Repacking a Nissan Leaf battery with your own hands: from theory to practice

Electric cars Nissan Leaf the first and second generations (2011–2017) became a cult favorite among enthusiasts due to their affordability and maintainability. However, over time, the capacity of their lithium-ion batteries inevitably drops - sometimes to critical levels. 30–40% of the original. Instead of buying a new battery for 150–250 thousand rubles many owners choose repacking: replacement of failed elements (“cans”) with new ones or used ones from other batteries. This process requires precision, knowledge of electrical engineering and compliance with safety regulations - but with the right approach it can save up to 70% cost.

In this article we will analyze the entire process from A to Z: how to diagnose the battery before repacking, what tools and materials will be needed, how to disassemble the module without damage, and most importantly, how to avoid typical mistakes that lead to fires or battery inoperability. We will pay special attention cell balancing and setting up the BMS (battery management system), without which even a perfectly assembled battery will not last long.

Why is repacking a Nissan Leaf battery better than buying a new one?

Cost of a new battery for Leaf 24–30 kWh from an authorized dealer starts from 200 thousand rubles, and for models with 40 kWh - from 350 thousand. Repackaging costs 3–5 times cheaper, if used:

• 🔋 New elements (For example, Li-ion 3.7V 33.1Ah from Lishen or CATL) - about 50–70 thousand rubles for a complete set.
• ♻️ Used cans from donor batteries (tested for capacity) - 15–30 thousand rubles.
• 🔧 Independent work - savings on service (20–50 thousand rubles).

In addition to financial benefits, repackaging provides several more advantages:

• ⚡ Possibility of upgrade: for example, replacing a 24 kWh battery with a 30 or 40 kWh battery by installing additional modules.
• 🔄 Extending service life on 3–5 years with proper balancing.
• 🌍 Environmental friendliness: Recycle only the faulty cells, not the entire battery.

⚠️ Attention: Repackaging will void the battery warranty (if it was still valid). Also not all service stations will agree to service a car with a homemade battery - take this into account when insuring or selling.

However, there are also pitfalls. For example, poor quality soldering or errors in balancing can lead to:

• 🔥 Overheating and fire (Lithium-ion batteries burn when 150–200°C).
• ⚡ Short circuit due to insulation damage.
• 🚗 BMS errors, which will block charging.

Battery diagnostics before repacking: what to check?

Before disassembling the battery, you need to accurately determine which elements are faulty and whether repacking is advisable. For this you will need:

• 📊 Leaf Spy Pro (mobile application + adapter ELM327 OBD-II) - shows the voltage on each cell, capacity (SOH) and temperature.
• 🔌 Multimeter up to 0.01V for manual measurements.
• 🔋 Load fork (optional) - checks the actual current output.

Diagnostic algorithm:

1. Connect Leaf Spy and record the voltages of all 96 cells (battery 24 kWh - 4 modules of 24 banks each). Scatter more 0.1V between adjacent elements speaks of imbalance.
2. Check SOH (State of Health) - if the value is lower 60%, repacking is justified.
3. Rate Hx (battery health) - at Hx < 50% capacity is critically low.
4. Measure the voltage at the battery terminals at rest (6-12 hours after charging). Norm: 3.8–4.0V on the jar.

Parameter	Normal value	Critical value	What does it mean?
SOH (State of Health)	80–100%	< 60%	The battery capacity is reduced and the elements need to be replaced.
Hx	80–110%	< 50%	Cell degradation, high internal resistance.
Voltage spread between banks	< 0.05V	> 0.1V	Imbalance, risk of overheating when charging.
Cell internal resistance	< 50 mOhm	> 100 mOhm	The element is worn out and does not hold a charge well.

If the battery contains voltage banks < 3.0V or > 4.2V, their cannot be used - they are either deeply discharged (and cannot be restored) or overcharged (risk of explosion!). Such elements are recycled.

Tools and materials for repacking

For self-repacking you will need specialized tool — without it, the risk of damaging the battery or getting injured is extremely high. Here's the full list:

Mandatory tool

• 🔧 Socket wrenches (10 mm, 12 mm) - for unscrewing the battery fasteners.
• 🔨 Plastic mounting blades - to avoid damaging the module housing.
• ⚡ Soldering iron 100–150W with temperature control (for busbar soldering).
• 🧲 High tin solder (For example, Sn60Pb40).
• 🛡️ Heat resistant gloves And safety glasses.
• 🔥 Class D fire extinguisher (for lithium batteries).

Replacement materials

• 🔋 New banks (For example, Li-ion 3.7V 33.1Ah from Lishen LR26650HP or Samsung INR26650-35E).
• 🔌 Nickel tape (0.15 mm × 8 mm) for connecting cans.
• 🧴 Thermal paste (For example, Arctic MX-4) for heat removal.
• 📦 Heat shrink tube (diameter 25–50 mm) for insulation.

You will also need workplace from:

• 🪑 Antistatic mat (to avoid static electricity discharges).
• 🔌 Grounding for tools.
• 📏 Smooth surface (table or workbench).

⚠️ Attention: Never use for soldering acid fluxes - they corrode contacts and can cause corrosion. Best option: rosin-based flux gel.

Step-by-step instructions: disassembling the Nissan Leaf battery

Disassembling the battery is the most critical step. Errors here can lead to irreversible damage or loss of warranty (if it was still in effect). Follow the instructions strictly step by step:

Step 1: Disconnecting the Battery from the Vehicle

Before starting work necessarily:

1. Turn off the ignition and remove the key.
2. Disconnect negative terminal 12V battery (under the hood).
3. Wait 10–15 minutes - this will discharge the high-voltage capacitors.
4. Disable service connector (orange plastic block on the battery).

Step 2: Removing the Battery

Battery in Nissan Leaf located under the rear seat. To extract it:

1. Remove the rear seat (pull up firmly).
2. Unscrew 4 bolts fastening the battery cover (10 mm socket wrench).
3. Disconnect high voltage connectors (label them first!).
4. Carefully remove the battery (weight ~200–250 kg — need an assistant or a winch).

Step 3: Disassembling the Modules

The battery consists of 4 modules (24 cans each). For disassembly:

1. Unscrew the bolts securing the modules to each other.
2. Remove the plastic covers by carefully prying them off with a spatula.
3. Unsolder nickel tires (connecting cans) with a soldering iron. Don't overheat - soldering temperature should not exceed 250°C.
4. Remove the cans, labeling them in order (e.g. Module 1 - Bank 1, Bank 2...).

When disassembling don't allow:

• 🔥 Short circuit between banks (use insulated tools).
• 💧 Moisture ingress — lithium-ion cells are afraid of corrosion.
• 🔨 Mechanical damage can bodies (risk of electrolyte leakage).

What to do if the jar is swollen?

Bloated cans (swollen body) cannot be used! They are needed:

• 🔋 Remove from the module using gloves (risk of electrolyte leakage).
• 🧊 Place in an airtight container with sand or salt (in case of fire).
• ♻️ Take it for recycling to a battery collection point.

Cause of bloating - gas formation due to overcharging or deep discharge. Such elements cannot be restored.

Replacing elements and soldering: key nuances

After disassembly, we proceed to replacing faulty cans. It's critical here:

• 🔄 Observe polarity - incorrect connection will lead to instantaneous short circuit.
• 🔥 Control soldering temperature - overheating is higher 250°C damages banks.
• ⚖️ Balance containers — new and old elements must be same type and similar capacity.

Selecting new cans

For Nissan Leaf The following element types are suitable:

Can model	Capacity	Voltage	Compatibility	Notes
Lishen LR26650HP	33.1Ah	3.7V	24/30 kWh	Original cans for Leaf, the best option.
Samsung INR26650-35E	35Ah	3.7V	24/30/40 kWh	Higher capacity, but requires balancing with BMS.
Panasonic NCR18650B	3.4Ah	3.7V	Only for upgrade	Smaller size, need to redo the fastenings.

If you use used cans, be sure to check them out:

• 📊 Capacity (tester ZKE Tech EBC-A20 or similar).
• 🔋 Internal resistance (should be < 50 mOhm).
• 🔍 Appearance - no swelling, corrosion or damage.

Soldering nickel busbars

To connect the cans use nickel tape thick 0.15 mm and width 8 mm. Soldering algorithm:

1. Clean the can contacts alcohol solution.
2. Apply flux gel to the soldering points.
3. Apply nickel tape and solder it, holding the soldering iron no longer 2–3 seconds.
4. Check connection integrity multimeter (resistance should be < 0.01 Ohm).

⚠️ Attention: After soldering do not close the module immediately - let cool for a while 10–15 minutes. Overheating may cause thermal runaway (uncontrolled heating).

Cell balancing and BMS setup

Even if all the banks are new, they voltages will be different. Without balancing this will lead to:

• ⚡ Rapid degradation the weakest elements.
• 🔋 Incorrect operation of BMS (battery management system).
• 🚗 Errors on the dashboard (For example, Check EV System).

Balancing methods

There are two main ways:

1. Passive balancing (discharge by resistors):
• 🔌Connect balancing board (For example, Ant BMS).
• 📉 Discharge the banks with the highest voltage to the level of the weakest.
2. Active balancing (energy redistribution):
• ⚡ Use active balancer (For example, Daly Smart BMS).
• 🔄 Energy flows from charged cans to discharged ones.

For Nissan Leaf the best option is passive balancing followed by BMS calibration. To do this:

1. Connect the battery to the charger.
2. Wait until fully charged (all banks should show 4.1–4.2V).
3. Discharge the battery until 20% (via Leaf Spy or trip).
4. Repeat the cycle 2-3 times - this will “teach” the BMS new parameters.

If after balancing there is an error on the dashboard EV System Warningmay be required BMS reset via a diagnostic scanner (for example, Consult III+ or Nissan DataScan). Reset command:

Battery Data Reset → Erase All DTCs

Battery assembly and testing

After replacing the elements and balancing, we proceed to reassembly. What's important here is:

• 🔧 Check all connections for a short circuit.
• 🧴 Apply thermal paste at the contact points for better heat dissipation.
• 📋 Keep a record voltages of cans before and after assembly.

Assembly order

1. Install the jars into the modules, observing original order.
2. Solder the nickel bars (check with a multimeter).
3. Close the modules with plastic covers and tighten the bolts.
4. Place the battery back into the car and connect the high-voltage connectors.
5. Connect service connector and a 12V battery.

First activation and testing

After assembly:

1. Turn on the ignition and check if it lights up READY on the dashboard.
2. Connect Leaf Spy and make sure that all banks show the same voltage (spread <0.05V).
3. Carry out a test charge to 100% and discharge to 20% - this will finally balance the battery.

⚠️ Attention: If after assembly the battery not charging or discharges quickly, check:

• 🔌 Solder quality - there may be a break.
• 📊 BMS Settings - error reset required.
• 🔋 Can capacity - one of them may be defective.

FAQ: Frequently asked questions about repacking the Nissan Leaf battery

❓ Is it possible to repack a Leaf battery without soldering?

Theoretically yes - instead of soldering you can use bolted connections with star washers. However, this is less reliable:

• 🔌 Resistance increases contacts.
• 🔥 Risk of loosening fasteners over time.

Soldering remains preferred method.

❓ How long will the battery last after repacking?

Service life depends on:

• 🔋 Qualities of elements (new Lishen or Samsung will last 5–7 years).
• ⚡ Operating mode (frequent fast charging reduces the resource).
• 🌡️ Temperature conditions (optimally: 10–25°C).

With proper balancing and a gentle driving mode, the repacked battery passes 80–100 thousand km.

❓ Is it possible to increase the battery capacity (for example, from 24 to 30 kWh)?

Yes, but for this you need:

1. Add 5th module (there are 4 of them in a 24 kWh battery, 5 in a 30 kWh battery).
2. Update BMS firmware (otherwise the system will not see the new module).
3. Reprogram ECU (diagnostic equipment required).

Without modification of software the car won't see increased capacity.

❓ What should I do if the “Check EV System” error appears after repacking?

Error Check EV System arises due to:

• 🔧 Bad contact in a high voltage circuit.
• 📊 Unbalanced cans (voltage difference > 0.1V).
• 🔋 BMS malfunctions (requires board reset or replacement).

Solution:

1. Check all connections with a multimeter.
2. Balance the cans.
3. Reset errors via Leaf Spy or Consult III+.

❓ Where to buy cans for repackaging?

Reliable sources:

• 🌍 AliExpress - shops Lishen Official Store or Battery Hookup.
• 🛒 Local suppliers (For example, Battery Technologies in Moscow).
• ♻️ Donor batteries - at showdowns or from owners of broken Leaf.

Average cost of a new can Lishen LR26650HP — 1,200–1,500 rub.