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

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

Coolpad Legacy CPLD-428 Replacement Battery 3.85V 3900mAh

Up to 21% off
New arrival
From $26.99 USD $33.99
Shipping calculated at checkout.
Fits Coolpad Legacy CP3705AS models and replaces OEM battery CPLD-428.
3.85V 3900mAh Li-Polymer cell delivers sustained voltage under modem and screen load without voltage cliff.
Connector seats into the Legacy battery slot with positive terminal orientation toward the device frame.
We ran this cell through five full charge cycles on a Legacy test unit; BMS accepted the new cell without fault codes or early cutoff.
On first use, disable fast charging for one complete discharge-charge cycle to let the fuel gauge IC recalibrate against the new cell discharge curve.
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

3.85V

Amp

3900mAh

Coolpad Legacy / CP3705AS — 3.85V Li-Polymer Replacement Battery (CPLD-428)

This is a 3900mAh Li-Polymer cell at 3.85V, built to fit the Coolpad Legacy (CP3705AS). It replaces the original CPLD-428 when the factory cell has degraded through repeated charge cycles. Voltage and capacity match the original spec: 3.85V, 3900mAh, 15.02Wh.

  • Legacy / CP3705AS platform fit: Both model variants share the same battery bay dimensions (88.24 × 66.30 × 4.25mm), connector pinout, and BMS handshake — so a single CPLD-428 cell covers the full Legacy lineup without modification.
  • Bench tested on actual hardware: We ran this cell through charge and load cycles on a CP3705AS unit. The BMS accepted charge current without tripping, voltage held steady under screen-on and modem load, and cutoff triggered cleanly at low-cell threshold.
  • Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell — preventing erratic percentage readings early on.

Why the Coolpad Legacy reports wrong battery percentage after a cell swap

The Legacy uses a coulomb-counter fuel gauge IC that builds its charge model against the original cell's capacity and internal resistance profile. When you fit a new cell, the IC is still running the old model. Until it completes a full discharge-charge cycle, the percentage display can read high or low by 10–20%. One full cycle — discharge to automatic shutdown, charge to 100% without interruption — resets the learned curve and brings the readout back in line.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC hasn't yet mapped the new cell's voltage cliff — the point where cell voltage drops sharply under modem or display load. The phone thinks it has charge left, but the cell voltage collapses below the BMS cutoff threshold under real load. The fix is the same full recalibration cycle: let the phone discharge to shutdown naturally, then charge uninterrupted to 100%. After one cycle the IC learns where the actual voltage floor sits and shuts down at the correct percentage.

Compatible Models

Legacy CP3705AS

Replaces Part Numbers

CPLD-428

Technical Specifications

Voltage3.85V
Amp Hours3900mAh
Capacity3900mAh
Rate15.02Wh
Net Weight57g /2.01 oz
Gross Weight107g /3.77 oz
Approximate Weight107g /3.77 oz
Dimension 88.24 x 66.30 x 4.25mm

Product Highlights

  • Brand: Coolpad
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Li-Polymer
  • Battery Type: Li-Polymer
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

Fast charging stopped working after I swapped the battery in my Coolpad Legacy — is the charger the issue?

The charger likely isn't the problem. On first cycle after a cell swap, the BMS on the new cell may not yet complete the USB-PD or proprietary protocol handshake required to unlock fast charge current. Plug in with fast charging enabled and let the first full charge complete without interrupting it. Fast charge typically activates normally from the second cycle onward once the BMS and charge IC have completed the initial negotiation.

My Coolpad Legacy gets noticeably warm near the battery area during the first few charges — should I be concerned?

Some warmth on the first one or two charges is expected. A new Li-Polymer cell has slightly higher internal impedance than a broken-in cell, so the charge IC dissipates more energy as heat while current flows into it. Warmth should reduce noticeably by the third charge cycle as impedance settles. If the phone becomes hot to the touch or charge stops and restarts repeatedly after the third cycle, check that the charge port and cable are clean and making full contact.

My Coolpad Legacy won't power on at all after the replacement battery sat in a drawer for a few months — what do I do?

Extended storage can drain a Li-Polymer cell below 2.5V per cell, triggering BMS lockout to prevent damage. Connect the phone to a wall charger — not a USB port — and leave it for 30–45 minutes without pressing the power button. Most BMS circuits require a minimum trickle charge before they release the lockout and allow a normal boot. If the charging indicator doesn't appear after an hour, try a different cable and adapter to confirm the current is actually reaching the cell.

Payment & Security

Payment methods

  • American Express
  • Apple Pay
  • Bancontact
  • 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

Coolpad Legacy Replacement Battery, 3.85V, 3900mAh, Li-Polymer 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