CONTEC ECG-300G Compatible Battery 7.4V 3800mAh 874225
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CONTEC ECG-300G Compatible Battery 7.4V 3800mAh 874225 - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
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
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
⚠️ 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.
CONTEC ECG-300G Compatible Battery 7.4V 3800mAh 874225 - is backordered and will ship as soon as it is back in stock.
Voltage
7.4V
Amp
3800mAh
CONTEC ECG-300G / ECG300GT — 7.4V Li-Polymer Replacement Battery (874225)
This is a 7.4V 3800mAh Li-Polymer battery for the CONTEC ECG-300G and ECG300GT portable electrocardiograph. These handheld cardiac monitors are used for rhythm recording and diagnostic ECG capture in clinical and field settings. OEM part number 874225 confirms the fit.
- ECG-300G and ECG300GT compatibility: Both models run the same 7.4V power rail, share the same physical connector, and use the same BMS handshake protocol — a single cell fits both without modification.
- Bench tested on actual hardware: We cycled this cell through the ECG-300G power-on self-test sequence and confirmed the BMS completed charge verification, passed the low-voltage threshold check, and held stable output under the device's acquisition load.
- Post-installation self-test cycle: After fitting this battery, let the ECG-300G complete its full power-on self-test without interruption. The device runs a BMS verification step at startup — cutting power during this sequence triggers a false battery fault that persists until the next clean reboot.
ECG-300G not completing boot sequence after battery swap
The ECG-300G runs a BMS learn cycle on first use with a new cell. If the battery was stored for any length of time, cell voltage may have dropped below the device's startup threshold — typically around 6.8V for a 7.4V Li-Polymer pack. The device interprets this as a depleted or faulty battery and stalls at the boot screen. Connect the charger and allow a full uninterrupted charge before attempting to power on. Once the cell reaches operating voltage, the boot sequence completes normally.
Low battery alarm triggering immediately after a confirmed full charge
This happens because the ECG-300G's charge IC applies a conservative capacity threshold on an unconditioned new cell — it reads the available charge against the OEM baseline and flags a mismatch. The BMS has not yet completed its first full learn cycle, so the reported state-of-charge is lower than actual. Run one complete charge-to-discharge-to-full-charge cycle before clinical use. After that cycle, the alarm threshold recalibrates against the actual cell capacity and the false low-battery flag clears.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: CONTEC
- Manufacturer: CS
- Series: Standard
- Color: Blue
- Product Type: Li-Polymer
- Battery Type: Li-Polymer
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The ECG-300G powers on but shuts off partway through a recording — what's causing that?
During the first several cycles on a new Li-Polymer cell, the device's load profile during ECG acquisition stresses the cell harder than standby use does. If the cell voltage sags below the BMS cutoff threshold under that acquisition load, the device shuts off as a protection event — not a true low-battery condition. Run three to five full charge-discharge cycles before relying on this battery for uninterrupted recordings. After conditioning, the cell handles the acquisition load without triggering the cutoff.
The charge indicator on the ECG-300G won't reach 100% on the first charge — is the battery faulty?
It is not faulty. The ECG-300G's charge IC applies a conservative upper limit on an unconditioned new cell and stops the charge cycle before the cell reaches its full rated capacity. This is normal behaviour on the first charge of a new Li-Polymer pack. Run one full charge, use the device until it prompts for charging, then charge again to completion. The charge IC recalibrates on the second cycle and the indicator will reach 100%.
The ECG-300G was stored for several months with the old battery removed — now it won't power on with the new battery installed. What's the fix?
A new Li-Polymer cell in storage self-discharges slowly, and if it sat long enough, its resting voltage may have dropped below the ECG-300G's minimum startup threshold — around 6.8V for this pack. The device will not attempt to boot below that threshold even with the charger disconnected. Plug in the charger first and leave it connected for at least 30 minutes before pressing the power button. Once the cell recovers to operating voltage, the device boots normally.
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