## Calculating Motor Run Time

The second factor we need to compute estimated run time is motor amperage draw, which is how much current a motor draws at a given speed. For example, marine batteries are rated on a metric called “amperage hours,” which is an indication of how long a battery can supply a consistent amperage. The larger the rating, the more power the battery can hold and the longer it will be able to power a motor.

### Considering Weather Conditions

In calm conditions, a motor drawing 020 amps to move a boat at medium speed may require 30 amps in windy or stormy seas and water conditions.

## How many amps does my trolling motor draw?

The 50 lb thrust trolling motor has a maximum amp draw of 52 amps/hr, but only 5 lbs more thrust. 3. Lower speeds use less amperage for the same thrust due to the larger windings in the 50 lb thrust model.

## How do you calculate amp draw on a motor?

You can usually find this information on the product label or in the owner’s manual, and then divide the wattage by the voltage (100 watts / 12 volts = 8.33 amps). This will give you an estimate of how much current your equipment will draw.

## What size battery do I need for a 40 lb thrust trolling motor?

We recommend a 12 volt deep cycle marine battery with at least a 110 amp hour rating, usually a group 27 size battery, because most trolling motor batteries fail due to improper charging.

## How long will a 100Ah battery run a trolling motor?

For 4 hours, a 100Ah lead acid deep-cycle battery will power a 30lb thrust trolling motor on Speed 4.

## How many amps is considered a parasitic draw?

A parasitic draw test requires a Digital Multi-Meter (DMM) that can handle a minimum of one milliamp and up to 10 amps.

## What is the formula to convert HP to amps?

Because the SI unit of power is the watt, it’s common to convert units before estimating amperage. A rule of thumb is to multiply the power in hp by 746 to get the power in watts.