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Redarc Smart Start Battery Isolator - 12 Volt - 100 Amp

Redarc Smart Start Battery Isolator - 12 Volt - 100 Amp

Item # 331-SBI12
Retail:$206.91
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Battery Charger
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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. 1-800-940-8924 to order Redarc battery charger part number 331-SBI12 or order online at etrailer.com. Free expert support on all Redarc products. Great prices and Fastest Shipping for Redarc Smart Start Battery Isolator - 12 Volt - 100 Amp. Battery Charger reviews from real customers.
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  • Reviews (20)
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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 Satisfaction Score:


Customer Reviews

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

Average Customer Rating:  5.0 out of 5 stars   (20 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.

by:

This is a great product. I use it to run my fridge in my Jeep to keep the second battery charged.




by:

Got exactly what I needed and very fast.




by:




by:

Review from a similar Smart Start Isolator in Battery Charger


Really like this isolator. Replaced two Cole-Hersey Isolators that failed prematurely in a Class C RV after only 11 and 3 months. Second photo shows Cole-Hersey replaced by Redarc shown in last picture




by:

Review from a similar Smart Start Isolator in Battery Charger


I use this in my Jeep to keep my second battery for accessories charged and ready. After a year of having it installed I couldn’t be happier with the product. I have spoken with the folks out in Australia at Redarc and find them to be very awesome to speak too.




by:

Review from a similar Smart Start Isolator in Battery Charger


I have used these redarcs a couple of times with great success but having this shipped in a very timely fashion from etrailer is fantastic!




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


by:

Review from a similar Smart Start Isolator in Battery Charger


works prefect




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.









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.




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.




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.




by:

Review from a similar Smart Start Isolator in Battery Charger


It's for my 04 Jeep Wrangler TJ.




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


by:

Review from a similar Smart Start Isolator in Battery Charger


Works great




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.




by:

Review from a similar Smart Start Isolator in Battery Charger





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!!!




by:

Review from a similar Smart Start Isolator in Battery Charger





by:

Review from a similar Smart Start Isolator in Battery Charger


Great product, great service.



20
20

See what our Experts say about this Redarc Battery Charger

  • Recommended Battery Isolator for Ram ProMaster with 220 Amp Alternator
    In regards to battery isolators, they should be rated at or close to the changing amperage rating of your alternator. They don't really need to exceed this as it's very unlikely your alternator will ever reach its max charging amperage therefore, I recommend the Redarc Smart Start Battery Isolator part # 331-SBI212 which is rated at 200 amps and the highest we offer. That said, these don't work with lithium batteries and the highest rated battery isolator we do offer for this is the Redarc...
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  • Can Battery be Jumped that Has Redarc Smart Start Load Disconnect for Manager30 System
    There's no reason you couldn't jump start a battery that's in use that has the Redarc Smart Start Load Disconnect for Manager30 Battery Management System # 331-SBI12-BLD installed. The type of voltage and amperage that a battery jump provides is right at the same as a fully charged vehicle battery so the presence of the additional amperage would not be an issue at all.
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  • Using Redarc Battery Isolator on Boat with Two Engines and Batteries
    This is a really good question. I spoke with my contact at Redarc and this is what they sent me: There are a few variables to the application but realistically keeping each engine with its own starting battery is recommended. The reason behind this is if there was an issue with one engine, you will always be able to run the other. My assumption is that your customer is wanting to run auxiliary equipment. If this is the case then another battery or battery bank is required and then run...
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  • Battery Charger Recommendation to Charge Trailer Battery from Alternator and Solar Panel
    The Redarc In-Vehicle BCDC Battery Charger # 331-SBI12KIT that you referenced can manage input current from a solar panel and an alternator as well as 12 volts to 24 volts so you'd be totally fine to use this. You would not be able to reverse the flow of the charge though and go from the battery bank you are charging back to the vehicle. It only allows charging in one direction. I attached a chart that shows how this wires up as well.
    view full answer...
    Image 1 for
  • How to Wire Two 6 Volt Batteries to a 12 Volt Battery
    I attached a picture that shows how to run batteries in both series and parallel. You will need to wire up the two 6 volt batteries like the picture on the left so that they would be in series and at 12 volts. To connect a 12 volt battery to that circuit you would need to run the positive post of the 12 volt battery to the positive side of the battery run on the in series batteries. Not the one that is connecting the two batteries, the one that would be the output of the two in-series...
    view full answer...
    Image 1 for
  • Should Batteries be Connected of Redarc Smart Start Battery Isolator
    Thank you for your purchase of the Redarc Smart Start Battery Isolator # 331-SBI12D from etrailer. In regards to the isolator, the two batteries would not be connected. Like you mentioned, the negative posts of each batteries would be grounded, as stated in the linked directions. I have added links to video reviews for you to check out as well.
    view full answer...
    Image 1 for Image 2 for
  • Will the Camper Battery Drain the Vehicle Battery While Plugged-In and Off-Grid Boondocking
    Yes, leaving the trailer attached to the vehicle via the trailer connector can drain the vehicle battery as the vehicle battery is providing power to the trailer battery via the battery charge line circuit run through the trailer connector. That said, if you install a smart device on this circuit it can sense when the vehicle battery gets too low and it will shut the circuit off, it can even take power from the trailer battery if the vehicle battery is too low to start the vehicle. The...
    view full answer...
  • Can Breakers be Used Instead of Fuses with Redarc Smart Start Battery Isolator
    Yes, if you wanted to use 100 amp circuit breakers with the # 331-SBI12D instead of the fuses you certainly could.
    view full answer...
  • Would Redarc Smart Start Battery Isolator Kit Work on 1978 GMC K25 Truck
    While your 1978 GMC truck is a bit older it does use a standard alternator like what the Redarc Smart Start Battery Isolator with Wiring Kit # 331-SBI12KIT was designed to work with so it would work great for you.
    view full answer...
  • Diagram Of Mounting Holes For Redarc Smart Start Battery Isolator 331-SBI12D
    As you can see in the attached photo, the Redarc Smart Start Battery Isolator - Dual Sensing - 12 Volt - 100 Amp # 331-SBI12D has bolt holes that are 2-1/8" from each other.
    view full answer...
    Image 1 for
  • How To Charge On-Board Auxiliary Battery from Start Battery on Vehicle
    If you're looking to change an on-board auxiliary battery from the main battery then I recommend using the Redarc Smart Start Battery Isolator with Wiring Kit part # 331-SBI12KIT. This kit has everything you need to hook up the auxiliary to the start battery and it has built-in features to prevent the auxiliary battery from draining the start battery.
    view full answer...
  • How To Fix Trailer Battery Draining Vehicle Battery
    It sounds like you have an issue with the trailer battery draining the vehicle battery and in which case you would just need a smart device that better manages what power you have. For example, you should only be charging the trailer battery while you are getting a charge from the alternator to the vehicle battery. In order to ensure this happens you can use the Redarc Smart Start Battery Isolator with Wiring Kit part # 331-SBI12KIT which will also shut power off to the trailer battery...
    view full answer...
  • Should I Install a Relay To Cut Power To Trailer Battery Charge on 7-Way with Vehicle Off
    The battery charge line circuit is not keyed in many vehicles from the factory meaning it has constant power. If you wish to install a simple isolator then you can do so but a better option is the Redarc Smart Start Battery Isolator with Wiring Kit part # 331-SBI12KIT which actually monitors the status of the start battery and uses that to determine when it should charge the aux battery. It can also pull power from the aux battery to charge the start if something goes wrong. This is a must...
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  • No Power To 12 Volt Pin In Trailer Connector on 2017 Ford F-350
    It doesn't work the way you think it does so that's probably why you think there is an issue. The circuit is usually only powered while traveling down the road and gear shifting takes place. The only way to get around this is to run a power wire of your own from the battery to the trailer connector. We do offer kits for this like the Redarc Smart Start Battery Isolator with Wiring Kit part # 331-SBI12KIT which is a bit better than the factory system in that it can sense trailer battery...
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  • Can You Install an Auxiliary Battery in a Truck Bed and Use for Power
    The only issue you'll run into installing an auxiliary battery in the truck bed would be keeping it charged. In order to do this you'll need to pull said charge from the vehicle's start battery unless you want to remove the battery and plug it in somewhere with a wall outlet each time. There also needs to be some sort of smart device in-between so you can be sure it doesn't pull too much juice from the vehicle's main battery. For this, I recommend the Redarc Smart Start Battery Isolator...
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  • Redarc Smart Start Battery Isolator Recommendation for 150 Amp/Hour Alternator
    Since the alternator is 150 amp/hours you'd want the Redarc Smart Start Battery Isolator # 331-SBI212D which is rated for 200 amps. The 100 amp kit would be too low rated for your alternator.
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  • Redarc Auxiliary Battery Isolator for 1992 Jeep Comanche with 90 Amp Alternator
    You basically just need to go with the Redarc Smart Start Battery isolator that has at least the amount of amperage required that your alternator puts out so for a 90 amp alternator you'd want the part # 331-SBI12D.
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  • Battery Isolator that Can be Used with Smart Alternator as well as Lithium Battery
    The Redarc Isolator part # 331-SBI212D does work with smart alternators but since Lithium batteries charge at a higher voltage you'd need to go with a different isolator if you do switch to Lithium batteries like with the part # 331-SBI12-LLD instead.
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  • Can Redarc In-Vehicle BCDC Battery Charger be Used to Jump Start Battery
    In addition to the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D you need to use a Redarc Smart Start Battery Isolator. I recommend using the Battery Isolator with Wiring Kit # 331-SBI12KIT if you don't already have the fuse kit, or part # 331-SBI12D if you do already have the fuse kit. With the isolator installed you can then connect a push-button into your system to help jump your start battery.
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    Image 1 for
  • How to Use to Motorhome Alternator to Charge Main Batter and/or Auxiliary Battery
    From the sound of your question, it sounds like you are trying to use your motorhome's alternator to charge your main battery along with an auxiliary battery. It also sounds like you already have a battery isolator, and that is exactly what you need. If you do not have one (or if you discover that yours is defective), a great alternative is the Redarc Smart Start Battery Isolator - 12 Volt - 100 Amp # 331-SBI12 along with the fuse kit # 331-FK100. I went ahead and attached a diagram of...
    view full answer...
    Image 1 for
  • 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 helpful.
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    Image 1 for
  • Are Fuses Needed When Using Redarc Smart Start Battery Isolator to Charge Secondary Battery
    If you're using the Redarc Smart Start Battery Isolator # 331-SBI12D between the start battery and your auxiliary battery (which is what I recommend for transferring the charge back and forth) then you will want to add a couple 100-amp MIDI fuses in-line before and after the isolator. These fuses can be found in the Redarc Fuse Kit # 331-FK100, which also comes with the fuse holders, hardware, and 4 cable crimp lugs. I have attached an image to assist. The Smart Start Battery Isolator...
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    Image 1 for
  • Recommended Battery Isolator for Diesel Truck Start and Nearly Dead Trailer Batteries
    With the Tow Ready Battery Isolation Solenoid # TR118665 you very likely could have the issue you are describing with a diesel truck if your accessory is connected to your ignition. If you want an isolator that will ensure you will be able to start your diesel truck a much better option is the Redarc Smart Start Battery Isolator - Dual Sensing - 12 Volt - 100 Amp # 331-SBI12D. This is designed for the dual battery systems of most diesel applications and will give you parallel charging....
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  • Using a Redarc Battery Isolator to Add a Second Battery to a 2009 Chevy Suburban 2500
    Yes, you can use the Redarc Smart Start Battery Isolator # 331-SBI12D on your 2009 Chevy Suburban once you add a second battery. Basically this charger will install between the two batteries. Your regular battery will get a charge from the vehicle alternator and the 2 batteries will "feed" each other as needed. You may also consider adding the TorkLift HiddenPower Under-Vehicle Battery Mount with Battery Box # TLA7730 which was designed for Chevy trucks but could be used with your Suburban...
    view full answer...


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Info for this part was:

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Installed by:
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Employee Chris R
Video Edited:
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Employee Brian T
Written by:
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Employee Kristina F
Updated by:
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