Ok I just connected a 1100gph pump to the "split-positive" system. 3 12v marine batteries in series for 36v with the positive connected to the positive of the pump and a single 12v marine battery connected to the neg side of the pump with the battery 36v and 12v negatives connected.
I connected a current meter to the 36v inline output to the pump and a voltmeter from the 36v pos to the 12v positive to monitor voltage differential.
Turned on the pump and took the following readings
Amperage started at 9 amps but dropped to 7.5 in 3 seconds and continued to stay steady for about 1 minute (duration of test).
Voltage was 24.5 volts prior to turning on pump. dropped to 21volts once pump turned on slowly reduced as the 12v battery charged and the 36v bank reduced.
Pump was running significantly stronger than running on 12v.
What I deduce from this.
When connecting a pump in this "split positive" configuration the differential voltage is not going to deliver a full 24v so amperage is not the same as connecting across a 24v battery bank to ground. The pump therefore will not deliver 2x the flow.
The pump output will only run based on the differential voltage which changes over time with the charge/discharge of the individual 36v and 12v battery banks.
The current draw will increase/decrease in relation to the differential voltage across the pump.
In this test the current was 9 amps upon start which is 3X the normal current and dropped to 7.5 or 2.5X the normal load.
Subdredger- If you have a 18amp fuse on the 4700gph pump and it is not blowing the fuse then the answer is quite simple. A combination of line losses and differential voltage between the batteries is preventing the actual voltage being delivered across the pump from increasing much more than it's actual operational voltage. You really need to connect a voltmeter across the pump leads while the pump is pulling current to verify. If you measure the voltage with the pump off you will simply read the voltage difference between the battery banks and not get a true operational reading which includes line losses etc.... I also recommend using a current meter in your testing.
Voltage sets the speed of a dc motor and an increase in voltage means an increase of current draw. A system which is current limited will keep the voltage reduced and the pump will not run at the desired speed.
I think everyone has probably experienced something like this when using a long run of extension cords to run a high amperage device like a saw etc.. It either doesn't start or it runs slow or blows fuses.
Great post Timberdoodle.
I think it's great you've taken the time to to run a pump a little different,and try this.
I will tell you here and now how i get rid of amp draw.
I have many ways of doing this both with water and electricity.
With water,its simple all i do is introduced a spin or a vortex going into the intake of the pump,it's like a tornado,or a cone base of cone or vortex in the river going to a point(tapering)right where
the impeller is being the point and then ad another vein straight after the impeller to vortex the water from a point out.
It's like if you run one of these pumps out of the water it spins,really fast,but if you add two vortexes going to a point with water ,right where the impeller is,the pump almost free runs,Amps drop right off.
I'm using the water to my advantage.On start up until water flows amps are high,but as soon as all is going amps drop right off.Schauberger.
The electrical way i have many,but remember ,someone ask me how i do it,so i told them.
It was never what i wanted to talk about here as it would take a very big book for people to get it.And this is about dredges not electricity.
What you say Timberdoodle holds true for the voltage dropping off with this circuit ,its because you are running from a high plus say 36v to a lower plus say 12v.
What is happening is the batteries are trying to equalize and are equalizing,the 36v drops the 12v chargers,You can now see electricity will charge as you do work and until you came along
and tried this you can see it is so.
I have over a hundred different ways of doing this.You have a basic circuit and the other end you have a very complicated circuit.
The circuit started with Tesla,it's called the tesla switch,then bedini had his take on it.
I will try my best here to explain here what i do in a high end circuit,and why i will not post the circuit here or anywhere,but i would be prepared to work online with you timberdoodle to put out a easy
SAFE circuit that people here can use,last thing i want is 6 foot fried salmon on the river bank.Let me know what you think.
The next thing you have to do Timberdoodle is ,you are going from 36v into 12v ,now flip the circuit so the 12v batteries are now 36v and the 36v are now 12v.
I flip this hundreds of times per second,so this right here is why my voltage doesn't drop.
My high end circuit is flipping the positive hundreds of times a second ,then i add a bedini ssg circuit to it.you see bedini has a ssg ciruit and he uses a wheel with magnets on it that spin past a coil,and when the wheel magnets spin past the coil you get a big back voltage spike that also charges your battery.Turn dc off in a coil you get a big spike,back spike,Whats not know is when you turn the power on you get a big forward spike as well.
But the pump has a coil in it yes?
pretty sure the pump has magnets in it as well yeh?
So in the end i'm using the spikes as well to keep the batteries charged.
So in the end this ciruit has capacitors,300v-600v spikes not what inexperienced people need to be concerned about in or near water.
My stage2 dredges all use capacitors with this circuit as i don't need to hold power,(amps)All have capacitors on board, no wires, no batteries.
Ever seen a 6 inch sniper dredge.
My stage three dredges run a different pump,the stage 1 dredge i put out there as you can buy all the parts ,easy,make it cheap,anyone can.But if you are having such trouble with this, the stage three dredge will be far beyond your understanding.
So everyone no more pics,reason being look at the post straight after every time i put a photo out there.
Stage three dredge uses a tesla pump/turbine,look under Nikola tesla patents you will find it.It took me 4 years to get this right,Keene almost have the pump housing correct but if they added another
intake to it opposite the first they would have two vortexes hitting each other ,change the impellers ,as of tesla patent ,this is the ultimate pump.Might take a little to get your head around it.
My trap.Lets say we are talking about a three inch pipe out of the nozzle look at the pic with 4 dredges in it,second dredge from the right is a 3 inch with a simple trap.
water comes out of nozzle and into 3 inch pipe then into a reducer in reverse 3inch reducer to 4 inch in REVERSE.THIS EXPANDS slows the water like a jet flare just before the trap ,like a river going down a gorge into a wide opening.next is a 4 inch t joint with a screw cap on it.dredge all day, undo cap, put pay in pan,pan.
The 4 inch dredge has a different reducer in reverse.All i have done is cut the pipe right above the trap and bend the back down ,so in the end you have the reducer in reverse and then the pipe also acts as a inside bend of a river.Simple .Gold most certainly goes into trap,secret now is keeping it there.
Look at a pic with the nozzle,this is where the water comes from for the trap,Notice the flow switch,it must be tuned,No use driving a un -tuned car,no use using a un-tuned dredge.
The other hose i use to blow crevices or hard pac.
The dredges have way more power than needed,IF YOUR 1 FOOT UNDER OR A HUNDRED,THE POWER IS THE SAME.
If you want to run these old school with one battery just buy a big 48v battery,any battery,put a pwm on it pulse width modulator ,this will give you any voltage you want,high voltage to remove overburden,low voltage to get pay and tune the flow to trap.
It's not a dredge that you turn a beginner loose with, hehe. It will suck the blood thru your finger tips if you get too close...
