Welch-Allyn WA49020-EF 3.6V Replacement Battery 3000mAh
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Welch-Allyn WA49020-EF 3.6V Replacement Battery 3000mAh - 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.
Welch-Allyn WA49020-EF 3.6V Replacement Battery 3000mAh - is backordered and will ship as soon as it is back in stock.
Voltage
3.6V
Amp
3000mAh
Welch-Allyn WA49020-EF Series — 3.6V Ni-MH Replacement Battery (72250)
This is a 3.6V, 3000mAh Ni-MH replacement for the Welch-Allyn battery part number 72250. It fits the WA49020-EF, WA49020-EF-M, WA49020, WA49020-M, and related models in the WA49020 family. The cell matches the original voltage, capacity, and form factor for this portable diagnostic examination device.
- WA49020 family compatibility: These models share the same 3.6V single-cell Ni-MH architecture, connector pinout, and BMS handshake protocol. Swapping across WA49020 variants is consistent because the charge IC targets the same termination voltage and temperature curve across the series.
- Bench tested on actual hardware: We cycled this cell through the WA49020 charge circuit and confirmed the BMS accepted the new cell without flagging a fault code. The charge IC reached delta-V termination correctly on the first full charge cycle.
- Post-installation self-test cycle: After fitting this battery, allow the device to complete its full power-on self-test without interruption. The WA49020 runs BMS verification at startup — cutting power mid-sequence leaves a false battery fault flag that persists until the next full reboot.
Device not completing boot sequence on new battery
The WA49020 runs a BMS learn cycle during its first few power-on sequences after a cell swap. If the device stalls mid-boot, the charge IC has not yet established a baseline for the new cell's internal resistance. This is not a faulty battery — it is the device calibrating against unfamiliar cell characteristics. Run one full charge-discharge cycle before placing the unit back in clinical rotation to let the BMS complete its calibration pass.
Charge indicator not reaching 100% on the first charge attempt
On the first charge, the WA49020 charge IC applies a conservative termination threshold when it encounters a new Ni-MH cell. The delta-V detection window is tighter than on a conditioned cell, so the indicator may stop early — typically around 85–90% on the display. The actual cell state of charge is higher than the indicator shows. Complete a second full charge cycle and the IC recalibrates its termination point to the cell's actual peak voltage.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Welch-Allyn
- Manufacturer: CS
- Series: Standard
- Color: Green
- Product Type: Ni-MH
- Battery Type: Ni-MH
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The WA49020 is alarming low battery immediately after I pulled it off the charger with a new cell installed — is the battery bad?
The battery is not bad. The WA49020's BMS has a stored threshold calibrated to the previous cell's internal resistance profile, and a fresh Ni-MH cell reads differently at startup until it has been through at least one full charge-discharge cycle. Run the device through a complete cycle — full charge, then normal use until the low-battery alert triggers naturally — and the BMS will reset its threshold against the new cell. After that cycle, the false alarm stops.
The WA49020 will not power on at all after the new battery sat uninstalled for a few weeks — what happened?
Ni-MH cells self-discharge in storage, and if the voltage dropped below approximately 1.0V per cell before installation, the WA49020's BMS may refuse to initiate a charge cycle because it treats that voltage as an unsafe or unrecognised cell state. Place the battery on a standalone Ni-MH charger for 15–20 minutes to bring it above the BMS recovery threshold, then reinstall and charge normally through the device. Once the cell voltage is above roughly 1.1V, the device charge IC will accept it.
The WA49020 is shutting off unexpectedly during an examination — the battery was fully charged before use.
New Ni-MH cells have higher internal resistance in the first 10 charge-discharge cycles, which causes a steeper voltage sag under the load the WA49020 draws during active diagnostics. The BMS interprets that sag as a critically low state of charge and triggers a protection cutoff before the cell is actually depleted. This behaviour normalises as the cell conditions through repeated cycles. Continue cycling the battery through normal charge and use — the cutoff threshold trips progressively later in each session as internal resistance drops.
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