There are some folks here that seem to know a lot about batteries and I have a question, but first an explanation of my intended use.My friend and I do a lot of river kayaking and fishing, sometimes up to 20 miles and up to 12 hours in one day. I am getting older and paddleing that far is sometimes very difficult.I am thinking of mounting a 30lb Minn-Kota trolling motor on my kayak to help out in the long holes of water between rapids. I found this battery at Academy Sports, Exide , weight is 23 lbs which is doable, 40 amp hours, reserve capacity 182 minutes, 160 cold cranking amps.I would only need the slowest speed on the trolling motor as we fish as we move along and we are never in a hurry (unless a storm in brewing). I am just wondering how long this small battery would last. I have no idea how much draw the trolling motor would use on the slowest speed.So, someone please give me a lesson on battery drain. 20 to 25 lb is my weight limit. This one is only $50. I really don't want to spend any more on a battery.Moved to Tech Issues forum from DIY.

Without knowing the wattage of the trolling motor, it's pretty much a guessing game. What I can tell you is that that battery is good for 20ah before becoming 50% soc and getting close to useless.

2oldman wrote:Without knowing the wattage of the trolling motor, it's pretty much a guessing game. What I can tell you is that that battery is good for 20ah before becoming 50% soc and getting close to useless.This is the trolling motor I have Minn Kota but I can't find any information on the power draw.I did find one chart that said it draws 7.2 amps on the lowest speed.

I found it on Amazon, and the first review said this: "Minn Kota recommends minimum of 105Ah marine battery while using this motor. I got the battery from WalMart for $69"There is more information there on amp draw in the reviews, or contact Minn Kota.

OK Juju, We have some problems here. - The motor (Minn Kota® Endura C2-30) is specified to draw 30Amps, but no rate down for less than full speed is given. - If you run at full rate from a 40AH battery, you won't get an hour plus. You will be lucky to get 3/4 before it studders to a halt, and an even an half an hour at flank will probably be damaging to the battery. => They get nasty when you ask them for more than 50% of their C/20 rate.=> Then there is the Peukert exponent that says if you pull power out at greater than C/20, you won't get all of it. - Only a true sealed battery should be put in such service. An AGM or GelCel will not dissolve your pants when things go wrong. Any battery with removable caps has that potential. (But, you may be so good you never flip a kayak - Right!)I did a lot of fancy electrics on performance cruisers before the depression shut me down. I can tell you have an interesting plan, but I think you may have to wait for LiPo to get affordable. Matt

How about some real life experience, and I'm an ET to boot. Without doing the math etc I can tell you a little battery like that on a tiny boat will give the grandkids about 4 hours of fun. I have an 8 foot porta bote that weighs about 60 lbs. With one person it really scoots with a 30 lb thrust motor. Using one as you want to should easily give you 4 hours total on the lowest setting. If solar would drop in price and become flexible one could visualize the top of a kayak covered with cells. One day soon I hope.

Battery Questions | Good Sam Community

Matt_Colie
Explorer II
Jan 02, 2014
OK Juju,

We have some problems here.
- The motor (Minn Kota® Endura C2-30) is specified to draw 30Amps, but no rate down for less than full speed is given.
- If you run at full rate from a 40AH battery, you won't get an hour plus. You will be lucky to get 3/4 before it studders to a halt, and an even an half an hour at flank will probably be damaging to the battery.
=> They get nasty when you ask them for more than 50% of their C/20 rate.
=> Then there is the Peukert exponent that says if you pull power out at greater than C/20, you won't get all of it.
- Only a true sealed battery should be put in such service. An AGM or GelCel will not dissolve your pants when things go wrong. Any battery with removable caps has that potential. (But, you may be so good you never flip a kayak - Right!)

I did a lot of fancy electrics on performance cruisers before the depression shut me down. I can tell you have an interesting plan, but I think you may have to wait for LiPo to get affordable.

Matt
2oldman
Explorer II
Jan 02, 2014
I found it on Amazon, and the first review said this:

"Minn Kota recommends minimum of 105Ah marine battery while using this motor. I got the battery from WalMart for $69"

There is more information there on amp draw in the reviews, or contact Minn Kota.
JnJnKatiebug
Explorer
Jan 02, 2014
2oldman wrote:
Without knowing the wattage of the trolling motor, it's pretty much a guessing game. What I can tell you is that that battery is good for 20ah before becoming 50% soc and getting close to useless.

This is the trolling motor I have Minn Kota but I can't find any information on the power draw.

I did find one chart that said it draws 7.2 amps on the lowest speed.
2oldman
Explorer II
Jan 02, 2014
Without knowing the wattage of the trolling motor, it's pretty much a guessing game. What I can tell you is that that battery is good for 20ah before becoming 50% soc and getting close to useless.

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