A brief discussion on the impact of Peukert’s law on batteries

In the process of using of batteries, have you found that when some batteries are used under high load, the battery life is much reduced than the theoretical value? If you happen to be using a lead-acid battery, then part of the reason for this is the so-called Proctor’s law. Next, let’s learn what Puckett’s law is and what its impact is on batteries?

What is Puckett’s law?

Peukert’s law was proposed by German scientist Wilhelm Peukert in 1897. It states that the capacity of rechargeable lead-acid batteries changes at different discharge rates. As the discharge rate increases, the available capacity of the battery will decrease. According to the actual situation of the battery, it can be expressed by the following formula: t = H(C/IH) k , where H is the rated discharge time (h) , C is the rated capacity at the discharge rate (Ah), and I is the actual discharge current (A), k is Peukert’s constant value and t is the actual time (h) of battery discharge.

The constant value k changes with the battery life and usually increases as the battery life increases. For lead-acid batteries, the constant value k is usually between 1.1 and 1.3.

Next, let‘s calculate the actual discharge time of the lead-acid battery through the above formula. there is a lead- acid battery with a rated current of 100Ah and a discharge of 20h, the constant value k is 1.2, and the battery is discharged at a current of 10A. Then it How long does it take to fully discharge? From the above formula, it can be calculated that it will take approximately 8.7 hours, which is less than the theoretical 10 hours.

The influence of Puckett’s law on lead-acid batteries

It can be seen from the above that under high load conditions, the higher the load, the less available energy the lead-acid battery can provide. This is why lead-acid batteries last less than theoretical time under load. This is mainly due to the chemical properties of lead-acid batteries.

The influence of Puckett’s law on lithium iron phosphate batteries

Compared with lead-acid batteries, lithium iron phosphate batteries are hardly affected by Puckett’s law. This is mainly due to the difference in the chemical properties of the two batteries. Therefore, lithium iron phosphate batteries have also become an effective alternative to previous traditional lead-acid batteries. Because lithium iron phosphate batteries are only slightly affected by Puckett’s law, they can release all of their stored energy and maximize battery performance.