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Hellroaring Technologies, inc.

Polson, Montana  -  USA

Our BIC-75300A Page 

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Hellroaring Technologies


Battery Isolator/Combiner

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Note: This page will be updated soon with more details on our new versions, the BIC-85300A (replaced the BIC-75300A), BIC-95300A, and BIC-95300B.  Essentially, these models are the same except that the BIC-85xxx has an improved ON resistance by 30% less, and the BIC-95xxx has an improved ON resistance by 50% less.  This means even less heat generated!  So, they can handle incrementally higher continuous currents.  The BIC-95300B goes on to provide built-in Transient Suppression, and the Sense resistor, and external diode built-in to the unit.  So, this makes for an even simpler, cleaner install.  Should you have questions regarding the differences, feel free to send e-mail or call with your questions.   Because the Sense function is built-in to the "B" terminal, there is no Sense terminal on this model...  See the image below.

BIC-95300B install small.jpg (11972 bytes)


Click this link to download the instructions (.pdf)


Our BIC-75300A is the most versatile isolator or combiner on the planet.  No other battery isolator has as much capability in such a compact package(That is, except for our newest versions, the BIC-85300A, and BIC-95300A or B.) If you leave its center conductor open, the unit will behave just like a BIC-75150A (except the "B" version).  But you can utilize this center conductor to split the current into two halves allowing double the current carrying capacity while sacrificing one polarity isolation.  For certain applications such as a backup starting battery, winching, and snowplow applications, this is an ideal configuration.   As with the BIC-75150A, this unit can be wired in parallel to increase the total current carrying capacity.

Compare the features below:


120 Amp, 2 Battery
Diode Isolator
Or Relay
Automatic Isolation
of 2 batteries
Yes No Yes Yes
(multiple configuration options)
Automatic Isolation
of 3 batteries
No (yes, other models) No No Yes *
(multiple configuration options)
No Spark switching N/A No Yes Yes
Built-In capability to wire for cranking or winching current boost No Yes Yes Yes
Built-In capability to configure for engine cranking when main battery has zero charge remaining. No Maybe No
(will likely crank if allowed at least 15 minutes to transfer charge)
Unit operation "ON" current draw is less than 0.012 Amps N/A No Yes Yes
Does not consume and dissipate power due to Main battery or Main system current No
(it does consume main system power!)
Yes Yes Yes

(depends on hookup configuration)

Can be used with up to 200 Amp alternator No Maybe
(depends on auxiliary system load)
(depends on auxiliary system load)

(depends on hookup configuration)

Power dissipated with 120 Amps from the alternator divided with 60 amps in main and 60 amps in auxiliary system About 120 Watts < 10 Watts About 36 Watts About 36 Watts
or About 7 Watts
(depends on which configuration you use)
Voltage drop at 5 amps to the auxiliary battery system about 0.8 Volts < 0.01 Volts (When New..) < 0.05 Volts < 0.05, <0.02, or < 0.01 Volts
(depends on configuration used)
Has Built-In visual indicator used for system diagnostics / status No No Yes Yes
Has Remote indicator connection No No Yes Yes
Uses premium quality corrosion resistant connection hardware No No Yes (solid brass and Stainless Steel) Yes (solid brass and Stainless Steel)
Physical size less than 30 cubic inches No Maybe Yes Yes
Physical height less than 2 inches No No (Typical) Yes Yes
Inrush Currents Controlled N/A No Yes Yes

* Partial isolation with three batteries. Consult tech support if considering three batteries with one unit.

The Hellroaring BIC-75300A is ideal for use in:

Note: The BIC-75300A works great for typical gasoline engines as a backup starting system, but use on a typical automotive Diesel Engine will require two units wired in parallel for satisfactory results!

This is what you get when you order the BIC-75300A: BIC-75300A-kit-small.jpg (19094 bytes) 
BIC-75300A unit
Sense Resistor
Small external diode
Terminal lugs
Heat Shrink
Prefabricated 6 AWG jumper wire
Prefabricated ground wire with fuse
Sheet Metal Screws
Tie Wraps
Cable Clamps


A Remote Module is available as a purchase option.: Remote Module small.jpg (18551 bytes)

Click here for the BIC Specifications.


For high amp circuits such as the backup battery  setup, we have available a fuse (150 amp) and fuse holder set.  Order part number FS-150A. fuse set1 small.jpg (6260 bytes)


Our BIC-95150B and BIC-95300B units are the most current version. The BIC-95150B is suitable for the Auxiliary battery setup or the Start side isolation method. The BIC-95300B is most suitable for the Backup battery setup.



Affordable! Click on our Sales page for Pricing.

No Sales Taxes!

Click here to order! - BIC Sales


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Copyright 1998-2008 Hellroaring Technologies, inc.
Last modified: 9/1/2008