What is State of Charge (SoC) and what should I set as limits?

SoC (State of Charge), or charging level as it can be translated into Swedish, is exactly as it sounds—a concept that describes, in percentage, how charged your battery is. It is expressed as a percentage of the battery's total storage capacity. When the battery is fully charged, SOC = 100%, and when it is completely empty, SoC = 0%. In the System Configuration, you can set the SOC limits within which your battery should operate. However, it is important to consider that some batteries do not fare well when discharged to 0%, and some batteries may generate a lot of heat loss when charged to 100%. This depends on the chemical composition of the batteries, and generally, batteries based on some form of lithium technology should never be discharged to 0%.

By setting limits on the battery's SoC, the depth of discharge of the battery can be limited. The depth of discharge is expressed as a percentage of the battery's capacity and indicates how much of the battery is utilized. In most batteries, the depth of discharge is limited for various reasons. This could be to reduce losses, increase lifespan, or have margins for special events. Some of the limitations are set by the battery manufacturer, and others can be chosen by the customer.

For example, the upper limit can be lowered to reduce wear on the battery, and the lower limit can be raised to, for example, have a reserve for a future backup system. When configuring a battery, you can choose a lower and an upper limit for SoC.

Ferroamp currently has integrations with the following batteries with the following recommended limits:

Nilar - Recommended depth of discharge 0 - 80%

The battery can be used in the range 0-100%. However, at SoC above 80%, losses and self-discharge in the battery increase, contributing to heat.

Ferroamp Power Station - Recommended depth of discharge 10-100%

Pylontech Rack - Recommended depth of discharge 15-100%

Pylontech ESS - Recommended depth of discharge 15-100%

To easily set recommended SoC limits for your battery, we recommend using our Battery Wizard, which you can read more about here.

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