how to install LFP start stop battery replacing lead acid battery in car correctly?

Nowadays, many auto garages & car owners start to replace lead-acid start-stop Batteries In Cars with lithium batteries. There are several important precautions during the operation, including:

1. Keep the car powered on as for some cars, power-off replacement may result in the reset of the vehicle's computer data.

2. Not all cars are suitable for using lithium-ion car start-stop batteries. Before installing the new lithium battery on the vehicle, it is necessary to use a diagnostic tool to check if the generator system is abnormal or if the battery is compatible with the car's generator.

Hello! The two points you summarized are correct and directly address the key points of the transition from lead-acid batteries to lithium batteries. This indicates that you have done a thorough job.

Next, I will provide additional information and elaborate further, and list some other crucial points to form a more comprehensive replacement guide.

Regarding "keeping the vehicle powered on continuously":

This is completely correct. For modern vehicles, especially those with start-stop functionality, power loss can not only cause minor issues such as radio lock codes and window lift learning, but also lead to data loss or reset of critical modules like the engine control unit and transmission control unit, resulting in driving performance problems. Using an external backup power source (such as a device with OBD interface or cigarette lighter interface is even better) is an absolutely recommended professional operation.

Regarding "Vehicle Compatibility Check":

This is extremely crucial. The method you mentioned of using a diagnostic tool for testing is the best way for post-event verification. However, it is actually more important to make the selection beforehand.

The charging management system of modern vehicles is calibrated based on the charging and discharging characteristics (voltage curve, internal resistance, charging acceptance capability) of lead-acid batteries. The chemical properties of lithium batteries (usually LiFePO4) are completely different. Although many lithium batteries are equipped with a battery management system (BMS) to simulate the voltage characteristics of lead-acid batteries, not all vehicle alternators can perfectly match them.

Core risk: If the BMS is incompatible with the vehicle's energy management system, it may lead to the following issues:

Alternator overload: When the BMS cuts off charging to protect the battery, extremely high voltage spikes will be generated, which may damage the alternator or other on-board electronic devices.

Insufficient charging or overcharging: The vehicle cannot accurately determine the actual state of the lithium battery.

Start-stop function failure: If the system detects "battery anomaly", the start-stop function will be disabled.

Other important missing points and supplementary suggestions:

1. Select lithium batteries specifically designed for vehicle start-stop systems

Not all lithium batteries can be used: It is necessary to choose products that are clearly labeled as "car start-stop batteries" or "EFB/LiFePO4 Hybrid Replacement". The built-in BMS in these batteries is specifically designed to handle the large current shock during vehicle startup, the frequent charging and discharging cycles, and the charging characteristics of the alternator.

2. Confirm battery type: The mainstream type of car start stop lithium battery is LiFePO4. This is because it has high safety and long cycle life, making it more suitable for starting conditions compared to lithium-ion batteries with a lithium cobalt oxide composition.

3. Confirm cold start current (CCA): The CCA value of the new lithium battery should be at least equal to or higher than the nominal value of the original car's lead-acid battery. The CCA of lithium batteries is usually very high, which is often an advantage.

4. Precautions for Physical Installation

● Dimensions and Polarity: Ensure that the physical dimensions of the new lithium battery match those of the original vehicle battery compartment, and that the positive and negative terminals are in the same position.

● Fixed: Lithium batteries are usually much lighter than lead-acid batteries, but they must be securely fixed using clamps or brackets to prevent them from shaking during travel and to avoid damaging the terminals or the battery itself.

● High-temperature resistance: Although LiFePO4 batteries have good high-temperature resistance, it is still advisable to avoid directly installing them in high-temperature areas such as the engine compartment (if the original position is in the engine compartment, please choose batteries with high-temperature resistance specifications).

5. Programming and Registration (Crucial!)

This is the step that is most easily overlooked but is extremely important. Many new luxury brands or models with intelligent power management systems (such as BMW, Mercedes-Benz, Audi, Land Rover, and many new models of Volkswagen and Ford) must use a diagnostic computer after replacing the battery to:

● Battery Registration: Inform the driving computer that a new battery has been installed.

● Battery Coding: Inform the driving computer of the technical type (such as changing from AGM to lithium iron battery) and capacity of the new battery.

If not programmed correctly, the vehicle will manage the charging based on the aging state of the old lead-acid battery, which may result in insufficient charging for the new lithium battery or overcharging, significantly shortening the battery cycle life and potentially causing system errors.

6. Safety Precautions

Protecting the BMS: as the BMS of lithium batteries is its brain and guardian during installation and disassembly, short circuits must be strictly avoided (direct contact between the positive and negative poles will generate a huge spark, which is extremely dangerous).

Professional Installation:Given all the complexities mentioned above, unless you are an experienced car DIY enthusiast with the necessary diagnostic equipment, it is strongly recommended that the operation be carried out by a professional car repair garage with experience in lithium Battery Replacement.

Summary of Standard procedure for replacing lithium batteries

● Preparation: Verify whether your vehicle model is compatible with lithium batteries (refer to forums, consult battery manufacturers and 4S stores).

● Correct selection: Purchase LiFePO4 lithium batteries specifically designed for vehicle start-stop systems, CCA compliance, and with appropriate size.

● Required tools: Prepare an external backup power supply and a professional diagnostic instrument (such as ODIS, ISTA, X-431, etc.).

● Safe disassembly: Connect the external power supply. First remove the negative terminal, then the positive terminal, and finally remove the old battery.

● Standard installation: Securely install the new battery. Connect the positive terminal first, then the negative terminal. Ensure that the terminals are firmly fastened.

● Computer operation: Use the diagnostic tool to register and code the battery (if the vehicle system requires it).

● Function verification: Start the engine, use the diagnostic tool to read the data streams such as the generator voltage and battery status, and ensure there are no abnormal fault codes. Test whether the start-stop function, air conditioning, headlights and other electrical devices are working properly.

● Road test and notification: Conduct a short road test and inform the owner of the initial usage precautions for the new battery (if any).

We hope the above information will help you select the appropriate start-stop lithium battery correctly, and also assist you in replacing and installing the original lead-acid battery in your vehicle properly. If you have any questions, please feel free to contact us by email. Thank you.