# electric motor battery



## redo23 (Aug 22, 2012)

Hey all
first time poster 

I just purchased my first canoe its a 4.5m b-line canoe with an electric motor 54lb sportfisher for $425

Just wondering how many amp hour battery im gunna need for the motor to troll and drive from place to place.

Cheers redo


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## Yak4ever (Nov 19, 2010)

,


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## Darwin (Jul 25, 2008)

In order to know how long the battery can run, you really need to understand the battery discharge characteristic & the connected load.

1. Assume your motor has max current draw 13A.
2. Using DMU-12-60 SLA battery (12V 60Ahr battery)

When we are talking about battery capacity, we always use Ahr rating. The value is based on 20hr discharge rate. 
Example 100Ahr battery discharged at 5A/hr rate. It can last long for 20hr (5A x 20Hr = 100Ahr), and then it should drop to manufacturer recommended cut off voltage

Example DMU-12-60 battery connected to motor with Max 13A consumption
If you refer to discharge table 13.6A line, you can see runtime is 3hr. It will then drop to 10.5V cut off voltage (at 25C temp)
As a conclusion, a 13A load should give you just over 3hr. It based on fully charged new battery at 25C operating temp.

For same battery connected to 37.8A load, it can only run 60min refer to graph. 
If your use 60Ahr/37.8A=1.58hr, you may have wrong impression it can run 1hr35min.
That means you are over estimated the runtime. You better carry a paddle with you.
If you keep discharging your battery below manufacturer recommended cut off voltage, you could damage it or reduce the lifetime.

The battery spec table give you some quick idea to see how the DMU-12-60 battery perform. I suggest download the battery spec you want to buy to understand the discharge characteristic before making any runtime conclusion. I wish this post is helpful to you.

Cheers
Darwin


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## JRF1973 (Dec 7, 2012)

I've used electric motors on my boat and I think the thing to be aware of is this:-

As the battery gets flatter, the boat goes slower and the tempation for a newbie is to try to go faster i.e crank it up !!

This is the trap, because the faster you try to go, the more juice you use and the quicker you have a flat battery.

I know that's not Albert Einstein stuff, and maybe it was only me, but the slower the boat went the harder I asked the electric to work. Trap for young players !

Regards

Justin


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## Glamo (May 15, 2012)

I use a 120amphr sealed agm battery which powers s 32 watersnake. You need to remember with sealed battery's, you shouldn't run them below half so effectively in my situation I have 60 amphr of use which works out to be around 2 hours at full speed non stop


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## Simoau (Apr 30, 2014)

Nice setup Darwin. I saw your video on Facebook. What brand of trolling motor do you use. Good luck with the bream


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