Building a 36volt DC submersible pump?

[Relict]

Hi all, I was wondering if anyone had attempted this? I / we have a couple of 240 v submersible pumps and I was considering building a Frankenstein version. I converted an ancient Hilti battery drill, (batts dead and no replacement option) to run on a 36v ebike battery. It's 20 amp hour and it's great for plugs and feathers, if using the 16mm ones. Also the battery was very cheap online, but it's shrink wrapped so need kept in a box... Also the drill is corded but it's a short cord, not a problem.
So having also replaced a Bosch drill motor, I see that 36v motors are available for pocket money online.
We currently are starting to be watered out at our fave dig, just as the place is starting to look very promising.
So I was thinking of re- motoring one of these items to make a pump that's convenient and unlikely to convert the digger into a Toby carvery choice.
Any experience, ideas or alternatives?

 

[ChrisJC]

How many Watts is the 240V pump? That will allow you to get a handle on how long a 36V battery might last, and what sort of amperage it might have to produce.

Chris.

 

[Relict]

How many Watts is the 240V pump? That will allow you to get a handle on how long a 36V battery might last, and what sort of amperage it might have to produce.

Chris.

Thanks Chris, yes I guess some straightforward maths will help. I was expecting the RPM to be an issue. Might need a drill gearbox as well! The pumps are on site (Stump Cross ) at the mo, I'm going to pick one up on Wednesday and take it home to play with. They are typically about 500w. I found some battery pumps but all small bore and would bung up.
Tom

 

[Flotsam]

A critical issue would be the head you would be pumping through. Quite literally, double the height, double the power/Amps.

 

[royfellows]

There are submersible pumps available, ebay for one source, that run on a low DC voltage and are designed for fish ponds. I believe the usual voltage is 12V, and on average pond pumps will cope with up to 2 metres. 12V is useful as car battery or 3 series LiIon cells are possible power sorces. Drill batteries may be internally re configurable if a higher voltage.

 

[Relict]

There are submersible pumps available, ebay for one source, that run on a low DC voltage and are designed for fish ponds. I believe the usual voltage is 12V, and on average pond pumps will cope with up to 2 metres. 12V is useful as car battery or 3 series LiIon cells are possible power sorces. Drill batteries may be internally re configurable if a higher voltage.

Hi Royfellows,
Have you come across any that cope with big dirty water? I found lots of these 12 v items, but they were all really small bore?
Thanks though!

 

[royfellows]

No, I have a lot of water features and koi ponds etc, but all my pumping is mains. The thing is that low DC voltage for outdoor use is becoming more common, so there should be some choice. All the pumps work by an internal impeller, a bit like an enclosed fan if you can picture it, so as long as no solid stuff like stones etc, you should be OK. In any event I would use a pre filter. I use these, they are foam rubber blocks, they stop my main filters becoming blocked with dirt. Not important for your use so wire gauze would suffice. I would certainly consider my suggestion.

This could be ‘dept of easy solutions’

 

[Relict]

No, I have a lot of water features and koi ponds etc, but all my pumping is mains. The thing is that low DC voltage for outdoor use is becoming more common, so there should be some choice. All the pumps work by an internal impeller, a bit like an enclosed fan if you can picture it, so as long as no solid stuff like stones etc, you should be OK. In any event I would use a pre filter. I use these, they are foam rubber blocks, they stop my main filters becoming blocked with dirt. Not important for your use so wire gauze would suffice. I would certainly consider my suggestion.

This could be ‘dept of easy solutions’

I'll take a look. It's often the case that internet searches are all about the key words. I'll add pond pump and take a look!
Cheers, Tom.

 

[Maj]

A couple of other things to consider is what height you have to pump the water and volume you need to shift. A centrifugal (impeller) pump will struggle if too high. We successfully used a marine/caravan 12v water pump, not the type that you dip into a water container but the type that would be permanently plumbed in. The pump was a positive displacement pump that had three non-return/flap valves. A couple of downsides was that it was not submersible and therefore required priming, and it would take about 1/2 hr to pump approx 100 litres, but we did have to pump it up quite a distance. But I guess larger capacity pumps would be available, we just used what I had available.

 

[Fjell]

I have one of these and it certainly shifts dirty water at some rate with about a 2m head including bend losses. These are single stage centrifugal pumps so you need to look at the head curve and work out if it is what you need as it is going to drop off a lot if you have much height or lots of sharp bends.

Johnson L4000 Heavy Duty Submersible Bilge Pump 12 & 24v

The best choices when you are looking for high performance, heavy duty pumps designed to meet the tough demands of commercial and recreational duty. Both pumps may be automatically controlled with either an automatic switch AS888 or an electronic float switch or the new Ultima Switch. Key...

www.thewetworks.co.uk

For high rate and pressure you need a multi-stage centrifugal pump, which is hard to buy cheap but you could improvise with multiple pumps.

 

[Jopo]

Search bilge pump on Amazon for example:

https://www.amazon.co.uk/ECO-WORTHY...M66JIEW/ref=psdc_319530011_t1_B07DPGH7TK?th=1

with 31mm OD outlet 4m head

or more expensive 12/24v dc borehole pumps with a larger head.

Jopo

 

[Relict]

Hi everyone, thank you very much for the information, it's all appreciated and I've since looked at lots and lots of 12v and 24v options, pond circulation, caravan pumps, sewage pumps, as a former sailor, bilge pumps and all. Still not convinced by these for a variety of reasons.
Spent today stripping out the 240v dirty water submersible recovered from the dig field yesterday. As expected it turned out to be an induction motor, forced into a steel tube by an interference fit with aluminium headings to house the bearings.
Omg it took some doing to prise out all that lot!
There is enough space in the housing for a 36 volt waterproof motor, available from Aliwotsit for about £30. Reason I'm trying to stick to that voltage is I have the sooner-dooper 36v ebike battery already.
Currently my plan is to saw off the old commutator, drill the shaft and bond it to the new motor drive shaft somehow. There may be epoxy resin involved. The shaft holds a fairly wicked looking fan blade compared with others I've seen.
I really take the points you have variously made regarding power,, head, bends etc.
It's great to have your input, at this stage I know I'm probably looking at a fail, but in the spirit of h&S, which my colleagues regularly laugh at, (don't look up!), I'm keen to find a safe solution to sumpy pumpy.... Digging cobbles,pebbles and sand underwater is pretty tough.
Hasta la Vista amigos