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Arco Marine
Arco Marine BI-0702 Battery Isolator

Arco Marine BI-0702 Battery Isolator

Best price now

$70.00at eBayChecked Nov 3

38% under what the other stores charge

Compared across 12 stores. Prices are checked against each store and labelled with when. Store links may earn us a commission.

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Price facts

  • Last seen at $70.00 at eBay on Nov 3.
  • Checked at 12 stores.

Our take on the Arco Marine BI-0702 Battery Isolator

The Arco Marine BI-0702 is a solid-state battery isolator for boats with one alternator and two battery banks. It lets charging current flow one way only, so the alternator charges both batteries in proportion to their needs and a fuller battery cannot drain into a weaker one. It is rated for 70A output and works with 10 to 350-amp alternators on 12, 24 or 32-volt negative-ground systems. It is a fit-and-forget part for dual-battery boats, but it will not work with 12-volt systems feeding 24-volt trolling motors or newer outboards that use rectifier-regulator charging.

Best forBoats with one alternator and two battery banksInboard and outboard setups with separate starting and house batteriesOwners replacing a failed isolator on older charging systemsKeeping a starting battery from being drained by house loads
Pros
  • Charges both batteries automatically while the engine runs
  • Blocks a charged battery from discharging into a weaker one
  • Works across 12, 24 and 32-volt negative-ground systems
  • Handles alternators from 10 to 350 amps
  • Direct replacement for Volvo 873120 and Sierra 18-6855
Cons
  • Not for 12-volt systems running 24-volt trolling motors
  • Not for newer outboards with rectifier-regulator charging
  • Solid-state design drops some charging voltage to the batteries
  • No switch position changes needed, but it does not replace a selector switch

Arco Marine BI-0702 Battery Isolator prices at every store

  • eBayNew

    Availability unknown

    $70.00Checked Nov 3
    Visit eBay
  • Boatersland MarineNew

    Availability unknown

    $83.99Checked Nov 3
    Visit Boatersland Marine
  • Marine Parts SourceNew

    Availability unknown

    $90.15Checked Nov 3
    Visit Marine Parts Source
  • Inverter Service CenterNew

    Availability unknown

    $90.15Checked Nov 3
    Visit Inverter Service Center
  • RV Parts SourceNew

    Availability unknown

    $90.15Checked Nov 3
    Visit RV Parts Source
  • Boat Owners WarehouseNew

    Availability unknown

    $102.99Checked Nov 3
    Visit Boat Owners Warehouse
  • MarineEngineParts.comNew

    Availability unknown

    $112.99Checked Nov 3
    Visit MarineEngineParts.com
  • Macomb Marine Parts and AccessoriesNew

    Availability unknown

    $113.95Checked Nov 3
    Visit Macomb Marine Parts and Accessories
  • ARCO MarineNew

    Availability unknown

    $113.97Checked Nov 3
    Visit ARCO Marine
  • Go2marineNew

    Availability unknown

    $124.24Checked Nov 3
    Visit Go2marine
  • WalmartNew

    Availability unknown

    $135.59Checked Nov 3
    Visit Walmart
  • PalmerPowerNew

    Availability unknown

    $136.76Checked Nov 3
    Visit PalmerPower

Store links may earn us a commission.

Arco Marine BI-0702 Battery Isolator price history

Lowest price we've seen: $70.00 on Nov 3 at eBay. Tracked across 12 stores since Nov 3.

From Marine Parts Source

  • 70 amp 2 bank battery isolator
  • 1 alternator post, 2 battery posts
  • Allows electrical current to flow in one direction only
  • Rated for 10 to 350 amp alternators on 12, 24, or 32 volt negative ground systems
  • Replaces Volvo 873120
  • Replaces Sierra 18-6855
Sizing
Not for use on 12 volt charging systems with 24 volt trolling motors or newer outboard engines with rectifier-regulator charging systems

About the Arco Marine BI-0702 Battery Isolator

The Arco Marine BI-0702 is a solid-state battery isolator for inboard and outboard boats. It connects 1 alternator to 2 batteries and handles up to 70A. It has 1 alternator post and 2 battery posts.

The isolator lets current flow in one direction only. The alternator can be connected directly to both batteries, and a higher-charged battery cannot discharge into a lower-charged one. Both batteries charge automatically, in proportion to their needs, whenever the engine is running.

When used with selector switches, the switch position does not need to change to charge both batteries. The isolator splits the alternator's charging current between the batteries regardless of switch position. It is rated for 10 to 350-amp alternators on 12, 24, or 32-volt negative ground systems. It cannot be used on 12-volt charging systems with 24-volt trolling motors, or with newer outboard engines that have rectifier-regulator charging systems.

Model
BI-0702
Type
Solid-state battery isolator
Max current
70A
Alternators
1 (rated for 10 to 350 amp)
Batteries
2
Posts
1 alternator post, 2 battery posts
System voltage
12, 24, or 32 volt negative ground
Replaces
Volvo 873120, Sierra 18-6855
Not for
12 V systems with 24 V trolling motors; outboards with rectifier-regulator charging

Questions and answers

Will it work with my outboard?
Only with older outboards that do not use a rectifier-regulator charging system. Newer outboards with rectifier-regulator charging are not compatible.
Can I use it with a 24-volt trolling motor?
No. It cannot be used on 12-volt charging systems that feed 24-volt trolling motors.
Does it replace my existing isolator?
It is listed as a replacement for Volvo 873120 and Sierra 18-6855, so check those part numbers against your old unit.
Do I still need a battery selector switch?
You can keep one. With an isolator, both batteries charge regardless of switch position, so you do not have to move the switch to charge them.
What alternator size does it support?
It is rated for 70A output and for alternators from 10 to 350 amps on 12, 24 or 32-volt negative-ground systems.
How many batteries does it charge?
Two. It has one alternator post and two battery posts.
Where is the Arco Marine BI-0702 Battery Isolator cheapest?
At eBay, for $70.00, 38% under what the other stores charge, as of our latest check.
Where can I buy the Arco Marine BI-0702 Battery Isolator?
12 stores we checked sell it, including Boatersland Marine, eBay, Marine Parts Source, Inverter Service Center, RV Parts Source.

Stores we've priced the Arco Marine BI-0702 Battery Isolator at

  • Walmart deals and prices

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