ARCO Marine BI-1203-3A Battery Isolator - 120A - 1 Alternator, 3 Battery [BI-1203-3A]
SKU: 75239541574

ARCO Marine BI-1203-3A Battery Isolator - 120A - 1 Alternator, 3 Battery [BI-1203-3A]

Sale price$131.39 Regular price$145.99
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Description

ARCO Marine BI-1203-3A Battery Isolator - 120A - 1 Alternator, 3 Battery [BI-1203-3A]BI 1203 3A Battery Isolator 120A 1 Alternator, 3 Battery The Arco Marine BI 1203 3A is an inboard outboard battery isolator that can handle 1 alternator, 3 batteries, and 120A max. Rated for use with 10 to 350 amp alternators on 12, 24, or 32 volt negative ground systems. *Includes exciter terminal Features: 1 alternator, 3 batteries, 120A max Inboard and outboard battery isolators are solid state devices that allow electrical current to flow in one

BI-1203-3A Battery Isolator - 120A - 1 Alternator, 3 Battery

The Arco Marine BI-1203-3A is an inboard/outboard battery isolator that can handle 1 alternator, 3 batteries, and 120A max. Rated for use with 10 to 350-amp alternators on 12, 24, or 32-volt negative ground systems.

*Includes exciter terminal

Features:

  • 1 alternator, 3 batteries, 120A max
  • Inboard and outboard battery isolators are solid-state devices that allow electrical current to flow in one direction ONLY, thus permitting the alternator to be connected directly to two batteries without fear of one higher-charged battery discharging into the lower-charged battery.
  • Both batteries are always being charged automatically, in proportion, to their needs whenever the engine is running.
  • When battery isolators are used in conjunction with selector switches, it is not necessary to change the switch position to provide for charging of both batteries.
  • Isolators provide proportioning of the output or charging current on the alternator to the batteries as required, regardless of switch position.

NOTE: Battery Isolators cannot be used on 12 volt charging systems with 24 volt trolling motors or newer outboard engines with rectifier-regulator charging systems.

This product may not be returned to the original point of purchase. Please contact the manufacturer directly with any issues or concerns.
Quick Guide (pdf)
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
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Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 75239541574

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chad martin
Chelsea, US
★★★★★ 4
Fresh Air Upgrade for My 2024 Impreza
Installed this in my 2024 Subaru Impreza, and it fit perfectly—no issues. The air smells noticeably cleaner now, and it took less than 10 minutes to swap out. The carbon and HEPA filtration does a great job clearing out odors, dust, and pollen—definitely an upgrade over the factory filter. The build feels sturdier than the OEM version, though it does have slightly fewer pleats. Might mean it needs replacing a bit sooner, but for the price and performance, I’m fine with that tradeoff. If you’re looking for a quick, affordable way to improve your cabin air, this one’s a solid pick. 
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Reviewed in the United States on June 26, 2025
G
Verified Purchase
Gram21
Phoenix, US
★★★★★ 5
Well built, good fit.
I like it so well, I just bought two more to keep on the shelf for when the price doubles. Seems better built than oem, but I don't know how you can judge the filtration; seems good though.
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Reviewed in the United States on May 6, 2026
L
Verified Purchase
LJ
Battle Creek, US
★★★★★ 5
Great product
Perfect fit for 21 Cross Trek
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Reviewed in the United States on February 12, 2026
M
Verified Purchase
Mr Frosty
Charlottesville, US
★★★★★ 5
Good fit, good value
Style: CF12436 Classic, Style: CF12436 Classic
Purchased this filter for my 2023 Outback. First off changing the cabin filter on this model Subaru is amazingly easy and can be done with no tools and no more then 5 minutes. Pictures posted show packaging, the paper "Blue" filter side, the "Black" charcoal side and the foam outer edge. The filter is well made and is very sturdy as the outer shell is plastic vs. other paper filters that are more flexible. Holding the filter in your hand and giving it a slite shake you can hear the activated charcoal within it. After installing the filter I had a few trips in the car, did I notice any difference in the air quality coming into the cabin....... no. But does this mean its not working? also no. What I can say is the filter fit snug and left no gaps, and with the plastic surroundings and foam in sure the filter will not be letting anything get by as it passes through the system. All and all this filter is well made and sturdy, and seems to be a good value with other paper only filters being about the same price.
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Reviewed in the United States on May 4, 2026
B
Verified Purchase
bin
Port Orchard, US
★★★★★ 5
Perfect Fit and Great Quality
Style: CF12552 Classic
The thickness is just right and fits perfectly. Easy to install, good airflow, and the air feels much cleaner after replacing the old filter. Great value for the price.
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Reviewed in the United States on May 22, 2026

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