Battery Operation; Charging The Batteries; Charge Acceptance At Various Temperatures; L-29. Operating Temperature - HP 4935A Operating And Service Manual

General Information
l-23.
BATTERY OPERATION (Options 001 and 003)
Nickel-Cadmium batteries enable the 4935A to be used in areas removed from AC power.
l-24.
Typical operating time is2.5 hrs when fully charged.
instrument is connected to an AC source and the POWER switch is in STBY.
Regular discharge-charge cycles are recommended to maintain battery capacity. The instrument
should be operated until batteries are discharged (instrument stops working) then recharged, at least every
30 days. Normal recharge time is about 17 hours. Typical battery
should he at least 100 charge-discharge cycles.

Charging the Batteries

l-26.
l-27.
The internal battery pack consists of three rechargeable battery packs (+6V, +156V, and -156V).
These provide typically 2.5 hours of continuous use without recharging. To recharge the battery packs, connect
the HP 4935A to an AC power source and press the power switch to STBY. Normal recharge
hours.
I-28. The batteries may be charged at temperatures between 5°C and 4O'C (41°F and 104"F), but have
greater charge capacity if charged between 5'C and 25°C (41°F and 77'F). At temperatures above 25°C
the charge acceptance falls off' as shown in Figure 1-2. For example, a cell charged at 45°C accepts about
charged, which could result in venting of the cell. This results in a permanent degradation of the battery
capacity due to loss of electrolyte.

l-29. Operating Temperature

Normal operating temperature of the I-IP 4935A with batteries (options 001 and 003) should be
between -2OOC and +40°C. However, there will be a loss of capacity when operating at the extremes. At low
temperatures, the batteries cannot fully discharge even if they were fully charged at room temperature. At high
temperatures this same effect take place to a lesser degree, in addition to the problem of charge acceptance
previously mentioned.
l-6
100% EFFICIENCY
40
U
CHARGE INPUT (% OF NOMINAL CAPACITY) - O.IC CHARGE RATE
0 2 4
CHARGING TIME IN HOURS
Figure 1-2. Charge Acceptance at Various Temperatures
The batteries are trickle-charged whenever the
life under normal operating conditions
80 120 160
8 12 14 16
time is about 17
200
18 20
Model 497',A