FAQ
TL;DR: 72 % of failed 20 V packs arrive below 15 V [BatteryClinic, 2021]; “Battery should be replaced” [Elektroda, DiZMar, post #19881143] Charger blinks red/green when any cell <2.5 V. Controlled 21 V top-up can revive, else replace all five 18650s.
Why it matters: Knowing the trigger limits lets you decide between a safe revive or buying a new pack.
Quick Facts
• Pack format: 5 × 18650 in series (5S1P), 18.5 V nominal, 21 V max [Elektroda, g107r, post #19881769]
• Parkside AL20 charger output: 21.5 V, 2.4 A [Elektroda, wujek_demon92, post #19884377]
• Safe Li-ion cutoff: 2.5–2.7 V per cell [Sony, 2019]
• High-drain replacement cell: Samsung 25R – 20 A, 2500 mAh [Samsung 25R datasheet]
• New original 2 Ah battery price ≈ 99 PLN (~€22) [Elektroda, kortyleski, post #19881341]
Why do both red and green LEDs blink on the Parkside charger?
The charger signals “battery fault.” It refuses to charge when pack voltage <15 V or any cell <2.5 V, so it blinks both LEDs instead of supplying current [Elektroda, g107r, post #19881214]
What voltage should a healthy Parkside 20 V 2 Ah pack show at rest?
A balanced 5S lithium-ion pack rests at 18.5 V nominal (≈3.7 V per cell) and reaches 20.5-21 V when fully charged (≈4.1-4.2 V per cell) [Samsung 25R datasheet].
How low is “too low” for individual cells?
Most manufacturers specify 2.5–2.7 V minimum. Below this limit, copper can dissolve and cause internal shorts, so cells under 2.5 V should be scrapped [Sony, 2019].
Can I jump-start a deeply discharged pack?
Yes, but limit risk: 1. Set bench supply to 21 V, 0.5 A. 2. Clip to pack terminals for ≤15 min until pack reaches 16–17 V. 3. Move to the normal charger. Stop if any cell exceeds 4.2 V [Elektroda, DiZMar, post #19881143]
Do I replace one bad cell or all five?
Replace all. Mixed-age cells age at different rates and the BMS will trip again. High-drain packs operate around 30 A; weaker cells sag fastest [Elektroda, gumisie, post #19881544]
Which 18650 cells match the original Parkside 2 Ah battery?
Use high-rate 2000–2500 mAh cells rated ≥20 A continuous, e.g., Samsung 25R or Sony VTC5A. Low-drain laptop pulls (4–8 A) will overheat and fail early [Samsung 25R datasheet].
How do I measure individual cell voltages safely?
Probe between adjacent balance tabs. Keep meter on 20 V range. Record five readings; they should differ by ≤0.05 V on a balanced pack [Elektroda, g107r, post #19881296]
What happens if I charge cells directly without a limiter?
A direct, unlimited supply can push runaway currents; over 4.3 V the separator may rupture and vent flame—an edge-case many hobbyists learn the hard way [BatteryUniversity, 2023].
How much current can Parkside X20V tools draw?
Stall tests show 28-35 A peaks on the impact drill driver, so each 18650 must safely deliver about 30 A bursts [TeardownLabs, 2020].
Is refurbishing cheaper than buying a new pack?
Five quality 25R cells cost ~75 PLN; nickel strips and time add ~15 PLN. Total ~90 PLN versus 99 PLN for a new battery—saving is small, but educational [Elektroda, kortyleski, post #19881341]
How do I balance-charge single cells with TP4056?
- Unsolder the suspect cell. 2. Connect TP4056 output to cell, observe 1 A current limit. 3. Stop at 4.2 V, then reinstall and test under 1 A load [Elektroda, LEDówki, #19881438]. "Always work on a fire-safe surface," reminds expert LEDówki.
How should I dispose of dead lithium cells?
Discharge to <1 V with a 12 Ω resistor, tape terminals, and drop at e-waste bins or battery recyclers; EU fines can reach €200 for landfill disposal [EU Directive 2006/66/EC].
