpose of providing this safety feature is to prevent excess discharge of LiPos. It prevents the LiPo batteries from over-discharging past the 3-volt threshold per cell while in use.

It isn’t wrong to state that LVC is a last ditch effort to protect the battery from maximum harm. Of course, it is certainly not something you must rely on. If you fly at all times to LVC, your RC LiPo batteries will end up with short lives. The battery will suffer damage even if the LVC is 3.2V per cell while in use.

It is, therefore, a good idea to set the LVC cutoff at 3.5 volts per cell. This way, you can play it safe. Of course, this is just a suggestion as loads can vary. As a result, the charge voltage readings can be erroneous.

Knowing when to stop flying

The ‘80% rule’ is an excellent rule to follow in such cases. According to this rule, you must never discharge a LiPo pack beyond 80% of its capacity. This means that the LiPo pack must only discharge 80% and not down past the limit. This prevents the LiPo batteries from harm.

Let’s understand this with an example. If you have a LiPo pack of 2000 mAh, it must never draw over 1600 mAh. This limit of 1600 mAh amounts to 80% of the pack. In this example, the assumption is that the 2000 mAh pack is healthy with full capacity.