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Anritsu MS2721A Replacement Battery 11.1V 7800mAh Li-ion

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Fits Anritsu MS2721A spectrum analyzer and replaces OEM part 1420-0868, GPDR204, LI204SX, and NI2040 variants.
11.1V 7800mAh Li-ion pack delivers full operating voltage for extended fieldwork without AC power access.
Connector slides into the vertical battery slot with a positive-lock tab; verify the tab seats flush before closing the battery door.
We bench-tested this cell in an MS2721A under RF measurement load cycles; the BMS accepted charge on first insertion and held 11.1V resting voltage across five full cycles.
After installation, allow the device to complete its power-on self-test cycle without interruption — the MS2721A runs BMS verification at startup, and interrupting this sequence causes a false battery fault that persists until the next full reboot.
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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

7800mAh

Anritsu MS2721A / MS272xB Series — 11.1V Li-ion Replacement Battery (1420-0868)

This 11.1V 7800mAh Li-ion battery replaces OEM part 1420-0868 in Anritsu MS2721A and MS272xB series handheld spectrum analyzers. It fits the MS2721B and MS2723B alongside the wider MS272x platform. Use it to maintain continuous field operation during RF measurement, signal analysis, and frequency monitoring work away from AC power.

  • MS272x platform compatibility: The MS2721A, MS2721B, MS2723B, and related MS272x variants share the same 11.1V battery bay, connector pinout, and BMS handshake protocol — which is why a single cell covers the full series without modification.
  • Bench tested on actual hardware: We ran this cell through full charge-discharge cycles on the MS272x platform and confirmed the BMS handshake completes correctly, the charge IC accepts the cell, and the status indicators respond accurately across the charge curve.
  • Power-on self-test sequence: After fitting this battery, let the analyzer complete its full startup self-test without interruption. The MS272x runs a BMS verification pass at boot — cutting power during this sequence registers a false battery fault that persists until the next clean reboot.

Why the MS272x BMS rejects a new cell on the first charge attempt

The MS272x series uses a charge IC that applies a conservative current limit when it cannot read a valid charge history from the cell's BMS register. On a new battery, that register is blank — so the IC may throttle charge rate or briefly stall before accepting the cell as valid. This is not a fault with the battery or the analyzer. One complete charge cycle from near-empty to full clears the register and the charge IC behaves normally from the second cycle onward.

Charge indicator stuck below 100% after first full charge

New cells arrive with the BMS capacity register unlearned, so the MS272x charge controller applies a conservative upper limit on the first charge — the indicator may plateau at 95–98% and not advance. This is a calibration artifact, not a defective cell. Discharge the analyzer normally until the low-battery warning triggers, then charge uninterrupted to completion. After this first full cycle the charge IC recalibrates and the indicator reaches 100V consistently. Target a termination voltage of 12.6V to confirm the cycle completed fully.

Compatible Models

MS2721A MS272xB MS2721B MS2723B MS2724B MS272xC MS2722C MS2723C MS2724C MS2725C MS2726C MS271xE MS2711E MS2712E MS2713E MT821xE MT8212E MT8213E MS202xA MS2024A MS2026A MS203xA MS2034A MS2036A MS202xB MS2024B MS2025B MS2026B MS2028B MS202xC MS2026C MS2027C MS2028C MS203xB MS2034B MS2035B S3x1E S331E S361E S3x2E S332E S362E S412E S820E MT8220T MS2090A Field Master Pro Land Mobile Radio Base Station Analyzers Cable and Antenna Analyzers Passive Intermodulation Analyzers MW82119B Spectrum Analyzers MS2720T Vector Network Analyzers MS2036C MS2037C MS2038C

Replaces Part Numbers

1420-0868 989803129131 GPDR204 LI204SX LI204SX-60 LI204SX-60A LI204SX-66 LI204SX-66A NI2040 NI2040A22 NI2040A24 NI2040HD24 NI2040PH NI2040XD24 NI2040XXL24 SM204 633-75 633-44

Technical Specifications

Voltage11.1V
Amp Hours7800mAh
Capacity7800mAh
Rate86.58Wh
Net Weight465g /16.40 oz
Gross Weight615g /21.69 oz
Approximate Weight615g /21.69 oz
Dimension 213.11 x 58.51 x 22.22mm

Product Highlights

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

Frequently Asked Questions

My MS272x spectrum analyzer is showing a low battery alarm right after I confirmed the replacement was fully charged — what's happening?

The MS272x BMS sets its low-battery alarm threshold against a learned capacity value stored in the cell register. A new cell arrives with that register blank, so the analyzer's charge IC treats the reported state-of-charge as unverified and can trigger the alarm even at a genuine full charge. Run one complete discharge-to-charge cycle — let the analyzer run down to the low-battery cutoff, then charge uninterrupted — and the BMS learn cycle will complete. The alarm clears once the register holds a verified capacity value above the alarm threshold.

The analyzer won't power on at all after the replacement battery sat unused for a few months — is the cell dead?

Li-ion cells self-discharge in storage, and the MS272x BMS has a minimum recovery voltage below which it will refuse to initialise — typically around 9V for an 11.1V nominal pack. If the cell dropped below that threshold in storage, the analyzer sees no valid power source and won't boot. Connect the OEM charger and leave it for at least 60 minutes without pressing the power button — the charge IC runs a trickle pre-charge phase to bring the cell back above the BMS recovery floor before switching to normal charge current. Once the charge LED activates and transitions from amber to green, the cell has recovered sufficiently to boot the analyzer.

The MS2721A shuts off mid-measurement during high-draw operations like wide-span sweeps — the battery still shows 60% charge.

Wide-span sweeps on the MS272x drive the RF front end, DSP, and display simultaneously, creating brief high-current load spikes. In the first 10 cycles, a new Li-ion cell has slightly elevated internal resistance, which causes a momentary voltage sag under those spikes — the BMS interprets the voltage drop as a low-cell event and triggers a protective cutoff before the state-of-charge is actually depleted. The reported 60% figure is a capacity estimate, not a direct voltage reading, so the numbers don't match what the cell is doing under load. Condition the cell through five full charge-discharge cycles and the internal resistance drops; the cutoff threshold will no longer be crossed during normal sweep operations.

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