Trolling Motor Battery

[madsalts]

When running a deep cycle battery, I know that current draw can be used to calculate run time as a factor of Ampere-hour of a battery. I also know that batteries should only be drained down to about 50-percent.

If running a trolling motor, should I calculate run time assuming that I can use all of the Ampere-hours listed on the battery?

Or, just half of Ampere-hours?

According to this site (https://www.trollingmotors.net/blogs/se ... r-run-time), if I have a 100-Ah battery and a trolling motor that draws 20 Amperes, then:

100-Ah rated battery / 20 Ampere load = 5 hour run time

Is this realistic?

Does this mean that the battery will be dead and drained below 50% after five hours?

Or, does this mean that after five hours the battery will be half drained?

Thanks.

Edit:

In real life, discharge rates and battery charge last for different lengths of time depending on different factors. It seems that battery Ah rating is at 20 hours at a 5 Ampere draw. I'd be pulling at least 7-Ampere with a trolling motor, and twice that (at least) if on high speed. When trolling at a reasonable speed, how many AH would bee needed to get, say, five hours of continuous trolling with a continuous run?

What pound thrust is your motor?

[jimh]

If a battery is rated as a 20-Ampere-hour battery, and if fully charged, and if the rating was calculated for a 5-Ampere load, and if you withdraw 5-Amperes for 4-hours, then the battery charge will be zero. The battery will have no stored electrical charge available.

The expected service life of a lead-acid storage battery wii be a combination of many factors, such as type of construction, quality of construction, type of discharge including rate and depth, and type of recharging including rates, voltages, and times. Generally you get what you pay for. If you want lots of stored energy, ability to deeply discharge, and long service life, it will cost a lot.

[rtk]

I have a 24-Volt electric trolling motor set up on my 1966 16 Boston Whaler. The batteries are AGM deep cycle batteries. I also installed a marine dual battery charger in the console.

I have run the batteries down quite low many times to a point where the electric trolling motor had very little available power left. I have not experienced a problem charging the batteries besides long charging times nor have I noticed any problems with battery capacity.

As Jim stated it is costly to set up this type of system with good quality components. The two batteries were approximately $500 and the battery charger was approximately $250.

Appropriately size marine quality wires and a circuit breaker will likely add another $150—and this is critical to performance.

I really don't worry about battery longevity. If they only last two years the way I use the system it is well worth the money for a more enjoyable fishing experience.

Rich

[jimh]

If the current drain is less than the specified Amperes used for the Ampere-hour rating, the battery should exhibit a slightly higher Ampere-hour capacity, and if the current drain is greater than the specified Amperes, the battery will very likely exhibit a reduced Ampere-hour capacity. Predicting how much change in either case is impossible; the battery manufacturer should provide guidance in the form of tables or graphs that show the behavior of the cell under different loads.

Battery service life is generally related to the number of discharge-recharge cycles, the depth of discharge, and the care and method of recharging.