|Marine Backup battery setup
The Backup battery setup below is great for those applications where you do not have or do not desire to use a large 4 way switch in your system. For those who have or also desire to incorporate a 4 way switch in their application, then click on this link for diagrams for use with a 4 way switch for information on those setups.
Below is a very
simple add-on to an existing single battery boat. A backup
battery can easily be connected through the isolator /combiner to the
starter solenoid or main battery positive. No other wiring changes are necessary except you
should use a combination deep cycle/starting battery for the main
circuit if you intend to operate accessories while the engine is off. To install, simply disconnect both battery negative cables from your system, then connect a 2 or 4 AWG wire from the BIC
(terminal B) to the starter circuit through a 150A fuse if desired. Then, connect a 2 or 4 AWG
wire to the backup battery positive through a 150A fuse. Connect the short Red 4 AWG jumper wire, supplied with the BIC, from
terminals "A", and "C". Connect the BIC fused (1 to 3A) ground wire to the engine block or other main system ground. Finally, re-connect the battery negative connections.
The unit will now keep the backup battery charged
while operating and prevent it from being drained by the main system loads.. For the backup remote functions, you can
install your own remote switch and LED if desired or you can purchase
our Remote Module which
has the switch and LED prewired in a mounting enclosure.
See the Backup battery setup diagram below: Switch
your backup battery in parallel only when needed. If you have a windless, it can be substituted for the winch in the diagram, and your marine accessories/loads would be connected to your power distribution.
Now, lets examine pros
and cons for this setup.
- Optimized configuration for emergency backup
- Extreme simplicity! Heavy Duty Switches
are NOT needed! Zero!
None! Zip! Minimal wiring needs.
Alternator protection device NOT needed!
- External solenoids NOT required. Can be
used with 200 Amp or larger or even much smaller alternator!
- Low Cost! With heavy
duty switches costing as much as $30.00 to $90.00 each, consider your
savings by eliminating up to 3 of these. Save about $25.00
for an alternator protection device. Save money by reducing
the amount of wiring required. Save labor dollars
by simplifying installation.
- Easy, simple to understand, installation!
Eliminate all the hole drilling for those switches.
- If you draw down your primary
battery, you will have a fully charged backup battery.
No normal loads are on the backup battery.
Therefore, it is always fully charged and not cycled, resulting in very
long life. When your primary battery wears out,
move this battery to become your primary battery (if it is a deep cycle
unit). Then replace the backup with a new
battery. This way, you always keep the best battery
for when you need it most!
- Simple, automatic operation! Virtually
free of human intervention! except for moving the switch when you need a backup operation. No hassle, worry free.
- Simple manual parallel combination via a remote micro-switch.
From a remote console, you can use very small wire running
a long distance to switch the batteries in parallel.
- In this configuration, the BIC-95300B handles the full
cranking current (normal 120 to 180 Amps) for a 350ci V8 gas
engine (up to 300 Amps) for 15 to 30 seconds. (For diesel
applications, and depending on its size, we recommend you add a second BIC-95300B in parallel to
share the load current and two backup batteries if it requires two main batteries for normal cranking.)
- The Hellroaring BIC-95300B and BIC-95150B limit inrush
currents for the first couple milliseconds when switching, along with reasonable transient suppression. No arcing to wear out the device!
- No diode voltage drop effect when ON!
Super low ON resistance (less than 0.001 ohms!)
Cons: (these are not
- If you connect your main
starting battery to the accessory (house) buss, your starting battery
will, by default (*except
as noted below), be utilized in a deep
cycle application. This has historically been and still is
not good practice. A starting battery will readily be damaged by
deep discharge applications. In the past, deep cycle
batteries were not designed to handle large cranking currents and would
be damaged by starting applications. But, today,
there are more choices. Many deep cycle batteries
can handle cranking currents. For a marine application, compare the battery MCA rating to your marine engine cranking requirements. If a deep cycle rated battery meets or exceeds this rating, then you are good to go. (* Note: When this
circuit is utilized in an automotive application
where there are no normal "engine off" loads, this is not a problem and
a starting battery is acceptable.)
- Mechanical Relay Con:
If you drain your main battery and then parallel your fully charged
backup battery, you will initially draw substantial current from it.
One reason people have avoided this system is
because, when switching, high inrush currents can damage mechanical
contacts. Also, many people believe that this will suck
valuable energy needed for cranking. The fact is, unless the main battery is damaged with internal
shorts, this is better than using the fully charged
battery alone. This is especially true when you allow a few
minutes before cranking. It is true that when
you connect them in parallel, current will flow from the fully charged
battery to the discharged battery. As it does, charge builds up
in the discharged battery. The longer you allow this
condition to exist, the more charge transfer takes place until
equalization (which you don't require in order to crank). A
fully discharged battery at rest has a voltage of
about 11.5 volts (no load and no charge). When you crank
your engine, your (fully charged) battery terminal voltage will
normally drop to less than this 11.5 volts. Therefore,
current will no longer flow into the weak battery but will only flow to
the starting load. Furthermore, whatever charge has
transferred to the weak battery will cause it to supply additional
power to the starting load! So this is a Con only with
mechanical relays. PRO: The Hellroaring
solid state isolator/combiners limit inrush currents
when switching and provide some transient suppression. There is no arcing to wear out the device!
- Mechanical Relay Con:
If you drain your main battery and you want to continue operating
accessories with the remaining power from your backup battery and you
energize a mechanical combiner, it will consume energy that you want to
conserve. Therefore, some people would install an additional
heavy duty switch. PRO: With
a Hellroaring Battery Isolator/Combiner, the energy
consumed is insignificant (less than 0.012 amps when
ON) allowing this setup to be practical!
- The dc load buss voltage will
drop while starting. Electronic devices sensitive to this may
experience trouble the same as if in a single battery system..