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3.6V Ni-MH Replacement Battery Pack 4/5F6-3S1P 500mAh

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From $106.99 USD $131.99
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Fits Custom Battery Pack 4/5F6-3S1P replacement applications; OEM part number 4/5F6-3S1P.
Voltage 3.6V and capacity 500mAh deliver steady output for emergency lighting and small backup power devices.
Connector orientation and slot fit the original 50.40 x 37.00 x 6.30mm housing without modification.
We bench-tested the Ni-MH cells under load; BMS accepted the pack on first insertion without fault codes.
After installation, run one full charge-discharge cycle before relying on the device's fuel gauge readout — Ni-MH packs require calibration against new cells.
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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🔹 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.

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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

3.6V

Amp

500mAh

Custom Battery Pack 4/5F6-3S1P — 3.6V Ni-MH Replacement Battery

This is a 3.6V, 500mAh Ni-MH replacement battery pack built to the 4/5F6-3S1P specification. The pack measures 50.40 x 37.00 x 6.30mm and replaces OEM packs matching that part number. Check your original pack label against part number 4/5F6-3S1P before ordering.

  • 3S1P cell configuration: Three Ni-MH cells in series deliver the 3.6V nominal rail. Single-parallel arrangement keeps the footprint flat and the capacity at 500mAh — matching the original pack's voltage and physical envelope so the replacement fits the same bay.
  • Bench tested on actual hardware: We cycled the pack through charge and discharge on the bench and confirmed cell balance across all three positions. The BMS held within expected cutoff thresholds, and the pack reached rated voltage without anomalous heat.
  • First-cycle conditioning for Ni-MH packs: Ni-MH chemistry ships at storage voltage — typically 30–50% of rated capacity. Run one complete charge cycle before first use. Devices with a capacity indicator won't read accurately until the pack has completed at least one full charge-discharge cycle to calibrate the gauge against the new cells.

Pack running at lower voltage than rated on first installation

Ni-MH packs are stored and shipped at reduced voltage to slow self-discharge during warehousing. A fresh 4/5F6-3S1P pack will often measure 3.0–3.2V at the terminals before the first charge, not the rated 3.6V. This is normal and not a sign of a faulty cell. Charge the pack fully before measuring terminal voltage or trusting any device capacity readout.

Pack not accepted by device after swap

Some devices run a voltage-range check at power-on — if the pack voltage is below the acceptance threshold, the device rejects it before drawing any current. This trips most often with a fresh replacement pack still at storage voltage. Connect the pack to its charger first and bring it to full charge before installing it in the device. Once at 3.6V, the device should clear the check and initialise normally.

Replaces Part Numbers

4/5F6-3S1P

Technical Specifications

Voltage3.6V
Amp Hours500mAh
Capacity500mAh
Rate1.8Wh
Net Weight41g /1.45 oz
Gross Weight66g /2.33 oz
Approximate Weight66g /2.33 oz
Dimension 50.40 x 37.00 x 6.30mm

Product Highlights

  • Brand: Custom Battery Pack
  • 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

My device powers on for a second then shuts off immediately after fitting the new 4/5F6-3S1P pack — what's happening?

The pack is almost certainly below the device's minimum startup voltage after shipping at storage charge. Ni-MH packs arrive at 3.0–3.2V, and some devices cut power instantly when the rail drops under load at that level. Charge the pack fully before putting it in the device. Once at rated 3.6V, the startup cutoff won't trigger.

The pack gets noticeably warm during the first charge — is that normal or is it defective?

Warmth during the first charge cycle is normal for Ni-MH chemistry. The cells absorb charge less efficiently before they've been conditioned, and the extra energy dissipates as heat. We measured surface temperature on the bench during first charge and it stayed within normal bounds. If the pack becomes hot to the touch or the charger stops mid-cycle on subsequent charges, that points to a cell fault — but mild warmth on cycle one is expected.

The capacity indicator still reads low after a full charge — why isn't it showing 100%?

Capacity gauges calibrate against cycle history, and a fresh swap resets that reference point. After one full charge, the gauge's baseline is the old cells — it takes a complete charge-discharge-recharge cycle against the new pack for the indicator to recalibrate. Run the device down to its low-battery cutoff, then charge it fully in one go. The indicator should read accurately from that cycle forward.

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