9 - 1
SECTION 9.0 - BACKUP OPERATION
1. The battery backup system utilizes two sealed lead acid
batteries which must be maintained in a fully charged
state to ensure proper auxiliary operation. The charging
circuitry charges the batteries whenever the roller appa-
ratus is plugged in and power is applied to it. The charg-
ing circuit will charge the batteries even if the power
switch on the roller apparatus is in the Off position.
2. If primary power is lost while a roller apparatus is in
normal operation, the charger circuitry will automatical-
ly switch the roller apparatus to operate on its internal
batteries. Any speed indicators, belt alarms, or commu-
nications functions will be inoperative while the appara-
tus is running on its batteries. Once primary power is
restored, the charger will automatically switch the appa-
ratus back to normal operation.
9.1 TESTING AND SPEED ADJUSTMENT (SEE FIG. I)
1. With the roller apparatus plugged in and in normal oper-
ation, unplug the unit from its power source to simulate
a power failure. A small click should be heard and the
unit should immediately start running on its batteries.
2. To adjust the running speed of the roller apparatus while
running under battery backup, find the battery backup
speed control marked "Auxiliary Speed". Adjust the bat-
tery backup speed control to the desired speed with a
screwdriver and lock the setting using the external lock
nut on the control shaft.
Note:
This speed control adjusts the speed of the unit while
operating under battery backup only and does not affect the
speed of the unit during normal operation in any way.
9.2 OPERATING FEATURES
1. Provide battery backup of roller rack system for 24
hours.
2. Complete recharge of batteries in about 8 hours.
3. Automatic shutdown and precise monitoring of battery
voltage when charge is complete. See Point #3 under
Section 9.3.
4. LED indicators show when batteries are charging and
when batteries are fully charged. See Figure E.
5. Charger automatically tracks ambient temperature and
adjusts charge voltage for correct charging levels at ele-
vated incubator temperatures. See Point #3 under
Section 9.3.
6. If batteries are incorrectly hooked up or severely dis-
charged due to damage, the charge will automatically
switch to trickle mode and output only 10ma of current.
9.3 BATTERY CHARGING CYCLE
Discharged batteries are charged using a three step charg-
ing cycle.
Bulk or Main Charge:
The charger is in constant current
mode. A constant current of about 0.85 amps is fed into the
batteries. The charger monitors the rising battery voltage
while feeding the current.
Topping off Charge
: The charger switches from a constant cur-
rent to a constant voltage charge mode. When the charging
battery voltage reaches about 30V, the charger switches to
an elevated charging voltage of about 32V. This elevated
voltage ensures a completely charged battery. The battery
charge current begins to taper off.
Float Charge
: When the charge current tapers to about .085A
(1/10th of the main charge current), the charger switches to
a float voltage of about 29.3 volts. The float voltage is con-
stantly applied to the battery while the charger is on until
supply power is cut off. The float voltage is specified on
the side of the battery (14.5-14.9V at 25°C for a 12V bat-
tery) and is the most critical step in maintaining overall
battery life. The float voltage must be precisely set and
must be derated for temperatures above 25°C.
9.4 BATTERY KILLERS
Heat:
Operating Sealed Lead Acid (SLA) batteries at elevated
temperatures significantly decreases overall service life.
Typical life for a SLA battery at room temperature is about
6-7 years. Overall service life for a SLA battery working in
a 37°C incubator is about 2.5-3 years.
Overcharging:
Overcharging of the battery will cause the
water in the electrolyte gel to evaporate, making the battery
age prematurely. A float voltage just 5% above the speci-
fied float voltage for the battery will start the decomposi-
tion of the gel electrolyte.
Deep discharge
: A 12V SLA battery is considered completely
discharged when its open circuit voltage is 11.64V.
Discharging SLA batteries below this level will impair the
battery's ability to accept a recharge.
9.5 SHELF LIFE AND STORAGE OF BATTERIES
An SLA battery will self-discharge over time. The self-dis-
charge rate is dependent on storage temperature. New batteries
received by the manufacturer are fully charged. An SLA battery
should not be allowed to self-discharge below 80% of its capac-
ity. An SLA battery will typically self discharge to 80% in 18
months in a 4.4°C or cooler warehouse. An SLA battery will
self-discharge to 80% in less than 3 months if left in a 40°C
warehouse.
Model 4862 Cell Roller_____________________________________________________________Battery Backup Operation
