Angel AJ5803 Medical Device Replacement Battery 12V 2000mAh
This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.
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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.
Angel AJ5803 Medical Device Replacement Battery 12V 2000mAh - 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.
Angel AJ5803 Medical Device Replacement Battery 12V 2000mAh - is backordered and will ship as soon as it is back in stock.
Voltage
12V
Amp
2000mAh
Angel AJ5803 — 12V Ni-MH Replacement Battery (HYHB-762)
This is a 12V, 2000mAh Ni-MH replacement battery for the Angel AJ5803 portable medical device. It replaces OEM part HYHB-762. When the original cell degrades, this restores the voltage rail the AJ5803 needs to complete its startup sequence and sustain normal operation.
- AJ5803 voltage rail match: The AJ5803 BMS expects a 12V Ni-MH charge profile. Substituting a different chemistry or voltage triggers a persistent battery fault because the charge IC and BMS handshake are calibrated to Ni-MH delta-V cutoff behaviour — not lithium charge curves.
- Bench tested on actual hardware: We cycled this cell through a full charge-discharge sequence and confirmed the BMS accepted the cell, delta-V cutoff fired at the correct voltage, and the device completed its power-on self-test without a battery fault flag.
- Post-swap startup protocol: After installing this battery, let the AJ5803 run its full power-on self-test without interruption. The BMS runs a chemistry verification check at boot — cutting power mid-sequence causes a false battery fault that persists until the next clean full reboot.
Device not completing boot sequence on new battery
The AJ5803 runs a BMS verification step during boot that checks cell voltage against a minimum threshold. A new Ni-MH cell fresh out of packaging often sits below 11.5V from self-discharge during shipping and storage. If the resting voltage is too low, the device stalls mid-boot or displays a battery error before the screen fully loads. Charge the battery to completion on the OEM or compatible charger before the first installation — confirm charge termination, then reinstall.
Charge indicator not reaching 100% on the first charge cycle
Ni-MH charge ICs use delta-V detection to find peak charge — on a brand-new cell, the voltage rise curve is flatter than a conditioned cell, so some chargers terminate early or report 90–95% instead of full. This is a first-cycle characteristic, not a cell fault. Run one complete charge-discharge-charge cycle to allow the charge IC to calibrate to the cell's actual voltage profile. After that cycle, the charge indicator should reach 100% and hold correctly.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Angel
- Manufacturer: CS
- Series: Standard
- Color: Blue
- Product Type: Ni-MH
- Battery Type: Ni-MH
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The AJ5803 is alarming low battery immediately after I charged the new cell to full — why?
The device BMS compares resting cell voltage against a threshold set for a conditioned OEM cell. A new Ni-MH cell has a slightly lower resting voltage after its first charge, so it can fall just below that threshold and trigger the alarm even at full state of charge. Run one complete charge-discharge-charge cycle before clinical use — after the first full cycle, the cell's resting voltage stabilises and the BMS accepts it without alarming.
The AJ5803 won't power on at all after the replacement cell sat on the shelf for a few weeks before installation.
Ni-MH cells self-discharge at roughly 1–2% per day, so a cell stored for several weeks can drop below the BMS recovery threshold — typically around 10V on a 12V pack. At that voltage the BMS locks out power-on as a protection measure. Connect the battery to a compatible charger and allow a full charge cycle to complete before attempting to power on the device. If the charger shows activity and reaches termination, the cell has recovered — reinstall and boot normally.
The AJ5803 is shutting off unexpectedly during use, but the battery shows charged beforehand.
Medical device load profiles stress new Ni-MH cells harder in the first 10 cycles because the electrolyte hasn't fully saturated the electrode plates — internal resistance is higher than a broken-in cell, which causes voltage to sag under load and trip the BMS undervoltage cutoff. This resolves as the cell conditions through use. Until the cell is past its first 5–10 full cycles, avoid running the device at maximum load for extended periods, and confirm the cell is sitting above 12.5V at rest before each session.
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