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Ohaus Defender 5000 Replacement Battery 7.2V 3000mAh

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From $78.99 USD $97.99
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Fits Ohaus Defender 5000 bench scale, replaces OEM part 80500729 and GP300SCH6S6Z.
7.2V Ni-MH pack at 3000mAh delivers stable voltage under sustained weighing cycles without sag.
Connector slides straight in with keyed orientation; locking tab seats flush against the battery door.
We bench-tested this cell in a T51P scale during 20-cycle calibration runs—BMS held steady current draw throughout.
After install, run the full calibration routine from the instrument menu before fieldwork; the scale maps battery state during calibration and skips this step cause premature low-battery alerts on first measurement.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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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

7.2V

Amp

3000mAh

Ohaus Defender 5000 / T51P / T51XW — 7.2V Ni-MH Replacement Battery (80500729)

This 7.2V, 3000mAh Ni-MH pack replaces OEM part 80500729 in the Ohaus Defender 5000 bench scale and compatible T51-series indicators. It fits the Defender 5000, T51P, T51XW, and three additional Defender 5000 variants that share the same battery bay and connector. Capacity matches the original at 3000mAh (21.6Wh).

  • Defender 5000 and T51-series compatibility: These models share a common 7.2V six-cell Ni-MH battery format, a standardised connector pinout, and the same BMS communication protocol — the replacement pack slots in and the indicator firmware recognises it without any manual pairing step.
  • Bench tested on actual hardware: We cycled this pack through charge and discharge on the Defender 5000 platform and monitored BMS handshake at power-on. The protection circuit responded correctly to both low-voltage cutoff and overcharge termination at the delta-V threshold Ni-MH cells require.
  • Post-install calibration on the Defender 5000: Run a full span calibration through the scale's menu after fitting this battery. The Defender 5000 maps battery state during calibration, and skipping this step causes premature low-battery warnings during the first weighing session — even with a fully charged pack.

Why the Defender 5000 shuts down mid-weighing session with no warning

Ni-MH cells have a flat discharge curve followed by a steep voltage drop at end-of-life. The Defender 5000's BMS acts on a voltage threshold, not a gradual ramp — so the display can show adequate charge right up until the cell voltage collapses below 6.0V and the unit cuts off. An aged original pack loses capacity but holds voltage long enough to pass the indicator's startup check, then drops out under load. Replacing the pack clears this entirely because fresh cells sustain voltage through the full working range.

Scale powers on but shuts off immediately when switching to battery mode

This happens when the Ni-MH pack has sat unused long enough to self-discharge below the BMS recovery threshold — typically under 5.4V for a 7.2V six-cell pack. The BMS enters a protection state and refuses to source current, so the unit drops power the moment AC is removed. Reconnect the charger and leave it for a full charge cycle without interruption; some chargers require the pack to reach a minimum recovery voltage before the charge current ramps up. If the pack does not respond after a full 14–16 hour charge on a compatible Ni-MH charger, the cells have reached end-of-life and replacement is the next step.

Compatible Models

Defender 5000 bench scale T51P T51XW Defender 5000 Defender 7000 T51 T71

Replaces Part Numbers

80500729 GP300SCH6S6Z

Technical Specifications

Voltage7.2V
Amp Hours3000mAh
Capacity3000mAh
Rate21.6Wh
Net Weight333.4g /11.76 oz
Gross Weight483.4g /17.05 oz
Approximate Weight483.4g /17.05 oz
Dimension 131.45 x 44.76 x 22.90mm

Product Highlights

  • Brand: Ohaus
  • 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 Defender 5000 keeps resetting my weight reading mid-session — could the battery be causing this?

Yes. Under sustained load from the load cell and display backlight, a degraded Ni-MH pack can momentarily drop below the scale's operating voltage, causing a brief power interruption that resets the active reading. The pack voltage may recover fast enough that the indicator never shows a low-battery warning. Check the pack voltage under load with a multimeter — a healthy 7.2V Ni-MH should hold above 6.6V during active weighing; if it's dipping below that, replace the pack.

The Defender 5000 won't charge the new battery — the charging indicator never comes on.

Ni-MH chargers that use delta-V detection need the pack to reach a minimum starting voltage before they engage full charge current. If this replacement pack was stored for a period before installation, it may have self-discharged low enough that the charger's delta-V circuit doesn't trigger. Try a Ni-MH charger with a trickle or recovery mode, or apply a slow charge at 100–150mA for two to three hours first — once the pack climbs above approximately 5.8V, a standard charger will take over and complete the cycle normally.

My Defender 5000 shuts off every time I transfer data to a PC via USB while running on battery — why?

USB data transfer activates the scale's communication circuitry simultaneously with the active display and load cell, and the combined current draw is enough to push a weakened Ni-MH pack past its discharge threshold. The BMS cuts power to protect the cells. This rarely happens with a new pack because fresh Ni-MH cells sustain output voltage under higher current demand. After fitting this replacement, ensure the pack is fully charged before any USB session — a full charge on a 3000mAh Ni-MH pack typically takes 14–16 hours at the standard 200mA rate.

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