There are 5 factors to consider when choosing a high output alternator for your application.

1. Current Output

Choosing the right sized alternator for your battery bank is important. A general rule of thumb is a 4:1 ratio – e.g. a 400Ah battery bank would need a 100A alternator. However, if using more high quality batteries (such as our Fullriver AGM), you could drop this ratio to 1:2 (or even 1:1) for very rapid recharge times (check with the battery manufacturer/supplier

first).

2. Application (low RPM, Commercial & Continuous Duty Use)

Our alternators vary considerably in their features, construction and cost. The range is split into different sections according to their ability to deliver higher current at low RPM and overall ruggedness.

6 Series - Small case, high output alternators, designed to be a direct replacement for OEM alternators.70-120 amps 12/24V.

XT Series - Small case, even higher output alternators. Perfect for vehicles and boats where larger case alternators cannot be fitted, yet high charge current is required. 90-250 amps 12V/24V.

9 series - Large case ‘Power Handlers’. Built for continuous duty in professional marine and large commercial systems. 60-240 amps 12/24/48V.

3. Fitting An Alternator

Retrofitting alternators can be an involved job. While some of our units are designed to be direct “bolt for bolt” replacement for existing alternators, be prepared to make bracket modifications and/or insert spacers/washers to make the unit fit. If you are not experienced with alternator installation, we advise you employ an experienced engineer to fit this for you. Detailed dimensional drawings of all Balmar alternators are available to download online via their respective product pages. Please ensure that you’ve checked that the alternator will fit in all dimensions. We recommend fully discussing your requirements with a qualified Merlin engineer. Book a call here.

4. Regulation

Balmar’s 6 Series and XT series alternators contain a built-in regulator, although it is recommended to use an external regulator, like the Wakespeed WS500 Pro, to maximise their output and efficiency. All other Balmar alternators within our catalogue require an external regulator. Fixed voltage output, single stage and advanced multi-stage regulators are available. All external regulators will work with all Balmar alternators.

5. Alternator Belt and Pulley Requirements

Higher output alternators (≥100A) require more drive power to be taken off the engine. For such installations, a dual vee pulley or Serpentine Pulley (also known as a K-type or J-type) is required. If the alternator output you have chosen exceeds the capability of your existing belt/pulley system, you can upgrade the pulley system using one of Balmar’s Alt Mount Pulley Conversion Kits.