LiPo batteries is one area of the RC hobby that can be fairly expensive. Especially if all the RC vehicles that you prefer to run, uses a different pack. The typical lifespan that we can expect from a LiPo battery pack can on average about 2 to 3 years.
For certain RC applications, the LiPo battery lifespan may very well be outside of this range. For example RC EDF jets or RC boats may have a shorter lifespan as these vehicles draw a lot of power from the pack. On the other hand trainer style RC airplanes, or scale RC boats pull significantly less power. These packs may last many years. For these reasons specifically, it is very important for us to maximize the battery lifespan so that we don’t need to be purchasing new batteries every year or two. That can be very expensive! Prolonging the life of your LiPo battery pack is not hard, follow these 5 ways:
Maximum Discharge Rate – LiPo Battery Lifespan
LiPo battery packs have a rating that allows one to understand the maximum amount of current the pack can discharge continuously. This is one of the most important specifications on a battery pack that you must consider for your application. The specification that we are referring to is known as the C rating. The C rating of a battery pack is explained further in this article.
In order to maximize the life of your battery, it is important to be certain that you have a lot of head room in the C rating of your pack. My recommendation is to only draw 50% of the maximum continuous power output that your battery specifications specify. If you have the ability to reduce the percentage, indeed do so! The smaller the load factor of the battery pack, the more that you are able to prolong the life of the battery pack.
Maximum Discharge or Run Time – LiPo Battery Lifespan
Maximum discharge refers to the maximum amount of capacity that you should pull from your LiPo battery pack. The magic rule that helps prolong the lifespan of a LiPo is 80/20. The meaning behind this rule is that the maximum discharged capacity should be no more than 80%. This leaves a minimum capacity in the pack of 20%. Following this rule will help increase the lifespan of your battery pack.
Be certain that you know the maximum run time that you have available in your RC to not discharge more than 80% of the capacity. The resting voltage of a battery pack that doesn’t exceed 80% discharge is approximately 3.7v.
Storage of a LiPo Battery – LiPo Battery Lifespan
Storing a LiPo battery pack is defines as not using the battery pack for more than 10 days. If you don’t plan to use the battery pack in the next 10 days, it is highly recommended to place the battery pack in to storage mode. What does this mean? Well let’s go through it. To maximize the lifespan of the battery pack, it is critically important to store the pack correctly.
To store a LiPo battery pack correctly, many chargers on the market can help with this. However, if your charger does not have a charging mode specific to storing the pack, you can do this manually. The voltage of the battery pack is a good indicator for an optimal storage specification. The recommended storage voltage for a LiPo battery pack is 3.80 to 3.85 volts. Battery capacity will be approximately 40-45% at the correct storage voltage.
Leaving your battery pack at maximum charge is one of the worst things you can do to the battery when you are not using it. At the same time leaving the battery near empty is also far less than ideal. Be certain to leave your battery pack at the storage voltage specification to maximize your LiPo battery lifespan.
Maximum LiPo Battery Temperature – LiPo Battery Lifespan
This factor that effects LiPo longevity is fairly straight forward. It doesn’t matter if you are or are not following any of the above tips if your LiPo is getting too hot. Like all electronic components, LiPo battery packs are no exemption. The amount of heat that your LiPo generates while being discharged is directly proportional to the lifespan of the pack. A pack that constantly gets hot will not last as long as a pack that stays cooler.
The maximum recommended temperature for a LiPo battery pack while in use is 60C or 140F. This is an absolute maximum. You can be certain that if your LiPo is achieving this temperature every run that you are degrading the lifespan. To maximize lifespan, decrease the amount of heat that your battery pack builds. You can do this by reducing the load of the battery pack. To reduce load, increase the amount of LiPo battery packs being used by wiring them in parallel. Or decrease the amount of load on your battery by reducing prop size or gearing.
Battery Charge Rate / Peak Voltage – LiPo Battery Lifespan
Battery packs being sold on the market today are advertising 5C and upwards of even 10+C charge rates! These are crazy! I believe anything more than 3C is crazy. 3C charging is very fast. What I have found is the most optimal battery charge rate when considering both quick charge and lifespan is 2C. Within about 30 minutes you can have a pack fully charged and you are not pushing the pack. You can be more conservative towards battery life by charging at a 1C charge rate.
The maximum specified fully charged voltage of a LiPo battery pack is 4.20 volts. Charging to this voltage actually degrades the lifespan of the LiPo battery. If you are to charge the battery pack up to a maximum below the 4.20v mark, you can increase the lifespan of the pack. Tesla actually uses this method to increase the lifespan of their lithium based batteries. What I do is take the battery pack off the charger as I see the pack starting to ramp down in current closer to end of charge. If your charger allows, you can also set the maximum peak voltage of a LiPo. Setting the maximum charge voltage to something less than 4.20 volts will prolong the lifespan. Setting anywhere from 4.10 to 4.18v will help, and obviously the lower you go, the longer the lifespan potential you will see.
Unfortunately everything in life is a trade off. Trading run time for battery life is one thing that we can do to increase the lifespan of our batteries. Ultimately, you get to decide if this is worth it.