Bushman’s 4700 gph bilge pump teething problems

G’day you mob,
Running the Bushman’s 4700 gph bilge pump (the ones that Gold Rat sell) with my high banker and it shuts down roughly every 15 minutes and needs to be left alone for another 15 minutes or so before it will start again.
It’s running off two 60ah lithium batteries in parallel (though I’ve run it on each battery separately with the same result) and the water it’s pumping is pretty dirty with sediment and sheoak needles, though not enough to jam the impeller.
Discharge hose is 50mm lay flat, run straight with no kinks.
Pretty sure It’s not the batteries’ BMS doing it, because I’ve tested another, smaller pump on them immediately after the big pump shut down, and it ran fine.
Any ideas? Is there some thermal cutoff switch that kicks in when it’s working too hard?
I’m pretty new to the world of DC so any input would be appreciated.
Cheers!

I notice the specs on his website say "43°C temperature limits", which doesn't sound very hot at all in tropical north Queensland. Your thermal cutoff switch idea is likely to be the answer, I reckon.

grubstake said:

I notice the specs on his website say "43°C temperature limits", which doesn't sound very hot at all in tropical north Queensland. Your thermal cutoff switch idea is likely to be the answer, I reckon.

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Yeah, I saw that as well but reckoned it would be fine running in the cool(ish) creek water, though I suppose that the motor could still easily hit 43 degrees if it’s struggling

There's a plastic impellor running in a plastic shroud, so the hot electric motor is insulated from the cool water. Because the whole pump is fully sealed and submersible, the motor heat will build up and can't quickly escape. The specs also say "17 Amp draw rated", which is 204 watts at 12 volts, so I wonder if the motor is actually rated for continuous use?

I m no expert but maybe get more flow by adding more water exit points on the spray bar, to alleviate some back pressure. The little pump I have actually works in reverse, simply by reversing polarity but it is obviously less efficient and pumps less water but in some situations at home sluicing cleanups it is a perfect speed.

grubstake said:

There's a plastic impellor running in a plastic shroud, so the hot electric motor is insulated from the cool water. Because the whole pump is fully sealed and submersible, the motor heat will build up and can't quickly escape. The specs also say "17 Amp draw rated", which is 204 watts at 12 volts, so I wonder if the motor is actually rated for continuous use?

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Yeah, good question. I assumed it would be but didn’t think to check.

retirement stone said:

I m no expert but maybe get more flow by adding more water exit points on the spray bar, to alleviate some back pressure. The little pump I have actually works in reverse, simply by reversing polarity but it is obviously less efficient and pumps less water but in some situations at home sluicing cleanups it is a perfect speed.

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Yeah, I had that thought myself, and tried running it straight out the 50mm hose. Same thing happened, bugger it.

Wonder whether a call to Gold Rat might help?

Mackka said:

Wonder whether a call to Gold Rat might help?

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Yeah, I’ve flicked him an email so I reckon he’ll know.
I just wanted to make sure I wasn’t missing anything obvious first, to avoid looking like too much of a clown

So I just heard back from Dustin and the thermal switch idea was correct; the motor is under too much stress.
Apparently lay flat will put the pump under too much load from friction loss, and the sheoak needles don’t help either.
The other thing is the whole unit is supposed to be under water, not just the pickup, to ensure motor cooling.
So there ya go. Hopefully this will help any others before they make my mistakes.
Cheers

I take it that it didn’t come with an instruction manual and i must admit that would be very handy.

I run mine in some pantyhose as a filter to keep the muck out and have added a variable controller and only dial up the amount of power/water required to make it run at optimum volume

Jamie.milner said:

I run mine in some pantyhose as a filter to keep the muck out and have added a variable controller and only dial up the amount of power/water required to make it run at optimum volume

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Cheers mate Do you find your filter clogs up quickly? I was using a sleeve of shadecloth for the same purpose and it choked up so quickly that it was more effort than it was worth

Mackka said:

I take it that it didn’t come with an instruction manual and i must admit that would be very handy.

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Yeah, definitely a few dos and donts would be a handy thing to chuck in the box, I reckon

Skid Dog said:

Cheers mate Do you find your filter clogs up quickly? I was using a sleeve of shadecloth for the same purpose and it choked up so quickly that it was more effort than it was worth

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There will be a point where it goes from being a water pump to a sludge pump which you don’t want to run through the sluice anyway as it will take the gold with it. But the super fine mesh of the pantyhose on top of a sieve works a treat. Never had a problem.

Jamie.milner said:

There will be a point where it goes from being a water pump to a sludge pump which you don’t want to run through the sluice anyway as it will take the gold with it. But the super fine mesh of the pantyhose on top of a sieve works a treat. Never had a problem.

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Yeah, it’s an age old challenge, I guess, getting gold out of thick clay. I’ll give the pantyhose a go for sure. Have to mount a lightning raid on the missus’ smalls drawer

feedback taken on fellas i've added a note to the listing about layflat not being suitable, its a bit hard to cover off everything people use a bilge pump for, i have customers using them to move their kayaks around : )

i think well work on a FAq's page t include with the product called "getting the most out of your bilge pump" but im my experience most people don't read the data sheets we supply

G0lddigg@ said:

feedback taken on fellas i've added a note to the listing about layflat not being suitable, its a bit hard to cover off everything people use a bilge pump for, i have customers using them to move their kayaks around : )

i think well work on a FAq's page t include with the product called "getting the most out of your bilge pump" but im my experience most people don't read the data sheets we supply

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But at least for those that do, the sheet is there Dustin and you are covered because you have supplied the info. Cheers Mackka.

Mackka said:

But at least for those that do, the sheet is there Dustin and you are covered because you have supplied the info. Cheers Mackka.

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100% mate