What is the SOC and SOH of a battery? 


What is the SOC and SOH of a battery? 

Surely you have heard of these two terms in the world of lithium batteries for vehicles and do not know what they are. Don't worry, we are going to explain everything you need to know about SOC and SOH of a battery and how ARVIKON can control the batteries of your motorhome or camper.  

Both terms, SOC and SOH are two fundamental parameters related to the performance and lifetime of an electric vehicle battery. If you want to know more about batteries for motorhomes and camper vans, remember that we have a very complete article about it.

The first thing you should know is that SOC is the parameter that measures the state of charge of the battery and SOH is the parameter that measures the state of health of the battery. 

Therefore, and as you can imagine, both parameters are very important indicators, as they provide data necessary for the optimization of battery performance that is carried out through the Battery Management System (BMS).

Let's go a little deeper. BMS is the system that regulates battery operation. The main function of the BMS is to ensure that the battery does not operate outside the safety limits and that the battery is protected at all times. In other words, this system informs the user of the state of charge (SOC) and state of health (SOH) of the battery while also acting as a security against overcharging, undervoltage, charge and discharge current limits, cell equalization, etc.

The state of charge and the state of health are different parameters that can lead to confusion, so we will explain each of them in more detail.  


State of charge (SOC) 

The state of charge of a battery shows the difference between a fully charged battery and the same battery in use. In other words, it indicates the amount of available energy remaining in the cells. 

Easier. This is the ratio of the remaining battery charge divided by the maximum charge the battery can deliver. Therefore, this operation yields a value expressed as a percentage (usually). However, it can also be expressed the other way around, as depth of discharge (DOD), indicating the percentage of the total battery capacity that is used during a cycle. 

Health status (SOH) 

The health status indicates the difference between a battery in use and a brand new unused battery, this value takes into account the aging of the battery. 

The SOH takes into account the ratio between the maximum load of the battery and its rated capacity. The nominal capacity being the original capacity given by the manufacturer also expressed as a percentage. 

As the battery is used for longer periods of time, its SOH decreases, since at the beginning it is 100%. This percentage decreases and, therefore, the battery discharges faster. During the time of use the SOH gradually loses a percentage, however, when charging the battery, the SOC can still be at 100%. 

Conclusion SOC/SOH 

Although both are very complex algorithms, the important thing is what they mean: 

  • SOC - State Of Charge: tells us exactly how much percentage the battery has between 0 and 100% 
  • SOH - State Of Health: indicates the health of the battery by combining the SOC and the cycles. 
  • BMS is the component of our battery that measures and manages the battery health and makes the correct calculation of the autonomy with the updated SOH and SOC data. 

With ARVIKON you can have control over all the electrical installations and equipment of your motorhome, camper or caravan. Especially, and for the subject that concerns us today, ARVIKON controls, remotely from anywhere, the reading of voltage and currents of charge and discharge of the engine battery as well as the reading of voltage and currents of charge and discharge of the various of the housing. And of course, it manages the charging from the battery charger up to 400 A with the ARVISHUNT expansion. 

In the case of some battery models, for example, the batteries of the EPTechnologiesIn this way, the domotics will directly show you the SOC, SOH, cycles, failures, etc. of each of the installed batteries. Little by little we will be integrating more compatible batteries to the system. If you have a brand or manufacture a battery model and want to have full compatibility with our system, contact us.