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Kirisun PT-3300 Replacement Battery 7.4V 1200mAh KB-33L

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From $32.99 USD $40.99
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Fits Kirisun PT-3300, PT-3500, PT-3800 radios and replaces OEM part KB-33L.
Delivers 7.4V at 1200mAh capacity — adequate for full-shift portable operation on standard duty cycles.
Accepts standard Kirisun two-way radio connector with positive contact orientation and mechanical locking tab.
Bench testing showed clean BMS response on cold insertion; no overcurrent spike during PTT transmission events.
On first dock insertion, if the charger displays a fault LED, remove the battery and wipe the gold contact strip with a dry cloth before reinserting — the PT-3300 platform requires a clean contact cycle to accept the new BMS handshake.
Extended delivery time

Available by SPECIAL ORDER. Delivery for this product typically takes 2 weeks.

Extra Discount: As a thank you for your patience, enjoy an extra 5% off 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.

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.

Voltage

7.4V

Amp

1200mAh

Kirisun PT-3300 / PT-3500 / PT-3800 — 7.4V Li-ion Replacement Battery (KB-33L)

The KB-33L is a 7.4V, 1200mAh Li-ion battery for the Kirisun PT-3300, PT-3500, and PT-3800 portable two-way radios. It matches the original pack's voltage rail and connector footprint. Capacity is 1200mAh (8.88Wh), consistent with the factory specification for this platform.

  • PT-3300 / PT-3500 / PT-3800 platform fit: All three models run the same 7.4V dual-cell configuration with an identical contact layout and BMS handshake protocol. A single battery variant covers the full range without any modification.
  • Bench tested on actual hardware: We cycled this pack through transmit loads on the PT-3300 chassis. The BMS held stable across repeated PTT bursts and did not trigger overcurrent cutoff under normal push-to-talk draw.
  • First insertion contact check: 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 Kirisun dock requires a clean contact cycle to complete the BMS handshake before charging begins.

Why the PT-3300 cuts out mid-transmission on a freshly inserted KB-33L

New Li-ion cells ship at storage voltage — typically 3.6–3.7V per cell, placing the pack around 7.2V at rest. When PTT is pressed, transmit current spikes and the voltage momentarily dips below the BMS cutoff threshold. The radio interrupts transmission and may appear to restart. A full charge cycle before field use brings both cells to 4.2V each and eliminates this behaviour entirely.

Bar indicator showing one fewer bar than expected after fitting the KB-33L

The PT-3300 series uses a voltage-threshold bar indicator — it reads pack voltage directly and maps it to bar levels. A new pack at storage voltage reads lower than a fully charged pack, so the display shows one or two bars instead of a full stack. This is not a fault with the cell. Charge the battery fully in the dock until the LED turns green, then reinsert — the indicator will reflect the correct charge state at 8.4V.

Compatible Models

PT-3300 PT-3500 PT-3800

Replaces Part Numbers

KB-33L

Technical Specifications

Voltage7.4V
Amp Hours1200mAh
Capacity1200mAh
Rate8.88Wh
Net Weight72.5g /2.56 oz
Gross Weight142.5g /5.03 oz
Approximate Weight142.5g /5.03 oz
Dimension 83.75 x 53.15 x 28.00mm

Product Highlights

  • Brand: Kirisun
  • 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 PT-3300 cuts out every time I hold PTT for more than a few seconds — is the KB-33L faulty?

The pack is almost certainly at storage voltage, not faulty. New Li-ion cells ship around 3.6V per cell, and transmit current spikes can drag a low pack below the BMS cutoff threshold mid-transmission. Charge the battery fully before putting it on shift. Once both cells reach 4.2V each (8.4V combined), sustained PTT hold will not trigger cutoff under normal RF load.

The charger dock is blinking a fault LED and won't start charging — what's happening?

The Kirisun dock runs a contact-verification step before it accepts a new pack. If the gold contact strip has any residue or wasn't seated squarely, the handshake fails and the fault LED stays on. Remove the battery, wipe the contact strip with a dry cloth, and reseat the pack with firm downward pressure until it clicks. If the LED still doesn't clear, check that the dock contacts aren't bent or oxidised — clean them with a dry cotton swab and try again.

The KB-33L sat unused in a drawer for several months and now the dock won't charge it at all — is it recoverable?

Extended storage can drop Li-ion cells below the minimum acceptance voltage — around 2.5V per cell — at which point the BMS blocks charging to protect the cells. Some chargers with a trickle-recovery mode will re-initialise the pack by applying a low-current pulse until voltage climbs back above the acceptance threshold. If the Kirisun dock won't respond, try a universal Li-ion charger with a recovery or "wake" function set to 7.4V — if the pack recovers to 7.0V or above within 15 minutes, the BMS has reset and normal charging can proceed.

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