BLOG: Power Perspectives

[#1]

When it comes to electric power generation, particularly in emergency and standby applications, it can be critical that power is uninterrupted. Many companies invest in UPS systems to prevent disruptions in electricity but rely on their generator set(s) to start and support their electrical loads, ensuring a constant supply of power during outages. Starting battery condition can be the difference between an efficient transition of power; and disastrous consequences from power loss, caused by the inability to start the engines.

The majority of generator failure-to-start problems are due to batteries in poor condition. Insufficient charges due to short run periods, or chemical deterioration over time leave batteries depleted and unable to start engines. Even with proper maintenance, as batteries age they will lose their ability to hold a proper charge and will need replacement to avoid starting issues.

Proper maintenance procedures and testing intervals will help ensure failure to start conditions due to poor battery quality, do not occur. Testing the output voltage of a starting battery is not enough to determine the capability of the battery when under load. In order to correctly assess starting battery conditions, a digital voltmeter, hydrometer, manual battery load tester or battery analyzer should be used to determine battery life.

Starting battery type will dictate the method of testing. If a sealed battery is being tested, a digital voltmeter and a manual load tester will determine battery condition. If the battery used requires maintenance, a temperature compensating hydrometer will test specific gravity and confirm the battery’s state of charge; but should still be load tested, along with verifying output voltage using a digital voltmeter. The alternative is a battery analyzer. It will confirm the condition of the battery as well as the state of charge; it is not dependent on the battery being charged before testing, and compensates for temperature.

Depending on generator charging system and features, starting battery life and condition may be monitored electronically; this however is no substitute for manual inspection and should not replace visual evaluation.

When inspecting and testing batteries:

• Always take proper safety precautions to avoid injury
• Inspect batteries for corrosion, abnormally warm temperatures and swelling
• Use baking soda and water solution to clean corrosion if present. Coating terminals in light silicon grease or petroleum jelly will slow corrosion buildup.
• When adding water to a battery, be sure not to overfill, and use distilled or demineralized water. Tap water will have an adverse effect because of its minerals and impurities.
• Test battery when fully charged. It is recommended that the surface charge be removed or the battery has set for an extended period (12 hours) before testing. (Does not apply to battery analyzer).
• When testing specific gravity, hydrometer readings should not vary more than .05 between cells.
• Always verify that the charging system is connected and working properly.

Too often starting battery maintenance and testing are neglected procedures which can lead to battery failure. The most common service calls for generators are failure to start due to battery failure. With so much riding on the ability of your investment to start and maintain your electrical loads, why take a chance with improperly maintained starting batteries?

A few things to consider:

• Are proper maintenance procedures in place to monitor battery condition on a consistent basis?
• Are the proper tools readily accessible to monitor and test battery condition?
• When replacing batteries, are replacements of equal size and rating, recommended by the manufacturer being used?
• When inspecting batteries, are other components of the starting and charging system being inspected to ensure there are no breaks in wire/ cable insulation or loose connections?

With proper maintenance procedures in place, combined with the appropriate diagnostic equipment; failure to starts issues due to poor battery condition can easily be avoided. Due diligence is a must when there is so much relying an efficient transition of power.

Share your battery maintenance thoughts, tips, and experiences by posting below.

[#2]

We had a similar experience in one of our projects where the client requested NiCd batteries for generator startup. They made a mistake by filling the batteries way before the generator commissioning and stored it on that condition. The batteries were left unmentained fr a few months. When we tried to start the generator during commissioning, the batteries failed and could not start the generator at all. We had to re-cycle the batteries by charging and discharging them a few times in order to revive them.

It is good to share the data about how to maintain the batteries because as you said, this might be the difference between powering the emergency loads or having a total blackout.

[#3]

As a CAT Dealer Product Support Rep, I have my customers on a 36 month cycle to replace batteries.  During annual service, we do check the batteries, but by being proactive, we can avoid those no start conditions, which usually fall on a Saturday night, or a holiday!

[#4]

Batteries can be very dangerous and it's important to have proper training in dealing with them to avoid personal injury.

[#5]

Nice info, but while your focus was on the batteries, the entire starting and charging system needs to be properly designed, installed and maintained, the best battery in the world will still not meet expectations if the entire system is not good.

First thing, make sure the right type battery is being used as a cranking battery, and the battery system is of the correct size, funny how many times this is wrong.

Batteries are temperature sensitive. High temperatures shorten life, batteries installed right next to generator discharge air outlets can suffer premature failure, or from radiated heat from the engine. Batteries that get too cold can't deliver needed cold cranking amps, and if the battery starts to freeze, it can lead to a battery explosion. Depending on your area and application you may need battery heaters.

BATTERIES ARE NOT STEP LADDERS!, I don't know how many times over the years I have been called out to a site because during the service before a technician used the battery as a step stool, and either damaged the caps, cable connectors or the wiring from the charger ( I will pick on this one more later).

Batteries should be properly protected and enclosed, and the surrounding area protected from potential acid spills. Frankly I thing CAT is way overdue for getting rid of the standard battery rack it supplies, time to provide a better battery box offering.

Batteries should be covered or protected from objects falling on them, ever seen a 9/16's wrench hit the terminals just right? 

Batteries need to be installed someplace that allows for regular and safe access/service. One dealer I know claimed that battery service was one of the biggest contributors to technician back injuries. Think about upsizing the cables and moving them to a place that they will be taken care as needed and maybe even live a better life.

Virtually all battery system in use in standby applications have AC powered battery chargers, or at least they should have.  Is the battery charger properly installed?  Was the float and equalize levels adjusted after installation? Is the charger the correct type for the batteries being used? How is the charger output connected to the batteries?  One of the most common problems I see is charger output leads connected directly to the batteries that have failed due to corrosion or fatigue, and recently this was the root cause of a battery fire at one facility. The wires should be connected to the starter terminals or a proper location on the engines electrical system.

Battery cables, they too have a service life limitation and many times I see brand new batteries sitting next to an engine that still doesn't start.  The connections need to be properly made, use the right connectors and the right installation tooling, improper connections can add significant voltage drop to a starting system.

Battery disconnect switches can also add to overall voltage drop and should also be inspected and checked regularly. If they are installed they should work right, if not take them off.

Think outside the box to improve overall starting system reliability. Maybe the customer has a fleet of vehicles that emergency generator starting batteries can be rolled into after a year or two on the gensets?

Ultimately the serviceing dealer or maintenance contractor is selling reliability, that the emergency generator will start when it needs to and keep running for a s long as it needs to.  Too many times I see nearly new batteries on a genset that failed to start, and usually for a simple or stupid reason.

My two cents worth, Mike L.