---
product_id: 94826253
title: "3500mAh Rechargeable Replacement Battery for Harman Kardon Onyx Studio 1/2/3/4 Wireless Bluetooth Speaker, Real Capacity, Same Quality as Original Battery"
brand: "kratax"
price: "153 Lei"
currency: RON
in_stock: true
reviews_count: 8
category: "Kratax"
url: https://www.desertcart.ro/products/94826253-3500mah-rechargeable-replacement-battery-for-harman-kardon-onyx-studio-1
store_origin: RO
region: Romania
---

# 3500mAh high capacity Includes screwdriver & pry bar Built-in multi-layer safety 3500mAh Rechargeable Replacement Battery for Harman Kardon Onyx Studio 1/2/3/4 Wireless Bluetooth Speaker, Real Capacity, Same Quality as Original Battery

**Brand:** kratax
**Price:** 153 Lei
**Availability:** ✅ In Stock

## Summary

> 🔋 Upgrade your sound, not your wait — power that keeps pace with your hustle!

## Quick Answers

- **What is this?** 3500mAh Rechargeable Replacement Battery for Harman Kardon Onyx Studio 1/2/3/4 Wireless Bluetooth Speaker, Real Capacity, Same Quality as Original Battery by kratax
- **How much does it cost?** 153 Lei with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.ro](https://www.desertcart.ro/products/94826253-3500mah-rechargeable-replacement-battery-for-harman-kardon-onyx-studio-1)

## Best For

- kratax enthusiasts

## Why This Product

- Trusted kratax brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Vibration-Free Sound:** Cushioning sponge strip minimizes noise, preserving audio clarity
- • **Effortless DIY Upgrade:** Complete toolkit included for seamless, no-fuss replacement
- • **Power Through Your Day:** 35% more battery capacity than original for extended playtime
- • **Universal Compatibility:** Perfect fit for Harman Kardon Onyx Studio 1-4 models
- • **Certified Safety Assurance:** ISO9001, RoHS & CE certified with overcharge & short-circuit protection

## Overview

The Kratax 3500mAh rechargeable replacement battery delivers 35% more capacity than the original for Harman Kardon Onyx Studio 1-4 wireless speakers. It includes all necessary tools for easy installation and features cushioning to reduce vibration noise. Built with the same quality and safety certifications as the original, it ensures reliable, long-lasting performance and protection against overcharging, short circuits, and over-discharging.

## Description

desertcart.com: Kratax 3500mAh Rechargeable Replacement Battery for Harman Kardon Onyx Studio 1/2/3/4 Wireless Bluetooth Speaker, Real Capacity, Same Quality as Original Battery : Electronics

Review: Decent kit, flawed speaker charging needs addressed - Kit is ok, I've used 3 of them now in a Onyx 2 and two 4's. Battery is smaller than the OEM cell but regular 18650's can in theory have the advertised 3500 capacity. I haven't been using them long enough to verify, but they are basically drop-in, charging works as normal, and the speakers work as normal again. The problem is if you leave them plugged-in all the time, the Onyx is just going to kill the battery again over time because there's no good shut-off behavior for charging while plugged-in. This is what is killing the battery, and it'll just happen again. What I've done is wired a simple switch into the positive battery lead and mounted it in the bottom of the carry handle recess. Charge the battery up, flip this switch off, and now you can leave the speaker plugged-in all the time without killing the battery. If I'm going to use it on battery power, switch the battery back on, top it off if need be, and unplug and go. Self-discharge of the battery is slow with it unconnected like this. I'm not sure if this is really worth the effort because the battery life is short no matter what, but I didn't see the point of even bothering with replacing the battery knowing it would just get killed again. The 2/3/4 are really great speakers and short of this battery issue mine have all held up for many years with nothing really beating them for the size/performance. If you regularly run yours off the battery then it is definitely worth the effort.
Review: Wonderful price but even better is the product itself - Great product and price, exactly as described and easy to install

## Features

- High Capacity: 3500mAh Kratax replacement battery has 35% more capacity than the original battery, providing longer lasting performance for your speaker.
- Easy to Use: The package includes the necessary screwdriver and pry bar for battery replacement, which makes it easy to replace the battery. The included cushioning sponge strip is used to wrap the battery to prevent vibration noise when playing music. The sponge of connecting cables can better protect the wiring from damage.
- Hassle-free Purchase: Made with accessories that are equivalent to the original battery and built with the same battery construction for smoother use.
- Applicable models: Compatible with Harman Kardon Onyx Studio, Onyx Studio 2, Onyx Studio 3, Onyx Studio 4 wireless bluetooth speakers.
- Safety Protection: Built-in protection circuits to avoid overcharging, over-discharging, short-circuit protection and charging protection to ensure the safety of the battery and speakers. Passed ISO9001, RoHS and CE international certification.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B07GYXWVTM |
| Antenna Location | Suitable for Harman Kardon Onyx Studio speakers |
| Battery Capacity | 3500 Milliamp Hours |
| Battery Cell Composition | Lithium Ion |
| Battery Cell Type | Lithium Ion |
| Battery Weight | 29 Grams |
| Best Sellers Rank | #1,140 in Portable Bluetooth Speakers #8,020 in MP3 & MP4 Player Accessories |
| Brand | Kratax |
| Built-In Media | Screwdriver, pry bar and cushioning foam strips |
| Compatible Phone Models | Harman Kardon Onyx Studio, Onyx Studio 2, Onyx Studio 3, Onyx Studio 4 |
| Customer Reviews | 4.5 out of 5 stars 388 Reviews |
| Item Dimensions | 4 x 4 x 1 inches |
| Item Weight | 87 Grams |
| Manufacturer | Kratax |
| Model Number | for Harman Kardon Onyx Studio speaker |
| Number of Batteries | 1 Lithium Ion batteries required. (included) |
| Recommended Uses For Product | Suitable for Harman Kardon Onyx Studio speakers |
| Reusability | Rechargeable |
| UPC | 680727739331 |
| Unit Count | 1.0 Count |
| Voltage | 3.7 Volts |

## Product Details

- **Battery Capacity:** 3500 Milliamp Hours
- **Battery Cell Composition:** Lithium Ion
- **Brand:** Kratax
- **Number of Batteries:** 1 Lithium Ion batteries required. (included)
- **Recommended Uses For Product:** Suitable for Harman Kardon Onyx Studio speakers

## Images

![3500mAh Rechargeable Replacement Battery for Harman Kardon Onyx Studio 1/2/3/4 Wireless Bluetooth Speaker, Real Capacity, Same Quality as Original Battery - Image 1](https://m.media-amazon.com/images/I/71dhN9-JwyL.jpg)

## Questions & Answers

**Q: Has anyone been using this replacement battery for more than a year?  Is it holding up well?  Does it hold a charge well after a year or 2 of use?**
A: Don't worry! Until now, we have never received any complaints from customers about the performance of battery was deteriorated gradually after one year's use.

**Q: Will the charger for the 2600 work with the 3500?**
A: If the batteries are the same style(work for Harman/Kardon Onyx Studio or Onyx Studio 2), the charger can be used for 2600mAh battery or 3500mAh battery. 
Please feel free to contact us if have any future questions, thank you!

**Q: Would this work on a Studio 3?**
A: We have received responses saying that the battery can work on Studio 4. We can assure that it can work on Studio and Studio 2, but Studio 3 we cannot be 100% sure of the compatibility.

**Q: Is this the most powerful, longest lasting best battery available for the hk onyx studio 4 bluetooth speaker please?**
A: Sure, our battery uses the same material and craftsmanship as the original battery. As long as you carefully replace it according to the video on YouTube, you will get a new speaker. If you have any problems after purchase, you can also full refund or replace it at any time.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Decent kit, flawed speaker charging needs addressed
*by T***3 on March 25, 2024*

Kit is ok, I've used 3 of them now in a Onyx 2 and two 4's. Battery is smaller than the OEM cell but regular 18650's can in theory have the advertised 3500 capacity. I haven't been using them long enough to verify, but they are basically drop-in, charging works as normal, and the speakers work as normal again. The problem is if you leave them plugged-in all the time, the Onyx is just going to kill the battery again over time because there's no good shut-off behavior for charging while plugged-in. This is what is killing the battery, and it'll just happen again. What I've done is wired a simple switch into the positive battery lead and mounted it in the bottom of the carry handle recess. Charge the battery up, flip this switch off, and now you can leave the speaker plugged-in all the time without killing the battery. If I'm going to use it on battery power, switch the battery back on, top it off if need be, and unplug and go. Self-discharge of the battery is slow with it unconnected like this. I'm not sure if this is really worth the effort because the battery life is short no matter what, but I didn't see the point of even bothering with replacing the battery knowing it would just get killed again. The 2/3/4 are really great speakers and short of this battery issue mine have all held up for many years with nothing really beating them for the size/performance. If you regularly run yours off the battery then it is definitely worth the effort.

### ⭐⭐⭐⭐⭐ Wonderful price but even better is the product itself
*by C***K on January 10, 2026*

Great product and price, exactly as described and easy to install

### ⭐⭐⭐⭐⭐ Works like new
*by J***S on May 8, 2025*

Well made, foam isolated to keep rattles out. Fit perfectly as described. Just like it always was. Easy to install, good accessory tools. Battery life is something you don't appreciate til it's gone.

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*Product available on Desertcart Romania*
*Store origin: RO*
*Last updated: 2026-02-25*