Firmware Version 143 ff. Rev 1.39 03.10.17
Dingo 4040P Reference Manual
36
A
A.3 Current limits & thermal derating
Current limits/short circuit protection
The charge input has a current limit which acts to
protect the Dingo from excessive charge current
and can be used to protect small batteries from
excessive charge rates. This is fixed at 40A for
programs 0-3 and is adjustable in program 4 at
the SET/REG/CLIM screen.
There is also short circuit protection. If the
current out from the terminal exceeds 74A,
then the charge switch is turned off. When this
disconnection occurs, the boost annunciator will
start flashing. It can be reset by a long push in the
SOLV screen
The load output has a current limit. This acts
to protect the Dingo from overheating due
to excessive load current. If the load current
exceeds 60A for the load disconnect delay time
(LDEL) then the load will disconnect.
As well as this current limit, there is load
short circuit protection. If the load current
exceeds about 200A, the load switch is turned
off immediately. If this occurs, the LOAD
annunciator will start flashing. It can be reset by a
long push in the LOAD/LINT/LSET screen
Thermal derating
The Dingo has an internal temperature sensor
which acts to protect it from overheating. The
charge current is reduced to limit the internal
temperature. The ability of the Dingo to operate
without reducing the charge current depends
on five factors - the ambient temperature, the
load current, the time that it has been hot, the
battery voltage and the number of external
devices attached to the serial bus.. For example,
it takes about 1 hour for the Dingo internal
temperature to reach equilibrium under fully
loaded conditions. It is difficult to construct a
simple derating table because of these factors.
The following information is a guide to what sort
of performance can be expected in a number of
situations.
1. 40A Charge current, 0A Load current, 12V
battery, No external devices
The controller may operate at full current up to
an ambient of 60oC (140
o
F)
2. 40A Charge current, 40A Load current, 48V
battery, 10 external devices
The controller can operate at full current up to
an ambient of 57oC (122
o
F)
If the ambient temperature is a few degrees
above this, it can take an hour or more from cold
before the Dingo will begin to limit the charge
current.
3. Calculate the limit
It is possible to estimate the ambient
temperature at which limiting will occur. This can
be calculated from the following approximate
formula.
Tamb (max) =70-0.0038(charge current)
2
-0.0031(load current )
2
-0.008(battery voltage)
Where currents are in amps, temperature in
o
C.
(Valid for Tamb 45-60
o
C. Limiting may occur at
or above this temperature
A.4 Block Diagram
This Dingo Controller is designed for common
positive installations (i.e. solar and load circuits are
switched on the positive side).
It has a reverse blocking mosfet switch between the
SOL- terminal and the BAT- terminal and a mosfet
switch between the LOAD- terminal and the BAT-
terminal. There is also an optically isolated low
current bi-directional mosfet switch between the
‘G’ terminals.
