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View Full Version : My advice regarding trolling motors and batteries



DanSkorupka
10-05-2012, 06:52 PM
Short story:
Buy New for both motor and batteries.
Get a smaller motor without any fancy bells and whistles
Get deep cycle batteries
Get the best batteries you can possibly afford
Get the biggest batteries you can reasonably have in your boat
Get a safe high quality smart charger and use only that.
Take good care of everything, just because it won't suddenly fail when abused doesn't mean it likes harsh treatment or will put up with it forever.

The Book:

Stay away from used motors. While a cheap used motor can sometimes be had for pocket money you are likely to get more than you bargined for, typically something wrong with it that will cost more than buying brand new to properly repair and may be downright dangerous. These "bargins" are often worth exactly their weight in high grade aluminum. A beat up gas outboard can sometimes make sense but there is little that can go wrong with low voltage gearless motor drives besides something important being physically broken.
The motor need not be fancy or an especially large model, but you will need the right kind of battery, a good one and it has to be big.
A good universal small boat motor is a 30 lb thrust minn kota. They share the same motor as the 35 and the continuous variable 40 and the earlier 50 lb models but are far cheaper. Wont plane anything, not even a small squareback canoe but it'll push a sizeable runabout with 4 people and 120 pounds of batteries around faster than anyone can comfortably row until the cows' grandchildren come home.
The heart of any electric vehicle (from a design standpoint these count) is not the motor but the battery. Small boats use deep cycle flooded lead acid batteries. They look like the battery in a truck but are different on the inside. Car batteries, known in the industry as starting batteries are good for starting engines and nothing much else. They will give a brief burst of enormous power just fine but try to pull 20 to 50 amps from them for a solid hour or more and you will kill them in no time.
Not all deep cycles are the same, a few brands are especially made to last.
The big names for heavy duty batteries are Trojan and Deka, at least in North America.
Trojans are very tough and are very friendly to deep discharge but need very frequent watering as they mostly don't have recombiners and have a lot of additives in the lead.
Deka batteries will last 7 to 10 years in deep discharge service without pampering, don't need as frequent electrolyte maintence as Trojans, are so good at pumping out amps that they are pressed into service as starter batteries for large cars, and are made in the US of American mined metal. The main drawback is they are very heavy and need to be recharged without being used occasionally as they will self discharge as bad as a car battery. Neither of these should ever be a problem in this application. Look for fine print saying "East Penn Battery company" These are the real ones. They tend to cause sticker shock but you get what you pay for.
Life may be too short to drink cheap whine but life is too long to risk cheap boat batteries.
Buy the biggest battery your boat can safely take the weight of and still carry its expected payload even if you do not use it for long distances.
Firstly the further you drain a battery the fewer times you can recharge it. For deep cycle lead acid batteries if you draw 50% of its capacity each time you use it you get to use it roughly 800 times before it dies, for drawing until 85% empty it can be less than 300 times.
Secondly due to a phenomenon called peukert loss a 100 amp hour battery will give not twice but almost three times the energy of a 50 amp hour battery when subject to a 30 amp load (about what a moderate size trolling motor uses)
By the same token if you have two batteries of the same size brand type and age it is better to wire them in parallel than to finish one and start the other. They will act as one big battery when wired in parallel. Don't wire in series unless you have a 24 volt motor.

My personal recommendation for trolling motors is get a 30 or 50 lb transom mount minn kota and invest in a group 31 size (group 27s hold just as much nowadays but sacrifices are made to cram that much energy in that little space) east penn build Deka deep cycle battery or better yet two of them to wire in parallel, and get the best charger you can get. Buy new, people tend to sell boat batteries when they are trying to evade the hazmat disposal fee on 50 pounds of useless lead with a gallon of sulfuric acid soaked into every crevice. Cheap chargers are just a transformer and a rectifier and will beat the living daylights out of even the best batteries, cutting their useful life by years. they also have a habit of making defective/damaged batteries explode. Get an industrial charger or a coast guard and UL or lloyds saltwater certified marine charger. For the cost of all this you can buy a gas outboard in good enough condition to start on half a pull without sputtering but you will get a safe, trouble free, comfortable, simple long lasting means of powering pretty much any small boat.
Besides, if one were to write a comprehensive list of worse ways to blow one grand it wouldn't fit in a library.

Gib Etheridge
10-05-2012, 10:17 PM
Thanks for that.

ataraxia
10-06-2012, 07:03 AM
Short story:
Buy New for both motor and batteries.
Get a smaller motor without any fancy bells and whistles
Get deep cycle batteries
Get the best batteries you can possibly afford
Get the biggest batteries you can reasonably have in your boat
Get a safe high quality smart charger and use only that.
Take good care of everything, just because it won't suddenly fail when abused doesn't mean it likes harsh treatment or will put up with it forever.

The Book:

Stay away from used motors. While a cheap used motor can sometimes be had for pocket money you are likely to get more than you bargined for, typically something wrong with it that will cost more than buying brand new to properly repair and may be downright dangerous. These "bargins" are often worth exactly their weight in high grade aluminum. A beat up gas outboard can sometimes make sense but there is little that can go wrong with low voltage gearless motor drives besides something important being physically broken.
The motor need not be fancy or an especially large model, but you will need the right kind of battery, a good one and it has to be big.
A good universal small boat motor is a 30 lb thrust minn kota. They share the same motor as the 35 and the continuous variable 40 and the earlier 50 lb models but are far cheaper. Wont plane anything, not even a small squareback canoe but it'll push a sizeable runabout with 4 people and 120 pounds of batteries around faster than anyone can comfortably row until the cows' grandchildren come home.
The heart of any electric vehicle (from a design standpoint these count) is not the motor but the battery. Small boats use deep cycle flooded lead acid batteries. They look like the battery in a truck but are different on the inside. Car batteries, known in the industry as starting batteries are good for starting engines and nothing much else. They will give a brief burst of enormous power just fine but try to pull 20 to 50 amps from them for a solid hour or more and you will kill them in no time.
Not all deep cycles are the same, a few brands are especially made to last.
The big names for heavy duty batteries are Trojan and Deka, at least in North America.
Trojans are very tough and are very friendly to deep discharge but need very frequent watering as they mostly don't have recombiners and have a lot of additives in the lead.
Deka batteries will last 7 to 10 years in deep discharge service without pampering, don't need as frequent electrolyte maintence as Trojans, are so good at pumping out amps that they are pressed into service as starter batteries for large cars, and are made in the US of American mined metal. The main drawback is they are very heavy and need to be recharged without being used occasionally as they will self discharge as bad as a car battery. Neither of these should ever be a problem in this application. Look for fine print saying "East Penn Battery company" These are the real ones. They tend to cause sticker shock but you get what you pay for.
Life may be too short to drink cheap whine but life is too long to risk cheap boat batteries.
Buy the biggest battery your boat can safely take the weight of and still carry its expected payload even if you do not use it for long distances.
Firstly the further you drain a battery the fewer times you can recharge it. For deep cycle lead acid batteries if you draw 50% of its capacity each time you use it you get to use it roughly 800 times before it dies, for drawing until 85% empty it can be less than 300 times.
Secondly due to a phenomenon called peukert loss a 100 amp hour battery will give not twice but almost three times the energy of a 50 amp hour battery when subject to a 30 amp load (about what a moderate size trolling motor uses)
By the same token if you have two batteries of the same size brand type and age it is better to wire them in parallel than to finish one and start the other. They will act as one big battery when wired in parallel. Don't wire in series unless you have a 24 volt motor.

My personal recommendation for trolling motors is get a 30 or 50 lb transom mount minn kota and invest in a group 31 size (group 27s hold just as much nowadays but sacrifices are made to cram that much energy in that little space) east penn build Deka deep cycle battery or better yet two of them to wire in parallel, and get the best charger you can get. Buy new, people tend to sell boat batteries when they are trying to evade the hazmat disposal fee on 50 pounds of useless lead with a gallon of sulfuric acid soaked into every crevice. Cheap chargers are just a transformer and a rectifier and will beat the living daylights out of even the best batteries, cutting their useful life by years. they also have a habit of making defective/damaged batteries explode. Get an industrial charger or a coast guard and UL or lloyds saltwater certified marine charger. For the cost of all this you can buy a gas outboard in good enough condition to start on half a pull without sputtering but you will get a safe, trouble free, comfortable, simple long lasting means of powering pretty much any small boat.
Besides, if one were to write a comprehensive list of worse ways to blow one grand it wouldn't fit in a library.

My advice: spare yourself all this hassle get a Torqeedo (http://www.torqeedo.com) with an integrated battery and a charger the size as the one on your laptop. Life can be easy.

bogdog
10-06-2012, 08:51 AM
Todd Wells of Bend, Oregon has an informative e-book about electric propulsion. http://www.electricoutboardhandbook.com/assets/Electric%20Outboard%20Drive%20for%20Small%20Boats. pdf

Breakaway
10-06-2012, 09:31 AM
My advice: spare yourself all this hassle get a Torqeedo (http://www.torqeedo.com) with an integrated battery and a charger the size as the one on your laptop. Life can be easy.

Can the Torqueedo run nav lights, charge your cell phone or handheld GPS, serve as ballast, etc?

Seems its horses for courses ( Like we haven't heard that here before)

kevin

Donn
10-06-2012, 01:14 PM
The model with the integrated battery would have to be wired for power output to external items, but it has a built-in GPS for speed and range calculations.

The external battery models are a better bet. They sell a fool-proof 2685 watt hour cell you can use as ballast, and to drive other appliances.

Breakaway
10-06-2012, 05:54 PM
The external battery models are a better bet. They sell a fool-proof 2685 watt hour cell you can use as ballast, and to drive other appliances.

Noted. Thanks.

Kevin

Chip-skiff
10-07-2012, 01:20 AM
My advice: spare yourself all this hassle get a Torqeedo (http://www.torqeedo.com) with an integrated battery and a charger the size as the one on your laptop. Life can be easy.

The Torqeedo motor is lovely, but quite expensive, and the integrated battery craps out pretty quickly.

I just bought a MinnKota Endura 30 (30 lb. thrust and 30-inch shaft) for $100. I've used this motor on a research boat and it's a very good value. A MinnKota charger was about $60. I've got a PowerSonic 1000 ah deep-cycle battery (from various solar power experiments, $225?) that will run the motor for hours.

https://lh3.googleusercontent.com/-2yIc4sav4s4/T-jYRwTTO0I/AAAAAAAACX8/AdhPAuK4JFM/s749/mtrmt6.jpg

The mount fits in the rudder gudgeons and uses rope steering. After this was taken, I got a 24 inch tiller extension so I don't have to scoot back to adjust the speed. Here's a thread on the setup:

http://forum.woodenboat.com/showthread.php?149549-Simple-Motor-Mount-for-Skiffs-and-Double-enders&highlight=

For a light, easily-driven hull, this inexpensive motor is a good choice. When I took the photo, it was pushing my Bolger Gypsy at about 5 knots against a 10-15 knot breeze on the 4 power setting (5 tops).

DanSkorupka
10-07-2012, 10:56 AM
I'm assuming you mean a 100 amp hour battery not 1000?
$225 is roughly the right price for a 12 volt 100 amp hour sealed lead acid battery.

For small boats: trolling motor or oars, for small fast boats gas, For big boats, Ray electric outboards or sails, For big and fast boats diesel.

RE: the torqueedo
It is a great piece of technology on paper and more efficient than a motorguide or minn kota but it isn't all it's cracked up to be.
Everything is made of plastic, I have handled them at west marine and can assure you even the 2000 and 4000 watt models (the Cruise as opposed to the smaller 400 to 700 watt Travel series) are far flimsier than the little tohatsu eggbeaters, even the high strung little 3.5 four stroke.
The motors are very high speed brushless PM machines taken from gigantic model airplanes and not given forced air cooling like the airplanes and with a plastic lower unit with a large air gap water cooling isn't going to do any good.
The bigger model spins up like a gas turbine, something like 12,000+ rpm at 24 volts, even more at 48 volts. The gearbox is tiny and IIRC doesn't have liquid lubricant so as to allow the boaters who have never worked a day in their life to never soil their hands changing lower unit oil. I know better than to do that to a half horse machine with 3/4 inch thick shafts at under 1200 rpm and I have never taken a formal mechanical engineering course in my life, torqueedo's technician-engineers (notice I didn't say design experts or mechanics, that is on purpose) thought they could get away with doing this to needle thin components at the powers and speeds that they did.
It is physically impossible to make something like that long lasting, abuse tolerant, reliable or cheap.
Even so they could cut the price to a quarter of what it is and still make a fat profit, remember they threw together existing off the shelf technology, cut a lot of corners that shouldn't be cut even on non critical dry land applications, and installed it in a plastic housing.
Torqueedo's batteries are junk, any Chinese or Korean battery maker that deserves to exist will happily sell you something with quadruple the cycle life that passes UN, DOT, and ISEC safety standards for carrying on civilian aircraft for less than half the price torqueedo charges for old lithium manganese dioxide cells.
Torqueedo is a tragic joke that would be a lot funnier if it weren't true.
They work miracles when they work but they are untrustworthy and if something goes wrong not even the dealers are capable of fixing it, they have to send it of to some state of the art facility in europe while you wait for weeks with an empty wallet, a barren transom, a short temper, and excellent rowing arms.
Story time:
Say some guy with his torqueedo is away for repairs is off in some beautiful foreign land with his gas backup engine, say he gets pulled over by the inshore navy for some fishing violation. He has read that their lethal force policy is even more permissive than a Texas Swat Team before the popularization of the tazer, but he disregards that because he is an invincible rich white man. Dealing with a malfunctioning gas outboard has made him furious and a big fine breaks the camels back. He reasons that his good rowing arms are great punching arms as well. As murphy's law would dictate the guy on the navy boat with a loaded Kalashnikov just yesterday saw his own son die at the propellor of a drunk white boater with his own eyes less than a mile from where this event is unfolding...
Torqueedo is happy that they get to sell a "certified pre owned" http://www.youtube.com/watch?feature=player_detailpage&v=towwx7KOWDE#t=104s engine.
If I got a free torqueedo new in box I wouldn't sell it I would pay someone to take it off my hands; I wouldn't use it on a pond that I could happily swim to shore from after a big meal.

Chip-skiff
10-07-2012, 05:50 PM
[QUOTE=DanSkorupka;3555748]I'm assuming you mean a 100 amp hour battery not 1000?
$225 is roughly the right price for a 12 volt 100 amp hour sealed lead acid battery.[QUOTE]

Right-o. Hit an extra zero. This is it:

http://www.atbatt.com/images_lg/ps-121000.gif
It was about $225 when I bought it 15 years ago. I think the quality is better than the ones sold at auto & marine stores. Practically no self-discharge at all, and it will run the MinnKota 30 motor for hours. It weighs 67 lb/30.5 kg, so it needs to be placed with proper trim in mind, and strapped to something solid.

blisspacket
10-27-2012, 10:53 PM
Every year at the Miles River Yacht Club there's an electric boat marathon that's 25 miles long around Wye island. Last year first and second place were won by Torqeedos. This year first and second and third were won by Torqeedos. The same first place winner this year as last year, presumably the same Torqeedo. I happen to like the T's because they use ball bearings in the motors. Pretty basic. Far better than a bushing. Yes, the T's use brushless motors and planetary gear reductions. EPowerMarine.com has a wealth of expertise with the machinery. They also sell the electric Parsun outboard, to add to the knowledge base here. For batteries, LiFePO sees to be the answer most popular at the moment. I've had good luck with the more prosaic NiMH cells from the salvage Prius market; their energy density isn't as good as LiFePO, but better than leadacid. Non of the electrics can really provide the performance of an equal weight of diesel or gas. If you're on a petro-verboten lake, however, and do want to take your grandkids waterskiing, here's your best bet:http://www.mtlcb.ca/electric.asp.