Battery Basics and Myths

Batteries are a critical part of keeping your AMETEK Solidstate Controls’ systems running throughout a power outage, but there are a lot of myths surrounding them. We’re going to break down some battery basics and myths for you.

Let’s start with the basics of batteries:

1. Why use batteries?

   Batteries are used to store power while the power is good, so if there is an AC outage your critical loads can be shut down in a controlled manner or temporarily run off the battery.

2. What am I looking at when I look at batteries?

   A single container with battery cells in it is called a jar while multiple jars placed together form a battery string.

3. Some common batteries you may use in conjunction with our systems are lead acid, nickel-cadmium (NiCad) or even Lithium Iron Phosphate. There are two main types of lead acid batteries: 1. Vented Lead Acid (VLA) 2. Valve Regulated Lead Acid (VRLA)
4. Cells are always listed at nominal voltage; lead acid is 2.0 V per cell while NiCad is 1.2 V per cell. The batteries for industrial UPS systems typically contain 60 cells of lead acid (nominal string voltage of 120 VDC) and 96 cells NiCad (nominal voltage of 115.2 VDC).

What are some of the most common questions and myths we hear about batteries?

1. What can cause a ground fault on a battery?

   While it’s rare for there to be a ground fault on a battery, there are two possible things that can cause one: 1. Electrolyte tracking from a battery to the rack (cracked battery) 2. The insulation on a battery cable failing and the cable is touching the rack.

2. Should I fill new batteries before putting them on charge if the electrolyte level is at or below the low level?

   You should not add water or electrolytes to cells before the initial charge. The gases produced by charging will displace the electrolyte and raise it to an acceptable level between the high- and low-level marks on the container. If you need to make adjustments, do so only when the cells are fully charged and stabilized at the float voltage.

3. The worst thing I can do is overcharge my battery.

   This is a common myth, the worst thing you can do is actually undercharge the battery. Prolonged undercharging causes excessive sulphation of the plates, which will eventually lead to irreversible loss of capacity. Overcharging the battery can slightly increase corrosion and lead to loss of water in the battery. In a vented lead acid cell (wet cell), it is not a concern as the water can be topped off. In a VRLA battery, it can cause the electrolyte inside the cell to dry out, which will eventually lead to battery failure.

4. If a VLA cell has a crack in the jar and is leaking electrolyte, can just keep topping it off with distilled water?
   While normal water loss through charging is caused by the chemical process that changes the water back into hydrogen and oxygen and the gas is expelled, no acid is lost in the process. It is only water, so topping up with distilled water is not changing the specific gravity of the cell in this circumstance. When there is a leak, it causes loss of electrolyte solution that contains acid. If you keep topping off with water, the solution will get diluted and the specific gravity will go down. This will reduce the capacity of the battery. 

If you’re interested in seeing visual examples and learning more about battery basics and myths, click here to watch our webinar on the topic. If you’re interested in speaking with one of our team members about the batteries connected to your AMETEK Solidstate Controls’ systems, contact us.