Why are lithium batteries connected in series?

Lithium batteries are connected in series when the goal is to increase the nominal voltage rating of one individual lithium battery - by connecting it in series strings with at least one more of the same type and specification - to meet the nominal operating voltage of the system the batteries are being installed to support.

Can you mix different capacity lithium batteries?

Yes, you can mix different capacity lithium batteries, whether a normal 12V 100Ah battery or a Lithium server rack battery. You can combine different capacity batteries in parallel. You cannot combine different capacity batteries in series. There are a few points you need to consider when wiring in parallel. Let’s explore these three points.

When should a lithium battery be connected in series?

You should connect lithium batteries in series when your device requires a higher voltage than a single battery can provide. For example, if your device operates at 7.4V, connecting two 3.7V batteries in series would be appropriate. This setup is commonly used in applications like electric scooters, drones, or other high-voltage devices.

Can lithium ion be combined with LiFePO4?

It is not possible to combine lithium-ion with LiFePO4. This is because lithium-ion has a slightly higher voltage than LiFePO4. The batteries get charged all at the same time. A smaller battery will be at the same voltage as a larger battery. Therefore, the state of charge will be equal in all batteries.

What if a battery pack has a low voltage?

If a lithium battery pack in your system has a low voltage, you must turn off power to the load. There is no alternative. @WhatRoughBeast Checking the low voltage limit wouldn't solve the reverse-biasing issue, would it?

What are the pros and cons of connecting batteries in series?

Connecting Batteries in Series Cons: No Increase in Capacity: While the voltage increases, the total capacity remains the same as a single battery. This may limit run time. Imbalance Risk: If one battery in the series is weaker or fails, it can affect the whole series, reducing performance or causing failure.