Battery Sizing And Runtime For Trolling Motors

Every Hightime motor is supplied without a battery. The factory reference across the range is a 100AH deep cycle battery, and the specification tables give you everything you need to work out what that means in hours on the water.

Read Rated Current Not Maximum Current

Two numbers are published for every series, for example 11A – 65A on the ET 65. The first is the rated draw at normal trolling speed; the second is the peak at full throttle. Runtime should be estimated from the rated figure because almost nobody trolls at full power all day.

The Arithmetic

Usable capacity divided by average current gives hours. A 100AH lead acid battery should not be taken below about 50 percent state of charge if you want it to last, so usable capacity is roughly 50AH. At the 11A rated draw of a brush motor that is a little over four hours of steady trolling. At the 5A rated draw of a brushless motor it is around ten hours. A lithium bank of the same nominal capacity gives more usable amp hours, so the same motor runs longer on the same label figure.

Watch The Voltage On Higher Thrust Models

The P250, P300 and MAX300 run on 24V, and the MAX300 48V and S Series run on 48V. That means two or four batteries in series, not one. Match the bank voltage to the motor exactly; a 24V motor on 12V will not simply run slower, and a 12V motor on 24V will be damaged.

Cable And Fusing

Size cable and fuse for the maximum current, not the rated current. An 80A peak on the P200 needs cable and a fuse rated above that with margin for the run length. Undersized cable shows up as voltage drop, a motor that will not reach full thrust and warm terminals.

Field Checks

• The DT, FT, M, P and S Series show battery voltage on the tiller head, so the operator can watch the bank fall
• Charge fully after every session; leaving a lead acid battery part discharged shortens its life
• Clean and protect terminals, especially after saltwater use

See also the saltwater care guide.