BU-104a: Comparing the Battery with other Power Sources

This article begins with the positive traits of the battery, and then moves into the limitations when compared with other power sources.

Energy storage

Batteries store energy well and for a considerable length of time. Primary batteries (non-rechargeable) hold more energy than secondary (rechargeable), and the self-discharge is lower. Alkaline cells are good for 10 years with minimal losses. Lead-, nickel- and lithium-based batteries need periodic recharges to compensate for lost power.

Specific energy (Capacity)

A battery may hold adequate energy for portable use, but this does not transfer equally well for large mobile and stationary systems. For example, a 100kg (220lb) battery produces about 10kWh of energy — an IC engine of the same weight generates 100kW.

Responsiveness

Batteries have a huge advantage over other power sources in being ready to deliver on short notice — think of the quick action of the camera flash! There is no warm-up, as is the case with the internal combustion (IC) engine; the power from the battery flows within a fraction of a second. In comparison, a jet engine takes several seconds to gain power, a fuel cell requires a few minutes, and the cold steam engine of a locomotive needs hours to build up steam.

Power bandwidth

Rechargeable batteries have a wide power bandwidth, a quality that is shared with the diesel engine. In comparison, the bandwidth of the fuel cell is narrow and works best within a specific load. Jet engines also have a limited power bandwidth. They have poor low-end torque and operate most efficiently at a defined revolution-per-minute (RPM).

Environment

The battery runs clean and stays reasonably cool. Sealed cells have no exhaust, are quiet and do not vibrate. This is in sharp contrast with the IC engine and larger fuel cells that require noisy compressors and cooling fans. The IC engine also needs air and exhausts toxic gases.

Efficiency

The battery is highly efficient. Below 70 percent charge, the charge efficiency is close to 100 percent and the discharge losses are only a few percent. In comparison, the energy efficiency of the fuel cell is 20 to 60 percent, and the thermal engines is 25 to 30 percent. (At optimal air intake speed and temperature, the GE90-115 on the Boeing 777 jetliner is 37 percent efficient.)

Installation

The sealed battery operates in any position and offers good shock and vibration tolerance. This benefit does not transfer to the flooded batteries that must be installed in the upright position. Most IC engines must also be positioned in the upright position and mounted on shock- absorbing dampers to reduce vibration. Thermal engines also need air and an exhaust.

Operating cost

Lithium- and nickel-based batteries are best suited for portable devices; lead acid batteries are economical for wheeled mobility and stationary applications. Cost and weight make batteries impractical for electric powertrains in larger vehicles. The price of a 1,000-watt battery (1kW) is roughly $1,000 and it has a life span of about 2,500 hours. Adding the replacement cost of $0.40/h and an average of $0.10/kWh for charging, the cost per kWh comes to about $0.50. The IC engine costs less to build per watt and lasts for about 4,000 hours. This brings the cost per 1kWh to about $0.34. Read more about the Battery Against Fossil Fuel.

Maintenance

With the exception of watering of flooded lead batteries and discharging NiCds to prevent “memory,” rechargeable batteries require low maintenance. Service includes cleaning of corrosion buildup on the outside terminals and applying periodic performance checks.

Service life

The rechargeable battery has a relatively short service life and ages even if not in use. In consumer products, the 3- to 5-year lifespan is satisfactory. This is not acceptable for larger batteries in industry, and makers of the hybrid and electric vehicles guarantee their batteries for 8 to 10 years. The fuel cell delivers 2,000 to 5,000 hours of service and, depending on temperature, large stationary batteries are good for 5 to 20 years.

Temperature extremes

Like molasses, cold temperatures slow the electrochemical reaction and batteries do not perform well below freezing. The fuel cell shares the same problem, but the internal combustion engine does well once warmed up. Charging must always be done above freezing. Operating at a high temperature provides a performance boost but this causes rapid aging due to added stress. Read about Discharging at High and Low Temperatures.

Charge time

Here, the battery has an undisputed disadvantage. Lithium- and nickel-based systems take 1 to 3 hours to charge; lead acid typically takes 14 hours. In comparison, filling up a vehicle only takes a few minutes. Although some electric vehicles can be charged to 80 percent in less than one hour on a high-power outlet, users of electric vehicles will need to make adjustments.

Disposal

Nickel-cadmium and lead acid batteries contain hazardous material and cannot be disposed of in landfills. Nickel-metal-hydrate and lithium systems are environmentally friendly and can be disposed of with regular household items in small quantities. Authorities recommend that all batteries be recycled. 

Comments

On August 1, 2011 at 2:59am
hoh wing tuck wrote:

Hi, I manage all the UPS installation across the Asia Pacific region.
I notice we have slightly different voltages for different sites.  The charging voltages range from 13.32 - 13.70 volts [per battery block].  According to some of the UPS manufacturers, the charging voltage should be 13.65 Volts and not lower.
We use mainly Valve Regulated Lead Acid battery for our UPS systems
How can I determine what is the optimum charging voltage for the systems.
What will happen is the charging voltage is too low or too high.  What is too low and too high.

On March 20, 2012 at 5:10pm
Frank Nichols wrote:

Q:  My home security system came with a 12-volt 4ah rated battery ... is there a problem if I use a 12-volt 5ah battery to replace?  Both are sealed acid type batteries.  Thanks.

On October 29, 2012 at 3:21am
alyas wrote:

hellow
i have a question about battery element tester
can i now , how work the element tester?
what about riplle and level on the battery element tester?
thanks

On February 27, 2013 at 1:55pm
eric wrote:

Hello, I was wondering how many cordless drill batteries are sold in the united states. I am doing a project on cordless drill batteries and needed to know statistics and the market for cordless drill batteries. Thank you

On June 26, 2013 at 8:11pm
Cori wrote:

I am designing a solar panel to charge a 12 volt 6 watt battery that will in turn charge an outsides flow meter. (must be rechargeable)  It will experience freezing temperature to high temperature of 99 Farenhiet. It will experience humidity. It will only have have a few hours to recharge due to optimal sunlight conditions. I want the battery to last a least a year to two years instead of its initial 4 months. The battery will be in constant use. What is the best type of battery for me? I have a decent budget, but it is not that large.

On August 25, 2013 at 9:36pm
Joe Sullivan wrote:

What exactly is “a few percent” when you say “discharge losses are only a few percent”?  And what do you mean by “discharge losses”?  Total capacity of the battery lost by each discharge?  Let’s say a few % is 3%, if you lose 3% of your battery each full discharge, you can only use your battery 33 times?

On February 26, 2014 at 4:59am
JEREMIAS DSOUZA wrote:

I want to charge my solar street light battery of 97.68 AH within 2 - 3 hours - what specifications should the Solar Panel fulfill. The existing Panel is of 12 W and seems insufficient
Thanks

Jeremias

On March 27, 2014 at 4:10am
Kerry Wagner wrote:

If you lose 3% of your batteries charge capacity at each charging then it retains 97% each charging.  That means if you charge it 10 times it will have 100% of it’s life times 0.97 to the 10th power left.
In an equation this looks like:
What’s Left = (100%) times (0.97 to the nth power)
Where “n” is how many times the battery is charged.
So after 33 charges there is still 36.6% of the battery’s charge capacity left.
The equation in Microsoft Excel is:
“=A2*(POWER(0.97,B2))”
where cell A2 has 100 in it and cell B2 has the number of charges the battery has experienced.  The equation above should be in cell C2.
Hope this helps.

On March 27, 2014 at 9:52pm
JEREMIAS DSOUZA wrote:

Dear Kerry,

That you for your explanation.
Basically I require to know if the electrical charge on the Solar panel of a particular capacity say 12 W can have the charge transferred in a faster time to the battery through a booster circuit i.e if the battery requires 6 hours for a full charge - can the charge be boosted to reduce the time to 3 hours

Regards,

Jeremias