ProMariner - Battery Isolator - 21302
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The ProMariner 2-130-2 Multi-Battery Isolator is a solid-state DC charging isolator for marine electrical systems with two alternator inputs and two independent battery banks. It allows compatible charging sources to replenish separate battery banks while helping prevent one battery bank from discharging into another. This style of isolator is commonly used on dual-engine boats, multi-bank starting/house battery systems, and marine installations where charging separation is required without using a manual battery switch as the only protection.
Key Features
- ProMariner part number: 2-130-2
- Catalog reference: PRO21302
- Product type: Multi-battery charging isolator
- Configuration: 2 alternator inputs / 2 battery bank outputs
- Amperage rating: 130 amp maximum alternator output rating
- Voltage compatibility: 6V, 12V, 24V, and 32V negative-ground DC systems
- Design type: Solid-state diode-based isolator
- Terminal design: Gold-plated terminal style with protective insulator boots
- Primary function: Allows charging of multiple battery banks while reducing bank-to-bank discharge
- Common use: Dual-engine marine electrical systems, starting/house bank separation, and multi-bank DC charging layouts
Product Compatibility
This isolator is intended for compatible marine DC charging systems with two alternators and two battery banks. It may be used in negative-ground electrical systems where the alternator output, battery bank layout, wiring size, and charging strategy match the isolator's rating and configuration.
Common system layouts include:
- Dual-engine boats with one alternator per engine
- Two-bank systems with separate starting and house batteries
- Marine DC systems requiring charging separation between independent banks
- 6V, 12V, 24V, or 32V negative-ground applications where the alternators and regulators are compatible with diode isolation
This is not a battery charger, battery combiner, ACR, or manual battery switch. It is a charging isolator and must be installed as part of a correctly designed marine DC system.
Fitment Notice
Confirm the alternator output rating, battery bank count, system voltage, negative-ground configuration, cable length, cable gauge, circuit protection, regulator type, and alternator sensing method before ordering. Standard diode isolators create a voltage drop across the charging circuit, commonly around 0.6V, which can affect charging voltage at the batteries.
This isolator is not recommended for self-energizing one-wire alternators unless the alternator manufacturer confirms compatibility. Systems using external voltage sensing may require regulator or sense-wire adjustments so the batteries receive the correct charging voltage.
When This Product Needs Replacement
Replace the isolator if battery banks are no longer charging correctly, one bank appears to drain into another, terminals are overheated or corroded, the isolator case is damaged, or voltage testing confirms excessive drop or failed diode operation. It should also be inspected during alternator replacement, battery bank upgrades, wiring refits, or conversion from a legacy charging layout.
Common symptoms of a charging isolator problem include weak battery charging, uneven battery voltage between banks, alternator output present at the alternator but not at the battery, hot terminals, melted insulation, or charging performance that changes when loads are applied.
Installation Notes
Mount the isolator in a dry, well-ventilated location close to the alternators when practical to reduce unnecessary cable length and voltage loss. Do not mount directly to the engine block or near exhaust manifolds, turbochargers, or other high-heat areas.
Use properly sized marine-grade cable, terminals, strain relief, and overcurrent protection for the alternator output and battery bank circuits. Keep all terminals clean, tight, and protected from accidental shorting. Confirm polarity and wiring layout before energizing the system.
Because alternator charging systems can be damaged by incorrect wiring, this component should be installed according to the ProMariner instructions, alternator manufacturer guidance, and applicable marine electrical standards. After installation, verify alternator output, voltage at each battery bank, charging balance, terminal temperature, and operation under load.
Alternate/Superseded Part Numbers
- ProMariner: 2-130-2
- Catalog number: PRO21302
- Common description: ProMariner Multi-Battery Isolator
- Configuration reference: 2 alternators / 2 battery banks
- Rating reference: 130 amp
Parts Desk Insight
The key decision is whether the boat needs a diode isolator or a zero-voltage-drop charging relay/ACR style system. Diode isolators are simple and effective for keeping banks separated, but the voltage drop must be considered. On modern alternator systems, confirm the regulator sensing method before installation so the batteries are not undercharged.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
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Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
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