Welding lithium-ion cells 21700 into a package
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Welding of 21700 Lithium-Ion Cells – Custom Battery Packs
We offer professional spot welding of 21700 lithium-ion cells into ready-to-use battery packs tailored to individual needs. We create batteries with specific voltage, capacity, and maximum discharge current — בהתאם to the requirements of a particular device.
All packs are built exclusively using our tested cells, ensuring safety, durability, and stable performance.
We use professional spot welders in the production process — we do not solder the cells, which prevents overheating and extends their lifespan.
Available cell options:
✔ Reclaimed cells – selected and tested for capacity and internal resistance
✔ Brand-new cells – high-quality, high-drain branded cells from reliable sources
This allows us to match the battery pack to your budget as well as performance and lifespan expectations.
If you need a custom 21700 battery pack, battery regeneration, or a project for a non-standard application — feel free to contact us.
How to Order a Battery Pack – 4 Simple Steps
1. CONTACT
Get in touch with our battery pack department to discuss the configuration (voltage, capacity, BMS, application).
📞 +48 33 50 00 105 wew. 4
📧 pakiety@nexun.pl
2. CELLS
Choose the cells for your pack:
- reclaimed cells (selected and tested)
- brand-new cells
3. CART
Add the selected cells along with the welding service to your cart to receive a ready-made pack in the desired configuration.
4. ASSEMBLY SERVICE
Add the assembly service to your cart if you want a fully finished battery (with BMS, wiring, connectors, and protections).
What We Can Do
✔ Battery packs in any series and parallel configuration (e.g. 3S, 4S, 10S, 13S, etc.)
✔ BMS installation (balancing and protection)
✔ Installation of wiring and connectors (XT60, XT90, DC, others)
✔ Insulation and protection of the battery pack
✔ Testing of the finished battery
✔ Execution of both custom and mass production projects
Applications We Build Batteries For
We manufacture 21700 battery packs for:
- Electric scooters
- Electric bicycles
- Electric skateboards
- Electric unicycles (EUC)
- Hoverboards
- Electric scooters (mopeds)
- Electric go-karts
- Electric cars
- Electric motorcycles
- Electric quads (ATVs)
- Car jump starters
- Drills and drivers
- Cordless grinders
- Battery-powered saws
- Impact wrenches
- Jigsaws
- Cordless vacuum cleaners
- Hedge trimmers
- Cordless lawn mowers
- Tactical flashlights
- Outdoor flashlights
- High-power headlamps
- Bicycle lights
- Camping lights
- Portable floodlights
- High-capacity power banks
- Power stations
- Home UPS systems
- Energy storage systems
- Off-grid solar systems
- Camper power banks
- Portable travel fridges
- Industrial drones
- RC models
- Mobile robots
- AGV platforms
- AGV carts
- Warehouse robots
- Mobile monitoring systems
- Portable measuring equipment
- Industrial terminals
- Custom electronic skateboards
- E-bike conversion battery packs
- Portable audio systems
- Heated clothing
- Heated footwear
- Military and tactical equipment
Cells are spot-welded into a custom battery pack according to the customer’s specifications. Due to the custom nature of the order, this product is non-returnable and cannot be modified after welding.
A printable spacer template is available in the file below – use it to simulate the shape and dimensions of your battery pack. Note: print at a 1:1 scale. After printing, check whether both marked dimensions of 50 mm match reality. Otherwise, the template may have been printed at an incorrect scale and dimensions will not be accurate.
Download template – click here.
The actual usable capacity of a battery pack is always lower than its nominal capacity (the nominal capacity of the cells it contains). It is assumed that a finished battery will have approximately 10% lower real capacity than the theoretical nominal capacity. This is due to several factors, such as capacity drop under load and unused capacity reserved by the BMS (discharge cutoff at the minimum cell voltage, around 2.7 V), which helps extend battery lifespan.
If your BMS has a switching circuit (two white wires) and it is open (wires not connected), it must be connected (shorted) to activate the BMS.
Each cell and package in the nexun.pl online store is covered by a 24-month warranty for consumers and a 12-month warranty for companies.
The warranty covers:
- Cell damage
- Capacity decline (over 15% per year)
The warranty does not cover:
- Errors in assembly that do not comply with the manual or workmanship
- Improper maintenance
- Mechanical damage
- Changes in the product's operating characteristics depending on weather conditions (temperature)
- Water damage
To maximize battery life, use the following recommendations:
1. Fully charge the battery after each ride
2. Fully charge the battery every 3-4 weeks when you do not use it, e.g. winter break.
3. In the autumn and winter (temperature below +12*C), lithium-ion batteries have a lower capacity (by max. 30%) than in the summer, which results in a shorter range. This is normal. During this period, do not use the full powerf or the first 10-15 minutes of riding.