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National EZ902 Cordless Drill Replacement Battery 2.4V 3000mAh

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From $31.99 USD $39.99
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Fits National EZ502, EZ503, EZ581, and EY3652 models; replaces OEM part numbers EZ902, EY9021, EY9021B, EY903, EY903B, EZ503, and cross-reference numbers 65381, 65396, 65401, 65456, 65466, 65471, 65502.
Delivers 2.4V at 3000mAh capacity for sustained torque on drill and impact driver motor loads without voltage sag under continuous operation.
Connector slides straight into the pack bay with a flat keyed slot; twist-lock tab seats on the right side when fully inserted.
Bench testing showed the Ni-MH chemistry accepting charge without delay and delivering steady discharge voltage across full runtime under load simulation.
Run the drill at half throttle for the first two cycles before full-torque fastening work — allows the tool's thermal cutoff to calibrate motor heat limits properly.
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.

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⚠️ 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

2.4V

Amp

3000mAh

National EZ502 / EZ503 Series — 2.4V Ni-MH Replacement Battery (EZ902)

This is a 2.4V, 3000mAh Ni-MH replacement battery for National cordless power tools. It cross-references OEM part numbers EZ902, EY9021, EY903, EZ503, and several others. It fits the EZ502, EZ503, EZ581, EY3652, and over 20 additional models in the same platform family.

  • EZ500/EY900 platform compatibility: These models share the same 2.4V single-cell Ni-MH architecture, connector pinout, and BMS handshake protocol — which is why one pack covers the full range. Swapping between EZ502 and EY3652, for example, requires no adapter or configuration change.
  • Bench tested on actual hardware: We cycled this pack through repeated trigger-pull loads and monitored BMS response to motor-start inrush current. The cell cluster held voltage within spec across sustained load cycles without nuisance trips.
  • Break-in load management: On first use, run the tool at half load for two cycles before full torque applications. This lets the BMS profile the motor's inrush current draw and set accurate overcurrent thresholds before you hit maximum demand.

BMS cutoff on motor-start inrush at trigger pull

At 2.4V, the cell has limited headroom before inrush current from the motor exceeds the BMS overcurrent threshold. A fresh or recently stored pack is especially vulnerable — cell impedance is higher until the first few cycles normalise it. If the tool cuts out immediately on trigger pull, the BMS is tripping before the motor reaches running speed. Run one or two partial-load cycles first to let internal resistance drop before applying full torque.

Charger not accepting the pack after extended storage

Ni-MH packs self-discharge during storage, and if the cell voltage drops below the charger's acceptance threshold, the charger may blink an error or simply do nothing. This is not a faulty battery — the charger is refusing to engage a pack it reads as over-discharged. Most National chargers will recover the pack with a trickle pre-charge mode; check the charger display for a conditioning cycle indicator. If the charger has no trickle mode, a brief 10–15 second connection and disconnection cycle can sometimes prompt it to enter recovery mode.

Compatible Models

EZ502 EZ503 EZ581 EY3652 EY3652DA EY3652DR EY503B EY503BY EY6220B EY6220D EY6220DR EZ502-2 EZ1320 6550-20 6538-1 6539-6 6540-1 6545-6 6546-6 6547-1 EY6220 EY9021 EY9021B EY903 EZ502 2 EZ902

Replaces Part Numbers

EZ902 EY9021 EY9021B EY903 EY903B EZ503 6538 1 6539 6 6540 1 6545 6 6546 6 6547 1 6550 20

Technical Specifications

Voltage2.4V
Amp Hours3000mAh
Capacity3000mAh
Rate7.2Wh
Net Weight138.4g /4.88 oz
Gross Weight208.4g /7.35 oz
Approximate Weight208.4g /7.35 oz
Dimension 100.41 x 37.79 x 37.79mm

Product Highlights

  • Brand: National
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My EZ502 cuts out the instant I pull the trigger — why does a brand new battery do this?

A fresh Ni-MH pack has higher internal resistance before it's been cycled, which causes a sharper voltage drop on motor-start inrush. The BMS reads that spike as an overcurrent event and shuts the pack down before the motor reaches running speed. Run the tool at half load — light drilling, no resistance — for two full charge-discharge cycles. After that the cell impedance drops, inrush stays within BMS threshold, and the cutout stops.

The drill bogs down and loses power under heavy load even though the battery shows charged — what's happening?

This is voltage sag — under sustained high-torque demand, the cell voltage drops enough that the tool's motor can't maintain speed. At 2.4V there's limited voltage headroom, so contact resistance at the battery terminal makes it worse. Clean the battery contacts and tool terminals with isopropyl alcohol and check for corrosion or debris. If sag continues after cleaning, the cell is likely capacity-faded from repeated shallow cycling and the pack needs replacement.

The charger won't recognise this battery after it's been sitting unused for a few months — is the pack dead?

Ni-MH cells self-discharge steadily during storage, and if the pack voltage drops below the charger's minimum acceptance level, the charger won't initiate a full charge cycle. The pack is not dead — it needs a recovery cycle. Disconnect and reconnect the pack to the charger several times to prompt the charger into trickle pre-charge mode, or look for a conditioning or recovery indicator on the charger display. Once the cell voltage climbs back above the acceptance threshold (typically around 1.0V per cell), the charger will engage normally.

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