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Hellroaring Technologies


Battery Isolator / Combiner

BIC-95150B small.jpg (9823 bytes)


Click this link to download the instructions (.pdf)

The BIC-95150B provides built-in Transient Suppression, and internal sensing.  So, this makes for the simplest and cleanest install compared to the original models.   This model is the choice for either an Auxiliary battery setup or the Start side isolation method. Should you have questions regarding this model or your application, feel free to send e-mail or call with your questions. 

This BIC allows you to isolate your starting battery from all your deep cycle or accessory loads and provide the most efficient charging to both battery systems.   The most popular installation, and the simplest, is the Auxiliary battery setup.    This setup allows you to automatically provide the charge path to your Auxiliary battery and keep it and its loads isolated from the main vehicle battery. The Auxiliary battery setup doesn't need to be matched to the alternator. But, rather it is more important to match it to what your Auxiliary battery side average loads may typcally see. For those applications where the Auxiliary battery setup is most desired, but more than 60 to 80 peak charge rate is needed, you can always use multiple BIC-95150B units wired in parallel runs to almost double or triple your current handling capability. But, most Auxiliary battery applications, only one BIC is needed. See the diagram below for the basic setup:

Auxiliary Battery setup diagram

FAQ: Why do you recommend a minimum of 20 feet of wire between the BIC and Auxiliary battery?

Answer: For a 12V Lead Acid battery based system, about 20 feet of wire will tend to limit the peak demand to the Auxiliary battery to about what that wire can handle in amperage. For the recommended maximum 8 AWG wire size, this tends to be about 60 to 80 amps peak, and under 50 amps on average. So, this practice will reduce the risk of overloading the system and helps the alternator to maintain regulation and for those times where the alternator output is fully consumed, it helps keep the voltage at the main system from dropping its voltage as much as it would with less length or larger wire. Bottom line, is this provides just the right balance of resistance in the charge line to yield a decent charge rate and excellent reliability. The BIC can handle up to 95A continuous, so this also provides a good margin for long term reliability. Using this method, some customers have reported reliable operation in excess of a dozen years and still operating like new.

For the less common application where one has a high output alternator, and the application uses high demand loads of long durations, i.e. greater than 1000W average demand load while driving, then one may consider the Start side isolation method. With this method, the high output alternator is re-connected to go directly to the Auxiliary battery so that all of its high output will be available directly to the high demand Auxiliary loads. Then, the BIC is connected between the Auxiliary side (i.e. alternator) and the main vehicle Start battery. See the Start battery isolation method diagram below. This isolation method is not the recommended method for most applications. But, for those applications that need it, the setup doesn't care how large the alternator and associated wiring is, nor how high the high power distribution loads are. What matters is that the main vehicle loads and start battery is not significantly greater than what is common for most vehicles.

Start Side isolation method diagram


Use it for : 

  • Auxiliary battery isolation from the main vehicle battery and system.
  • Faster charging of your Deep Cycle battery banks with high output alternators.
  • RV / Trailer / Camper deep cycle battery isolation.
  • Starting boost (although not normally recommended).
  • 4x4 / RV security auxiliary battery / Winch boost.
  • Mobility Vans Auxiliary battery power.
  • Dual battery installations for Power Audio systems.
  • Starting Battery isolation for boats.  
  • Trolling Motor battery charging from Outboard Motors.
  • Locksmith vans.
  • Many other 12Vdc applications.


Hellroaring BIC-95150B

Premium Quality Features:

  • Designed for automotive and marine, 12 Volt negative ground systems only.
  • Automatic Electronic Isolation (switches ON when charge voltage is available. Switches OFF when the voltage drops below any surface charge.  Although not normally recommended, switching voltage thresholds can be modified from standard settings with the use of an external resistor if desired. )
  • Very low voltage drop (No diode effect! Functions like a heavy duty relay.)
  • Rated for up to 95 Amps continuous; 150 Amps short term at an ambient temp of +65C (+149F).
  • Configured for starting battery isolation, can be used with alternators with greater than 300 amp outputs.
  • Very low operation current (< 0.012 A when ON, < 0.0005 A when OFF.)
  • Built-In LED indicator. (Provides diagnostics of battery system)
  • Output connection for a Remote LED indicator.
  • Remote Switching Capability (for drawing power from both batteries when desired) to ON, Automatic, or OFF (disables automatic switching).
  • Compact Size (less than ½ the size of similar rated diode isolators or other combiners.)
  • Simple installation (Works great with internal sense alternators.)
  • Upgradable (You can increase current handling capability simply by adding a second BIC-95150B in a parallel run.)
  • All Solid State Design (No mechanical parts to wear out.)
  • Premium Quality Solid Brass (tin plated) Terminals with large surface contact area ( for maximum current transfer. )
  • Hex Base Terminal Design (for strength.  Only a nutdriver needed to tighten!)
  • Premium Quality Stainless Steel signal terminals.


This is what you get when you order the BIC-95150B:
BIC-95150B unit (With 1/4-28 Terminal Studs)
Terminal lugs - 2 ea 8AWG with 1/4 ring
Nuts, 1/4-28 & 6-32
Heat Shrink
Sheet Metal Screws
Ground wire with fuse holder and terminal lug
Fuse, 3A
Nylon Cable clamps
Nylon tie wraps
Nylon Cap Nuts for insulation


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


You can purchase your fuses or circuit breakers locally.  Or, you can purchase a 50 amp, manual reset dc circuit breaker from us added to your order. Circuit protection should be used within 1 ft of each battery end of the charge line. So, most applications would use two CB-50A breakers.

Order CB-50A.:



Hellroaring BIC FAQ

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.



No Sales Taxes!

Yes, I want to Buy!! Click on our Sales link in the contacts section at the bottom of this page for current pricing and sales.

Still have questions? Send an email to the email address link on our contact information below.

 Click here for the BIC-95150B instructions and specs.




Contact Information

For General Information, Sales, Technical or Customer Support:

Telephone: 406-883-3801
Postal address: P.O. Box 1521, Polson, MT 59860
Electronic mail: sales23@hellroaring.com
Sales/Pricing info: Sales page

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Send mail to sales23@hellroaring.com with your orders, questions, or comments.

Copyright 1998-2023    Hellroaring Technologies, inc.
Last modified: 10-31-2023