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  5. Vehicle Battery to Auxiliary Battery
Redarc Smart Start Battery Isolator - 12 Volt - 100 Amp

Redarc Smart Start Battery Isolator - 12 Volt - 100 Amp

Item # 331-SBI12
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Battery Charger 331-SBI12 - Vehicle Battery to Auxiliary Battery - Redarc
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This 100-amp dual-battery isolator pulls power from your start battery to charge your auxiliary battery. Isolator switches off to prevent dead battery if start battery voltage drops too low. Compact design for versatile mounting. Call 800-298-1624 to order Redarc battery charger part number 331-SBI12 or order online at etrailer.com. Free expert support on all Redarc products. Guaranteed Lowest Price and Fastest Shipping for Redarc Smart Start Battery Isolator - 12 Volt - 100 Amp. Battery Charger reviews from real customers.
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  • Reviews (12)
  • Q & A (6)
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  • Why etrailer?

Redarc Battery Charger - 331-SBI12

  • Battery Isolators
  • 12V
  • Redarc
  • Vehicle Battery to Auxiliary Battery

This 100-amp dual-battery isolator pulls power from your start battery to charge your auxiliary battery. Isolator switches off to prevent dead battery if start battery voltage drops too low. Compact design for versatile mounting.


Features:

  • Battery isolator protects start battery from auxiliary drain in multiple battery setups
    • Transfers charge from start battery to auxiliary battery once start battery gains charge from alternator
    • Stops charge transfer if start battery voltage drops too low, preventing excessive discharge
  • Override wire allows for emergency starts and simple fault detection
    • Attach to a switch (sold separately) to manually reverse charge and jump-start a dead start battery
    • Connect to an LED (not included) that can be mounted in your cab for easy viewing of diagnostics
  • Silver contact points ensure long life and corrosion resistance
  • Compact design allows for versatile installation
    • Mount the isolator in a convenient location near the start battery
    • 8-Gauge cables, fuses, and connectors sold separately
  • Made in Australia


Specs:

  • Application: vehicles with standard or temperature-compensating alternators
  • Maximum continuous current: 100 amps
    • Standby current: less than 5 mA
  • Output connection: 12V DC
  • Overall dimensions: 3-1/8" long x 2-15/16" wide x 2-1/2" tall
  • 2-Year warranty


With this dual-battery isolator, you can transfer power from your start battery to an auxiliary battery without draining your start battery. As long as your vehicle is on and the alternator is supplying power to the start battery, the Smart Start will transfer some of that power to your auxiliary battery. When your vehicle is shut off, the isolator will separate its connection and stop pulling power. This ensures that your start battery is protected so that no matter how weak your auxiliary battery becomes, your start battery won't be left flat. As a result, you can venture out without the fear of running into a dead battery.


Parallel Charging for Optimal Functioning

REDARC Smart Start Dual Sensing Battery Isolator Parallel Charging Setup Diagram

The Smart Start connects in-line between your start battery and the auxiliary battery. This way it can pull the charge directly from the battery instead of pulling from an outside source, like your vehicle's alternator. This method of charging is called parallel charging.


REDARC Smart Start Dual Sensing Battery Isolator Priority Charging Setup Diagram

Most other battery isolators on the market use priority charging. In a typical priority charging setup, the alternator provides charge to either the start battery or the auxiliary battery, but not to both simultaneously. This can leave both batteries underpowered. With parallel charging, the power is drawn directly from the start battery, which removes stress on the alternator because it doesn't have to manage both batteries separately. This streamline connection of the Smart Start to the start battery also prevents potentially damaging voltage surges that can occur when a priority charger switches over between batteries.


Additional Features

The blue override wire attached to the Smart Start allows for additional features, like the Start Assist function. This function allows you to jump-start a dead start battery using the auxiliary battery. Just connect the blue wire to a push-button switch (sold separately) to create a bridge of power from the auxiliary battery to your dead battery. Great for those mornings when you leave the radio on too long or forget to close the vehicle door.


You can also connect the blue wire to an LED (not included) to create an in-cab fault indicator. There is an internal LED on the unit itself that provides fault detection. This system communicates by causing the LED to flash a certain number of times to indicate errors. For example, 2 flashes signals over-voltage, and 3 flashes signals a voltage drop or excessive current draw fault. By connecting an additional LED to the blue wire, and running that up to your cab, you can more quickly assess these faults than if you had to peer into your engine compartment to see the light on the unit itself.


For assistance in wiring the Smart Start to include these optional features, please refer to the diagrams below:


Redarc Smart Start Battery Isolator Optional Wiring

Compact Design for Versatile Mounting

Mount the battery isolator in a location near your vehicle's start battery. The compact design of the unit allows you to have a good deal of flexibility when selecting a mounting location. A couple of places to consider would be in front of the radiator or behind the headlight assembly. You will need to make sure that the location you choose is not exposed directly to engine heat.


Once the unit is securely mounted, attach each battery to one of the terminals on the Smart Start. It is important to use the proper gauge wire for your particular application. If the cable length that you need is under 10', make sure that the wire gauge is 8 AWG. If you will be using between 10' and 20' of cable, you will want to select a thicker 6-gauge wire. To prevent damage from overload and short circuits, you will want to use MIDI fuses (331-FK100 - sold separately) to ensure that current is efficiently transferred.


For assistance in properly wiring the Smart Start, please refer to the diagram below:


Redarc Smart Start Battery Isolator Wiring Diagram



SBI12 REDARC Smart Start Battery Isolator - 12 Volt - 100 Amp

Installation Details 331-SBI12 Installation instructions


California residents: click here



Customer Reviews

Redarc Smart Start Battery Isolator - 12 Volt - 100 Amp - 331-SBI12

Average Customer Rating:  5.0 out of 5 stars   (12 Customer Reviews)

This 100-amp dual-battery isolator pulls power from your start battery to charge your auxiliary battery. Isolator switches off to prevent dead battery if start battery voltage drops too low. Compact design for versatile mounting.

- 331-SBI12
by:



- 331-SBI212
by:

Review from a similar Smart Start Isolator in Battery Charger


I put this on a 2013 chevy HD 4 wheel drive and it works very well. I have my main battery went bad and I open the hood and flip the switch and the accessory battery started my truck. thank you for having good products for us to buy when we need something,


Comments
It is still working very well and if I was to buy another truck i would put one on it.
Tommy R - 09/02/2021


- 331-SBI212D
by:

Review from a similar Smart Start Isolator in Battery Charger


I purchased the Redarc 331-SB1212D battery charger during the 2018 Christmas holiday season, it shipped with good efforts from etrailer. It is installed on a 2009 Chevy 5500 diesel powered cab and chassis truck , 2 on-board factory batteries in combination with add on 2 battery auxiliary bank, chassis mounted. I have extra heavy auxiliary power leads wire loom insulated routed with 350 amp Anderson connectors located at the ends , 1 lead to the front bumper , 2 leads to the rear bumper and a small 2/0 lead routed to the cab with 175amp Anderson connector for a 650 watt inverter. This application provides jumpstart service and remote power for dump trailer and 3000watt inverter power . This system has an additional provision to combine all batteries for heavy winching or sub zeros self jumpstart . My installer provided the additional switching to Redarc design specification.



- 331-SBI12D
by:

Review from a similar Smart Start Isolator in Battery Charger


Works great



- 331-SBI212D
by:

Review from a similar Smart Start Isolator in Battery Charger


With a flip of a switch from the drivers set, I'm able to re-charge the coach batteries from the vehicle battery via this Redarc Battery Charger while driving to the next camping adventure.



- 331-SBI12KIT
by:

Review from a similar Smart Start Isolator in Battery Charger


Wonderful instructions, plenty of wire, and a very good product. Will try and update this review in a year! Thanks for putting the pieces together. All solid quality, 60 amp fuses, and neatly trimmed heavy gauged wire.



- 331-SBI12D
by:

Review from a similar Smart Start Isolator in Battery Charger


works great would but anain


Comments
works perfect would buy again
David - 08/14/2020


- 331-SBI12KIT
by:

Review from a similar Smart Start Isolator in Battery Charger


It's for my 04 Jeep Wrangler TJ.



- 331-SBI212D
by:

Review from a similar Smart Start Isolator in Battery Charger


Great product, great service.



- 331-SBI12KIT
by:

Review from a similar Smart Start Isolator in Battery Charger


Awesome product, easy to install and come with all parts needed to install second battery!!!



- 331-SBI212D
by:

Review from a similar Smart Start Isolator in Battery Charger


This bad boy had me at dual sensing, and 200 amps is exactly what I need for my beefy house battery bank. One knock might be a short ground wire, but otherwise great product.



- 331-SBI212D
by:

Review from a similar Smart Start Isolator in Battery Charger


Product works as expected and I would recommend it to anybody needing a product like this.


12
12

Ask the Experts about this Redarc Battery Charger

  • How to Jump Start Vehicle Battery From Aux Battery with Redarc BCDC Charger
    Than you so much for your recent purchase! If you want to be able to jump start your vehicle's battery using the auxiliary battery your best option really is to add the Redarc Smart Battery Isolator (SBI) # 331-SBI12 to your existing setup that includes your Redarc BCDC Charger # 331-BCDC1225D. I reached out to my contact at Redarc and this is the specific isolator they recommended to work with this charger for this purpose. I have attached a wiring diagram that you might also find...
    view full answer...
    Image 1 for
  • How to Charge Truck Bed Camper Battery from Vehicle
    You are on the right track to answering your question of "why isn't the battery," being charged as the reason is that the charge circuit of your vehicle just can't carry enough amperage/voltage to keep the battery charged. The reason this is the case for your new setup is most likely because your new camper has a larger battery and/or has appliances that just draw more which uses more of the battery and the current circuit just can't keep up. So the wiring of the 12 volt charge circuit...
    view full answer...
  • Connecting 2 12 Volt Batteries in Parallel on my Polaris Ranger
    This is a good plan to help ensure you don't get stranded. To start You want to use a heavy gauge wire to connect batteries in parallel. I generally make the jumper you need from MaxxTow Jumper Cables part # MT89FR you can cut these down to whatever size you need then add on the appropriate cable ends to connect to your battery. For the isolator using the Redarc Smart Start Battery Isolator part # 331-SBI12 will handle all you will be putting it through I really like the isolator here...
    view full answer...
  • Can Redarc BCDC Battery Charger # 331-BCDC1240D Be Used to Charge 2 Trailer Batteries
    I spoke with my contact at Redarc regarding the In-Vehicle BCDC Battery Charger # 331-BCDC1240D. He said this unit could charge two batteries on the trailer but only if they were pretty close together and of the same chemistry. If this is the case then you can add the Redarc Smart Start Battery Isolator # 331-SBI12 between the two batteries to prevent one feeding into the other. I have attached a short video review that you can check out as well. Otherwise your best option for charging...
    view full answer...
  • Comparing CTEK D250S and SmartPass vs Redarc DC-DC Charger
    I reached out to my contact at CTEK and the CTEK D250S Dual Battery Charger 12V- 20a, 5 step, Heavy Duty CTEK40186 (discontinued) does utilize the Maximum Power Point Tracker (MPPT) as well. When partnered with the (discontinued) Smartpass CTEK56676 you will be able to run your fridge/freezer as you stated. The Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1240D will also be able to accomplish this so it is a better option for this application. You will also need the fuse kit # 331-FK60...
    view full answer...
  • Is There a Diode in the Circuit to the RV Auxiliary Power
    No, there is not a diode in the circuit feeding the RV Auxiliary power. It sounds to me that you are wanting to use the solar panels on your RV to maintain the charge on your 2004 Chevrolet Silverado. You will not be able to use the solar panels to charge the battery on your truck. Unless you used the solar panels to power your RV and plugged a charger like the CTEK MULTI US 7002 12-Volt Universal Battery Charger # CTEK56353 into your RV outlet. If you are concerned about your RV...
    view full answer...

Do you have a question about this Battery Charger?




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Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jeff D
Installed by:
Jeff D
Employee Chris R
Video Edited:
Chris R
Employee Brian T
Written by:
Brian T
Employee Kristina F
Updated by:
Kristina F

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