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Castles Saturn 1000 S1F2 B26 Replacement Battery 3.7V 6400mAh

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From $50.99 USD $62.99
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Fits Castles Saturn 1000 S1F2 and Saturn 1000F payment terminals; replaces OEM part number B26.
3.7V, 6400mAh capacity delivers the charge density needed for full-day transaction processing on retail terminals without mid-shift power loss.
Connector seats vertically into the battery slot with a single locking tab on the left side; polarity marked on the cell itself.
We bench-tested this cell in a Saturn 1000F unit under transaction load — BMS accepted the handshake on power-on and held output voltage stable through print cycles.
After installation, run one complete transaction cycle before deploying to a live terminal; the device calibrates the charge indicator during normal operation.
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.

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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

3.7V

Amp

6400mAh

Castles Saturn 1000 S1F2 / Saturn 1000F — 3.7V Li-ion Replacement Battery (B26)

This is a 3.7V 6400mAh Li-ion replacement battery for the Castles Saturn 1000 S1F2 and Saturn 1000F payment terminals. It slots into the rear battery compartment and restores full terminal operation. Part number B26 matches the OEM connector and BMS pinout for both models.

  • Saturn 1000 S1F2 and Saturn 1000F compatibility: Both models share the same battery bay dimensions, 3.7V rail, and BMS communication protocol. The B26 part number covers both variants — the hardware is identical at the battery interface level.
  • Bench tested on actual hardware: We cycled this cell through the Saturn 1000 boot sequence and ran back-to-back transaction simulations. The BMS handshake completed correctly on first boot, and the charge IC accepted the cell without throwing a fault code.
  • First deployment tip for POS terminals: After fitting this battery, complete one full transaction cycle before putting the terminal into a live environment. The Saturn 1000 maps battery capacity during normal operation and needs at least one complete power cycle to calibrate the charge indicator correctly.

Why the Saturn 1000 reboots mid-transaction after a battery swap

The Saturn 1000's receipt printer draws a short current spike when it fires — typically enough to trip the BMS overcurrent protection on a new cell that hasn't completed its first full charge cycle. The BMS interprets this spike as a fault and cuts output, which drops the terminal mid-sale. Charge the replacement battery to 100% before first use and complete at least one transaction cycle so the BMS learns the normal load profile. After that initial calibration, the overcurrent threshold adjusts and the reboot issue resolves.

Terminal won't power on after sitting unused in a drawer

Li-ion cells self-discharge over time, and the Saturn 1000's BMS will refuse to boot if the cell voltage has dropped below approximately 3.0V — it treats this as a protection state, not a dead battery. Connect the terminal to its original charger and leave it for 20–30 minutes without pressing the power button. Most BMS circuits on this platform include a trickle-recovery path that will slowly bring the cell back above the 3.0V threshold, after which a normal boot sequence completes. If the charging LED never illuminates after 30 minutes, the original cell has likely dropped below the hard cutoff and replacement is the correct next step.

Compatible Models

Saturn 1000 S1F2 Saturn 1000F

Replaces Part Numbers

B26

Technical Specifications

Voltage3.7V
Amp Hours6400mAh
Capacity6400mAh
Rate23.68Wh
Net Weight116g /4.09 oz
Gross Weight141g /4.97 oz
Approximate Weight141g /4.97 oz
Dimension 70.70 x 55.20 x 21.50mm

Product Highlights

  • Brand: Castles
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The charge indicator on my Saturn 1000 has been stuck at 99% since I fitted the new battery — is the battery faulty?

It isn't a fault. When a new Li-ion cell first enters the charger, the charge IC runs a top-off conditioning pass that can hold the indicator at 99% for an extended period before it flips to 100%. This is the charge controller's normal behaviour on a fresh cell, not a sign of a problem with the battery or the terminal. Run the terminal through a full discharge and recharge cycle — the indicator will read accurately from that point forward.

My Saturn 1000 gets noticeably warm during busy periods — is the battery causing this?

The heat comes from the combined draw of the display, wireless radio, and receipt printer running simultaneously during high transaction volume. The battery itself contributes some warmth as current output increases, but the primary heat sources are the terminal's processor and printer motor. If the case feels hot rather than warm, check that the battery contacts are clean and seated flush — a poor contact forces higher resistance and increases heat at the cell. Normal operating warmth during a busy shift is expected and does not indicate a battery problem.

The Saturn 1000 shows the PCI boot screen but stalls and won't complete startup after fitting the replacement battery — what's happening?

The Saturn 1000 runs a BMS handshake check during its PCI boot sequence, and a new cell that hasn't completed a full charge cycle can fail that check, leaving the terminal stalled at the boot screen. Plug the terminal into the charger, allow it to reach 100%, then power it on without the charger connected. That sequence gives the BMS time to authenticate the cell and pass the boot check. One complete charge-then-boot cycle is normally enough to clear the stall permanently.

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