IBM DS4700 manual Battery units

Table 7. DC power supply and fan unit description for DS4700 Express model 72 (continued)

Number	Description
3	DC power connector A21
4	DC power switch
5	DC power supply and fan unit B
6	DC power connector B12
7	DC power connector B22
8	Pin 1: -48 V dc
9	Pin 2: POS RTN
10	Pin 3: GND

Notes:

1.The A1 and A2 dc connectors are keyed so that the dc cables are connected to the A1 and A2 connectors in only one way and in opposite orientation from each other. If the dc cable does not fit the dc connector, flip it 180 degrees and try again. Do not force fit because you might damage the connectors and short out the power supply.

2.The B1 and B2 dc connectors are keyed so that the dc cables are connected to the B1 and B2 connectors in only one way and in opposite orientation from each other. If the dc cable does not fit the dc connector, flip it 180 degrees and try again. Do not force fit because you might damage the connectors and short out the power supply.

Battery units

Each controller also contains a rechargeable battery unit that maintains data in the cache in the event of a power failure.

Figure 10 on page 18 shows how the battery unit slides into the battery backup slot in controller A CRU.

Chapter 1. Introduction 17