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

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

Marshall Middleton Replacement Battery 11.1V 3350mAh Li-ion

Up to 20% off
New arrival
From $43.99 USD $54.99
Shipping calculated at checkout.
Fits Marshall Middleton portable speaker, replaces OEM battery C406A7 or C406A1.
11.1V, 3350mAh cell delivers 37.19Wh total — sufficient for full-volume audio playback cycles on this mid-range Bluetooth unit.
Connector slides into the battery cavity with a single locking tab; orientation is keyed to prevent reverse insertion on the Middleton platform.
We bench-tested this pack in a Middleton speaker at sustained 80% volume; BMS accepted the charge handshake without fault codes and held regulation under combined amplifier and Bluetooth radio load.
On first insertion, if the speaker fails to wake from USB-C charging, allow the cell to sit on charger for 90 seconds — this Li-ion BMS needs time to negotiate PD voltage after a deep discharge below the radio module's minimum acceptance threshold.
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

11.1V

Amp

3350mAh

Marshall Middleton — 11.1V Li-ion Replacement Battery (C406A7)

This is an 11.1V, 3350mAh Li-ion battery for the Marshall Middleton portable Bluetooth speaker. It replaces OEM part numbers C406A7 and C406A1. Fit the new cell when the original no longer holds a charge or shuts down mid-session.

  • Middleton-specific fit: The Middleton runs a three-cell Li-ion pack at 11.1V nominal to feed its Class-D amplifier and Bluetooth radio simultaneously. Both C406A7 and C406A1 share the same voltage rail, connector, and BMS handshake, so this replacement works across both OEM revisions.
  • Bench tested on actual hardware: We cycled this cell through the Middleton's full charge and discharge sequence. The BMS communicated correctly with the speaker's fuel gauge, and charge termination triggered cleanly at capacity — no false-full cutoffs observed.
  • Monthly discharge cycle for the Middleton: The Middleton is commonly left on a desk and topped off before it drops below 50%. Doing that consistently causes fuel gauge drift on the Li-ion cell. Let the speaker discharge below 20% at least once a month before plugging in — this keeps the gauge calibrated and slows capacity fade.

Why the Middleton distorts audio before the battery indicator reaches empty

At high volume, the Class-D amplifier draws sharp current spikes. As the cell ages and internal resistance rises, those spikes cause voltage sag — the pack momentarily dips below the amplifier's clean-operation threshold even though the fuel gauge still reads 20–30%. The amplifier clips because it can't sustain the supply voltage under load, not because it's faulty. Fitting a fresh cell with lower internal resistance eliminates the sag and restores clean output down to true low-battery levels.

USB-C not waking the Middleton after leaving it stored for months

Li-ion cells self-discharge slowly during storage. If the Middleton sits unused for several months, the pack can drop below the USB-C PD minimum acceptance voltage — typically around 2.5V per cell — and the charger won't negotiate a connection. The speaker appears completely dead even on a working cable. Try a 5V 500mA USB-A to USB-C cable first; some chargers will trickle current at low voltage where PD won't. If the pack fails to recover after 30 minutes at trickle, the cell is below recovery threshold and needs replacement.

Compatible Models

Middleton

Replaces Part Numbers

C406A7 C406A1

Technical Specifications

Voltage11.1V
Amp Hours3350mAh
Capacity3350mAh
Rate37.19Wh
Net Weight150g /5.29 oz
Gross Weight175g /6.17 oz
Approximate Weight175g /6.17 oz
Dimension 70.00 x 57.00 x 20.60mm

Product Highlights

  • Brand: Marshall
  • Manufacturer: CS
  • Series: Standard
  • Color: Blue
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My Middleton shows a full charge on the indicator but the audio cuts out after about an hour — is the battery the problem?

Yes, this is fuel gauge drift caused by shallow cycling. When the Middleton is repeatedly topped off before dropping below 50%, the BMS loses track of true capacity and reports full when the usable charge is well below that. The indicator reads healthy right up until the cell can no longer sustain the amplifier load. Run the speaker down past 20% before charging for two or three consecutive cycles — if the indicator still cuts out early, the cell has degraded and needs replacing.

Bluetooth drops out specifically when the volume is turned up loud — it's fine at low volume, why?

At high volume the amplifier and Bluetooth radio are both drawing peak current at the same time. On a degraded or high-resistance cell, that combined draw causes the pack voltage to sag momentarily. The Bluetooth radio loses its stable supply voltage and the connection drops, even though the amplifier continues playing. The fix is a fresh cell with low internal resistance so the pack can sustain both loads simultaneously without the voltage dip.

The Middleton feels noticeably warm through the fabric grille after an hour of play — is that the battery overheating?

The heat comes from two sources stacked in a compact enclosure: the Class-D amplifier generates heat under continuous load, and the Li-ion cell also produces heat as it discharges. The fabric housing traps both. Normal operating temperature for the cell is up to around 45°C surface temp — if the grille is uncomfortably hot to hold for more than a few seconds, check that the ventilation slots on the housing are unobstructed. Playing at sustained high volume in direct sunlight accelerates this; dropping volume by 20% is enough to reduce amplifier heat significantly.

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

Marshall Middleton Replacement Battery, 11.1V, 3350mAh, Li-ion 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