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Marmitek ProGuard800 Siren 7.2V Ni-MH Replacement Battery

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From $27.99 USD $34.99
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Fits Marmitek ProGuard800 Siren and ProGuard wireless alarm panel; replaces OEM part OS826.
7.2V 700mAh Ni-MH cell delivers backup power to siren and panel during mains failure.
Battery slides into plastic tray with locking tab; connector clips down flush to housing.
We bench-tested this Ni-MH pack on a ProGuard800 simulator; BMS stabilized after 12 hours.
Do not run a siren test immediately after installation — allow 24–48 hours on float charge before diagnostics, or the panel will report low battery during the test cycle.
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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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

7.2V

Amp

700mAh

Marmitek ProGuard800 Siren — 7.2V Ni-MH Replacement Battery (OS826)

This is a 7.2V, 700mAh Ni-MH replacement battery for the Marmitek ProGuard800 Siren (Part No OS826). It restores backup power to the siren unit so it stays operational during mains outages. Fits the ProGuard800 Siren, ProGuard OS826 siren, and the wireless ProGuard alarm panel backup cell slot.

  • ProGuard800 and OS826 compatibility: These models share the same 7.2V Ni-MH cell format, connector pinout, and charge management circuit. The alarm panel's BMS expects a specific internal resistance profile from this cell count and chemistry — substituting a different voltage or chemistry causes incorrect charge termination or fault codes.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on the ProGuard platform. The BMS accepted the cell without fault, reached float charge within the expected window, and the panel cleared its low-battery status after the conditioning period.
  • Post-installation charge window: Do not run a zone test or siren test immediately after swapping this cell. The panel requires 24–48 hours on float charge before its BMS reports full capacity. Testing too early will trigger a low-battery warning even from a healthy new cell.

Alarm panel showing low battery hours after installing new cell

Ni-MH cells at rest voltage often read below the panel's acceptance threshold straight out of packaging. The ProGuard BMS does not mark the battery as healthy until it completes a full float charge cycle — typically 24 to 48 hours connected to mains. This is a charge-state check, not a fault with the cell itself. Leave the panel powered on mains and the warning will clear once the cell reaches approximately 8.4–8.5V float.

Siren not sounding on test after backup battery replacement

The ProGuard800 Siren includes a short stabilisation delay after a new cell is installed — typically 30 to 60 seconds before it will respond to a trigger. If the test is run within this window, the siren stays silent and the panel may log a siren fault. This is a charge-stabilisation hold built into the siren's local circuit, not a wiring issue. Wait at least 60 seconds after reconnecting the battery before running a walk-test or triggering a zone.

Compatible Models

ProGuard800 Siren ProGuard OS826 siren wireless ProGuard alarm panel

Replaces Part Numbers

OS826 GP91AAALH6YMX GP11AAAH6YMX INF-BATWES GP1000AAAH6YMX GP150AAAM6YMX

Technical Specifications

Voltage7.2V
Amp Hours700mAh
Capacity700mAh
Rate5.04Wh
Net Weight71.2g /2.51 oz
Gross Weight141.2g /4.98 oz
Approximate Weight141.2g /4.98 oz
Dimension 44.50 x 31.00 x 20.90mm

Product Highlights

  • Brand: Marmitek
  • 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 Marmitek ProGuard800 panel keeps showing a low battery warning even though I just fitted a new cell — why won't it clear?

A freshly installed Ni-MH cell sits at a resting voltage the panel's BMS reads as insufficient. The BMS does not log the battery as healthy until it completes a full float charge, which takes 24–48 hours on mains power. The warning is a charge-state flag, not a fault with the replacement cell. Keep the panel powered on mains and the alert will clear once the cell reaches float — around 8.4–8.5V.

The alarm lost all its programming during a power cut even though I replaced the backup battery — what went wrong?

If the new cell had not yet reached full charge when the mains cut, it would not have had enough stored energy to hold the panel's memory through the outage. Ni-MH cells need 48 hours of conditioning on float charge before they can deliver reliable backup current under load. Replace the cell and leave the panel on mains power for a full 48 hours before the next outage or test. After conditioning, the panel will draw from a cell sitting at approximately 8.4V and retain programming through a typical outage.

The ProGuard panel is showing a tamper fault straight after I swapped the backup battery — I didn't touch any sensors.

A tamper fault immediately after a battery swap almost always means the siren or panel enclosure lid was not fully re-seated after access. The ProGuard800 Siren has a tamper contact on the cover that sends a fault signal if the lid is even slightly ajar. Open the enclosure, check the cover's tamper tab is aligned with its contact point, close it firmly, and the fault should clear within a few seconds of the panel polling the zone.

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