Is Your LiPo Safe To Charge | WHEN TO THROW IT OUT

Product Reviewed / Discussed

This video isn’t a typical single-product commercial review. It’s a safety-focused guide about:

• LiPo (lithium polymer) battery charging and retirement
• How to test and dispose (“kill”) damaged packs using specific tools/gear

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Main Features / Methods Mentioned

When to Retire LiPo Packs

Retire the pack if any of the following is true:

• Undervoltage: Any cell is < 3.0 V/cell, verified with a cell checker.
• Failure to hold voltage overnight:
  • Even if the pack is at storage or full charge, if a cell voltage drops significantly overnight, it indicates a bad/unstable cell.
• Unequal discharge / cell imbalance in practice:
  • Cells that don’t drop relatively evenly are a red flag.
  • Example given: in a 6S pack, one cell may “linger” much higher near the end of flight.

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Charging / Voltage Guidance

• 4.5 V/cell: Presented as essentially unsafe—described as “basically guaranteed” to cause fires.
• ~4.25 V/cell: May reduce lifespan, but is framed as not inherently as dangerous as 4.5 V/cell.

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Checking “Physical Damage” Safely (Internal Resistance)

The video emphasizes measuring internal resistance rather than trusting what the pack “looks like.”

• Use a portable charger that can measure internal resistance (example: ISDT Q6).
• If one cell’s internal resistance is way different from the others, that cell is likely damaged → retire the pack.

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Disposal / “Killing” a Bad Battery

The guide includes methods to discharge damaged packs before disposal.

Wire-wound resistor method

• An example setup includes a wire-wound resistor (about ~0.5 ohm / 60 W mentioned; exact value uncertain).
• Discharge by leaving it connected overnight until depleted.
• Safety caveat: the video notes this isn’t the absolute safest setup—better to do it outside (e.g., driveway).

Smoke-stopper bulb method

• Use a current-limited light bulb setup to discharge with limited current (about 2–3 amps mentioned for the use case).
• The video explicitly warns not to do this with 6S (voltage/current behavior may not match what’s needed).

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Parallel Charge Board Risk (Gear-Related Guidance)

Even with safety features (like polyfuses):

• Parallel charging can spread failure
  • If one pack has a bad cell (even becoming dead/0V overnight), it can damage corresponding cells in all other packs on the board.

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Key Pros (Implied Strengths)

• Clear, measurable decision rules for retiring LiPos based on observable symptoms.
• Internal resistance testing helps identify damaged cells even when a pack seems fine off-load.
• Disposal/discharge methods are presented to reduce the chance of a bad pack later being stored/left to fail unsafely.

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Key Cons / Risks Called Out

• Recovered / “trickle charged back” LiPos

  • The host says some goggles packs might survive recovery, but for quad LiPos he does not recommend recovering after deep discharge (< 3.0 V).
  • Even if recovery “works,” the risk and performance degrade (e.g., higher internal resistance, more voltage sag, worse flight performance).

• Fire risk is low but real

  • Healthy packs usually won’t ignite “without warning,” but damaged cells increase risk, and the risk can’t always be quantified.

• Parallel charging can be catastrophic

  • One dead/bad pack cell can damage the entire batch when packs are connected in parallel.

• Indoor discharging is less safe

  • The guide describes discharging in a closet/indoors as requiring active monitoring.
  • If overheating/crackling occurs, he would move it outside.

• No second chances

  • The approach is conservative: once failure indicators appear, the pack is retired/killed.

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Comparisons / Context Made

• Charging targets:

  • 4.5 V/cell vs 4.25 V/cell
    • 4.5 V/cell: described as near-certain fire risk
    • 4.25 V/cell: reduces lifespan but is framed as less inherently dangerous

• Parallel vs individual charging:

  • Parallel charging is claimed to be okay only if every pack is healthy.
  • Otherwise, one bad cell can damage others.

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Unique Points Mentioned (Complete List)

1. “Don’t do anything super dumb,” e.g., don’t charge to 4.5 V/cell.
2. Packs that caught fire usually had warning signs beforehand.
3. Cell checker rule: retire if any cell < 3.0 V/cell.
4. Deep discharge damages cells; recovery may work for some goggles packs but not recommended for quad packs.
5. For quad use, below 3.0 V/cell implies performance loss (higher internal resistance, worse voltage sag).
6. A pack can look okay after flight because cells may recover voltage off-load, masking damage.
7. Example: a 6S pack showed rapid end-of-life sag (about 20 → 17V) then landed; one cell barely above ~3.0 V.
8. After storage charging to 3.8 V/cell, the next day the pack’s cell voltage dropped again (bad/unstable cell).
9. Rule: if at storage/full charge the next day you see a significant drop, retire.
10. Example imbalance: one cell low (e.g., 3.4 while others ~3.79–3.8 on a 4S context) indicates imbalance/damage → retire.
11. Assess safety/condition via internal resistance matching across cells.
12. Example gear: ISDT Q6 can measure internal resistance during charging.
13. One cell with significantly higher/lower internal resistance indicates damage.
14. Risk is gradual; spontaneous fires are “relatively low,” but cannot be fully predicted.
15. No second chances / kill/retire once failure indicators appear.
16. Splitting packs (removing bad cell) is possible but has its own risks.
17. Wire-wound resistor discharge method; discharge about overnight until dead.
18. Best practice location: discharge outside, not in a flammable closet.
19. Light-bulb smoke-stopper method relies on current limiting (~2–3 amps); works for 4S but not recommended for 6S.
20. Parallel charging board risk: a pack with a dead cell (even 0 V) can damage cells on other parallel-connected packs.
21. Parallel charging doesn’t inherently harm healthy packs; the problem is one bad cell damaging all.
22. Emphasis on immediate retirement when any abnormal behavior occurs.
23. Disposal guidance: take dead packs to a recycling/disposal shop (e.g., Batteries Plus mentioned).
24. Infrared thermal validation example: failing cell(s) become much hotter during discharge.

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Ratings / Numerical Scores

No formal star ratings or review scores are provided.

Key numerical thresholds and figures mentioned:

• < 3.0 V/cell ⇒ retire
• 4.5 V/cell ⇒ described as basically guaranteed dangerous
• 4.25 V/cell ⇒ reduces lifespan; framed as less inherently unsafe than 4.5
• Example storage target: 3.8 V/cell
• Example internal resistance readings (spoken example): 11/8/8/18
• Smoke-stopper current limit: ~2–3 amps
• Resistor method example: ~0.5 ohm / 60 W (exact certainty unclear)

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Overall Verdict / Recommendation

The video strongly recommends:

• Retiring LiPo packs immediately when there’s evidence of cell failure, including:
  • Any cell < 3.0 V/cell
  • Failure to hold voltage
  • Significant overnight voltage drop
  • Unequal cell behavior during discharge
  • Mismatched internal resistance

And it specifically warns:

• Do not rely on “it was fine after trickle recovery” for quad LiPos.
• Avoid parallel charging unless you’re confident every pack is healthy.
• Use a safe, current-limited discharge/disposal method for damaged batteries.

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Speaker Views / Contributors

• Joshua Bardwell (main speaker/author):
  • Provides the safety rules, thresholds, examples, and a conservative “no second chances” policy.
  • Mentions another person’s pack (e.g., “Drew’s pack”) as practical demonstration, including thermal evidence; that person’s commentary isn’t presented as a distinct viewpoint.