TETRA SC20 Replacement Battery 7.4V 3300mAh Li-ion
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TETRA SC20 Replacement Battery 7.4V 3300mAh Li-ion - 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.
TETRA SC20 Replacement Battery 7.4V 3300mAh Li-ion - is backordered and will ship as soon as it is back in stock.
Voltage
7.4V
Amp
3300mAh
TETRA SC20 / STP9000 Series — 7.4V Li-ion Replacement Battery
This 7.4V, 3300mAh lithium-ion battery replaces the original pack in the TETRA SC20, STP9000, STP9040, STP9200, and compatible variants in the same platform family. It fits the same battery bay and connects to the same contact strip used across this TETRA TETRA series. Voltage and capacity match the OEM specification exactly.
- SC20 and STP9000-series platform fit: The SC20, STP9040, and STP9200 share the same battery form factor, contact layout, and BMS handshake protocol. One pack covers the full platform because the voltage rail and connector footprint are common across these TETRA models.
- Bench tested on actual hardware: We ran this pack in an SC20 dock and monitored the BMS initialisation cycle. The protection circuit accepted the charge current without tripping, and the radio recognised the pack and moved through all bar indicator states as expected under load.
- First insertion into the dock: If the charger dock shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The TETRA platform requires a clean contact cycle before the dock accepts the new BMS handshake and begins charging.
Why the SC20 cuts out mid-transmission on a new battery
During PTT, the SC20 draws a short, sharp current spike to power the RF output stage. If the BMS interprets that spike as an overcurrent event, it trips and disconnects the cell — dropping the transmission instantly. This is more common at storage voltage, where internal impedance is slightly elevated and the BMS threshold is easier to hit. The fix is to seat the pack in the dock and let it charge to at least 7.0V before first use, which lowers impedance and brings the spike within the BMS acceptance window.
Bar indicator showing one fewer bar than expected on a new pack
New cells ship at storage voltage — typically around 3.6–3.7V per cell, or roughly 7.2–7.4V for the pack. The SC20's voltage-threshold bar indicator reads that as one bar below full, which looks like a fault but is not. A full charge cycle brings the pack to approximately 8.4V, and the indicator will move to the correct level. Do not return the pack before completing one full charge from the dock.
Compatible Models
Technical Specifications
Product Highlights
- Brand: TETRA
- 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
My SC20 cuts out the moment I press PTT — is the new battery faulty?
This is a BMS overcurrent trip, not a dead cell. The transmit current spike on PTT briefly exceeds what the BMS allows at storage voltage, where cell impedance is slightly higher than normal. Charge the pack fully before first use — once it reaches 8.4V, impedance drops and the spike stays inside the BMS acceptance window. If it still cuts out after a full charge, check that the contact strip is clean and seated flat.
The dock LED has been blinking amber for two hours and never switches to green — what's wrong?
A new pack shipped at storage voltage can sit below the minimum voltage the dock will accept for a standard charge cycle. Remove the pack, wait 30 seconds, and reseat it firmly — the dock needs a clean contact cycle to re-read the BMS and restart the charge sequence. If the fault LED persists, wipe the gold contacts on both the pack and the dock with a dry cloth before reinserting. The pack should begin charging once the dock registers a voltage above its acceptance threshold.
The radio drops to noticeably weaker TX output after a few hours of heavy use — is the battery draining too fast?
This is voltage sag under sustained RF load, not early depletion. As the pack discharges, voltage drops under the continuous draw of repeated transmissions, and the SC20 automatically reduces TX power to stay within operating limits. It is normal behaviour tied to the cell's state of charge, not a fault with the pack. If the drop happens within the first hour of a fully charged pack, check that the contacts are clean and that the pack is fully seated — a partial connection raises contact resistance and accelerates sag.
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