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What You Need to Know About Depth of Discharge

Posted by Crown Battery on Nov 26, 2018 3:15:00 PM

Your battery's performance and life span can be affected by a number of factors. Following best practices for battery maintenance and avoiding bad habits can ensure a long and useful life for a battery. Battery DOD has a greater impact on a battery than you may think. Here's what you need to know about battery depth of discharge:

What is Depth of Discharge?

Depth of Discharge (DOD) refers to how much energy is cycled into and out of the battery on a given cycle. It's expressed as a percentage of the total capacity of the battery. For those new the industry, DOD sounds like it may be a difficult topic to understand, but  it's actually simple. For instance, a battery that has been drained 30% has a 30% DOD, and 70% of its capacity remains. But how does DOD affect your battery's performance? Keep reading to learn more.

Avoid Fully discharging your battery

The more frequently a battery is charged and discharged, the shorter its lifespan will be. Discharging a battery entirely, dramatically shortens the useful life of the battery. Which is why all batteries need extra power reserves for safety and near-empty batteries can’t provide enough. Some days, you’ll use more electricity, because of heavier loads, higher temperatures, etc. Or solar or wind systems won’t produce enough energy.

Keep batteries above 20% storage

When batteries have less than 20% storage remaining, you can run out of electricity. That could mean no power for HVAC loads, inadequate power for large appliances, even downtime for manufacturing and shipping operations.

High DOD can also shorten battery life

A high rate of battery discharge happens when a battery releases a high amount of energy in a given time. Some batteries do this as a result of quality deformation, while others are just designed this way. Deep discharging can drastically shorten battery life -- and that means you’ll pay for more for energy storage.

To good to be true dod rates

Beware of companies that promise 80% - 100% DOD rates . This isn’t just dangerous for your system’s performance and longevity —it’s also a common sales ploy to sell you an undersized system (and make the price, for less storage, seem less overpriced).

Protect yourself

Size batteries for no more than 50% DOD — and comparison shop based on that number. You need extra energy reserves, no matter which battery technology or company you select. Make sure you get the system you need and deserve.

What if my current system drops below 50% DOD often?

Installing an extra battery usually helps. Depending on your installation, a backup generator can also ensure you have power during extended deep discharging.

Tags: Battery Maintenance