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Topic: Reverse Polarity Bait Tank Pump - Possible?  (Read 6386 times)

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steveislost

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I'm looking to reduce the amount of flow on my Attwood 500GPH bait pump.  An easy solution seems to be reversing the wires and running it at reverse polarity.  Is that a viable solution?  It seems like an easy solution but have not heard it being done very often.  I am running this with a 12V 7.5ah battery which powers my 12V Led lights tube and possibly my fish finder so can't go 6V battery route.

My other options are to run a CPU case fan adjustor or a standard timer 7 seconds on 14 seconds off, but looking at the cheapest viable option.

Any help/advice appreciated.


polepole

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Uses 6V battery


AlsHobieOutback

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Maybe you could use a DC-DC Converter?  http://www.powerstream.com/dcdc.htm 

"These are regulated switching power converters (switchmode), designed to allow the use of 6VDC equipment in 12V or 24V vehicles. These 6V output converters have been designed to be very rugged electrically and can be operated continuously at 75°C (65°C for the 5A version)."
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KayakJames

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i think if you reverse polarity the pump will meerely run backwards meaning suck instead of blow so no real gain there possibly a voltage regulator to cut it down from 12 to 6 volts is a viable option, but there again prolly the same money as a 6 volt battery. good luck
Where did he go george


sharky

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Uses 6V battery
+1. Works great. 6v 12 ah sla lasts all day


mickfish

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Attwood Adj. sprayer head, $3.99 at Walmart.

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steveislost

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Thanks for the input guys.  I did finally get almost everything, enough to test drive it, and reversing the polarity works great.  Not sure of longevity and any damage it will do, but it definitely dropped the volume.  I don't know if it is at the fifty percent level, but full blast red-red, black-black, it totally overwhelmed my 3/4 elbow outflow.  By switching the wires it backed it down so it was just slightly ahead of the drain.  I just had to dial it in with the 90 Degree Atwood Adjustable Spray Head - $8.99 at West Marine (damn it, I was trying to be the budget conscious guy, mickfish you owe me $5.00 for helping me out too late  :smt012 :smt044).  Oh well, I saved some cash by hacking that sprayer head in half and using the elbow for my drain and the sprayer for the sprayer.  Works sweet.  I have just one more mod to get it fully functional and I'll throw a write up.  Unless it burns up and melts then I never attempted this.


polepole

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The adjustable sprayer head would reduce the volume, but it will also concentrate the pressure.  That's not always a good thing in the small area of the bait tank we tend to carry, especially for more sensitive baits, such as chovies.

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CGN-38

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 :smt075

  Can you explain how reversing the polarity of the power leads causes the pump to actually pump in water?  I'm expecting to read that in doing so, your bait tank was emptied in a rather quick fasion.  Something is not computing.
« Last Edit: July 14, 2011, 09:15:42 AM by CGN-38 »


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steveislost

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polepole- The decrease in flow that I needed wasn't really that much so not much reduction was needed.  I have the outlet angled at the sidewall to make the whirlpool so shouldn't be an issue.

CGN-38 - No clue thats why I inquired.  Water does actually flow in the right direction.  If it does actually reverse motor direction then I am assuming the reduction of flow is due to less push by the fins going in the wrong direction (as  well as possible routing).  I do hear a drop in pump speed between the two which I originally thought was due to less power being sending to the pump.  It could just be the sound of it going in opposite direction.  There were enough guys doing it this way for me to warrant trying it.  I just was concerned about pump life. 



Garety

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reversing the polarity should not increase the battery life, or damage the pump, just make it run back wards Im honestly supprised it still manages to suck,

the 3 solutions
I have seen are the 6 amp battery- lower volume due to lower voltage.

The automatic switch that goes on and off every 30 seconds or minute

the last option, One i have on my kayak is the Manual switch, I just turn it on for 2 minutes every hour or so, and my bait does fine in my bristol bay bait tank.


Dale L

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I'm going out on a limb here with my explanation but I did take a similar bilge pump apart once.

These pumps work on centrifigual force in that the intake is in the center of the pump and the impeller spins throwing the water out to the outer circumfrance of the pump housing creating outward pressure and flow, the blades on the little impeller are designed to do this most efficiently in the "normal" rotation direction (read that as curved or slanted in a certain direction). When you reverse polarity the pump does spin backwards but the water is still sucked in the center and thrown to the outside of the pump, ONLY since the impeller is designed to work by spinning in the "normal" direction it works really inefficiently when spinning in the opposite direction.

What this means is that it definetly cuts down on the flow but probably won't make the battery last any longer and might even make it die faster because of the inefficient action of the impeller.

And of course I could be completely wrong in this particlular case.
« Last Edit: September 15, 2011, 07:56:29 PM by Dale L »


steveislost

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Dale, your spot on, or at least what I did finally find out by reading about others who have done the same.  It does run backwards and with a drastic reduction in efficiency.  For me it was one of those deals where something actually worked out optimally (versus the usual where it not only doesn't work but it breaks three other things).  I should do a write up on the tank as it is finished and I have tested it.  The net result was that it pumps just enough to get the water level past my middle level drain outlet and just to the edge of the upper level drain but not enough volume to go past the upper drain.  It's rather perfect in that the drain outlets are like 3/4" outlets and they aren't overwhelmed.  It is just strong enough to create an easy whirlpool without a heavy gush.  Just a really uneducated guess I would say that it is probably running at maybe 15-20% efficiency.  I sink tested it with the correct polarity and it would totally overwhelm the tank.  I would almost have to have the spray nozzle turned off to get it to reduce to a manageable level.  With the reverse polarity I use the sprayer strictly for directionality and zero reduction in flow.