Critical Power Experts - Generex Active Battery Management
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ACTIVE BATTERY MANAGEMENT Balancing Charge Voltage, Battery Replacement and Extending Battery Life. Dave Cleveland – Critical Power Experts [email protected] (844) 4-CPEX-UPS
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Transcript of Critical Power Experts - Generex Active Battery Management
ACTIVE BATTERY MANAGEMENTBalancing Charge Voltage, Battery
Replacement and Extending Battery Life.
Dave Cleveland – Critical Power [email protected]
(844) 4-CPEX-UPS
MODULE CONNECTION
Each battery has an individual module connected to the positive and negative post. Each module is capable of taking voltage, temperature, and impedance readings.
BATT BATT BATT BATT
BATT BATT BATT BATT
Positive
Negative
Module
MODULE CONNECTION
Most importantly since each battery has a module, the webmanager can actively use each module to evenly distribute charging current. This maintains each battery at equal voltage.
BATT BATT BATT BATT
BATT BATT BATT BATT
First lets take a look at normal charging methods.
FLOAT CHARGE
During a float charge a fixed voltage is supplied to the battery string and current is varied to maintain that voltage. Since we’re using 8 batteries in this example we’ll use 108 VDC as our supplied voltage.
BATT BATT BATT BATT
BATT BATT BATT BATT
Batt Volts Batt Volts
1 13.2 5 13.5
2 13.5 6 13.5
3 13.5 7 13.5
4 13.8 8 13.5
Total Volts 108
FLOAT CHARGE
As long as the sum of each battery’s voltage is 108 VDC the battery is at 100% charge. Looking at the chart below we can see that two (for simplicity) batteries have different voltages from the target of 13.5.Batt Volts Batt Volts
1 13.2 5 13.5
2 13.5 6 13.5
3 13.5 7 13.5
4 13.8 8 13.5
BATT BATT BATT BATT
BATT BATT BATT BATT
Total Volts 108
FLOAT CHARGE
This can be caused by many variables, however, when batteries are placed on a float charge a range of battery voltages is not only expected but is not correctable.
Batt Volts Batt Volts
1 13.2 5 13.5
2 13.5 6 13.5
3 13.5 7 13.5
4 13.8 8 13.5
BATT BATT BATT BATT
BATT BATT BATT BATT
Total Volts 108
EQUALIZING CHARGE
One method used to correct the voltage separation is to raise the voltage of each battery above the normal charging voltage. This places each battery in an over charge condition.Batt Volts Batt Volts
1 13.2 5 13.5
2 13.5 6 13.5
3 13.5 7 13.5
4 13.8 8 13.5
BATT BATT BATT BATT
BATT BATT BATT BATT
Total Volts 108
EQUALIZING CHARGE
The theory is by overcharging all of the batteries for a period of time any batteries with low voltage will eventually raise their voltage to meet or “equalize” with the other batteries in the string.Batt Volts Batt Volts
1 13.6 5 13.9
2 13.9 6 13.9
3 13.9 7 13.9
4 14.2 8 13.9
BATT BATT BATT BATT
BATT BATT BATT BATT
Total Volts 111
EQUALIZING CHARGE
By forcing current through fully charged batteries each battery is at an increased risk of gassing and therefore shortened life expectancy and overall capacity. In this case battery #4 could possibly reach 14.2 VDC.Batt Volts Batt Volts
1 13.6 5 13.9
2 13.9 6 13.9
3 13.9 7 13.9
4 14.2 8 13.9
BATT BATT BATT BATT
BATT BATT BATT BATT
Total Volts 111
EQUALIZING CHARGE
This method has long been debated, however it is not only still used in some machines, it is recommended. Powerware 9390’s come with an automated version of a periodic equalizing charge.Batt Volts Batt Volts
1 13.6 5 13.9
2 13.9 6 13.9
3 13.9 7 13.9
4 14.2 8 13.9
BATT BATT BATT BATT
BATT BATT BATT BATT
Total Volts 111
THE ALTERNATIVE
With individual modules connected to each battery using a complex and finely tuned algorithm our Active Battery Management System is able charge each battery to within a 100th of a volt. Batt Volts Batt Volts
1 13.2 5 13.5
2 13.5 6 13.5
3 13.5 7 13.5
4 13.8 8 13.5
Total Volts 108
BATT BATT BATT BATT
BATT BATT BATT BATT
THE ALTERNATIVE
Each module is able to allow a very small amount of charge current to pass, therefore slowly bringing each battery to a perfect charge voltage.
Batt Volts Batt Volts
1 13.2 5 13.5
2 13.5 6 13.5
3 13.5 7 13.5
4 13.8 8 13.5
Total Volts 108
BATT BATT BATT BATT
BATT BATT BATT BATT
THE ALTERNATIVE
Lets add green bars to each battery to graphically represent our starting voltage. Using the top of the battery to represent 100% charge.
BATT BATT BATT BATT
BATT BATT BATT BATT
RAISING VOLTAGE
First lets see how the battery management system can raise voltage on battery #1.
BATT BATT BATT BATT
BATT BATT BATT BATT
RAISING VOLTAGE
The modules can create a parallel path for current to flow. Here each module allows ~300mA of current to flow with the exception of module 1. That small amount of charging current will raise that battery’s voltage.
BATT BATT BATT BATT
BATT BATT BATT BATT
RAISING VOLTAGE
Each of the batteries with a bypassed module pass a small amount of charging current. The module on battery 1 does not. Battery 1 accepts the additional charging current and individual voltage rises slowly.
BATT BATT BATT BATT
BATT BATT BATT BATT
LOWERING VOLTAGE
By simply reversing this alignment for batteries with higher voltage, all other batteries maintain charge while the high battery drifts down to meet the other voltages.
BATT BATT BATT BATT
BATT BATT BATT BATT
NORMAL OPERATION
Here is an example of logged data collected by a Webmanager after a battery had been first connected to the Active Battery Management System.
NORMAL OPERATION
The top graph is individual voltages for each of the 40 batteries. The bottom is the logged equalization of each individual module that was required to regulate voltage.
NORMAL OPERATION
The batteries were brand new and connected to a Mitsubishi 9900 UPS. It took approximately 2.5 hours for each battery to reach 13.67 VDC exactly.
ADVANTAGES
Maintaining each battery’s voltage exactly and individually provides many advantages such as:
• Reduced gassing due to high charge voltage• Reduced sulfation due to low charge voltage• Keeping within manufacturer’s warranty conditions• Prolonging overall battery life and capacity• Replacement of an individual battery does NOT
negatively affect other batteries in the string
MORE ADVANTAGES
The Generex hardware is also capable of capturing and storing data at a high rate which gives the capability to:
View and manipulate trend data dynamically
MORE ADVANTAGES
The Generex hardware is also capable of capturing and storing data at a high rate which gives the capability to:
Automatically capture discharge data and produce reports
MORE ADVANTAGES
The Generex hardware is highly capable and highly programmable. Here are some additional features:• Provide up to the minute resistance readings on command• Provide thermal runaway protection for an individual
battery string • In the rare event of a battery failure or complete discharge
it can provide failure data immediately• UPS Operating Parameter and Alarm integration• Annual discharge testing or battery verification• Email or text alarm notifications • Have a request?
FINAL
Actively managing batteries in critical environments has obvious advantages and will soon be the industry standard. No product on the market today can offer more with a proven track record than the Generex product line.
I have been installing and commissioning Generex systems for several years. Let me bring my experience and expertise to your Generex BACS installation.
Dave Cleveland – Critical Power [email protected]
