80lb electric motor what size batteries

[Parrot_King]

I have just bought an 80lb bow mount electric motor and was after some advice on the size batteries i will need. The motor is 24volts and i will only be using it for trolling lures in my 4.5m tinny for about 5-8 hours each time. Also the box says the motor uses 48 watts is this at max speed? Also how fo you work out how long a battery will last. Any help would be great

Cheers mike

[rayken1938]

It will be 48 amps not watts and that will be at max speed.
Rough rule of thumb divide the amps into the capacity of the battery and you will get the answer in hours but remember this is to completely discharge the battery and you should never discharge your batteries belor 2/3rds of their capacity if you want good battery life.
What throttle settings you use will depend on the size of your boat and what speed you wish to troll at. If you wish to troll at slow speeds and a small throttle setting the battery will last a lot longer.
See if you can get some stats on current draw versus throttle settings.
What brand motor? Does it have a maximiser? Also beware that a lot of the chinese motors may be rated at a certain thrust and when you read the small print they do not advise using them for extended periods at full power.
Cheers
Ray
Cheers
Ray

[netmaker]

buy the biggest amp hour deep cycle batteries your budget allows. the amount of time you get out of them is entirely dependent upon how hard you work it. there is no hard and fast way to work it out unless you work on maximum power consumption as anything less is a variable. the manufacturers website should give you more info if you want the finer details.

[Parrot_King]

Thanks ray its a jw watersnake. Not sure what a maximizer is or if its got one. If i was to run the batteries fully flat once would this destroy them permanently? From my calculations a 100aH battery would only run my motor gull speed for 2 hours does this sound right? Are there any big aH batteries that are light weight? So am i looking at 300 plus aH batteries to do the job?

[bar raider]

But u hardly ever troll at full speed, when trolling it might be only be about half speed give or take. So u then get 3to5 hours actual trolling time which makes a for a full day out on the water. 2 x 80 ah ( to get 24v) should be ok, but as said go bigger if you can afford it.

[rayken1938]

The watersnake does not have a maximiser.
They draw 48 amps.
I run a 80lb watersnake stern mount on an old 4.3 clark abalone.
I have 2 X 125 a/h batterys in series .
Trolling for bass I only use no 2 speed setting which gives me 2kph and get over 6 hours
Using full power for over 2 hours the batterys still read 24v.
From memory I think that They recommend that you do not allow a 12v battery discharge below 11.7v.
So I think that you will need a couple of 125 a/h deep cycles.
Cheers
Ray

[NAGG]

As has been mentioned - buy the biggest batteries that you can afford & fit
You dont have a big heavy boat to start with , so that's a big plus as you will be running on much lower settings.
I had a 74lb in my 5M Hornet (2 x 100amp AGMs) & that was fine for a days fishing (lurecasting) but I found myself in conditions that were less than perfect (windy & or tide ..... & depending on your load) well - you soon wished that you had more. So anything less that 100amp is madness & 120ish will see you in a much happier place & having batteries that will last you longer.

Chris

[matt fraser]

Another vote for 2 x 120 amp/hr batteries, and you will need a good charger too.

Cheers,

Matt

[Parrot_King]

Thanks for all the replies, Can anyone suggest any good brand 120aH Batteries? and how much they cost? also i am running dual batteries at the moment so am i better off getting rid of both of these and get 1 good battery since i will be runnning 2 up front for the elcectic motor? The 2 batteries i have are Seamaster gold MFM50's would these be sufficent to run the electric or too small as i dont know how powerful they are? Also what is a good charger?

Any ideas would be great

[Apollo]

Thanks for all the replies, Can anyone suggest any good brand 120aH Batteries? and how much they cost? also i am running dual batteries at the moment so am i better off getting rid of both of these and get 1 good battery since i will be runnning 2 up front for the elcectic motor? The 2 batteries i have are Seamaster gold MFM50's would these be sufficent to run the electric or too small as i dont know how powerful they are? Also what is a good charger?

Any ideas would be great

I think you will find your seamasters are cranking batteries and you will need deepcycle batteries for your electric, so unfortunately you will be having four batteries in your boat. I have to have the same in mine! I agree with the other that 125+Amp hr is a good place to start for your deep cycle batteries.

[NAGG]

Without going down the AGM path - which will cost a bomb @ around $500 each
My choice in a wet cell would be Trojans ...... they have a sound reputation for this application .

Chris

[Nicko_Cairns]

Hey,

I'm running 2 x 97 amp hour batteries and they work a treat, it's pretty rare that I run my electric anywhere near 100%. Cheers.

[chris69]

Get one good battery for the starting and for deep cycle batteries AGM turbo batteries 120amp are good around $350 each there at brendale if you live close by and get a good 12 to15 amp charger bias have a good 12 amp charge for around $100.

[Mike Delisser]

I just bought a new 120 amp hr Amptec from Battery Traders in Moss St Springwood for $200

[Parrot_King]

Thanks for all the replies fellas, would i be right in saying my electric motor will chew 22 amps at half speed if 48 amps is full speed?

[Daintreeboy]

Hard to say without knowing the specs and the power curve. Having said that I highly doubt the power curve is linear so you will draw less than that at half speed. How much is a guess without the curve data.

[chris69]

Do your self a favour and ring Jarviswalker who supply the watersnake electrics and ask the question ,there the best to answer this question as there techies should know this.