AMT 12-2 Trickle Charger / Battery Maintainer

Keep Your Vehicle Starter Battery Maintained with the AMT 12-2

The AMT 12-2 Trickle Charger / Battery Maintainer is designed to help keep your vehicle’s starter battery charged when a solar or mains charger is charging your leisure (auxiliary) battery.

The AMT 12-2 automatically monitors the voltage of both batteries and transfers charge from the leisure battery to the vehicle battery when the selected voltage conditions are met. This helps maintain the starter battery while making use of available charge from the leisure battery.

Suitable for compatible 12V and 24V battery systems, the AMT 12-2 automatically detects battery voltage and can be configured for different alternator types and battery chemistries, including lithium batteries.

Key Features and Benefits

• Automatic starter battery maintenance: Transfers charge from the leisure battery to the vehicle battery when the programmed voltage conditions are met.
• Designed for solar and mains charging systems: Helps maintain the vehicle battery while a solar or mains charger is charging the leisure battery.
• Smart alternator compatible: Supplied configured for smart alternator vehicles with regenerative braking.
• Configurable operating programmes: Offers eight settings to suit different alternator types, battery chemistries and charging requirements.
• Lithium battery compatible: Can be configured for use with lithium leisure batteries.
• Automatic 12V / 24V detection: Detects battery voltage automatically, allowing operation with compatible 24V systems.
• Charge-pooling function: Helps optimise charge retention across the leisure and vehicle batteries.
• Low-voltage protection: Stops charging if the vehicle battery voltage falls below 11.5V.
• Selectable charging current: Provides up to 2A or 3A maximum charging current, depending on the selected programme.
• Ignition and override inputs: Supports disabling or temporarily activating the trickle charger through external signals.

How Does the AMT 12-2 Work?

The AMT 12-2 monitors the voltage of the leisure battery and the vehicle starter battery. When the leisure battery voltage is above its selected threshold and the vehicle battery voltage is below its selected threshold, the unit transfers charge to the vehicle battery in short bursts.

This allows available energy from the leisure battery to help maintain the starter battery when the vehicle is parked or not being driven.

Charging conditions depend on the selected programme and battery voltage. The unit will not supply charging current if the vehicle battery voltage falls below 11.5V, helping prevent the charger from attempting to charge a deeply discharged starter battery.

Charge-Pooling Function

The AMT 12-2 incorporates a charge-pooling function to help optimise charge retention across both batteries.

Charge pooling can take place when:

• The leisure battery voltage is at least 0.3V higher than the vehicle battery voltage, or 1.0V higher when using lithium batteries.
• The vehicle battery voltage is below 12.1V.

By sharing available charge under these conditions, the AMT 12-2 helps maintain battery state of charge and supports battery longevity.

Technical Specifications

Installation and Setup

Correct wiring and programming are important for reliable operation. Both the leisure battery and vehicle battery inputs must be connected with the correct polarity before a signal or power supply is applied to SW1.

The selected operating programme should match the vehicle’s alternator type and leisure battery chemistry. Always verify the selected programme after configuration.

Why Choose Sunshine Solar?

Sunshine Solar has over 20 years of experience supplying solar and battery products. Our technical team can help with product information, compatibility and setup advice, with customer support available over the phone.

For assistance with the AMT 12-2, contact Sunshine Solar Ltd Technical on +44 (0)1508 488188.

PRODUCT CODE: AMT12-2

Frequently Asked Questions

What is the Ablemail AMT 12-2 used for?

The AMT 12-2 is a trickle charger and battery maintainer that helps keep a vehicle’s starter battery charged while a solar or mains charger is charging the leisure battery.

Does the AMT 12-2 charge the starter battery automatically?

Yes. It monitors both battery voltages and transfers charge from the leisure battery when the selected voltage conditions are met.

Is the AMT 12-2 compatible with smart alternators?

Yes. It is supplied configured for smart alternator vehicles with regenerative braking, using Setting 4 as the factory default. The operating programme can be changed to suit other compatible vehicle and battery configurations.

Can the AMT 12-2 be used with lithium batteries?

Yes. The unit can be configured for lithium battery applications. Select the programme appropriate for the alternator type and battery chemistry.

Does the AMT 12-2 work with 24V batteries?

The unit automatically detects battery voltage and is designed to work with compatible 24V battery systems.

What is the maximum charging current?

The maximum charging current is 2A for Settings 1–4 and 3A for Settings 5–8.

Does the AMT 12-2 protect a low vehicle battery?

Yes. The unit stops supplying charging current if the vehicle battery voltage falls below 11.5V.

What does the charge-pooling function do?

Charge pooling allows available charge to be shared between the leisure and vehicle batteries under specified voltage conditions, helping maintain their state of charge.

Operating Settings and Compatibility

The AMT 12-2 has eight selectable operating settings. Settings 1–4 are suitable for most applications, while settings 5–8 are higher-power versions intended for systems with greater parasitic battery drain.

The unit is supplied configured for Setting 4, intended for smart alternator vehicles and regenerative braking. Users can select a different programme to suit their vehicle and battery requirements.

Choose the setting that matches the vehicle’s alternator type and the leisure battery chemistry. Vehicles with smart alternators should use a smart-alternator setting.

Charging Current and Cycle

The maximum charging current and operating cycle depend on the selected programme:

The AMT 12-2 supplies charge in short bursts rather than continuously.

Ignition and Override Functions

Ignition Input – SW1

Applying an ignition signal to SW1 disables the trickle charger. This allows the charger to be disabled through an ignition signal or compatible external control.

Override Input – SW2

Applying a signal to SW2 activates the trickle charger in a repeating cycle of approximately:

• 9 seconds ON
• 1 second OFF

The override function can provide manual charging or allow control through external equipment. During override operation, the LED illuminates amber.

Important: Using the override function may discharge either the leisure battery or the vehicle battery. Monitor battery voltages when using this function.

LED Operating Indicators

The AMT 12-2 uses an LED to indicate operating status:

• Green: Charging current is flowing to the vehicle battery.
• Amber flashing: The charging circuit is enabled and the vehicle battery voltage is above its selected threshold.
• Red flashing: The leisure battery is above its selected threshold, but the vehicle battery voltage is below 11.5V.
• Amber during override: The override function is active.