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Forum Index : Solar : Running pool pump with treadmill motor - directly off solar panels
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rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 852
Posted: 01:54pm 28 Jan 2021
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Hi everyone, I wanted to do a post on a project I have had running for the last year.
I had looked all over the place for answers as to whether I could run a pool pump directly from solar and with a bare minimum of control electronics ... but could never find anything ... other than other people asking the same question.
I found this forum 18 months ago in the middle of 2019 and got all excited about building some sort of inverter and adding a forklift battery to help reduce our power costs.
In the process of asking questions and trying to understand my best plan of attack, I realised that our pool pump was a large part of my annoyance with power useage/wastage ... and with a fair bit of prompting from Warpspeed, decided to experiment with tackling that.
Tony's suggestion was that I hook up a DC treadmill motor to the pump ... and match it with enough panels to drive it sufficiently ... and see if I could eliminate that usage from our bill.
To cut a long story short, I did exactly that ... and have had the pool pump running for a year on solar ... apart from when we switch over to mains to vacuum ... or need to circulate water at night after adding chemicals etc.
Apart from the mechanics of the system ... there is only a DC treadmill motor, a string of panels, a solar isolation switch ... and a diode to prevent the treadmill motor feeding power back into the panels if I switch on the pump's 240V AC motor (without isolating the panels or removing the belt).
Where before on AC it was set to run for 4 hours each day (probably should have been 6 hrs) ... now it runs most of every day, as long as there's enough sunlight to spin the motor.
I ended up using 6 x full size 250 watt 30 volt panels in series ... though in reality I should probably have 2 strings of 6 in parallel ... so it definitely does not run at full power for all that time. In fact it would rarely run at full power.
To give some idea, it might run at 50psi pressure at the filter ... and if I switch over to mains, it might go to 70psi. Of course it often runs way lower than that when conditions are poor ... or the belt is coming loose and needs to be nipped up.
Having said that, I regularly check the pressure of the feed-in to the pool to feel what the flow is like ... and it still moves a fair volume of water by the end of the day.
Certainly we need full pressure for vacuuming and various treatment type functions ... but the majority of the time (95%) we just need the water circulating through the filter.
I had investigated variable speed pumps in the past ... and the manufacturers make the point that the water does not need to be circulated flat-out to do the job ... and a fair bit of their power savings were through running them slower when possible. Only problem with them is the initial purchase cost.
... anyway, now that we're back into summer ... and I've made a bit of an effort to fine tune the pipes and fittings ... I've found that I can use the Kreepy Krauly pool vacuuming system quite effectively on solar on an average day.
In my next post I'll go over the process I went through and exactly what I used.
Cheers, Roger
rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 852
Posted: 02:21pm 28 Jan 2021
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The pool pump is a 1.5hp Onga and has a cowling on the end of the motor covering a simple pressed on plastic fan.
I hoped that I could remove the fan ... find a pulley of some type that could be held on with a grub screw ... then match up something for the treadmill motor.
After looking at various taper fit pulleys ... being a bit scared off by the prices ... as well as the fact that there was not a lot of shaft sticking out ... and also thinking of the friction that would be created by having a V-Belt tight enough to drive properly ... I was starting to have second thoughts.
Fortunately Tony came to the rescue when he sent me a link to some ribbed pulleys on eBay ... which just so happened to have the same profile ribbing as my existing treadmill motor pulley. He had calculated what sizes I most likely would need ... so I sent off an order for a selection.
They come in various bore diameters ... and I was fortunate enough to find some marginally smaller than the shaft size. I'd like to tell you I machined down the shaft to fit properly ... but I ... ahem ... powered up the motor and used a file to take the tops off the faint spline that was used to hold on the fan.
It only needed about half a mm off to accept the new pulley ... so it was a pretty simple exercise, if somewhat rough! A couple of grub screws holds it firmly in place.
I had already collected a dozen 250 watt 30 volt panels, so I simply leaned some against the inside of the pool fence ... which fortunately happens to face north ... and hooked 6 in series ... for a total of 180 volts.
Check the pictures to see my first set-up.
It ran pretty well and I was happy with the performance, though I was a little casual about how hard the motor was working.
I bought an optical tacho and noted speeds with various loads and size pulleys.
It only took about two weeks before the brushes burned out on the poor little motor and cooked it beyond repair.
Fortunately, in the mean time I had picked up another complete treadmill for $50 ... and this one had a physically much larger motor. I had to rebuild my motor mounting arrangement ... but it turned out pretty well ... and is relatively easy to adjust the belt tension.
I did measure the brushes before I installed the motor but despite spending ages on eBay etc ... could not find any brushes the same size. I probably do need to check them again ... but they've been going for more than 12 months already.
With the first treadmill motor and under Tony's guidance, I had removed the flywheel section of the treadmill motor pulley so that when I needed to run it on AC ... the AC motor wouldn't have such a hard job to get it up to speed.
I simply drilled a series of holes through the cast material and went up in sizes until it fell off. Then a few minutes on the grinder and it was nice and smooth. When the first motor failed and I replaced it, I never got around to removing the flywheel on the second motor ... but the majority of the times I do use AC, I remove the belt anyway ... just run it off with my fingers.
So, conclusions
In many ways it has been a success and I will certainly keep it running as long as I'm able. Over summer with the extended run times it definitely has done a great job.
I'm not sure about over winter though ... we had left the pool go, as far as checking and maintenance ... so it went pretty green. The pump still ran plenty of time each day ... but of course lack of chemicals and proper testing means it didn't have much of a chance.
Now that I've taken over the maintenance side from my wife, I'll see how I go looking after it in the coming off season. I work from home and I walk past it a dozen or so times every day, so no real excuses I guess ... plus my wife is a volunteer ambo ... and lots of shifts keeps her more than busy.
I can still see a time when I have a decent sized inverter that can run the pump at 100% ... as well as the pool solar pump, to warm it up properly. At present of course that requires AC ... and during the swimming season needs to run a few hours a day as well to keep the temperature up.
Edited 2021-01-29 00:22 by rogerdwCheers, Roger
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 08:45pm 28 Jan 2021
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A great writeup there Roger, and some excellent results.
This is certainly something quite new, I have never heard of anyone else attempting anything quite like this, and the internet is full of people trying out different ideas. Edited 2021-01-29 07:08 by WarpspeedCheers, Tony.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 12:16am 29 Jan 2021
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You have done very well with this. It's a great low cost and simple application of " appropriate technology" and making use of repurposed materials. You even managed to use the same pump for DC and AC use.
One thing that may be of help when driving with AC is an automotive over run clutch. They are used on alternators on Toyota's among other vehicles. Basically allow drive one way but not the other. You could set it up so the DC motor drove the pump but the AC motor wouldn't drive the treadmill motor. Might be some gains and less wear and tear there.
What size ( power) is the treadmill motor? Most I have seen are around 180-200W. I can see you have geared this down but given most pool pumps are 750W + I have seen, I'm a bit surprised the treadmill motor has the grunt to do the job with sufficient flow rates.
One great thing with those poly Belts apart from lower losses, is that you don't need near as much wrap or tension to get the things to bite. You could easily add another motor in a tri configuration to increase the power and speed and lower the load on the individual motors.
What might work really well on a multi function and aesthetic level is to put the panels up and use them to build like a cabana roof where you have the shade sail now. Wouldn't take much and you could increase your PV area and using the panels as the roof which wouldn't even have to be sealed but easily could, for a shaded or storage area or put a BBQ or whatever under.
I'm considering doing just that with an extension to the side of my garage. Give me room for another 20x 270W panels. I can get panels cheaper than I can buy the same amount of colourbond so I'll use them as the roof.
The other thing might be to just stand the panels flat on the fence. You would loose some efficiency obviously but if you went right along the fence you could make that up and it would probably look more like they were supposed to be there than just put there.
Good practical setup and well done! Thanks for showing it. Very interesting and inspiring.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 12:40am 29 Jan 2021
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Roger and I discussed alternator over run pulleys, but the problem is that most are designed to fit a standard 17mm alternator shaft with a keyway and a big nut.
The rear fan shaft on Rogers pump motor is rather short and of a much smaller diameter, it was only ever intended for a small plastic motor cooling fan.
The trick has been to match the solar panels to the motor requirement, then match the motor to the pump with a suitable pulley ratio. It seems Roger has all that pretty well sorted out.Cheers, Tony.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 12:54am 29 Jan 2021
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With my pool at the last place, made a pool cover out of that thick black builders plastic Sheet. Was 4M wide but my Pool was 5.5 So I welded it together with a soldering iron. Yeah, I know how that sounds and exactly what I thought too when I saw it on the net but it worked unreal and took Little practice to get it right. I had a big electric iron anyway with maybe a 10MM wide tip and did a double seam which was overkill anyway.
You simply could not tear the plastic at the join. It was by far the strong not the weak spot.
In winter I simply pulled the sheet across the top and floated it on the water and held it in Position with long lengths of heavy timber and bricks. About 5 years later when I did the second one, I made pockets on the edges and inserted lengths of conduit couple of meters down the ends, blew a bit of plastic rope through with a wad of rag on the end with the compressor and drilled some tie points in the side of the cement pool edge and tied it off. Much neater tidier. You only have to stop the wind getting under and lifting it and can have a bit of slack in the middle, does not have to be tight or above the water.
This cheap cover worked fantastic. Kept all the dirt, dust and leaves out and the best part was, it kept the sun out from cooking off the chlorine. I ran the Pump and Chlorinator a couple of hours a WEEK and it never went green. Chlorine levels were always very high in fact. When there was a lot of rain, the water sat on the top of the plastic and I just pumped that off so the chemical balance and salt wasn't diluted and wasted. Of course it stopped all evaporation as well.
When the weather warmed up, it also made a great pool heater. I had the pool at a house that I ran my business from initially and didn't live there for a number of years and before the kids came along. My cousin came to visit one time from interstate early in the summer. The pool was still covered and when I opened it up, the water was more than warm. It was hot at first but even when I ran the pump and took away a lot of the stratification, I measured it at still being 40oC. This was a 5.5x 11M 80K L pool. That's a LOT of heating! 100% surface for solar absorption heaters are considered ideal for where I am and that's exactly what I had at a fraction of the price.
Years later when the kids came along I would keep it warm by half covering it and then fully at the beginning and end of the season. It made a Big difference. The best part was keeping the thing clean and the reduction in running costs in power and especially Chemistry.
You can get the builders Film I think they call it at bunnings and in different thicknesses either up to 200 or 250 UM. Get the thickest you can and shop around. I got mine Much cheaper than that when they called it BBC instead of " Bunnys" but I think they sell it even now for about $150 a 50 M roll which will last forever and probably pay itself back the first season. I think I paid $50 for mine at the time at some plastics suppliers nearby and that was definitely a ROI within one season. I still have a heap on that roll and I bought it over 25 years ago!
It lasts years as a cover, I only re did mine though physical damage of tree limbs falling on it and bastard kids in the rental next door lobbing bricks at it but it fended off a fair few of those too.
It's really cheap and easy to do this and nothing like pulling the cover back early in the season and finding the only thing in the pool is a bit of dust that probably settled out the water and the Chlorine level is sky high even with minimal running of the chlorinator which burns off in a day or 2 anyway. One go round with the Krualy and you are well and truly open for business. :0)
bob.steel Senior Member Joined: 27/02/2020 Location: AustraliaPosts: 188
Posted: 08:41am 29 Jan 2021
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Just summing it in my head. 6 panels 250 watt at 30 volts , thats 1.5 Kw giving 180 volts so 8 amps or so.
If you added 2 more panels ,one either end,you would get 240v DC and maybe 10 amps .
Could I suggest a $1300 Inverter hybrid like MPP HV2-5048 that will output 240v AC up to 20 amps which should drive your original motor at full speed when you have good sun or put all the rest of your panels on it to 22 in total (2 strings of 11) max and get heaps of useable power on winter days .
You don't need batteries and its not tied to the grid unless you want that.Sounds to me like a lot less mucking about even though I see you like that. You could probably run a fair bit of other stuff on 240 as well in the day.
Its a bit more expensive but a fella in aus sells them with a warranty .I doubt the Taiwanese one is worth much. Edited 2021-01-29 18:44 by bob.steel
Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1024
Posted: 09:47am 29 Jan 2021
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Nice work Roger, The same can work for a garden that is far away from a power source. When I was about 7yr old,(Mid 80's) got hold of an old Ajax piston pump and done it all up nicely, never used it until last year. Mounted an old 32vdc washing machine motor on it and connected up 5 250w solar panels and its run well (garden and dam is 250m from the house) up until 2 week's ago when the leather buckets give up. Needed it working so made up a 3D printed piston with grooves for O rings (not ideal but needed) to get it going again in a hurry.
There is a small 400w Onga pump I would probably drive the same way with a multi V belt, The motor is one of those universal motors that can be found in some old washing machines and already has a multi V's cut into the shaft, probably not powerful enough to run a pool pump, I think the Onga pool pumps are much more powerful than the old garden variety.
Definitely a good project that can be built with scrounged parts.Cheers Aaron Off The Grid
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 10:34am 29 Jan 2021
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I had never thought of this for irrigation....
But a rain water tank, and a pump, would make a rather interesting project. The more sun, and the longer the days, the more irrigation. Perfect.Cheers, Tony.
rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 852
Posted: 03:16pm 29 Jan 2021
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Wow, thanks for all the feedback and great responses Dave, Bob and Aaron ... and a special thanks to Tony for spurring me on.
Just to answer some of the comments ...
Both the DC motors had very little detail on them, but believe it or not ... both were labeled as 3hp. The original AC pump motor is 1.5hp.
I agree with the comments on the belt too ... it's not under a lot of tension and behaves quite well. I think that when I run the pump on AC, it gives it a bit of a hiding and needs to be adjusted again sooner than normal.
Having said that I've probably only adjusted it half a dozen times in a year.
I also think it could do with a bit of a 'sticking' agent to help prevent slip. There's a fine line between slipping and adding enough friction to start to load it down. When I was home on the farm we used 'Black Jack' ... a thick sticky treacle like substance on any flat belts to help prevent slipage and improve drive.
I'll have to try one of the farm machinery places ... I'm sure there would be a modern day spray-on version ... with a more pc name!
Regarding the panels ... I had always planned to put them on the shed roof for more sun. Where they are, there's shadow on one end until about 8am or so and at the other end from about 6 pm. If I was to get really serious I would add another 6 series panels in parallel with the first lot.
I did try adding more panels in series but it did not help ... the series panels limit the current anyway to a bit over 7 amps.
It's a pity you're so far away Dave or I'd be putting in an order for 10 or 12kW of panels seeing you have the knack for picking them up so cheaply.
I think I'm ready now to build an inverter and run a roof full of panels to tackle the rest of our loads ... so I don't expect I'll try and take this system any further ... though I'll definitely leave it as it is until I get to the next stage.
I had read about your black plastic pool cover trick before too Dave ... I need to study what you've suggested and ask more questions.
I have to admit I've always wondered why I can have 20,000 litres of rainwater in a tank for years and years and it never gets full of algae or goes off like a swimming pool ... is it something about being in the dark. Is that why the black plastic worked so well for you?
Great work on your project too Aaron, it's amazing what can be cobbled together with old and new stuff ... and especially creating 3D parts to keep it all going. If you're looking for a decent DC motor, treadmill motors can be sourced pretty cheaply ... but of course you never know if it's going to be any good until you find one and try it.
Regarding irrigation, a friend is using our glasshouses and he's fitted two panels and is planning on pumping water for his plants ... plus he uses an inverter to run a fan on hot days so they don't get too hot. Just so many options and things to try. Cheers, Roger
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 08:04pm 29 Jan 2021
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The other way to do this might be to use a spring loaded tensioner. Done that on a couple of generator setups. you could have the belt loose enough so when the tensioner wasn't engaged, the belt slipped freely for when you were driving the pump on AC. Reconnect the spring or have the tensioner on a lever ( and the lever itself can be the tension weight) and the treadmill motor will be engaged. you can get them off cars and I have seen skateboard wheel used as the rollers as well.
I can't get enough lately. Was reading yesterday that the solar installs last year was well up despite the way things were going but I'm not seeing that anywhere much in Sydney reflected in used panels being available. If I could get enough to satisfy what I could sell, I'd be making serious money!
Yes, I think it's all about keeping the light out. Without that the algae can't grow. The UV also kills the chlorine so no light, no algae and lots of Chlorine to stop it anyway.
That said, I have a translucent IBC full of water up the back that's been there over a year. No algae in that. It's capped so no air either but maybe the plastic filters the UV as well or some other wave length that the algae needs? I know the plastic in those tanks is UV stabilised but I don't know if that means it won't pass it or it's just to stop the plastic degrading?
OTOH, could be residue of whatever was in it. Seem to recall that not being great and washing it out but who knows?
I use car radiator fans off a panel on my inverters so they don't get too hot! :0)
Yes there are lots of things to try. I didn't realise treadmill motors could be so powerful. I'll keep my eye out for some.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 10:33pm 29 Jan 2021
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Roger, As Dave says, more belt tension would be very helpful, and a really strong spring tensioner would be the way to go. A suitably long lever that sockets in (like a jack handle) to easily override the spring, would be a convenient way to slip the belt on and off when full mains power operation is required.
My treadmill motor also came without its rating sticker, but by using Google image, I looked at pictures of treadmill motors until I found one that looked the same. The aluminium motor end plates also had the initials of the Chinese company that made it, so I was able to identify the exact motor and get some data on it. I have not tried to buy replacement brushes for it yet, but that should not be too difficult.
Dave, Treadmill motors definitely do have a lot of grunt, but they have rather poor cooling, and are not really suitable to run continuously flat out for long periods.
I use one on my standby petrol powered battery charger, and I have hooked it up to one of those 12v dc bilge blowers advertised on e-bay. That makes a huge difference to the temperature of the windings and the bearings.
The hot tip with any treadmill motor might be to not overload the motor. Allow it to run fairly free at high rpm and high voltage, and keep the current and torque down. Its only current that heats up the windings.
That way, it can produce significant horsepower at relatively low current, and run cooler. Use a pulley ratio high enough to let the motor rev fast, and let the pulley ratio multiply the torque.Cheers, Tony.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 02:34am 30 Jan 2021
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I have seen and admired pictures of your ingenuity with the fan Cooled treadmill Motor Tony. Gells perfectly with my position on fan Cooling inverters.
I was thinking exactly what you were saying with the suggestion of doubling up on the treadmill motors with a Y configuration. The heat aspect did not come to mind but I was thinking if these were well loaded, sharing the work between 2 Motors would help with longevity and may use no more power than one motor while allowing the revs and flow rate of the pump to come up to where it was driven off AC.
I have had a little to do with pumps especially bigger one's and I know that they can fall off their efficiency Curve real fast if under driven especially with some types. That said, For longevity purposes, in industry they are often over specced and under driven with a VFD so they do last better.
I had to attend a 50Kw pump once that was on a cooling tower for an office building in the city. Someone and no idea whom could have gotten in there, Messed with the speed settings on the VFD and the thing got air in it. The thing was making a racket like it had swallowed a bunch of 2" Impact sockets. You could hear it through the pipes 3 floors away. I was literally scared to go near it as I thought it could come apart at any second.
I shut it down, called a mate who said it's just got air in it, start it up again slow and ramp it up gradually. I said no, this is a lot more than air. This is metallic hammering like an engine that's thrown a Rod and the clutch at the same time. He convinced me otherwise ( well not so much convinced, I did what he said to prove I was right!) and sure enough, the thing bled and it went back to running smooth as could be. Re set it to the correct speed and that was it.
Had I not heard and done it myself, Id' still not be convinced that was nothing more than air in it and not a couple of housebricks with the racket it made.
I have seen alternators converted to motors on the net. They appear to be quite powerful if driven with an appropriate ESC. Usually they use electric bike controllers but the things would have the advantage of good cooling and durable bearings as well as easily replaced brushes.
This is excellent. I've been wanting to set up a treadmill motor running directly off solar to power an old piston pump for water transfer and irrigation on my uncles farm. We did fool around a bit one day and temporarily connected a treadmill motor to the pump in question and ran it off 10 250w panels for a half hour or so. It did seem to work quite well, although we didn't have much head on the pump at the time.
I've been wanting to build some kind current boosting/mppt controller to make it start earlier, run longer, and do better on cloudy days. But maybe we'll just direct drive it and be done with it. Just have to find a way to prevent it running dry. Moving some water is always better than moving no water.
And I figure I can water cool the motor by wrapping some copper line or even garden hose around it and plumbing some water from the pump through it.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 04:50am 31 Jan 2021
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The problem with motor cooling of brush type motors, is that there is just no thermal path between the armature and the outer steel motor casing.
It really needs airflow, BIG airflow through the length of the motor to cool the spinning armature windings and the commutator, and brushes. Contact cooling the outside is just not going to work with this type of dc motor.
Induction motors are a very different thing. The windings are attached thermally to the outer motor frame, and you can just blow air over the usually finned outside of the motor. The cylindrical rotating part in the middle, is just a lump of solid metal, and it can run incredibly hot without it being a problem.Cheers, Tony.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 05:46am 31 Jan 2021
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I don't know what it is with this thing of Copper coils and why people on the internet ( not you Jacob) think of them as the go to solution for everything and mislead people. Lack of knowledge of Physics I guess.
I have seen endless examples of this where people preach flawed ideas and info to those like Jacob looking for a solution to a problem.
The problem with a copper coil in this case is you would have a sharp arc on the copper which has a tiny contact area with the motor casing or any other tube shape which inevitable it is suggested you wrap the copper around. You could have a pipe glowing red hot and I'd suggest the difference in heat transfer between it being wrapped in contact and an inch away would be minimal because the radiant energy would be stronger than the thermal transfer.
Think of a Tyre on the road and the small contact patch that has and the tyre flattens out. A railway wheel is in fact efficient because the wheel and track are solid so there is little friction. Same with a tube of copper. If the contact area is small, so it the thermal conduct path.
It's a very flawed but widely spread misconception.
In this case the over riding factor is as Warp says but if you were doing to an induction motor or say an engine Cylinder that was round on the outside, wrapping a coil would still provide VERY little thermal transfer contact area. You would have to braze or weld the tube to increase the surface area and the thermal bond to get it to near work and then you are only going to have 50% contact area at best.
Many years ago when looking at veg oil forums, people used to ask about wrapping copper around the exhaust to heat the oil. The parroted mantra was it would get too hot and burn the oil. I argued that it wouldn't put much heat at all into the oil unless the coil was brazed to the dump pile with a lot of filler material or wrapped and insulated in heat shield. Of course I was told I was an idiot etc. to the point I got the sh*ts and set it up.
I wrapped about a foot length of exhaust pipe closest to the turbo dump pipe in copper which was quite a few feet of the small tubing and had a thermo probe wrapped in thermal grease and tape in and out of the coil. I got some useless 12 oC heat rise or something when I had the truck Climbing the steepest hill flat out for miles around. As I said all along, to make it work you'd have to increase the surface area of the exhaust tube to the oil with something like a tube in tube design and by the time you do that with no heat regulation, far better off sticking with the normal method of using a liquid to liquid heat exchanger off the coolant which was far more stable and limited temp wise.
For these treadmill motors, I think warp has already nailed the simplest and most effective approach with sucking air through the motor itself. Car alternators work much the same way. The ones with exposed fans pull the air through the whole alt where the enclosed ones generally have 2 fans, one for the armature and one for the control circuitry but the are both Pulling air through not blowing it as it's usualy more effective to let nature do the work with ambient air pressure trying to fill a void the fan creates than trying to blow and work against that air pressure.
We've already tried it with garden hose wrapped around the motor on a 24vdc diaphragm pump - intended for intermittent use and not continuous duty like we were asking of it. Also a brushed dc motor with the same kind of spinning armature windings. It worked well enough. The DC motors on those diaphragm pumps are a fairly well sealed unit with no fan, so maybe they've somehow achieved a better thermal path from the armature to the case.
And maybe the garden hose is better than copper in that it flattens out a bit and offers more contact area on the motor casing.
In any case it seemed to work ok for the little pump, and even if it doesn't work so well on the treadmill motor, I can't see how it could hurt.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 06:43am 31 Jan 2021
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I suggest you get one of those infrared temperature measuring guns and see what is actually happening to the armature temperature looking through the ventilation holes in the motor end plates.
Its kind of like having the engine in your car overheating, and spaying cold water onto the bonnet. Then putting your hand onto the bonnet and saying "yup she's cool now" no worries.
All we can do here is offer advice. What you choose to do is entirely up to you.Cheers, Tony.
I don't think thats a fair analogy at all. In this case the pump did not over heat and kept running just fine. If I sprayed water on the bonnet of an overheating car I would expect it to continue overheating and I would end up with a seized engine and/or a warped head.
In this case the outside of the motor was getting very hot and when we wrapped the hose around it, it stopped getting hot. This tells me that a) the heat was finding a path from the armature to the outside of the motor, and b) that the hose was taking that heat away.
All that said, I don't disagree at all with you regarding cooling of treadmill motors(or brushed DC motors in general) by blowing air down the guts of them.
It just didn't occur to me when we were playing with the small pump and since it worked I haven't thought about it again till today. And it wasn't an option in that situation anyway.
When I was in canada I built a few small conveyor belts using treadmill motors for a guy who was in the bottle recycling business. We had trouble with one in particular getting hot because the fan on the motor was broken. He's got it going well enough with a little desk fan blowing air over it but I would like to set up one of those bilge blowers as someone else mentioned. That said, its been going for about 4 years now, probably 6-8hrs a day, 5-6 days a week. I've been very impressed with its longevity.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Voltage: 24V Power: 370W Solar Panel and Regulator Requirement ( not included ) : 550W (min) Solar Panels or deep cycle batteries Head: 25m Inlet and Outlet: 1 inch BSP Current 15A Max Flow (L/Hr): 2200 Clear, free from solid or abrasive substances, Overall Dimension (cm): 26 X 13 X 15
First thing you learn about any non certified, non industrial pump is manufacturers lie. ALL of them and that's not the ones flogging stuff on fleabay. The ones that are.... well they just pull numbers out their nether regions with no relationship to reality at the best of times and not just on pumps.
If they say this thing will do 25M head I'd think it may do 5. 3 should be reliable with still reasonable flow rate. Still useable for a lot of things. They say 2200L Hmm Yeah nah. That's Probably at zero lift and head. Like most things, lots of ways to fudge the numbers and they will fudge them beyond belief and more.
That's what they call s turbo pump so it has a very small impeller as can be seen in the casing and it will have hacksaw like cuts in the rotor instead of actual blades. They have very little lift. I'd think this thing good for 500- 1000 L hr. If it has positive lift like sitting at the bottom of a tank and pumping higher, will do better, If it's pulling up a meter, if it will do that, lower end of the scale.
They don't specify lift and there is most likely a reason for that, it sucks. May need a positive pressure feed like bottom of a tank to really get on song or be a good Circ pump.
"Stainless Steel Pump Housing & Shaft"
No way in hell is that housing stainless. It's cast crap. The impeller probably is too and I'd be amazed if the shaft is. Used these in the AC version and did come across one which appeared to be a brass impeller but the rest was just like this one. Pay to drain them after use as the rubbish they use in the casing corrodes and seizes them. Can be difficult to free up again.
It might be useful to someone looking for a DC pump and be fine as long as used VERY conservatively with in the specs and de rated.
Other things for conservative use are marine Bilge pumps. The big once can flow a LOT of water but nothing like what they say. They tend to use brushed motors so run time is not that long and longevity is variable. They do have large Impellers though and I have used them for pumping veg oil and they weren't bad as it wasn't too cold. Once it gets a bit thich they struggle.
The turbo water pumps won't move it very well at all. Best pumps for that are the ones with the impellers large than the motor body. They bite and really push water and oil along.
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