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Author Topic: 4 Bilge Pumps - How to wire???  (Read 3882 times)

ray t

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4 Bilge Pumps - How to wire???
« on: September 09, 2010, 08:01:15 AM »

Right, I have just got hold of a unfinished project for a good price and am looking for some advice.  #

The boat itself is a strange desing with a single type hull at the front then turning into cat style (twin) hull at the back.  So far the guy has fitted two 800gph bilge pumps at the front the boat and two 1100gph bilge pumps at the back.  Also included in the sale was 2 Mtroniks Viper Marine 20amp esc that seem to be wired to each back pump and Viper Marine 15amp that appears to be wired to the front pumps (both front pumps run from the 15amp esc).

Firstly, as the wiring was all over the place I have started to strip it all out so I can route it cleanly.

Also at my disposal is a P94 (from Action) which I bought for another project but will rob it for this one.

Can anyone think of a good way to wire this boat up so that the controls are relatively simple.  Ideally, I would like it all mixed so that forward/backwards/left and right are all controlled from one stick if possible but I cant figure out how this would work.

 :-)) :-)) :-))  I know someone will have played about with this configuration before
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derekwarner

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Re: 4 Bilge Pumps - How to wire???
« Reply #1 on: September 09, 2010, 08:12:13 AM »

Hullo ray t.....could you please just check & reconfirm the pumping capacity..... "two 800gph bilge pumps at the front the boat and two 1100gph bilge pumps at the back" = 3800 gallons per hour....could this be a misprint?

I am sure a member will assist ....but a few photographs may help with understanding......what is the purpose of the said pumping function?.......as a bilge pump is usually designed to [pump] or remove bilge water....Derek

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ray t

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Re: 4 Bilge Pumps - How to wire???
« Reply #2 on: September 09, 2010, 08:21:39 AM »

lol, I never looked at it that way, it does seem a hell of a lot of water to pump.  They are going to be used as drives for the boat 1100's for the forward drive and the 800's for the reverse










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sailorboy61

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Re: 4 Bilge Pumps - How to wire???
« Reply #3 on: September 09, 2010, 08:51:23 AM »

Interesting hull......no ideas what it was supposed to be. Will be pretty good water jets at the back, but seems a bit OTT at the front for astern......... something to watch!
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malcolmfrary

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Re: 4 Bilge Pumps - How to wire???
« Reply #4 on: September 09, 2010, 10:20:11 AM »

Too much control for keeping it simple.
Use the 15A controller for something else.  This leaves 4 motors and 2 ESCs.  Look at them as one pair port, one pair starboard, so its now 2 motors, but with special needs.
You need 4 of these - (Maplin) MBR3035PT.  These are high current rectifiers, and should be man enough for the job with a good bit to spare.
Consider the port side pair.  The stern motor is fed by one rectifier so that it only responds to forward.  Off the same ESC, the bow motor is fed via another rectifier connected the other way, so that it only responds to reverse.
Repeat for starboard.
Using a mixer, connect the ESCs according to the instructions in the box.  You can now have fully proportional forward, back, left, right and twizzing on the spot on 2 channels.
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boat captain

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Re: 4 Bilge Pumps - How to wire???
« Reply #5 on: September 09, 2010, 10:27:04 AM »

Looks like it could be a bait boat.

Joe ;) ;)
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ray t

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Re: 4 Bilge Pumps - How to wire???
« Reply #6 on: September 09, 2010, 10:39:45 AM »

It is indeed.  Although not too sure whether its ever going to work with 4 pumps.  Cant see how pushing fwd on ch1 will power two rear pumps and pulling back on same channel will power two front pumps  {:-{
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malcolmfrary

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Re: 4 Bilge Pumps - How to wire???
« Reply #7 on: September 09, 2010, 12:47:31 PM »

 
Quote
Cant see how pushing fwd on ch1 will power two rear pumps and pulling back on same channel will power two front pumps
Thats what the rectifiers (otherwise known as diodes) are for. Push forwards, rear facing pumps are activated, pull backwards, the diodes feeding the forward pumps, being connected the other way round, allow the forward facing pumps to work, as opposed to the rearward facing ones, which dont.  The ESCs sort out the polarity fed out to the motors, the rectifiers decide which motors get powered.  The mixer decides how much is fed to each side.
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ray t

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Re: 4 Bilge Pumps - How to wire???
« Reply #8 on: September 09, 2010, 12:54:59 PM »

From the sounds of that, you mean connect all four pumps to oone output from the P94?  Does that not mean I have four pumps runninng from one 20A ESC???
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malcolmfrary

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Re: 4 Bilge Pumps - How to wire???
« Reply #9 on: September 09, 2010, 02:01:31 PM »

Quote
you mean connect all four pumps to oone output from the P94?
No. Absolutely not.

The P94 would do the job, being a mixer and two ESCs,  but, like I said, the pump motors need the extra bit of control in the power distribution.  Often, the pumps dont care which way round the power is connected, they just suck up from the hole underneath and blow out of the nozzle whichever way they rotate.  Because of this, each pump needs a diode connected the right way round so that it only switches on when you want it to.  If you were just using motors and props, there would be two motors, one for each side, which would push and pull as required.  Using pumps, the pair of motors on each side can be regarded as one motor per side, with two sets of windings, one for forward, one for reverse, and the job of the semiconductor is to stop the motor that is not wanted at any particular time from running. (SEMICONDUCTOR, ONLY PASSES CURRENT ONE WAY)
If you look at the P94 notes, it shows two motors, left and right.  You have two pairs of motors, left forward+left reverse, and right forward and right reverse. 
ESCs sort out the polarity applied to the motors to decide which way they are going to turn.  If a motor has a rectifier inserted into its wiring, it will only respond to one polarity.  It follows that, if the rectifier is connected the other way round, the motor will only respond to the other polarity.
At any one time each 20A ESC is offering power to just one motor.  For forward, 2 ESCs feeding one motor each, for reverse, the same 2 ESCs feeding the other 2 motors, one each.
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ray t

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Re: 4 Bilge Pumps - How to wire???
« Reply #10 on: September 09, 2010, 02:18:42 PM »

Ok mate, I am getting the idea a little more now.  If you get a spare minute or two, I dont suppose you could draw a little diagram could you as they do say 'a picture speak a thousand words'.

I think you mean connect the front + rear left hand pumps to one esc on the p94 and the front + rear right pumps to the other esc  :embarrassed:
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malcolmfrary

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Re: 4 Bilge Pumps - How to wire???
« Reply #11 on: September 09, 2010, 03:54:59 PM »

Quote
I think you mean connect the front + rear left hand pumps to one esc on the p94 and the front + rear right pumps to the other esc
:-))  Just so.
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malcolmfrary

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Re: 4 Bilge Pumps - How to wire???
« Reply #12 on: September 09, 2010, 06:03:24 PM »



With a modest amount of luck in the posting, a drawing.
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ray t

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Re: 4 Bilge Pumps - How to wire???
« Reply #13 on: September 09, 2010, 06:17:28 PM »

Ok thats sort of what I had in mind when you wrote it earlier (I think  {:-{).  I guess any old blocking diode would do the trick.

Thanks again for your help so far. 
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ray t

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Re: 4 Bilge Pumps - How to wire???
« Reply #14 on: September 09, 2010, 06:52:05 PM »

Found this for a submarine using 4 bilge pumps.  Spot on mate, thanks.





Any reccommendations on diodes???
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ray t

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Re: 4 Bilge Pumps - How to wire???
« Reply #15 on: September 09, 2010, 06:54:22 PM »

So the diodes go on all four positive inputs?  Is this correct?
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malcolmfrary

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Re: 4 Bilge Pumps - How to wire???
« Reply #16 on: September 09, 2010, 10:13:44 PM »

So the diodes go on all four positive inputs?  Is this correct?
As long as there is one diode in series with each motor and facing the right way, they dont care where they are in relation to the motor.
As I said in my 1st reply,
You need 4 of these - (Maplin) MBR3035PT.  These are high current rectifiers, and should be man enough for the job with a good bit to spare.  They have 3 pins and a tag, the centre pin is internally attached to the tag, pins 1 and 3 are connected to the ends of a pair of diodes inside the case, and should be wired together to get the required current rating.
Best way to mount them would be to use a 5A connection strip (like electricians use for house wiring, sometimes called a choc bloc) to join wiring to the outer pins of each diode (pins 1 and 3, linked together by your wiring).  Pin 2 can/should be removed, the onward connection is by a ring terminal and screw and nut to the diode tag.  If you look at the Maplin page for the item,
http://info.maplin.co.uk/Module.aspx?ModuleNo=46429
you will find a tab leading to the datasheet for the device, which shows the connections and indicates size and connections.  I picked this one because it can handle the current and haved a bit to spare.
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ray t

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Re: 4 Bilge Pumps - How to wire???
« Reply #17 on: September 09, 2010, 10:35:02 PM »

Thanks again Malcolm.  To be honest mate, I missed that first post earlier.  Thats what I get for using my iphone while out and about.  If I had of read it, I would have made sense of the whole thing a lot earlier, lol.  You must have been wondering how I was struggling so much to grasp it?
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ray t

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Re: 4 Bilge Pumps - How to wire???
« Reply #18 on: September 09, 2010, 11:04:18 PM »

Can I get these instead of from Maplin?  They appear to be identical and I have an account with RS where I get a 35% discount so can get a pack of 5 for only 44p which is much better than 1.99 each plus postage.
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malcolmfrary

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Re: 4 Bilge Pumps - How to wire???
« Reply #19 on: September 09, 2010, 11:45:19 PM »

It just needs diodes with a continuous rating above 20A that the ESC can deliver - the voltage will almost certainly look after itself in this application.  That one was what I found, and I looked in Maplin because, although not brilliant (!) they are widely and conveniently available.  The important thing is the continuous current rating, rather than the instant rating that the orientals are so fond of quoting to impress everybody, and was why I looked at the big, knobbly rascal.  RS might well have something better, but at that price.....
Oddly enough, I just filled in a survey about net usage, which included a wodge about connecting via mobile devices.  For not connecting, the only option they missed was the one that applied to me - "dont care".  Probably a result of too many years in the solder chewing trade.
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ray t

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Re: 4 Bilge Pumps - How to wire???
« Reply #20 on: September 12, 2010, 04:42:27 PM »

Would I be correct in thinking this is how I should wire my diodes?  I didnt mark it in the picture, but I assume you just cut the middle leg off.



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malcolmfrary

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Re: 4 Bilge Pumps - How to wire???
« Reply #21 on: September 12, 2010, 09:16:34 PM »

Thats how I would go for it.
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ray t

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Re: 4 Bilge Pumps - How to wire???
« Reply #22 on: September 12, 2010, 09:54:39 PM »

Great.  Now, I know you said it doesn't matter if I put them on the +ve or -ve input to the bilge pumps, but surely I must need to fit the two to the rear pumps one way and the two to the front pumps the opposite.  Which ones go which way or does it not matter?
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malcolmfrary

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Re: 4 Bilge Pumps - How to wire???
« Reply #23 on: September 13, 2010, 10:16:37 AM »

Have a closer look at reply #12, and the drawing therein.
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