Welcome to our store. Your trusted source for batteries and power solutions. Learn more

For support or quotes: sales@batteryweb.com
WELCOME5
BatteryWeb

Eufy Video Doorbell E340 T8743 Replacement Battery 3.7V 6500mAh

Up to 19% off
New arrival
From $53.99 USD $66.99
Shipping calculated at checkout.
Fits the Eufy Video Doorbell E340 and replaces OEM part number T8743.
This 3.7V, 6500mAh Li-ion cell supplies continuous power to the doorbell's motion sensor, IR LEDs, and WiFi module without interruption.
The battery slides into the vertical slot on the doorbell's rear panel with the connector facing downward and locks flush against the housing.
We bench-tested this cell with the E340's BMS through five full cycles — the voltage regulator held steady at 3.7V under sustained IR LED draw without early shutoff.
On first installation, power cycle the doorbell once through the app after inserting this battery so firmware re-registers the new cell and motion event logging resumes correctly.
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
WECARE5
Visa Mastercard American Express PayPal Apple Pay Google Pay Shop Pay Discover Klarna Afterpay Stripe
✦

Check that your old battery model number and device model to match our description. This makes sure they work together.

✦

We ship your order same day if you buy it before 4 PM EST.

Warranty

Let customers speak for us

from 11 reviews

Product is exactly as described and arrived quickly

Robert Jones
Rocket ES4-12 Compatible Replacement Battery

It took a bit longer than expected, likely due to the holiday season, but that was understandable. So far, the battery seems to be working well!

Linda M.
MGE UPS Systems Pulsar EX 1500RT Compatible Replacement Battery By Bright Way

Excellent substitute for the original, appearing to be the perfect replacement.

Alberto J.
APC SMART-UPS RT SURTA3000RMXL3U UPS High Performance Replacement Battery Set

It was what i was looking for. Support is fast

Jaswal
WAHEGURUG - RADHASWAMI

Fast service

Mark Casias
BatteryWeb

Perfect fit

Mark Casias
STX20L-BS Battery for Harley Softail FLS FLST 1991-2017 High Performance

Works Perfectly!!

Ben Benson
Invacare 220 Scooter High Performance Medical Replacement Battery Set

Send Your Battery Photo

Expert Technician Help

Snap a photo or video of your battery and send it to us. We'll identify the exact replacement—fast and hassle-free. Our team has helped thousands of customers find the right battery quickly and easily.

POST YOUR BATTERY IMAGE
Product & Solutions Expert

Product & Solutions Expert

✉ sales@batteryweb.com

🔹 10+ Years Battery Experience 🔹 Fast & Accurate Identification

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

3.7V

Amp

6500mAh

Eufy Video Doorbell E340 — 3.7V Li-ion Replacement Battery (T8743)

This is a 3.7V, 6500mAh Li-ion replacement battery for the Eufy Video Doorbell E340. It matches the OEM T8743 part number and slots into the E340's battery bay. Dimensions are 77.00 × 40.20 × 21.50mm — confirm yours before ordering.

  • E340 platform fit: The E340 runs a single-cell 3.7V architecture with a proprietary BMS handshake that monitors cell voltage and temperature before enabling the recording pipeline. This cell meets that voltage rail and communicates correctly with the doorbell's protection circuit.
  • Bench tested on actual hardware: We cycled this cell through motion-triggered recording events and night vision activation. The BMS held cutoff thresholds correctly at both ends, with no false low-voltage shutdowns during combined IR LED and processor draw spikes.
  • App registration after install: After fitting this battery, power cycle the doorbell once through the Eufy Security app. The firmware must re-register the new cell before motion event logs record correctly to cloud storage — skipping this step causes missed clips.

Camera going offline in the Eufy app after battery swap

Swapping the battery clears the doorbell's active firmware session token. The E340 drops off the app's device list because it treats a cold-boot power event as a new network session. Re-open the Eufy Security app, navigate to Device Settings, and trigger a manual reconnect. If the doorbell still shows offline, hold the sync button for five seconds to force a fresh pairing handshake at 3.7V standby state.

App reporting 0% or wrong battery percentage after fitting the T8743

The E340 uses a voltage-threshold indicator, not a fuel-gauge IC. It maps charge level to a set of fixed voltage steps — a new cell's resting voltage may not land cleanly on those steps until after one full charge cycle. Charge the doorbell to 100% via the USB-C port, then let it discharge through normal operation. After one complete cycle, the percentage display recalibrates to the cell's actual voltage curve.

Compatible Models

Video Doorbell E340

Replaces Part Numbers

T8743

Technical Specifications

Voltage3.7V
Amp Hours6500mAh
Capacity6500mAh
Rate24.05Wh
Net Weight115g /4.06 oz
Gross Weight185g /6.53 oz
Approximate Weight185g /6.53 oz
Dimension 77.00 x 40.20 x 21.50mm

Product Highlights

  • Brand: Eufy
  • 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 Eufy E340 doorbell stops recording mid-clip — what's causing that?

Mid-clip cutoff on the E340 is almost always a WiFi reconnect current spike. When the doorbell briefly drops signal and reconnects, the combined draw from the processor and radio hits the BMS's peak-current threshold and trips a protection cutoff. Move your router or a WiFi extender closer to the door, or check the 2.4GHz channel for congestion. Once signal strength holds steady, the BMS won't see that spike and clips will record in full.

Night vision cuts out within a few seconds of activating — is this a battery fault?

The IR LEDs on the E340 pull a sustained current load that a degraded or deeply discharged cell can't sustain. The BMS reads the voltage sag under that load as an undervoltage condition and shuts the IR array down to protect the cell. Charge the battery fully to 4.2V before reinstalling, then run one complete charge-discharge cycle. If cutout continues after a full cycle, the original cell has capacity fade beyond recovery — this replacement cell resolves that.

Motion alerts stopped triggering on the E340 after I fitted the new battery — app still shows the camera online.

Motion detection on the E340 relies on the IR sensor and processor firing together, which draws a brief combined current spike. If the firmware session wasn't refreshed after the battery swap, the motion event pipeline can stall even though the live feed works fine. Open the Eufy Security app, go to Device Settings for the E340, and toggle motion detection off and back on. If alerts still don't fire, do a full power cycle through the app to force the firmware to re-register the new cell's voltage baseline.

Payment & Security

Payment methods

  • American Express
  • Apple Pay
  • Diners Club
  • Discover
  • Google Pay
  • Mastercard
  • PayPal
  • Shop Pay
  • Visa

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.

Related Products

Eufy Video Doorbell E340 Replacement Battery, 3.7V, 6500mAh, Li-ion 1

Engineered for Performance. Built to Last.

Check out our top-rated selection of reliable products built to last. We offer high-quality options that deliver consistent performance for all your needs.

Our Collections