|I am interested
in installing a 2 battery
set up in my Jeep. I do not have a winch but I do have many off
road lights. I also have a 50 amp stereo system. If I used one of your
2 battery setups. What would be the best way to set it up? Run
all the auxiliary lights off the second battery? or just leave the
second battery as a back up starting battery? Will both batteries
Our preference is to use
the Basic Backup Battery system. It is very
simple to install and provides the most power available for starting,
and especially useful in cold weather conditions. With this
setup, you run your lights and stereo from the main battery side.
Under normal operation, they will be powered by your alternator.
If your alternator can't keep up or if you operate with the engine OFF
and your main battery becomes drained, your Backup Battery
will remain fully charged and ready to go. If
you regularly use engine off loads, you should use a high CCA rated
deep cycle battery such as an Optima Yellow Top for your main battery.
When using a Hellroaring BIC unit, both batteries receive charge
automatically from the alternator.
am interested in installing a dual battery system in my pickup
I would like to use the aux battery for power to a CB radio, possibly a
winch and use for emergency starting of the vehicle. I assume
that the battery will be kept charged by the truck alternator. Do
your isolators work in this manner? Which system would you
recommend?? Is installation simple enough for an amateur to
install?? Thanks for any information.
Again, our preference is
to use the Basic Backup Battery setup. It
provides the most power available for starting or winching. With this
setup, you run your lights, stereo, winch, etc... from the MAIN battery
side. Since you always have a fully charged backup starting battery,
there is no need to separate your vehicle and accessory load
circuits. If your main battery becomes drained or otherwise lacks
sufficient power, your backup will remain fully charged and ready to
go. When you winch, you can enable the backup for extra power
However, In order to gain full
cranking capability, you must not connect any loads to the backup
battery to preserve isolation. Simply connect them to the Main
battery. This setup is very simple to install
(e.g. 2 AWG wire from starter to BIC, 4 AWG wire from BIC to backup
battery, short 6 AWG jumper wire, small ground wire, small wire from
BIC to Remote switch, and small wire from Remote switch to BIC battery
terminal, small wire from BIC to Remote LED, and small wire from LED to
If you must have loads on both batteries,
then choose one of the two methods described below. Either of
these setups will isolate them in both directions and provide automatic
charging to both. However, neither will
allow full cranking current for emergency
starting. Full cranking capability means
that if a main battery is effectively disconnected,
all cranking current must go through the BIC. Most
situations require less than full cranking capability. Either
of these two setups will provide boost current if the
main battery has a partial charge. :
Starting Battery Isolation: If you
choose isolation between the alternator and the main battery, you must
choose weather to keep the ignition, fuel pump, etc... circuits on the
main side or move them to the auxiliary side. Other items like
AC, lights, etc... should be moved to the auxiliary side. But,
you do not need to be concerned with your alternator size. With
this setup, you will not have full backup cranking capability, but it
keeps the main battery from being drained by auxiliary loads. You
may experience quicker starts if you move the ignition circuits to the
Auxiliary Battery Isolation: If
you choose isolation between the alternator and auxiliary battery, you
need to consider your maximum alternator output and your maximum load
on the auxiliary side to not exceed the rating. This is also
simple to install. With this setup, you will not have full backup
cranking capability, but it also keeps the main battery from being
drained by auxiliary loads.
In any of these setups, both batteries receive charge automatically
from the alternator.
found your page
while looking for some alternator theory.
How would your isolator work on fuel injected cars? I'm thinking
that the fuel pump, ecm, etc... also needs power while cranking.
For the starting battery
isolation setup, you have a choice to leave the ignition, fuel pump,
ECM circuits, etc... either connected to the main battery or the
auxiliary battery side. If connected to the main battery side,
the primary risk of drainage is due to alternator failure or leaving
the keys ON. If you connect these circuits to the auxiliary
battery, you may experience faster starts simply because the ignition
circuits will have a higher voltage during cranking. The
Auxiliary battery does not drop its voltage during cranking like the
main battery does. If your alternator fails or if the auxiliary
battery becomes drained, your engine will crank, but will not run
unless you manually combine the batteries. Simply flip the Remote
Switch and power from the main battery will flow to the ignition
I'm interested in using
your BIC-95300B in a couple of my 4x4 vehicles and trailers. However I'm
not really clear about one of the BIC-95300B features.
BIC-95300B both hookup to and charge a 3rd battery while still providing
the capability of jump-starting the starter battery from the 2nd or 3rd
battery? If not, How can it provide this capability?
The reason for this is that I need to setup my 4x4 with 2 batteries
with the jump-start capability and still be able to charge the trailer
battery when I tow it along.
is essentially dedicated to the Backup battery setup where the Backup battery must be reserved all by itself (i.e. no loads conntected to it)..
However, you can connect a third battery bank in another way.
Connect the BIC-95300B for a Backup Battery Configuration.
Use a high CCA rated deep cycle battery such as the Optima Yellow Top
or Odyssey battery, or Centennial RV battery for the primary (main) battery. Then connect the trailer battery
wire to the alternator/main battery circuit. Since you have a
fully charged backup battery, you don't need to worry about draining
your main battery with the trailer connected. When you disconnect
the trailer and go off 4 wheeling, you will still have the fully
charged backup battery.
If you must have isolation to the trailer battery and
have backup starting capability, you can use the BIC-95300B for the
backup battery and also connect a BIC-95150B between the alternator and
trailer battery connector.
do I know
if the Hellroaring BIC-95150B or BIC-95300B is compatible
with my vehicle/alternator system?
If your vehicle
is a 12 Volt, negative ground system, either unit is
compatible. However, if you choose an auxiliary battery
isolation configuration, you must be aware of the maximum current load
you intend to draw continuously to your auxiliary battery system
(auxiliary load plus 40-50 amps for charging if the alternator is 90
amps or larger). We aim to limit the peak demand to the Auxiliary battery side to about 60 to 80A by recommending a minimum length of 20 feet of 8 AWG wire for the charge line. This tends to work well even with large output alternators when the Auxiliary battery bank is under about 200 AH of capacity. For higher capacity battery banks, we would recommend adding a few more feet of length to the charge line. When configured for the basic starting battery
isolation or the basic backup battery setup, virtually any size
alternator is suitable.
generally a normal condition, especially in cooler weather.
To check its function, switch ON your headlights for a few seconds and
the LED should go out. The LED remaining ON after the
engine is switched OFF indicates that Both
little load (this is a good indication!) After the surface
charge dissipates or if a sufficient load is applied, the LED will go
out and the batteries will be isolated. You can actually use this
indication to obtain a rough measure of full charge. For
example: If (after the vehicle has been sitting for a while) you start
your engine, the LED comes ON. If you immediately switch
OFF the engine, you should notice that the LED goes out very
quickly. This is because the main battery did not have time
to obtain and replace the charge removed during starting and the
auxiliary battery did not have time to build up a surface
charge. When the engine was switched OFF, the main battery
reduces the system voltage and consumes current from the auxiliary
battery which causes the BIC-75150 or BIC-75300 to quickly enter
isolation mode. See LED
I'm concerned about not
obtaining full charge efficiently due to diode isolator voltage drop.
Does either of the Hellroaring isolators have this effect?
Both of the Hellroaring BIC-95150B
isolators use solid state switching
technology, not just simple diodes. When your auxiliary
battery reaches full charge, you can expect less than a 0.005 Volt
It is often less than the voltage drop across
the wiring used to connect it! On our original test vehicle, a
4x4 suburban, the voltage drop at full charge measured about 0.001 Volt
across a BIC-75150. The drop across the BIC-95xxx models are even less because their On resistance is less than half that. See No diode effect!
I won't use relays or
solenoids in my system because I'm concerned about
from a fully charged battery to a fully
discharged battery and causing damage to them. How do the
Hellroaring isolators handle this?
in parallel, a fully discharged battery voltage will quickly rise and
the fully charged battery voltage will quickly be reduced.
Both of these conditions as well as the wiring resistance's and battery
internal resistance's tend to reduce the maximum current transfer.
In addition, the BIC controls the switch ON rise-time to limit inrush currents over the first 2 milli-seconds, unlike the
instant ON of solenoids or relays. When switching with the
BIC-95150B or BIC-95300B, the expected maximum current transfer should be
less than 35 Amps. This level will not damage the battery.
The rapidly blinking LED
serves as a diagnostic tool. This can indicate one of
several conditions. See LED Diagnostics.
If you have a long run of wire from your
alternator to your BIC-95150B or BIC-95300B, and your auxiliary battery
has been discharging a while, it will attempt to draw maximum currents
initially. The Hellroaring BIC units will sense the voltage
drop across the length of wire and go in pulsing mode. For
example: assume your auxiliary battery system attempts to draw 40
amps of charge and accessory current. Your BIC-95150B is
mounted on your trailer through 35 feet of 10 AWG wire to the
alternator. Your alternator is outputting 14.5
Volts. There will be a 1.4 volt drop in the wiring to the
trailer so the BIC-95150B will see 13.1 Volts. This low
voltage will cause the BIC-95150B to switch off. When the
current stops, the voltage will rise again and the unit will switch on
again (after a short delay.) You will see this as a rapidly
blinking LED. This will effectively reduce the average
current in half. If you want more continuous alternator
current available, you have at least three choices: Increase your wire
size, or you can use the remote sense wire (of an "A" model only) and connect it closer to the
alternator end, or you can mount the BIC-95150B closer to the alternator
If you have a shorter run of wire (<20
feet) of 10 AWG or larger, this indication will serve as a warning
indicator that you have excessive
resistance in your
connections. If you did not have a Hellroaring Battery
Isolator/Combiner, you would not notice this condition until your
battery fails to perform. You should investigate and
correct this condition soon or you risk a chronic undercharged battery
condition and pre-mature failure.
If you are attempting to supply charge or load current
in excess of your alternator capability, you will see the blinking
LED. The blinking does not hurt anything. Eventually,
charge current may be reduced and blinking will stop. This is an
indicator that your alternator is marginal to supply your electrical
demands. If this is unusual for your particular setup, check for
excessive resistance (described in 2 above).
Most likely, nothing is
wrong with the isolator. There can be several conditions
that may exhibit a "no indication". See LED Diagnostics
the remote switch is not in the OFF position.
If your main and/or auxiliary system is using
more load than your alternator can provide, then the BIC unit will stay
disconnected. If this condition exists for an extended
period, the battery (connected to the side opposite the alternator)
will not charge. To solve this, you can reduce your load
or upgrade to a larger alternator.
Your alternator may have failed.
Check the belts and the alternator output.
Your connections may be loose or may
have excessive resistance due to corrosion. Check the connections for a
clean solid connection.
If you are using a remote LED, verify that the
built-in LED also is not illuminated. If it is illuminated, the
isolator should be working. Check the remote LED and its
BIC-95150B does not need to handle 400 Amps. It is true that
a stalled starting motor can consume up to 400 amps
at 10 Volts. However, due to wiring voltage drops and
battery internal resistance, the starting motor (for a gasoline
engine) usually does not see more than about 300 amps and then, only
for a fraction of a second. Diesel engines, however, will likely see more (up to double).
On our test vehicle, a 4x4 suburban, the initial starting
current was measured at < 300 amps for the first 50 milli-Seconds
and then cranking averaged < 160 Amps at 0 degrees C.
The BIC-95150B is not intended for full cranking current. When
using the BIC-95150B, you should not attempt cranking while combined if
your main battery can not supply some major current (e.g. clicking
solenoid, slow cranking, etc..) You must allow sufficient time
for charge current to transfer. Or, you must jumper the battery
positives together after combining them with the BIC-95150B.
The Hellroaring BIC-95300B in the Backup battery setup particularly comes in
handy during extreme cold weather, i.e. < -10F. As the
main battery voltage drops during the cold cranking load, the auxiliary
battery supplies extra power to keep the voltage up and crank the
engine. See Cold Weather Starting or Auxiliary
A single Hellroaring BIC-95300B configured for high
current with 2 AWG wire to the starter will handle the full
cranking current of a typical 350 cubic inch V8 gasoline engine.
supplies the most power transfer for cold weather or
winching. Small Diesel engines will require two BIC-95300B units
wired in parallel to achieve full cranking current capability.
want extra power
for my winch but it is rated up to 400 amps. These
operate longer than starting motors. Won't this burn up the
You will likely
burn up your winch before you hurt the BIC-95300B. If you use the
Basic Backup Battery setup, you will be
able to winch as long as your winch and batteries can handle.
When you operate your winch, you will likely have a near fully charged
main battery. In addition, the BIC-95300B can handle up to
190 amps continuously. Your backup battery can supply boost
current to reduce the voltage drop at your main battery
terminals. There are several points to keep in mind:
The only current through the Hellroaring
BIC-95300B will be from just the backup battery. For batteries of
equal charge, you can supply up to 300 amps continuously without
alternator (for as long as the battery charge lasts and the winch
Your winch will quickly burn up if it is
operated at full load continuously. A winch MFG. recommends
less than 20 seconds at full load. Therefore, you likely will not
operate at full load for very long.
Most winch ratings are at 12 volts. Full
load (stall) current will be less due to battery terminal voltage drop.
You can expect no more than about 88% of the rated current at full load
(with a single battery). For the 400 amp rating, this
is about 350 amps. With the Hellroaring BIC-95300B and another
battery, this may be about 375 amps.
Your alternator can supply a portion of the
current. This will be your alternator rating less about 10
to 15 amps for engine operation. Subtract more if you have
other loads like headlights. With a 100 amp alternator, this
should still leave about 75 amps for the winch. Even more
is available with higher output alternators.
When wired for the Backup Battery setup, the
and backup battery
will initially deliver close to 1/2 of the main battery current to the
winch. For the example
above, the batteries
together will supply about 300 amps (375 amps less the 75 amp
alternator output). Of this 300 amps, the main battery will
supply about 160 amps and the auxiliary will supply about 140
amps. The backup will supply slightly less due to the
typical unequal lengths of wire to the winch and some slight BIC
resistance. This combination will increase the operating capacity
to about 300% compared to a single battery alone. This is
an excellent increase in performance. If the alternator
output is not available, the BIC-95300B can handle initial currents up
to 300 amps short term or a 500A inrush for 50 mS..
But, since a winch will quickly burn up if
operated at full load for more than 20 seconds, a more realistic
example will be the winch operating in the range of 125 to 200
amps. At the 200 amp load, the batteries together must
supply 125 amps. Under this condition, the main battery
would be expected to deliver 65 amps and the backup battery would be
expected to supply about 60 amps. If the main battery
charge is low, the backup battery and BIC-95300B will supply the
majority of the 125 amps or more if needed.
With a BIC-95300B configured for the Backup
Battery setup, you can also leave it in Auto mode and winch with your
main battery only, thereby reserving your backup battery as a starting
backup. In this case a battery such as an Optima yellow top
(deep cycle) would be ideal as your main battery and any standard
starting battery as your backup. If you winch often, and if you
plan to use both batteries during winching, then both should be deep
cycle rated batteries.