How to Balance Batteries in Series – Charge Each Battery Individually for Greater Performance & Lifespan
Linking 12 Volt batteries in series is an easy way to create higher voltage 24V, 36V and 48V battery systems. Before linking batteries in series however it is helpful to first charge each battery individually. This is called balancing batteries in series, also known as voltage matching.
Balancing batteries in series has two big benefits:
- The total capacity of the system will be higher. This means more runtime for your golf cart, trolling motor, solar battery bank, or whatever you are powering.
- The lifespan of each battery will be longer since the stress of running to empty is evening shared by all batteries instead of a single battery.
Dakota Lithium Iron Phosphate (LiFePO4) batteries have a very long lifespan (typically 5 – 15 years, backed up by an 11 year warranty), and twice the usable power of traditional batteries. To ensure you are getting the maximum performance and lifespan we recommend all customers balance their batteries before linking them in series.
Here’s directions on how you can balance your batteries in series:
- Use a 12V Dakota Lithium or LiFePO4 compatible charger to charge each battery individually (all Dakota Lithium batteries 50Ah and larger come with a free 12V 10Amp LiFePO4 charger). The LED light on the battery will be red when charging and will turn green when the battery is fully charged. You only need to do this once before you set up your system. In the future you can charge the entire system with the higher voltage charger.
- Once all batteries are fully charged you can install them in series to create a higher voltage system (24V, 36V, 48V, etc.). The batteries in the system are now balanced.
- When charging in the future it may be more convenient to use a higher voltage Dakota Lithium or LiFePO4 compatible charger to charge the entire set when linked (for example, a 36V battery set can be charged with a 36V LiFePO4 battery charger).
- Do NOT use a 24V, 36V, or 48V charger to charge a single 12V battery pack. The higher voltage charger is only for charging the full set / series system at a high voltage. It is too much power for charging a single 12V battery pack.
Performance impact / benefit of balancing lithium batteries in series:
- Increases the run time of what you are powering by 10 – 20%
- Increases the lifespan of the batteries by 1 to 3 years depending on use.
Engineering explanation (why balancing batteries in series helps improve performance)
- Federal DOT shipping regulations require that Dakota Lithium batteries (and all lithium or LiFePO4 batteries) are shipped at a low state of charge (<20%). This means each battery arrives near empty and with a slightly different charge and slightly different voltage.
- Charging each 12V battery individually ensures that each battery is full and at the same voltage before the batteries are linked in series. This is called “matching the voltage / voltage matching”, or “balancing the batteries” and increases the total runtime and lifespan.
- If the batteries are linked in series when near empty and then charged with a higher voltage charger the battery charger will read the system as “full” once one of the batteries in the set is fully charged, even if one or two other batteries in the set are only 75% full.
- If one of the batteries in the system is at 75% capacity the system will only perform with 75% of capacity, even if the other batteries are at 100%.
- If one of the batteries in the system is at 75% capacity the system while the others are at 100% then every time the system runs to empty the single battery will be discharged to zero, and experience higher stress, resulting in a shorter lifespan.
- By charging each battery individually before linking in series to create a higher voltage system you have made sure that all batteries are 100% full and that your system is performing at its best.
When should I balance my batteries in series in the future?
- Balance your batteries after long periods of storage (>3 months), or if you see a significant performance drop.
- Balancing your batteries once a year will extend the battery lifespan.
How do I link batteries in series or parallel?