Table of Contents
Introduction
Lithium polymer (LiPo) batteries have become the de facto standard for RC vehicles due to their high power-to-weight ratios. This allows models like the Traxxas line of trucks and buggies to reach incredible speeds and performance benchmarks. However, LiPo batteries require careful use and maintenance to maximize their lifespan and safety.
A common problem that Traxxas LiPo battery users notice over time is swelling of the battery cells and packs. This swelling indicates gas buildup inside the LiPo pouches and points to potential issues. Swollen LiPo batteries should not be used further and may need to be handled carefully to avoid safety risks.
This article will cover the typical causes of Traxxas LiPo battery swelling, steps you can take to potentially fix mildly swollen packs, whether swollen LiPos are dangerous, when to stop using and properly dispose of ballooned packs, and tips to help prevent swelling issues in the future through proper use and storage.
Key Takeaways
- Overcharging and deep discharging are the primary causes of LiPo battery swelling. Always use a proper balance charger and low voltage protection.
- Mildly swollen packs may be temporarily repaired by discharging to storage voltage then refrigerating. But swelling is usually permanent.
- Severely swollen or ballooned LiPo batteries should be immediately retired and disposed of properly due to risk of fire or rupture.
- Use the recommended charger for your LiPo battery and follow manufacturer charging/discharging guidelines.
- Inspect battery packs carefully for any signs of swelling or deformation from their original shape.
- Puffy or bloated cells mean the battery has been damaged and should no longer be used to avoid safety hazards.
- Take steps to maximize cycle life of LiPos through careful charging, storage, and avoiding deep discharges to reduce swelling risks over time.
- Swollen lithium polymer batteries become unstable and unpredictable as swelling increases, posing serious safety risks if they are continued to be used.
Reasons Why Traxxas LiPo Batteries Swell
There are several root causes that can result in the cells of your high performance Traxxas LiPo battery packs ballooning over time:
Overcharging
The number one cause of LiPo swelling is overcharging the batteries consistently beyond the maximum voltage threshold, usually around 4.20V per cell for Traxxas packs.
Charging beyond the rated voltage causes lithium plating that deposits metal inside the cells. This builds up pressure and gases that have nowhere to go in the rigid pouches, resulting in swelling deformation.
Always use a balances LiPo charger that automatically stops at the correct full voltage to avoid overcharging. And do not leave batteries charging unattended – disconnect once fully charged.
Running the Batteries Too Low
Just as exceeding maximum voltage can damage LiPo cells, so can deeply discharging them below the minimum safe voltage of around 3.0V per cell under load.
Deep cycling causes internal short circuiting and electrolyte decomposition again leading to gas buildup and swelling deformation of the cells.
Use an ESC with proper low voltage cutoff protection or a voltage alarm to warn when your LiPo is nearing minimum voltage so you can stop running it.
Using an Improper Charger
LiPo batteries require a balance charger that charges each cell individually while equalizing them. Using a NiMH-only charger that lacks balance charging can overcharge individual cells resulting in swelling.
Stick with recommended Traxxas LiPo compatible chargers like the EZ-Peak Live, or high quality aftermarket RC balance chargers with storage mode. Avoid cheap chargers without balancing.
Old Age and Cycling
After hundreds of charge/discharge cycles, LiPo batteries experience gradual internal changes leading to some gassing and swelling, especially if ever overcharged or deeply discharged.
Swelling from aging may be unavoidable, but proper care minimizing charge voltage and depth of discharge will maximize pack lifespan before swelling becomes a problem.
How to Fix a Swollen LiPo Battery
If you notice mild swelling in your Traxxas LiPo pack, there are some steps that may potentially reverse the damage and fix the battery:
- Stop using the swollen battery immediately
- Discharge the battery to storage voltage (3.8V per cell)
- Place the battery in a LiPo safety bag
- Apply gentle pressure to redistribute cell contents
- Place in freezer for 24 hours to solidify electrolytes
- Allow to return to room temperature before retesting
This “refrigeration method” may temporarily reduce swelling by safely redistributing cell contents and electrolyte. However, it is not guaranteed to work if swelling is advanced or shorts are present. A severely swollen battery should be properly disposed of.
Is a Swollen LiPo Battery Dangerous?
A mildly puffed LiPo battery may be temporarily repaired and safely discharge to storage voltage under careful monitoring. But once swelling becomes pronounced, the battery poses serious risks:
- Rupture and fire from short circuiting
- Additional gas buildup from charging
- Internal damage causing voltage drops
- Unpredictable voltage spikes and current surges
- Reduced structural integrity making packs fragile
Heavily swollen cells start building much more internal pressure that could lead to catastrophic failure, especially if further charged. The battery should be quarantined in a fireproof LiPo bag and disposed of properly. Never attempt charging or discharging swollen packs.
Conclusion
Lithium polymer batteries offer the huge power and current capabilities necessary for Traxxas RC models to achieve insane speed and performance. But the downside is handling LiPo batteries requires careful charging practices and discharge protection to avoid swelling issues over time.
Check your packs after each run for any signs of puffiness or bulging. If swelling is noticed, stop using the battery immediately and consider the refrigeration method to potentially revive mildly bloated packs. Severely swollen LiPos should be quarantined and disposed of safely.
Following manufacturer charging recommendations, using compatible balance chargers, avoiding deep discharges, and taking steps to maximize LiPo lifespan through limited cycles and proper storage will help reduce risks of swelling. But some amount may still occur naturally over time. Inspect batteries frequently and retire any that show pronounced swelling signs before running them further.
FAQ
How can I tell if my LiPo is starting to swell?
Look for small bumps or bloated spots on the pack. Also watch for packs getting harder to fit into models. Any change in shape from flat new condition could indicate swelling.
Can I prevent swelling by charging at lower voltages?
Yes, charging to lower peak voltages like 4.10V instead of 4.20V will put less strain on cells over many cycles and slightly improve lifespan at cost of capacity.
What causes individual cell swelling vs entire pack?
Uneven cell balancing during charging or discharged results in individual cell swelling. Poor quality manufacturing or damage also causes uneven swelling.
Is it safe to store swollen LiPo batteries inside models?
No, swollen LiPo packs should be kept in a fireproof bag or lipo sack away from vehicles and stored carefully in case of rupture or leaks. Never leave unattended.
Can I discharge a puffy pack to 0V safely?
No, swollen cells should never be discharged below storage voltage of 3.8V since internal damage makes deep discharge extremely dangerous for swollen packs.