JLG sky trak mmv Service Manual page 581

12
13
Input
Equalizer
Output
Ground
7
With an equalizer installed, both batteries will maintain
equal charges, and 12V-load power will be drawn from
both batteries equally.
As a consequence of the above operation, it can be stat-
ed that if one of the batteries is discharged, the battery
with the most charge will furnish power to the 12V load.
This can be understood using the above description and
considering that one battery has a reduced terminal volt-
age due to its lower charge state. Eventually, the battery
charges will balance, and then both batteries will furnish
power to the load.
This section describes the battery equalization process
for batteries at rest. The point here is that the equalizer is
operating even when the engine is OFF, which is com-
mon for these devices.
The equalizer is designed to operate continuously. It is
built with a "sleep" mode that reduces circuit draw to typ-
ically 2.6mA after the batteries are balanced.
Note: 24V loads do not impose a battery imbalance
condition. Since the batteries are in series, all current
delivered to the 24V load is, necessarily delivered by
both batteries equally.
Model MMV Rev. 12/04
14
"B" Battery
12 Volts
Load Current =
"A" Battery Current +
"B" Battery Current
"A" Battery
Current
11
12 Volt
9
Load
"A" Battery
12 Volts
8
10
Equalizer Operation: Engine ON
Note: Nominal charge voltage for 24V vehicular sys-
tems is 27.6 to 28.4V and 13.8 to 14.2V for 12V systems.
For our purposes we will use 28V and 14V, respectively.
Approximate temperature = 73°F (23°C).
Consider the situation with the engine running. The alter-
nator (15) is producing (16) 28V, which is also the
input voltage (17) to the equalizer (18). The equalizer
now generates half of this (i.e.14V) at its output. This pro-
vides the optimum charge voltage (19) for the "A"
battery (20). This also means that there must be 14V
charge voltage (21) for the "B" battery (22), therefore,
both batteries receive optimum charge voltage with the
equalizer in operation.
Alternator Output Current
MM4480
16
Equalizer
Input
Current
Alternator
24 Volts
15
* - Current required for battery balancing
Electrical System
17
"B" Battery
12 Volts
Equalizer
"A" Battery
Charging
Current
18
"A" Battery
12 Volts
21
22
19
12 Volt
Load
20
MM4490
10.101