Yaesu FNB-26L Replacement Battery 7.4V 2500mAh Li-ion
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Yaesu FNB-26L Replacement Battery 7.4V 2500mAh Li-ion - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
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
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
⚠️ 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.
Yaesu FNB-26L Replacement Battery 7.4V 2500mAh Li-ion - is backordered and will ship as soon as it is back in stock.
Voltage
7.4V
Amp
2500mAh
Yaesu FT-25R / FT-65R / FTA-250L — 7.4V Li-ion Replacement Battery (FNB-26L)
This is a 7.4V, 2500mAh Li-ion battery pack built to the FNB-26L specification. It fits the Yaesu FT-25R, FT-65R, and FTA-250L handheld transceivers. All three radios share the same battery bay geometry, connector pinout, and BMS handshake protocol.
- FT-25R, FT-65R, and FTA-250L compatibility: These three radios run on the same 7.4V rail and use an identical battery latch and contact arrangement. Yaesu standardised the BMS communication across this platform, so one pack covers all three without modification.
- Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on the FT-25R platform. The BMS handled PTT transmit spikes without tripping, held voltage above the radio's low-battery cutoff through sustained keying, and accepted a full charge cycle in the Yaesu desktop charger without fault indication.
- First-insertion contact check: If the charger dock shows a fault LED on first insertion, remove the pack and wipe the gold contact strip with a dry cloth before reseating firmly. The Yaesu dock requires a clean contact cycle to complete the BMS handshake before charging begins.
Why the FT-25R drops to reduced TX power mid-shift on a new pack
A new FNB-26L ships at storage voltage — typically around 3.7V per cell, not the 4.2V full-charge peak. When the radio draws transmit current from a partially charged pack, the voltage sags under load and the radio's power management steps down RF output to protect the finals. This is not a faulty cell. A full charge cycle before extended use brings both cells to 4.2V and eliminates the sag. Run the pack through one complete charge in the desktop charger before taking it out in the field.
Bar indicator shows one fewer bar than expected after inserting the FNB-26L
The FT-25R reads battery level by measuring pack voltage against fixed thresholds — it does not track charge state any other way. A new pack at storage voltage sits below the top threshold, so the display shows one bar short of full even though the pack is not depleted. This resolves completely after one full charge cycle. Once the pack reaches 8.4V at the terminals, the radio will read the correct bar level on next power-up.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Yaesu
- 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
The FT-25R cuts out completely when I press PTT — is the new FNB-26L pack tripping the BMS?
Yes, this is a BMS overcurrent response to the transmit spike on a pack that hasn't been fully charged yet. The FNB-26L ships at storage voltage, and at that state the BMS trips faster under the sudden current draw of a PTT press. Charge the pack fully in the Yaesu desktop charger first — a complete cycle raises cell voltage to 4.2V per cell and widens the BMS overcurrent headroom. After a full charge, re-test PTT; the cutout should not recur.
My Yaesu charger dock blinks a fault LED and never starts charging the new pack — what's wrong?
The Yaesu dock requires a clean BMS handshake on insertion, and contaminated or slightly misaligned contacts break that cycle before charging starts. Remove the FNB-26L, wipe the gold contact strip with a dry lint-free cloth, check the dock contacts for debris, then reseat the pack with firm, even pressure until the latch clicks. If the fault LED clears within 10 seconds, charging has started; if it persists, check that the pack is seated flush — even a 1mm gap on the contact rail is enough to prevent handshake completion.
The FT-25R worked fine for the first hour on the new battery, then TX power noticeably dropped — is the pack failing already?
This is voltage sag under sustained RF output, not early cell failure. As the pack discharges toward the lower end of its voltage curve, the FT-25R's power management steps down transmit output to keep operating within safe voltage limits — the radio is protecting its final stage transistors. Check the bar indicator at the point the drop occurs; if it shows two bars or fewer, the pack is simply running low, not defective. Recharge fully and the full TX power level returns.
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