Help sought for DIY 12V for 120V Blender Boat Motor

Howdy, I’m hoping someone could give me a hand with jerry rigging a DIY trolling motor battery for a small boat (not a toy, but made out of many many water bottles, pvc, etc.) that will not get too much use. I need it to be very inexpensive and reasonably light. 10 D cells in a PVC pipe would be great. 20 would not be too bad. I am pretty much electrically illiterate. Here is what I have so far. I have an immersion blender … one of those things that Emeril Lagasse calls “boat motors”. I can attach a drive shaft and propeller to it. Because it is designed for being in liquids with more resistance than water (though with a smaller prop/blade), I think it will have sufficient torque to get some push. I will not know if it is enough until I give it a try, but I do know that weed wackers can be so converted and I don’t think they have much torque. The part I am stuck on is hooking it up to batteries. It is a 120V plug in device. I have a small 75 Watt inverter. I can plug the blender into the inverter and that into a car lighter and it runs well. I have hope! I understand that I should have 120 Watt inverter, but 75 is what I have. I have an accessory car lighter outlet to plug the inverter into. It has a red line with a fuse box mid way and a black line, identified as a ground line with a loop at the end. The directions say to screw that loop into the frame of a car and connect the red to the hot battery line. But as I am not using a car that is not of much help. I tried stringing 10 AA batteries together end to end, temporarily held snug with duct tape, and connect it to the inverter with the accessory lighter plug outlet, but I did not have any luck. The motor did not spin and the inverter power light did not come on. I used electrical tape to connect the red to the positive end of the string and tried taping the black to the negative and also to a knife to ground. I tried AA as I know those will get used one way or another. I did not want to invest in D’s until knew it would work. As I understand it, D’s will last longer. (I am not interested in re-charging). Since then, I came across a few bits of info on another site. One thread mentioned using a spring from, say a flash light, at the negative end and a bolt at the other. Another said that PVC was great for grounding. Some useful bits of info are that in addition to the 120V, the motor runs at 1.0 Amps. I do not know if the 60 hertz is relevant. Does any one have any ideas about how to do something this? Do I just need to replace the fuse and try again with D’s? How do I connect the lines? Wrap the red around a bolt through a capped pvc tube and tape the ground to the side of the tube, with a spring in the other capped end touching the negative end? Do I need two 10 series in parallel? I can stack batteries end to end, but how do I connect parallels, especially without soldering? I do not want to use a 12 volt car or marine battery. This motor is not going to get enough use to justify the cost of such a battery and charger and I do not what to deal with the weight. If I can get 10-15 minutes of power from a stack of D-cells (hopefully more time), I would call that a success as this is a learning experience as much as anything. An hour would be much better. Thanks in advance for any help.

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LasVegas10 years ago
In the long run, it would be a lot less expensive and effective to go to someplace like BGMicro and purchase a motor that will run on your batteries. A DC motor driven directly will give you more power for longer than trying to convert the power (loss) and the drive a motor beyond the capabilities of the inverter (more loss).
Wolfsire (author)  LasVegas10 years ago
Well, I haven't quite given up. http://forums.batteryspace.com/forums/viewtopic.php?p=29622#29622

LV, btw, that is where I am, I'm sure you are right about getting another motor, but I haven't a clue as to what to get.

I’d guess maybe this one?

http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=9983
. Being as the motor is only ~1-1/4" long by ~1-3/8" dia (motor/gearbox is less than 3" long), I doubt it will have enough torque/HP (didn't see any ratings), but I guess it depends on how fast you want to go. . I also have doubts that 48RPM will be fast enough, but really have no idea how fast it needs to be. I'll guess in the high 100's.
. PS: If I were looking, I'd start at boat stores and see if they have some "junk" (still run, but not in good enough shape to sell to a "real" customer) trolling motors laying around for cheap. Maybe second-hand stores or flea markets. You'll probably even get the controller.
Wolfsire (author) 10 years ago
Alright. Thanks you for your replies. I'll drop this idea, check out e-bay for some not too expensive second hand trolling motors and possibly convert the blender into a 12VAC saw. I was an instructable for making a blade.
NachoMahma10 years ago
. While I don't recommend using 120VAC on a small boat, all you need are a car battery (or other 12VDC source) and a small inverter.