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Forum Index : Other Stuff : F&P Petrol battery Charger
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| MickWh Newbie  Joined: 08/05/2010 Location: Posts: 19 |
I have an old horizontal shaft 7hp motor that I was thinking about close-coupling to a rewired F&P. Thinking I may as well go Delta config, as low startup is not going to be a problem. The primary purpose for this is to use as a battery charging unit for my off-grid 24v house system. I have a few concerns however; Not sure how fast the motor spins, but could it possibly be too fast and destroy the F&P rotor? Electronics- out of F&P and through a rectifier to get DC, I imagine I need a regulator, or is it possible to get away without one? Any other points or hints would be appreciated. Many Thanks, Michael. |
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AMACK Senior Member  Joined: 31/05/2009 Location: AustraliaPosts: 184 |
Hi Mick, The F&P's on spin when in the machine turn at around 1000 -1800 rpm. There have been a few in the past that have been converted over to Petrol motors I think there is one on the project page. AMACK *Note to self 1. Make it thick 2.Make it heavy. 3.Make it stronger than it should be. 4. Don't rush the first job as the second job will cost more and take mor |
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| MickWh Newbie Joined: 08/05/2010 Location: Posts: 19 |
I did look around the site for info, and saw the home made charger on the project page, however that was a joining of a motor to an alternator, so has regulators built in and is specifically designed to run at engine speeds. Unless of course I missed the project that uses a F&P motor. |
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Tinker Guru  Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
You could always use a V-belt with reduction pulleys, 3:1 reduction should do. This will also be easier to set up as no precision shaft alignment is required. Pulleys can be found in many older washing machines, sometimes with a good V-belt as well. Klaus |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5036 |
Yeah I agree, you dont want to spin the F&P much over 1000rpm, it will loose efficiency and could fly apart, its just not designed to ever go that fast. Tinkers comments about a 3:1 v-belt are spot on, I dont expect the motor would run much over 3000rpm. You WILL MOST DEFINATELY need to rewire the stator, probably into something like a 14X1C! In standard trim, the F&P could put out over 500VAC at 1000rpm, lethal. Add to that a diversion controller. Honestly, I would use a vehicle alternator instead. Its much safer, and its going to work out of the box. Glenn Page on F&P rewiring http://www.thebackshed.com/windmill/FPRewire.asp The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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merca Newbie Joined: 07/02/2011 Location: AustraliaPosts: 2 |
Hi Mick - joined up tonight just so I could reply to your Post ;) I have made several versions of a 24 V battery charger. My current version has a 6.5 HP Honda spinning a 24 V Lucas alternator (regulator removed/replaced) via roughly a 2:1 ratio, 'A profile' fan belt. It works really well, pumps out about 40 amps for 3-4 hrs (RPM dependent) for 3 odd litres of unleaded petrol. It doesn't need to rev that high with the 2:1 ratio and I find the heat in the alternator gets too much over 40 amps anyways. The fanbelt drive is high maintenance with the belt wearing out regularly. I put an idler pulley in to reduce the belt slapping around and that has helped, but if you can devise a direct drive (shaft to shaft) coupling - that would be the way to go ;) I tried and failed, needed a flexible 'universal joint' type coupling that could handle the horsepower and different shaft sizes... Now the 24 V alternator was $120 from a wreckers, but I also want to try a F&P (or 2) drive as they are cheap and readily available. The www.ecoinnovation.co.nz site has a kit for sale (F&P drive, bearing block, pulley etc) - not sure what rewire option they use - maybe a 7x2C at low RPM's ?? Maybe drop them an email and ask what they would suggest ? Then you could rewire one yourself. Trouble with the petrol motor battery charger is the noise... now a quiet old Lister diesel would be the way to go... Good Luck !!! Merca |
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| merca Newbie Joined: 07/02/2011 Location: AustraliaPosts: 2 |
Oh and on the regulator side of things, I just have it wired it up to the shunt side of my Plasmatronics PL40 Solar Controller ;) |
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shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210 |
Hi i have one of these the alternator is a caterpillar 24 volt 95 amp it was on an old 8 hp briggs until it died of old age now its on a kola ten hp electric start motor and when my bank is down it needs all ten hp to run the alternator (works real hard) here is a picture of the old motor setup not tidy but it worked. 
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| MickWh Newbie Joined: 08/05/2010 Location: Posts: 19 |
Thanks for the idea here guys, much appreciated. I decided to go with a 24v alternator + built in regulator for convenience. My setup looks remarkably like yours Shawn, old B&S motor with alternator beside, will get a pic up soon I hope. Would I be able to connect the new 50amp alternator directly to my 1660ah battery set, or do I need something else ??? |
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| shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210 |
Hi mick mine has a built in regulator to and dc comes out so i connected it straight up to my 1000 ah bank the motor works hard for a while then eases up holding bank at 27.5/28 volts. If you are woried about what volts it will run up to first connect it to a couple of old car batteries and test the volts after a while with it running. |
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| MickWh Newbie Joined: 08/05/2010 Location: Posts: 19 |
Thanks Shawn, good idea with the car batteries, it all SHOULD work, just feeling a bit paranoid. The alternator is supposed to be 24V 50amp DC with built in regulator, so I didn't think it I would need anything else. About the only other thing I thought about was the direction of spin of the alternator, bloody thing came with absolutely no documentation, I judged it on the fins on the fan, guessing it was designed to blow air through the unit. I had someone raise the concern that maybe the batteries would try and pull too much power out of the regulator or possibly the amount of power in the batteries would try and run the alternator like a motor. Both of which I don't think could happen, but didn't have the right answers, so I thought I would ask here. |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Mick Most automotive alternators run clockwise looking at the front of the shaft, a clue is the cooling fan as it is designed for the rotation. All the best Bob Foolin Around |
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mid north Matt Regular Member  Joined: 06/01/2011 Location: AustraliaPosts: 58 |
have alook on the projects page where gizmo reversed the alternator fan blades so it could run stationary motor anticlock direction Pt Wakefield Matt |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Crew Just a quick note on rotation direction. I believe the fan is designed the same as the impeller in a volute pump. The thing spins such that it draws air from the center and slings it out; not scooping up air and shoving it back through the windings. The idea is to pull cool air from the back side of the thing through the warm or hot windings and sling it off at the front. So, figure which way would draw from the center and sling to the perimeter of the machine and that's the direction it should be spun. Hope that helps. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| MickWh Newbie Joined: 08/05/2010 Location: Posts: 19 |
Thanks Mac, well both motor and alt spin anti clockwise so thats a bonus. I got it all up and running, I have to turn the alt "off" when starting the motor or it loads up too much and the motor doesn't start properly. So thats fine, turn off alt, start motor then flick back on and it makes a rather odd "grinding" noise. I have no idea if something has gone horribly wrong or if it is as simple as bushes bedding in. |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
"grinding " noise sounds bad. If you had it apart take it apart again and see what's rubbing where. Maybe you put something in the wrong way round. Bedding in brushes should not make any noise. When you turn it 'off' I hope you do that by reducing the field current. Disconnecting the output of a spinning alternator is not a good idea, its output needs to be clamped by the battery voltage or you run the risk of blowing all the diodes. Klaus |
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| MickWh Newbie Joined: 08/05/2010 Location: Posts: 19 |
Ah no didn't know about the problem of a free spinning alt, so maybe I have blown it up already, was a new unit off ebay. Looks like I need to get something like this ?? Ebay AFD Switch |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Save your money about the switch, it is a battery selector/ combiner and does the diode blow up thing for sure if you have not done it already  .
Find the wire that goes to the slip ring brush (the field supply) and interrupt that if you want to take the load of the alternator. Come to think of that, I remember seeing an article on the net where someone mounted an alternator to the flywheel of an outboard motor and had a clever circuit involving a light bulb or resistor to automatically remove the load until the motor ran. Google might find it, it was a message on a sailing newsgroup. You can test the diodes with a multimeter but if that is news to you it might be better to do some read up on basic electricity, diodes especially. Good luck. Klaus |
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