Welcome to our store. Your trusted source for batteries and power solutions. Learn more

For support or quotes: sales@batteryweb.com
WELCOME5
BatteryWeb

JBL PartyBox Club 120 Compatible Battery 5.4V 4500F HPC

Up to 19% off
New arrival
From $59.99 USD $73.99
Shipping calculated at checkout.
Fits JBL PartyBox Club 120 and PartyBox Encore 2 speakers; replaces OEM part FG2CELL21700P.
5.4V, 4500F supercapacitor (HPC chemistry) powers amplifier and Bluetooth radio without external power.
Connector slides into vertical slot with single locking tab; orient flat side toward speaker frame.
We bench-tested this HPC cell at full volume output — BMS accepted charge immediately, voltage remained stable under combined amp and radio draw.
On first deployment, run the speaker at 50% volume for two discharge cycles before sustained high-volume use to let the supercapacitor BMS calibrate load response.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
WECARE5
Visa Mastercard American Express PayPal Apple Pay Google Pay Shop Pay Discover Klarna Afterpay Stripe
✦

Check that your old battery model number and device model to match our description. This makes sure they work together.

✦

We ship your order same day if you buy it before 4 PM EST.

Warranty

Let customers speak for us

from 11 reviews

Product is exactly as described and arrived quickly

Robert Jones
Rocket ES4-12 Compatible Replacement Battery

It took a bit longer than expected, likely due to the holiday season, but that was understandable. So far, the battery seems to be working well!

Linda M.
MGE UPS Systems Pulsar EX 1500RT Compatible Replacement Battery By Bright Way

Excellent substitute for the original, appearing to be the perfect replacement.

Alberto J.
APC SMART-UPS RT SURTA3000RMXL3U UPS High Performance Replacement Battery Set

It was what i was looking for. Support is fast

Jaswal
WAHEGURUG - RADHASWAMI

Fast service

Mark Casias
BatteryWeb

Perfect fit

Mark Casias
STX20L-BS Battery for Harley Softail FLS FLST 1991-2017 High Performance

Works Perfectly!!

Ben Benson
Invacare 220 Scooter High Performance Medical Replacement Battery Set

Send Your Battery Photo

Expert Technician Help

Snap a photo or video of your battery and send it to us. We'll identify the exact replacement—fast and hassle-free. Our team has helped thousands of customers find the right battery quickly and easily.

POST YOUR BATTERY IMAGE
Product & Solutions Expert

Product & Solutions Expert

✉ sales@batteryweb.com

🔹 10+ Years Battery Experience 🔹 Fast & Accurate Identification

Battery Care Tips

🔹 Getting Started

Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.

🔹 Keep It Healthy

Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.

Delivery and Shipping

🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.

Disclaimer

⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.

🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

5.4V

Amp

4500F

JBL PartyBox Club 120 / Encore 2 — 5.4V HPC Replacement Battery (FG2CELL21700P)

This is the FG2CELL21700P replacement battery for the JBL PartyBox Club 120 and PartyBox Encore 2 portable speakers. It runs at 5.4V with a 4500F (24.3Wh) capacity, matching the original cell specification. It restores wireless operation when the factory pack has degraded or failed entirely.

  • PartyBox Club 120 and Encore 2 compatibility: Both models share the same 5.4V HPC cell format, connector pinout, and BMS handshake protocol — that is why one part number covers both. Swap in either unit without modification.
  • Bench tested on actual hardware: We cycled this pack through repeated charge and discharge sequences on the PartyBox platform. The BMS accepted the cell, reported state-of-charge accurately to the speaker's indicator LEDs, and held voltage steady under combined amplifier and Bluetooth radio draw.
  • Monthly discharge cycle for PartyBox users: If the speaker sits on a shelf or desk and gets topped off before dropping below 50%, run it down past 20% at least once a month before recharging. Constant shallow cycling causes fuel gauge drift and accelerates capacity fade on this cell chemistry.

Audio distortion before the battery indicator reaches empty on the PartyBox Club 120

The PartyBox Club 120 amplifier draws a sharp current spike at high volume. When the cell ages and internal resistance rises, voltage sags under that spike even though the indicator still shows charge remaining. The amplifier clips because rail voltage has dropped below its operating floor, not because the pack is actually empty. Replacing the cell restores the voltage headroom the amplifier needs and pushes that clipping point back to where it belongs — near actual depletion.

Speaker won't wake from USB-C after sitting unused for several weeks

HPC cells that have self-discharged below the USB-C Power Delivery minimum acceptance threshold will not trigger the PD handshake. The charger sees no valid negotiation response and supplies nothing, so the pack stays dead. Connect the speaker to a 5V 1A USB-A source instead — this bypasses PD negotiation and trickle-charges the cell back above the threshold. Once the indicator shows at least one LED, switch back to the USB-C charger and complete a full charge cycle.

Compatible Models

PartyBox Club 120 PartyBox Encore 2

Replaces Part Numbers

FG2CELL21700P

Technical Specifications

Voltage5.4V
Amp Hours4500F
Capacity4500F
Rate24.3Wh
Net Weight180g /6.35 oz
Gross Weight250g /8.82 oz
Approximate Weight250g /8.82 oz
Dimension 89.40 x 48.90 x 25.20mm

Product Highlights

  • Brand: JBL
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: HPC
  • Battery Type: HPC
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My PartyBox Club 120 shows a full charge but the audio starts cutting out after extended play — is that the battery?

Yes, and the cause is voltage sag, not a flat cell. As the original pack ages, internal resistance climbs. Under the combined current draw of the amplifier and Bluetooth radio at high volume, the pack can no longer hold the voltage rail steady, so the speaker's protection circuit interrupts audio even though state-of-charge reads fine. Replacing the cell with a fresh FG2CELL21700P restores the voltage headroom that circuit needs. After fitting the new pack, run one full discharge-to-20% cycle before topping off to calibrate the fuel gauge.

Bluetooth drops out specifically when the volume is loud but stays connected at low volume — what's happening?

The Bluetooth radio and the amplifier share the same battery rail. At high volume, the amplifier pulls a current spike that sags rail voltage; the radio module drops out because it falls below its minimum operating voltage at exactly that moment. This is not a Bluetooth interference issue — it is a voltage delivery issue. A worn cell with elevated internal resistance makes the sag worse. Fitting a replacement cell with lower internal resistance typically eliminates the drop-outs at high volume.

The PartyBox Encore 2 charges normally but seems to hold noticeably less charge than it used to — what causes that?

Shallow cycling is the most common cause. If the speaker is recharged every time it drops to 50% or higher without ever running it down further, the fuel gauge drifts and the cell itself develops a shortened charge window through shallow-cycle degradation. This is not a fault in the charger or the electronics. Run the pack down past 20% once, then charge it fully — if the indicator recovers and playtime improves, the original cell was experiencing gauge drift. If it does not recover after two full cycles, replace the pack with the FG2CELL21700P.

Payment & Security

Payment methods

  • American Express
  • Apple Pay
  • Diners Club
  • Discover
  • Google Pay
  • Mastercard
  • PayPal
  • Shop Pay
  • Visa

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.

Related Products

JBL PartyBox Club 120 Replacement Battery, 5.4V, 4500F, HPC 1

Engineered for Performance. Built to Last.

Check out our top-rated selection of reliable products built to last. We offer high-quality options that deliver consistent performance for all your needs.

Our Collections