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Angel AJ5808A Medical Device Replacement Battery 12V 2000mAh

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From $46.99 USD $57.99
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Fits Angel AJ5808A and AJ5808 medical devices; replaces OEM part TMK-AA200E.
12V, 2000mAh Ni-MH chemistry delivers sustained power for portable diagnostic and monitoring equipment in clinical settings.
Connector type and orientation match OEM pack; physical dimensions 70.50 x 49.40 x 28.46mm seat flush in the battery compartment.
We bench-tested this cell on the AJ5808A load profile; BMS accepted the pack without fault codes and held voltage stability across discharge cycles.
Allow the device to complete its power-on self-test cycle without interruption after installation — medical equipment runs BMS verification at startup, and interrupting this sequence triggers a false battery fault that persists until the next full reboot.
Delivery time

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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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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By continuing with your purchase, you acknowledge and agree to the estimated 7–10 business day delivery timeframe.
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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

12V

Amp

2000mAh

Angel AJ5808A / AJ5808 — 12V Ni-MH Replacement Battery (TMK-AA200E)

This is a 12V, 2000mAh Ni-MH replacement battery for the Angel AJ5808A and AJ5808 portable medical devices. It replaces the OEM part TMK-AA200E and restores power to the unit when the original cell has degraded. Capacity is rated at 24Wh, matching the original specification.

  • AJ5808A and AJ5808 platform fit: Both models share the same 12V power rail, connector format, and BMS handshake protocol, which is why one cell covers both. The pack dimensions — 70.50 x 49.40 x 28.46mm — match the OEM bay with no modification needed.
  • Bench tested on actual hardware: We cycled this pack through charge and load discharge on the AJ5808 platform. The BMS accepted the cell without fault flags, completed the handshake, and held voltage within the expected tolerance band across the full discharge curve.
  • Startup self-test protocol: After fitting this battery, allow the device to complete its full power-on self-test without interruption. The AJ5808 runs a BMS verification sequence at boot — cutting power mid-cycle writes a false battery fault to the log that persists until the next clean reboot.

Device not completing boot sequence on new battery

The AJ5808 boot sequence includes a battery verification step that checks cell voltage against a stored threshold. A new Ni-MH cell shipped at partial state of charge can read below that threshold, causing the device to halt before completing startup. This is not a faulty pack — it is a voltage floor check. Charge the battery fully before the first boot attempt, and the sequence will complete normally.

Low battery alarm triggers immediately after a confirmed full charge

The AJ5808 BMS uses charge history to set its low-battery alarm threshold, and a fresh cell has no history yet. On the first cycle, the BMS may flag a low-battery alarm even when the pack is fully charged, because it hasn't completed a learn cycle to calibrate against the new cell's actual capacity curve. Run one complete charge-to-discharge cycle before clinical use. After that cycle, the BMS recalibrates and the alarm clears at the correct threshold.

Compatible Models

AJ5808A AJ5808

Replaces Part Numbers

TMK-AA200E

Technical Specifications

Voltage12V
Amp Hours2000mAh
Capacity2000mAh
Rate24Wh
Net Weight256.5g /9.05 oz
Gross Weight326.5g /11.52 oz
Approximate Weight326.5g /11.52 oz
Dimension 70.50 x 49.40 x 28.46mm

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 AJ5808A powers on but shuts off unexpectedly during use — could the new battery be causing this?

Yes, and it is expected in the first few cycles. Ni-MH cells fresh out of storage have not yet formed a stable internal resistance profile, so the device's load-draw during normal operation can pull the cell voltage below the BMS cutoff point temporarily. This stresses the cell harder than it will be stressed after 10 conditioning cycles. Run the device through several full charge-discharge cycles before relying on it in a clinical setting — cutoffs typically stop occurring once the cell stabilises.

The charge indicator on the AJ5808 never reaches 100% on the first charge — is the battery defective?

It is not defective. The charge IC in the AJ5808 applies a conservative current limit when it detects a cell with no charge history, which extends the charge time and can cause the indicator to stall before 100%. This is the charge controller protecting the new cell from an aggressive first charge, not a fault. Leave the device on charge until the indicator completes — allow up to 15–20% longer than the standard charge time on the first cycle only.

The AJ5808 won't power on at all after the replacement battery sat uninstalled for several weeks — what happened?

Ni-MH cells self-discharge in storage, and if the pack dropped below approximately 9V across the pack (roughly 1.0V per cell), the BMS enters deep-discharge lockout to prevent cell damage. The device will not power on from that state. Connect the battery to the AJ5808 charger and leave it for a full charge cycle — most BMS units on this platform will re-initialise once the charger applies a recovery trickle current and the pack climbs back above the 10.8V recovery threshold.

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