--- product_id: 543396952 title: "5 pcs 18650 Lithium Li-ion Battery Charger Board 3.7V 4.2V to 5V/9V 1A DC-DC Step Up Boost Module Adjustable charge and discharge + 5 pcs 18650 battery box" brand: "youmile" price: "€ 17.62" currency: EUR in_stock: true reviews_count: 3 category: "Youmile" url: https://www.desertcart.hr/products/543396952-5-pcs-18650-lithium-li-ion-battery-charger-board-3 store_origin: HR region: Croatia --- # Adjustable 3.7V–5V/9V output boost Simultaneous charge & discharge at 1A 5x 18650 Li-ion batteries included 5 pcs 18650 Lithium Li-ion Battery Charger Board 3.7V 4.2V to 5V/9V 1A DC-DC Step Up Boost Module Adjustable charge and discharge + 5 pcs 18650 battery box **Brand:** youmile **Price:** € 17.62 **Availability:** ✅ In Stock ## Summary > 🔋 Boost Your Power Game with Smart, Portable Energy! ## Quick Answers - **What is this?** 5 pcs 18650 Lithium Li-ion Battery Charger Board 3.7V 4.2V to 5V/9V 1A DC-DC Step Up Boost Module Adjustable charge and discharge + 5 pcs 18650 battery box by youmile - **How much does it cost?** € 17.62 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.hr](https://www.desertcart.hr/products/543396952-5-pcs-18650-lithium-li-ion-battery-charger-board-3) ## Best For - youmile enthusiasts ## Why This Product - Trusted youmile brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Smart LED Indicators:** Stay informed with intuitive red/blue LEDs showing charging and standby status at a glance. - • **Dual Input Convenience:** Supports USB Type-C or solder joint input for flexible charging options. - • **Customizable Voltage Output:** Easily switch between 5V and 9V outputs to match your device needs with precision. - • **Safe Parallel Battery Setup:** Designed for parallel connection only, ensuring stable and reliable power delivery. - • **Power Your Projects Anywhere:** Compact 5-pack 18650 batteries with a versatile boost module for on-the-go energy. ## Overview This 5-piece 18650 Lithium-ion battery kit includes a DC-DC step-up boost module capable of adjustable 3.7V to 5V/9V output at 1A, supporting simultaneous charging and discharging. Featuring dual input options (Type-C and solder joint), smart LED charge indicators, and a battery box, it’s ideal for DIY electronics, mobile power supplies, and portable device charging. ## Description Product DescriptionFeatures:Support type-c interface input and solder joint input0V activation, 2.9V trickle charge.Up to 1A programmable linear charging current.For single cell 3.7V Li-ion battery, full 4.2V.Constant current/constant voltage charging with over temperature protection.Soft start to limit inrush current with battery reverse connection protection.Low power standby to extend battery life.Charging status dual output, no battery and fault status display.With charging indicator.Working temperature: -40~80 ℃.Input voltage range: 4.2V~6.5V.Output voltage: 4.2V-28V adjustable.Maximum power: 5W.How to connect the battery:1.The battery is connected to B+ and B-, the module is protected, so there is no need to short the T point, otherwise the discharge protection will fail.2.After connecting the line you can use a screwdriver to adjust the output voltage you want.3.Battery selection 3.7V lithium battery, full voltage of 4.2V, battery type can be 18650, polymer and other batteries.4.Batteries can only be connected in parallel, not in series.Package Includes:5 x 18650 Lithium Li-ion Battery Charger Board5 x 18650 Battery box Review: Great for any 3.7v battery applications. - Very useful little chip. -: If you battery already has protection circuitry make sure to solder the two pads on the back together to bypass this chips protection circuitry... Review: So far everything works (not true of some of the Youmile stuff). - Voltage adjustment work and the charging is also OK. ## Features - 【What it does】:The 18650 Lithium Li-ion Battery Charger Board can be used as a mobile power supply to power lithium-ion battery devices, adjustable output voltage.Can charge and discharge at the same time, the maximum current is 1A. - 【Output and input】: The module supports type-c interface input and behind the labeled input solder joint input, choose one of them can, the recommended voltage of about 5V.Module marked with two outputs these two outputs are the same. - 【Charging indicator】: Module can roughly judge the working status by two LEDs and other states, CHRG is red light, STDBY is blue light;Battery charging state red light is bright, blue light is not bright,full bright blue light, red light is slightly bright. - 【Note】: The batteries can only be connected in parallel, not in series;the batteries cannot be reversed;the random voltage of this module needs to be checked with a multimeter. - 【Application range】: It can be used for DIY multimeter, mobile power supply, PCB power protection board, mobile phone charging. ## Technical Specifications | Specification | Value | |---------------|-------| | Manufacturer | Youmile | | Part number | JK-YM-648 | | Item Weight | 50 g | | Package Dimensions | 16.5 x 8.7 x 2.5 cm; 50 g | | Item model number | JK-YM-648 | | Batteries included? | No | | Batteries Required? | No | ## Images ![5 pcs 18650 Lithium Li-ion Battery Charger Board 3.7V 4.2V to 5V/9V 1A DC-DC Step Up Boost Module Adjustable charge and discharge + 5 pcs 18650 battery box - Image 1](https://m.media-amazon.com/images/I/71o7eu0RrAL.jpg) ## Customer Reviews ### ⭐⭐⭐⭐⭐ Great for any 3.7v battery applications. *by S***U on 11 August 2025* Very useful little chip. -: If you battery already has protection circuitry make sure to solder the two pads on the back together to bypass this chips protection circuitry... ### ⭐⭐⭐⭐⭐ So far everything works (not true of some of the Youmile stuff). *by D***. on 21 May 2024* Voltage adjustment work and the charging is also OK. ### ⭐ Zero consistency *by J***S on 6 May 2025* All 5 turned out to be rubbish 3 out of 5 didn't work out the packed absolute rip off ## Frequently Bought Together - Youmile 5 pcs 18650 Lithium Li-ion Battery Charger Board 3.7V 4.2V to 5V/9V 1A DC-DC Step Up Boost Module Adjustable charge and discharge + 5 pcs 18650 battery box - EEMB Lithium Polymer battery 3.7V 2000mAh 103454 Lipo Rechargeable Battery Pack with wire JST Connector for Bluetooth Speaker and Dashcam-confirm device & connector polarity before purchase - Youmile 5 Pcs 4.3V-27V Charging Discharge Module Adjustable Step Up Module+18650 Battery Holder with Red and black lines for 18650 Lithium Battery Fast Charging Boost Mobile Power Protection PCB Board --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.hr/products/543396952-5-pcs-18650-lithium-li-ion-battery-charger-board-3](https://www.desertcart.hr/products/543396952-5-pcs-18650-lithium-li-ion-battery-charger-board-3) --- *Product available on Desertcart Croatia* *Store origin: HR* *Last updated: 2026-04-23*