Every LiPo wears out. The question we hear at the counter is how fast, and how to tell when a pack that still charges is done. There's no single number printed on the label, because a pack's life depends far more on how it's charged, run and stored than on the brand.
This guide uses Battery University's lithium-ion research and Traxxas' and Spektrum's own guidance to explain what a "cycle" really costs, what internal resistance (IR) tells you, the habits that add life, and the signs that a pack should be retired. Your pack maker's manual still has the final word for that pack.
The Short Answer
A lithium pack typically gives about 300 to 500 full charge and discharge cycles before its capacity falls below 80 percent. You can stretch that a lot by not running packs flat, storing them at a partial charge, and keeping them cool.
- Shallower discharges mean more cycles: Battery University's table shows roughly 300 cycles at 100 percent depth of discharge and about 1,000 at 40 percent.
- Rising internal resistance makes a pack sag under load, run hot, and cut out early.
- Track IR against the same pack's own readings when it was new, not against someone else's numbers.
- Retire any pack that is swollen, soft or damaged, no matter how few cycles it has.
1. What a LiPo Cycle Really Costs
Battery University's article on capacity loss says lithium- and nickel-based batteries deliver roughly 300 to 500 full discharge and charge cycles before capacity drops below 80 percent, and that capacity fade is mostly a function of cycle count and age. It suggests replacing a pack at 80 percent capacity, though the cutoff varies by use.
Depth of discharge matters most
A full cycle is much harder on a pack than a partial one. Battery University's guide to prolonging lithium batteries lists cycles until capacity drops to 70 percent for NMC-type lithium-ion cells at different depths of discharge:
| Depth of discharge | Approximate cycles |
|---|---|
| 100% | ~300 |
| 80% | ~400 |
| 60% | ~600 |
| 40% | ~1,000 |
| 20% | ~2,000 |
For a hobbyist that means landing or parking the truck with charge left in the pack. A timer set so packs come back well above your cutoff does more for pack life than almost anything else.
Full charge voltage and time at full
The same Battery University guide says every 0.10 V per cell reduction in peak charge voltage is said to double cycle life, with 4.20 V per cell rated at 300 to 500 cycles. Its article on what ages lithium-ion adds that the longer a battery sits at high voltage, the faster it degrades, especially when it's warm. You don't need to undercharge for a race day, but don't leave packs sitting full.
Hard pulls and heat
Battery University's discharging basics notes that hobby packs discharged at 30C have a short life expectancy, and the aging article says moderate charge and discharge currents reduce structural wear. Heavy bashing, big props and hot days all count. Let a hot pack cool before you charge it, and don't push a pack harder than its rating.
2. Internal Resistance: Your Pack's Health Report
Capacity tells you how much energy is in the pack. Internal resistance tells you how easily it can deliver it. Battery University's article on rising internal resistance says high resistance causes the voltage to drop under load, triggering an early shutdown, and causes the battery to heat up. It also notes that capacity alone is of limited use if the pack can't deliver the stored energy effectively.
What it feels like
A pack with rising IR still charges to full, but it feels soft: punch fades early, the low-voltage cutoff trips sooner than it used to, and the pack comes off hot. The aging article explains why IR rises: a layer grows on the anode as the cell ages, obstructing the chemistry and increasing internal resistance. Cold also raises resistance, and Battery University warns that warming a tired pack gives a little extra runtime but doesn't restore it.
How to measure it
Many hobby chargers show IR after a charge. Spektrum's S250 Smart charger manual, for example, has an Internal Resistance screen showing each cell's reading, and for Spektrum Smart packs it shows battery history with the number of cycles and a fault log of over-voltage, under-voltage and over-temperature events.
Compare a pack against itself
Battery University's guide to measuring internal resistance says the resistance method works best when comparing the readings of a given battery from birth to retirement, and that readings depend on the measuring method. So different chargers can give different numbers for the same pack. Write down each cell's IR when a pack is new, measure on the same charger at a similar temperature and charge level, and watch the trend. One cell climbing well above the others is a warning even if the total looks fine.
IR isn't the whole story
The same guide cautions that resistance doesn't reveal the full state of health and often stays flat with use and aging. Use it alongside run time, cell balance and how the pack looks and feels.
3. Habits That Add Life (and Signs It's Time to Retire)
Most packs die early from a few avoidable habits: running them flat, storing them full or empty, and charging them hot. Fix those and the cycle count takes care of itself.
Don't run it flat
Traxxas' battery basics says LiPo batteries can be damaged by over-discharging and to always turn Low-Voltage Detection on. Its speed controls alert you below 3.2 V per cell, but they read total pack voltage, not each cell. Traxxas gives the example of an unbalanced pack where one cell has dropped to 3.0 V: that cell has been over-discharged, which shortens the life of the pack. Balance charging every time and check cells with a voltage checker.
Store it half full and cool
Traxxas recommends storing LiPos at about 50 percent charge, using the charger's storage mode if you won't use a pack for a week or more, and its LiPo page warns that storing packs discharged for longer than 7 days may over-discharge them. Battery University's storage table shows why cool and partial is best: after a year at 25°C, a lithium-ion cell kept at 40 percent charge retained about 96 percent of its capacity versus 80 percent for one kept full, and at 40°C the figures were 85 and 65 percent. Don't leave packs in a hot car in a Georgia summer.
Retire it when you see these signs
- The pack is swollen, feels soft, or has damage to its covering. Traxxas says never to use or charge a battery in that condition.
- Run time has fallen to around 80 percent of new, or the pack hits cutoff well before it used to.
- One cell won't stay balanced with the others, or keeps reading low after rest.
- IR has climbed steadily from its new readings and the pack runs noticeably hotter.
- Frayed wires or damaged insulation. Traxxas says to inspect packs after every use.
Safe disposal
For a damaged pack, Traxxas says to place it in an open, safe area away from flammable materials and watch it for at least 30 minutes, then fully discharge it by submerging it in salt water (1/2 cup salt per gallon) for 24 hours before disposal. Check your county's rules for battery recycling, and see our LiPo storage and disposal guide for more.
Conclusion
A LiPo typically gives a few hundred full cycles, but how you use it decides whether you get the low end or several times more. Leave charge in the pack, store it around half full in a cool place, let it cool before charging, and keep a record of each pack's internal resistance from new. When a pack swells, loses a cell's balance, or sags and runs hot, retire it.
Not sure whether a pack is still healthy? Bring it to our Cumming showroom and we'll check it with you, or contact the shop.
Gear Mentioned in This Guide
Spektrum S250 2x50W AC SMART Charger (SPMXC2060)
Shows per-cell internal resistance after a charge, plus cycle count and a fault log for Spektrum Smart packs. Has storage voltage and auto storage.
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LiPo Voltage Indicator (8S) with Buzzer Alarm
Plugs into the balance lead to show each cell, so you catch a weak cell before it drags the pack down.
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Spektrum Smart Battery Checker & Servo Tester XBC200 (SPMXBC200)
Quick per-cell voltage checks at the track or field, and Smart battery data on compatible packs.
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Racers Edge LiPo Battery Charging Safety Bag (up to 6S) (RCE2100)
Charge and store aging packs in a fire-resistant bag, as Traxxas recommends for charging.
Shop nowFrequently Asked Questions
How many cycles does a LiPo last?
Battery University puts lithium batteries at roughly 300 to 500 full discharge and charge cycles before capacity falls below 80 percent. Shallower discharges and cooler, partial-charge storage can stretch that well beyond 500.
What is internal resistance in a LiPo?
It's how much the pack resists delivering current. As it rises with age, the pack's voltage sags under load, it heats up and it hits cutoff sooner. Many chargers display it per cell after a charge.
What internal resistance means a LiPo is bad?
There's no universal number, because readings vary by charger and measuring method. Compare a pack against its own readings when new, and watch for one cell rising well above the others.
Is it bad to store a LiPo fully charged?
Yes. Traxxas recommends storing LiPos at about 50 percent charge, and Battery University's data shows lithium cells kept full lose capacity much faster in storage, especially when warm.
When should I throw away a LiPo battery?
Retire any pack that is swollen, soft or physically damaged right away. Also retire packs whose run time has dropped to around 80 percent of new or that won't stay balanced.
Sources and Further Reading
- Battery University: BU-802 What Causes Capacity Loss?
- Battery University: BU-808 How to Prolong Lithium-based Batteries
- Battery University: BU-808b What Causes Li-ion to Die?
- Battery University: BU-501 Basics about Discharging
- Battery University: BU-802a How Does Rising Internal Resistance Affect Performance?
- Battery University: BU-902 How to Measure Internal Resistance
- Traxxas: Battery Basics
- Traxxas: LiPo Batteries
- Spektrum S250 Smart charger manual (PDF)
