FAQ: Why do Yaskawa MP Controllers and ServoPacks use multiple batteries?
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Yaskawa motion systems use lithium batteries for mainly two different functions: maintaining Absolute encoder data and preserving CPU non-volatile memory.
The encoder battery used with the ServoPacks (JZSP-BA01) is required if a multi-turn absolute encoder is needed because it holds the multi-turn encoder data when the drive power is down. Therefore, when setting the drive to use the absolute encoder as an incremental encoder or a single-turn absolute encoder, the encoder battery is not needed. The encoder battery power can be applied via the battery case on the ABS encoder cable (CN2), or through the I/O connector (CN1, for example Sigma7 ML-III ServoPack, pins 14[+] & 15[-]).
Figure1
When using an absolute encoder without the encoder battery case, the battery can be connected to through CN1 connector on the ServoPack:
Figure2
Figure3
The Absolute Encoder Current Draw specification is:
- 20 μA when ServoPack is powered off
- 3 μA when ServoPack is powered on (w/o diode in place)
To determine the worst case battery life, divide the A-hour rating of the battery by the Sum of the current of all encoders when powered off.
For example, assume 16.5 A-hr battery and 16 Encoders are connected: 16.5 A-hr / (.000020 A * 16) = 51500 hours or 5.8 years
For installing and replacing the battery in the ServoPack, refer to:
- YASKAWA SIGMA-7 AC Servo Drives and Motors Technical Supplement (YAI-KAEPS80000123F)
- YASKAWA AC Servo Drives Sigma-V Series Product Catalog (YEA-KAEPS80000042)
The other type of batteries is used for the MP controllers. These batteries (JZSP-BA01) provide a backup power for the CPU non-volatile memory, preserving the SRAM data when CPU power is down. This data includes the retained variables, the alarm history, the absolute encoder offset and the real-time clock data. The SRAM can last for one hour without the battery connected. This battery must be replaced while power is supplied, within 2 weeks of when the BAT indicator first lights. For the MP2600, the SRAM battery power can be applied through the battery connector (CN14), or through the I/O connector (CN13 pins 7[+] & 32[-]).
Figure4
For installing and replacing the battery in the CPU, refer to:
- YASKAWA MP3200iec Machine Controller Hardware Manual (YAI-SIA-IEC-5)
- YASKAWA MP2600iec Hardware Manual (YEA-SIA-IEC-6)
More references on the encoder usage in Yaskawa motion systems:
SAFETY PRECAUTIONS AND INSTRUCTIONS FOR USE OF FAQ INFORMATION!
Please read and understand the product instruction manual before installing, servicing or operating Yaskawa products. FAQ content and illustrations are provided as technical advice to augment the information in manual, not supersede it. It is not possible to give detailed instructions for all types of installation or support activities. The information described in the FAQs are subject to change without notice to improve the product or FAQ. Yaskawa assumes no responsibility for errors or omissions or damages resulting from the use of the information contained in any FAQ. All warnings, cautions and product instruction for product use must be followed. Installation, operation and maintenance should be carried out by qualified personnel. Failure to observe these and other precautions highlighted in the product manuals will expose the user to high voltages resulting in, serious injury or death. Qualified personnel are defined as individuals who are familiar with the installation, starting, operation and maintenance of Yaskawa products of the type described and have proper qualifications to perform the work.
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2121 Norman Drive South
Waukegan, IL 60085