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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Gas powered battery charger.
I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. It would have been nice this winter when we had the ice & snow storm and the battery was weak on the seldom driven 4WD diesel truck. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... RogerN |
#2
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Gas powered battery charger.
On Feb 8, 8:17*pm, "RogerN" wrote:
I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. |
#3
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Gas powered battery charger.
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#4
Posted to rec.crafts.metalworking
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Gas powered battery charger.
wrote in message news:d82ffccf-fad7-4a08-a367- ... A good idea, BUT....work out how much motor power you would need to get the alternator up to 70 amps...not a small motor....and coupling it to the motor is no trivial matter either - but thats OK, no way could you charge a battery at 70 amps anyway...let us know how you get on, if you have the bits lying around then it would be fun - btw, you would need to work out pulley ratios to get the alternator into its power band without revving the motor to blazes - and some sort of governor..(only if your obsessive...) Andrew VK3BFA. I was thinking about something like a 3hp Briggs & Stratton that already has a governor. IIRC, those engines have a maximum RPM around 3600 so if I used a pulley twice the diameter of the alternator pulley it would give me up to 7200 RPM on the alternator. All my autos that have tachometers show from 2000 to 2600 rpm at 60mph. The engine pulley looks (haven't measured yet) to be 3 to 4 times the diameter of the alternator pulley. That would spin the alternator maybe 6000 to 10,000 rpm. In my car when I have the lights and heater on, at idle the lights dim and the fan slows, when I get over about 1200 rpm things pick back up. For experimenting, I could get a used lawn mower and cut the engine hole pattern in a flat plate. Then cut holes for mounting the alternator and install pulley and belt. It would be ideal if I could find a mower with a deck flat enough to mount the alternator, kind of like a riding mower mount. It would be nice to find a smaller lighter motor maybe perhaps a chainsaw engine or good weed eater engine. RogerN |
#5
Posted to rec.crafts.metalworking
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Gas powered battery charger.
On Sun, 8 Feb 2009 03:17:57 -0600, "RogerN" wrote:
I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. Yes, typical alternators for passenger cars range from 50A, maybe even less for the smallest cars, up to 70-80A, maybe as high as 100A. Larger than that, and they'll most likely be 24V. Note that some car manufacturers equip their cars with different alternator sizes depending on which part of the world they will be sold in. If you're looking for a big one, look for cars imported from a cold part of the world. Remember that an automotive alternator can be damaged if it is run without a battery connected. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... Check the specs for those types of batteries. They may not be able to handle as high a charge current as a starter battery. -- RoRo |
#6
Posted to rec.crafts.metalworking
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Gas powered battery charger.
"Mach1" wrote:
Build a good cage around the alternator. At 10,000 rpm there could be pieces going into earth orbit. The ratio of the crank pulley to alternator pulley on cars is ~2:1. Almost all IC auto engines can hit 5000 rpm before rev limiting takes place. Just out of curiosity, has anyone ever had an alternator blow up from rpm? Wes |
#7
Posted to rec.crafts.metalworking
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Gas powered battery charger.
RogerN wrote:
I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. It would have been nice this winter when we had the ice & snow storm and the battery was weak on the seldom driven 4WD diesel truck. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... RogerN I was pretty serious about doing one of those a few years ago for a power unit that would be used to run power tools in remote locations. The volunteer group we work with had been building some bridges etc. on trails in remote locations, but I never got a roundtuit. :-) I wanted it to be realy light weight to make it practical to carry and only needed enough power to run a few power tools. I had a device once on a car, Subaru, that made the alternator put out 110 V which I actually used to run a power saw so I know it is practical. Good luck and let us know if and when you get it going. ...lew... |
#8
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Gas powered battery charger.
"Wes" wrote in message ... "Mach1" wrote: Build a good cage around the alternator. At 10,000 rpm there could be pieces going into earth orbit. The ratio of the crank pulley to alternator pulley on cars is ~2:1. Almost all IC auto engines can hit 5000 rpm before rev limiting takes place. Just out of curiosity, has anyone ever had an alternator blow up from rpm? Wes Saw it happen on a 55 chevy street drag car. Missed a shift and it fragged the alternator pulley. Threw 4 or 5 chunks through the fiberglass hood. Alternator RPM was probably 15,000 to 18,000 when it de-constructed. |
#9
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Gas powered battery charger.
I'm just finishing up a class demo unit that uses a 62 amp Motorcraft
alternator. I wasn't happy with the positive ground on that unit but was cheap and had the external voltage regulator that I needed. 62 amps at 13 to 14 volts is around 850 watts. Calcs out to 1.15 HP theoretical. Any of the 3 to 5 hp B&S, Tecumseh, import specials, etc should work fine at full load. To build what you are talking about, I'd get Delco alternator with the internal voltage regulator. If you happen to have a used one, the rebuild kits run about $15. Amperage varies considerably from a low of about 60 amps to around 135 on the units used on police cruisers. You probably don't care, you don't really want to charge the battery much faster than 30 to 50 amps. As for how fast to spin the alternator: Here is the measured performance curve for the Motorcraft alternator: (rebuilt unit came with a printed inspection tag) rpm amps 1600 11 2000 24 2500 43 3000 53 4000 61 5000 65 I'd expect the Delco units to be similar so driving it 1:1 from a 3600rpm lawnmower engine would be fine. I've tried both belt drive and direct drive using a Lovejoy connector. Using the Lovejoy required some special machining to get it to connect up: the armature is axilially posititioned in the bearing by the nut on the pulley. I think I'd stay with a belt drive for your application. On gotcha to keep in mind: the case on the alternator is one side of the circuit. It's tough to make a mounting where the chassis of your charging rig is not grounded to the case of the alternator. If all the batteries and equipment you work with are negative ground, should not be an issue. But if you have an old positive ground vehicle or one with multiple batteries in series, you really have to watch where you set up the charging rig. And a last thought: there are some aftermarket add on boxes that use a different voltage regulation curve to get 120 volt power out. Really trashy frequency and voltage regulation but they will run a small universal drill. These are pretty much gone now, the decent 12 volt inverters are much more user friendly. Have fun! RogerN wrote: I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. It would have been nice this winter when we had the ice & snow storm and the battery was weak on the seldom driven 4WD diesel truck. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... RogerN |
#10
Posted to rec.crafts.metalworking
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Gas powered battery charger.
"RoyJ" wrote in message m... I'm just finishing up a class demo unit that uses a 62 amp Motorcraft alternator. I wasn't happy with the positive ground on that unit but was cheap and had the external voltage regulator that I needed. 62 amps at 13 to 14 volts is around 850 watts. Calcs out to 1.15 HP theoretical. Any of the 3 to 5 hp B&S, Tecumseh, import specials, etc should work fine at full load. To build what you are talking about, I'd get Delco alternator with the internal voltage regulator. If you happen to have a used one, the rebuild kits run about $15. Amperage varies considerably from a low of about 60 amps to around 135 on the units used on police cruisers. You probably don't care, you don't really want to charge the battery much faster than 30 to 50 amps. I have a Ford F350 with a 7.3L Diesel and 2 batteries. On a cold icy snowy morning I decided to try to drive it to work (4X4) and the batteries were too low to get it started. I charged it with my plug in charger but it took a good while to get enough charge to start. I thought if I had a gas powered alternator charger I could use it if I had trouble starting the truck after work. I haven't tried one but I have doubts about those jump starters being able to get the diesel running in cold weather. Thanks for the information on the alternator, maybe I should select a pulley to give 5000 alternator RPM at 3600 motor RPM, giving maximum alternator output at maximum motor RPM. RogerN snip |
#11
Posted to rec.crafts.metalworking
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Gas powered battery charger.
On Feb 8, 4:07 pm, RoyJ wrote:
And a last thought: there are some aftermarket add on boxes that use a different voltage regulation curve to get 120 volt power out. Really trashy frequency and voltage regulation but they will run a small universal drill. These are pretty much gone now, the decent 12 volt inverters are much more user friendly. Have fun! Have a look at http://islandcastaway.com/stuff/wind...%20Secrets.htm As long as you are building something, you might as well have it work to run power tools with universal motors. Dan |
#12
Posted to rec.crafts.metalworking
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Gas powered battery charger.
There IS one, and only one small gas generator already made that can
produce 70A DC. No longer made, now. I picked one up off Ebay last year for $45. needed carb work, but worked well afterwards. All the current crop of small gens all seem to do just 8A or so DC. Heres one I butchered: http://www.seanet.com/~jasonrnorth/gen.htm JR Dweller in the cellar On Sun, 8 Feb 2009 03:17:57 -0600, "RogerN" wrote: I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. It would have been nice this winter when we had the ice & snow storm and the battery was weak on the seldom driven 4WD diesel truck. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... RogerN -------------------------------------------------------------- Home Page: http://www.seanet.com/~jasonrnorth If you're not the lead dog, the view never changes Doubt yourself, and the real world will eat you alive The world doesn't revolve around you, it revolves around me No skeletons in the closet; just decomposing corpses -------------------------------------------------------------- Dependence is Vulnerability: -------------------------------------------------------------- "Open the Pod Bay Doors please, Hal" "I'm sorry, Dave, I'm afraid I can't do that.." |
#13
Posted to rec.crafts.metalworking
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Gas powered battery charger.
Robert Roland wrote:
On Sun, 8 Feb 2009 03:17:57 -0600, "RogerN" wrote: I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. Yes, typical alternators for passenger cars range from 50A, maybe even less for the smallest cars, up to 70-80A, maybe as high as 100A. GM alternators on most current models are 105 amp units. Trucks have 120 amp units. ALL of them are 3 phase AC units that use regulation and diodes to create 12 volts. You can use a custom regulator and have AC in just about any voltage you like. Or you can also make a nice portable welder using them. Larger than that, and they'll most likely be 24V. Note that some car manufacturers equip their cars with different alternator sizes depending on which part of the world they will be sold in. If you're looking for a big one, look for cars imported from a cold part of the world. Remember that an automotive alternator can be damaged if it is run without a battery connected. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... Check the specs for those types of batteries. They may not be able to handle as high a charge current as a starter battery. -- Steve W. |
#14
Posted to rec.crafts.metalworking
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Gas powered battery charger.
I'd be looking for an alternator off a police car or a large, maybe diesel,
truck or maybe a Ford F350 Camper Special. I have the Ford parked in my drive. It carries two batteries. Ask at the auto parts store you should have no trouble finding an alternator rated for at least 100 amps. T "Lew Hartswick" wrote in message news RogerN wrote: I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. It would have been nice this winter when we had the ice & snow storm and the battery was weak on the seldom driven 4WD diesel truck. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... RogerN I was pretty serious about doing one of those a few years ago for a power unit that would be used to run power tools in remote locations. The volunteer group we work with had been building some bridges etc. on trails in remote locations, but I never got a roundtuit. :-) I wanted it to be realy light weight to make it practical to carry and only needed enough power to run a few power tools. I had a device once on a car, Subaru, that made the alternator put out 110 V which I actually used to run a power saw so I know it is practical. Good luck and let us know if and when you get it going. ...lew... |
#16
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Gas powered battery charger.
--Done frequently by 'newbies' at Burning Man. Noisy and inefficient
but cheap. Better long-term solution: go solar or windpowered with an inverter. Costlier but lasts forever. -- "Steamboat Ed" Haas : Do us a favor and rescue Hacking the Trailing Edge! : a doggie or three... www.nmpproducts.com ---Decks a-wash in a sea of words--- |
#17
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Gas powered battery charger.
On Sun, 08 Feb 2009 08:43:09 -0800, JR North
wrote: http://www.seanet.com/~jasonrnorth/gen.htm NICE!!! Gunner "Not so old as to need virgins to excite him, nor old enough to have the patience to teach one." |
#18
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Gas powered battery charger.
On Sun, 8 Feb 2009 03:17:57 -0600, "RogerN" wrote:
I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. It would have been nice this winter when we had the ice & snow storm and the battery was weak on the seldom driven 4WD diesel truck. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... RogerN I did this about 20 years ago. Used a 3/12 HP Briggs engine and some alternator that was given to me. No regulator though. I used a big pulley on the engine to get the alternator spinning fast enough. I supplied field current through a rheostat to get the desired voltage at whatever load was on the thing at the time. If I was to do it again I'd use a one wire GM alternator so that there would be good voltage regulation. I had to reduce the field current manually as the battery charged. I seem to remember that the 3/12 HP engine was underpowered for the alternator I used which was (I think) a 35 amp unit. ERS |
#19
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Gas powered battery charger.
On 2009-02-08, RogerN wrote:
I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. It would have been nice this winter when we had the ice & snow storm and the battery was weak on the seldom driven 4WD diesel truck. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... How would you deliver such a device to a stranded car? -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#20
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Gas powered battery charger.
"Ignoramus24731" wrote in message ... On 2009-02-08, RogerN wrote: I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. It would have been nice this winter when we had the ice & snow storm and the battery was weak on the seldom driven 4WD diesel truck. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... How would you deliver such a device to a stranded car? -- I wouldn't want it for a stranded car because you could just jump start the car unless it's positioned where you can't get close enough to jump start. My recent experience was that my truck was stranded at home and I had to wait a while to get enough charge to get it to start (diesel pickup with 2 batteries). So I was thinking of buying one of those heavy duty battery chargers but even that would be useless if you lost power, unless you have a generator. For the price of a heavy duty battery charger I thought I could buy a $100 Wal-Mart lawn mower, then with an alternator, belt, and motor pulley I should be in the $200 range for a portable high current battery charger. So, after the ice and snow and getting enough charge to start the truck, I thought it would be nice to have a small gasoline powered charger that I could put in the truck just in case the truck doesn't start after work. Other uses would include being able to take it along when fishing to recharge the trolling motor battery and taking it to the R/C flying field to recharge the battery used to charge the electric models. Also could be nice for camping or anywhere else that 12V lead acid batteries need charged. One of the websites I saw used one for charging their drag car between races. From what I've been reading I should be able to make my own regulator control to recharge other voltage vehicles like golf carts, electric fork trucks, or whatever up to around 110V or so. I just wish I could figure out a way to make it work in a small, light, and economical package. RogerN |
#21
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Gas powered battery charger.
On 2009-02-08, RogerN wrote:
I wouldn't want it for a stranded car because you could just jump start the car unless it's positioned where you can't get close enough to jump start. My recent experience was that my truck was stranded at home and I had to wait a while to get enough charge to get it to start (diesel pickup with 2 batteries). So I was thinking of buying one of those heavy duty battery chargers but even that would be useless if you lost power, unless you have a generator. For the price of a heavy duty battery charger I thought I could buy a $100 Wal-Mart lawn mower, then with an alternator, belt, and motor pulley I should be in the $200 range for a portable high current battery charger. So, after the ice and snow and getting enough charge to start the truck, I thought it would be nice to have a small gasoline powered charger that I could put in the truck just in case the truck doesn't start after work. A lot easier would be to buy a good DC power supply. I have this one: http://yabe.algebra.com/~ichudov/mis.../ebayhist.html (I am no longer selling them). Or a proper battery charger, should cost you $100 or so used. There are many battery chargers that have decent capabilities. Is your system 12v or 24v. 24v may get you into realm of forklift battery chargers. Other uses would include being able to take it along when fishing to recharge the trolling motor battery and taking it to the R/C flying field to recharge the battery used to charge the electric models. Also could be nice for camping or anywhere else that 12V lead acid batteries need charged. One of the websites I saw used one for charging their drag car between races. From what I've been reading I should be able to make my own regulator control to recharge other voltage vehicles like golf carts, electric fork trucks, or whatever up to around 110V or so. I just wish I could figure out a way to make it work in a small, light, and economical package. Considering all the time and various doodads, pulleys, switches, guards, dolly, etc, I cannot see how you can make one cheaper than $300-500, even without adding your time to the cost. A used quality charger will cost you only $100 and will work great. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#22
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Gas powered battery charger.
On 2009-02-08, Ignoramus24731 wrote:
On 2009-02-08, RogerN wrote: I wouldn't want it for a stranded car because you could just jump start the car unless it's positioned where you can't get close enough to jump start. My recent experience was that my truck was stranded at home and I had to wait a while to get enough charge to get it to start (diesel pickup with 2 batteries). So I was thinking of buying one of those heavy duty battery chargers but even that would be useless if you lost power, unless you have a generator. For the price of a heavy duty battery charger I thought I could buy a $100 Wal-Mart lawn mower, then with an alternator, belt, and motor pulley I should be in the $200 range for a portable high current battery charger. So, after the ice and snow and getting enough charge to start the truck, I thought it would be nice to have a small gasoline powered charger that I could put in the truck just in case the truck doesn't start after work. A lot easier would be to buy a good DC power supply. I have this one: http://yabe.algebra.com/~ichudov/mis.../ebayhist.html (I am no longer selling them). Or a proper battery charger, should cost you $100 or so used. By the way. Another advantage of having a decent DC power supply is that you can use it for a bazillion of other uses, such as plating, derusting, running DC motors, etc etc. They are not too expensive on ebay. Here's a pretty extreme one 20v, 120a: http://cgi.ebay.com/HP-6011A-20V-120...QQcmdZViewItem I bought a 6269b power supply (0-40v, 0-50A) for $31 on ebay locally to me (Fermilab used to dump their stuff on ebay). This sort of stuff gives you a lot of versatility on one package, takes a lot less space than a lawnmower engine with car alternator, and is very clean. You can charge your trolling motors from your car. i There are many battery chargers that have decent capabilities. Is your system 12v or 24v. 24v may get you into realm of forklift battery chargers. Other uses would include being able to take it along when fishing to recharge the trolling motor battery and taking it to the R/C flying field to recharge the battery used to charge the electric models. Also could be nice for camping or anywhere else that 12V lead acid batteries need charged. One of the websites I saw used one for charging their drag car between races. From what I've been reading I should be able to make my own regulator control to recharge other voltage vehicles like golf carts, electric fork trucks, or whatever up to around 110V or so. I just wish I could figure out a way to make it work in a small, light, and economical package. Considering all the time and various doodads, pulleys, switches, guards, dolly, etc, I cannot see how you can make one cheaper than $300-500, even without adding your time to the cost. A used quality charger will cost you only $100 and will work great. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#23
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Gas powered battery charger.
On Sun, 8 Feb 2009 05:20:14 -0600, "RogerN" wrote:
wrote in message news:d82ffccf-fad7-4a08-a367- ... A good idea, BUT....work out how much motor power you would need to get the alternator up to 70 amps...not a small motor....and coupling it to the motor is no trivial matter either - but thats OK, no way could you charge a battery at 70 amps anyway...let us know how you get on, if you have the bits lying around then it would be fun - btw, you would need to work out pulley ratios to get the alternator into its power band without revving the motor to blazes - and some sort of governor..(only if your obsessive...) Andrew VK3BFA. I was thinking about something like a 3hp Briggs & Stratton that already has a governor. IIRC, those engines have a maximum RPM around 3600 so if I used a pulley twice the diameter of the alternator pulley it would give me up to 7200 RPM on the alternator. All my autos that have tachometers show from 2000 to 2600 rpm at 60mph. The engine pulley looks (haven't measured yet) to be 3 to 4 times the diameter of the alternator pulley. That would spin the alternator maybe 6000 to 10,000 rpm. In my car when I have the lights and heater on, at idle the lights dim and the fan slows, when I get over about 1200 rpm things pick back up. For experimenting, I could get a used lawn mower and cut the engine hole pattern in a flat plate. Then cut holes for mounting the alternator and install pulley and belt. It would be ideal if I could find a mower with a deck flat enough to mount the alternator, kind of like a riding mower mount. It would be nice to find a smaller lighter motor maybe perhaps a chainsaw engine or good weed eater engine. RogerN A rotary lawn mower engine is NOT a good choice unless you install a HEAVY pulley. The blade is the flywheel - and without it you will have a BEAR of a time starting it, and it won't idle. Lawn mower engines have lightweight aluminum flywheels. Tiller and snowblower engines (and generator engines) have heavy cast iron flywheels. Other than that, it will work. Google "other power" and you will find a site dedicated to the concept. |
#24
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Gas powered battery charger.
On Sun, 08 Feb 2009 12:27:32 +0100, Robert Roland
wrote: On Sun, 8 Feb 2009 03:17:57 -0600, "RogerN" wrote: I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. Yes, typical alternators for passenger cars range from 50A, maybe even less for the smallest cars, up to 70-80A, maybe as high as 100A. Larger than that, and they'll most likely be 24V. Lots of 115 amp rated auto alternators at 12 volt. Even a good number of 135s. However, MOST are good for maximum output for only a very few minutes before they start to overheat. Note that some car manufacturers equip their cars with different alternator sizes depending on which part of the world they will be sold in. If you're looking for a big one, look for cars imported from a cold part of the world. Remember that an automotive alternator can be damaged if it is run without a battery connected. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... Check the specs for those types of batteries. They may not be able to handle as high a charge current as a starter battery. A properly regulated alternator will not put more power into a battery than it wants to accept. |
#25
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Gas powered battery charger.
On Sun, 08 Feb 2009 09:58:29 -0500, Wes wrote:
"Mach1" wrote: Build a good cage around the alternator. At 10,000 rpm there could be pieces going into earth orbit. The ratio of the crank pulley to alternator pulley on cars is ~2:1. Almost all IC auto engines can hit 5000 rpm before rev limiting takes place. Just out of curiosity, has anyone ever had an alternator blow up from rpm? Wes Almost impossible. Ever look at the rotor in one of those things? As a rough guess, 25000 RPM MIGHT do it if the bearings didn't go first. |
#26
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Gas powered battery charger.
In article ,
"RogerN" wrote: I just wish I could figure out a way to make it work in a small, light, and economical package. Economical - pick up a free "broken" mower, which usually just needs the snot cleaned out of the carb, rather than buying one. [or chainsaw or weedwhacker or blower...] Small - not too hard, if you get rid of the rest of the lawnmower and make a frame to fit just the alternator and motor. Light - well, here you'd want to look for a motor that's rather less overkill for the job of running the alternator, so as to reduce the weight and size of the biggest component. Unfortunately most common engines smaller than the smallest-size pushmower engines are annoying 2-strokes. However, if you were to do some crafty metalworking you could make a nice little engine of exactly the size you want - and have some fun shop-time to boot, while not spending too much money. OTOH, for off the shelf (but not too economical, I'd guess) I wonder what the bigger model airplane engines might do, power-wise. Hmm quick look finds a 1.7 hp - but $450 - not too economical. Nice and small, though. If you have some really old junque I think the washing machine motors (I've never seen a gasoline washing machine motor in person, but I gather they were the tinkerer's engine of choice back in a day before mine) would be about the right size. -- Cats, coffee, chocolate...vices to live by |
#27
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Gas powered battery charger.
On Sun, 08 Feb 2009 08:18:11 -0700, Lew Hartswick
wrote: RogerN wrote: I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. It would have been nice this winter when we had the ice & snow storm and the battery was weak on the seldom driven 4WD diesel truck. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... RogerN I was pretty serious about doing one of those a few years ago for a power unit that would be used to run power tools in remote locations. The volunteer group we work with had been building some bridges etc. on trails in remote locations, but I never got a roundtuit. :-) I wanted it to be realy light weight to make it practical to carry and only needed enough power to run a few power tools. I had a device once on a car, Subaru, that made the alternator put out 110 V which I actually used to run a power saw so I know it is practical. Good luck and let us know if and when you get it going. ...lew... 110 volts DC though, so brush universal motors only, and NO variable speed tools. |
#28
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Gas powered battery charger.
"Ignoramus24731" wrote in message ... On 2009-02-08, RogerN wrote: I wouldn't want it for a stranded car because you could just jump start the car unless it's positioned where you can't get close enough to jump start. My recent experience was that my truck was stranded at home and I had to wait a while to get enough charge to get it to start (diesel pickup with 2 batteries). So I was thinking of buying one of those heavy duty battery chargers but even that would be useless if you lost power, unless you have a generator. For the price of a heavy duty battery charger I thought I could buy a $100 Wal-Mart lawn mower, then with an alternator, belt, and motor pulley I should be in the $200 range for a portable high current battery charger. So, after the ice and snow and getting enough charge to start the truck, I thought it would be nice to have a small gasoline powered charger that I could put in the truck just in case the truck doesn't start after work. A lot easier would be to buy a good DC power supply. I have this one: http://yabe.algebra.com/~ichudov/mis.../ebayhist.html A current limited voltage limited power supply would probably be OK for a charger, but you'd still need a generator to make it portable. (I am no longer selling them). Or a proper battery charger, should cost you $100 or so used. There are many battery chargers that have decent capabilities. Is your system 12v or 24v. 24v may get you into realm of forklift battery chargers. My system is 12V but from what I've been reading I should be able to make a regulator that will allow the voltage to be adjusted from around zero to over 100VDC. Other uses would include being able to take it along when fishing to recharge the trolling motor battery and taking it to the R/C flying field to recharge the battery used to charge the electric models. Also could be nice for camping or anywhere else that 12V lead acid batteries need charged. One of the websites I saw used one for charging their drag car between races. From what I've been reading I should be able to make my own regulator control to recharge other voltage vehicles like golf carts, electric fork trucks, or whatever up to around 110V or so. I just wish I could figure out a way to make it work in a small, light, and economical package. Considering all the time and various doodads, pulleys, switches, guards, dolly, etc, I cannot see how you can make one cheaper than $300-500, even without adding your time to the cost. A used quality charger will cost you only $100 and will work great. That would certainly work but I'd also need a generator to get the same functionality. RogerN |
#29
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Gas powered battery charger.
On Sun, 08 Feb 2009 15:55:38 GMT, "Bill Marrs"
wrote: "Wes" wrote in message ... "Mach1" wrote: Build a good cage around the alternator. At 10,000 rpm there could be pieces going into earth orbit. The ratio of the crank pulley to alternator pulley on cars is ~2:1. Almost all IC auto engines can hit 5000 rpm before rev limiting takes place. Just out of curiosity, has anyone ever had an alternator blow up from rpm? Wes Saw it happen on a 55 chevy street drag car. Missed a shift and it fragged the alternator pulley. Threw 4 or 5 chunks through the fiberglass hood. Alternator RPM was probably 15,000 to 18,000 when it de-constructed. ANd that was likely an aluminum pulley?? Not the stock one. |
#30
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Gas powered battery charger.
On Feb 8, 4:46*pm, "RogerN" wrote:
"Ignoramus24731" wrote in message On 2009-02-08, RogerN wrote: I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. ...I just wish I could figure out a way to make it work in a small, light, and economical package. RogerN Lots of interesting ideas here. I've used a jump start battery pack to start the truck when it had an excessive drain (stuck relay), run the TV from a small inverter when the power was out, and power a winch when I get stuck. It doesn't have the capacity of a gas generator but it stores nicely behind the seat so I have it with me when the generator is back home. The Powermate emergency starter packss that are 2" square X 8" long are even easier to store in the car. If you like to tinker they have an inverter that bumps up the internal voltage so you could use one to pump electricity "uphill" to fully charge one 12V battery from another. Jim Wilkins |
#31
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Gas powered battery charger.
On Feb 8, 1:17*am, "RogerN" wrote:
I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. |
#32
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Gas powered battery charger.
On Sun, 08 Feb 2009 16:01:53 -0600, Ignoramus24731
wrote: Considering all the time and various doodads, pulleys, switches, guards, dolly, etc, I cannot see how you can make one cheaper than $300-500, even without adding your time to the cost. Blink blink......sounds like a challenge. Want to make a wee wager? WEG....... A used quality charger will cost you only $100 and will work great. Having a handy 110vt outlet will cost considerably more out on a lake... Gunner "Not so old as to need virgins to excite him, nor old enough to have the patience to teach one." |
#33
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Gas powered battery charger.
On Sun, 08 Feb 2009 16:01:53 -0600, Ignoramus24731
wrote: On 2009-02-08, RogerN wrote: I wouldn't want it for a stranded car because you could just jump start the car unless it's positioned where you can't get close enough to jump start. My recent experience was that my truck was stranded at home and I had to wait a while to get enough charge to get it to start (diesel pickup with 2 batteries). So I was thinking of buying one of those heavy duty battery chargers but even that would be useless if you lost power, unless you have a generator. For the price of a heavy duty battery charger I thought I could buy a $100 Wal-Mart lawn mower, then with an alternator, belt, and motor pulley I should be in the $200 range for a portable high current battery charger. So, after the ice and snow and getting enough charge to start the truck, I thought it would be nice to have a small gasoline powered charger that I could put in the truck just in case the truck doesn't start after work. A lot easier would be to buy a good DC power supply. I have this one: http://yabe.algebra.com/~ichudov/mis.../ebayhist.html (I am no longer selling them). Or a proper battery charger, should cost you $100 or so used. There are many battery chargers that have decent capabilities. Is your system 12v or 24v. 24v may get you into realm of forklift battery chargers. Other uses would include being able to take it along when fishing to recharge the trolling motor battery and taking it to the R/C flying field to recharge the battery used to charge the electric models. Also could be nice for camping or anywhere else that 12V lead acid batteries need charged. One of the websites I saw used one for charging their drag car between races. From what I've been reading I should be able to make my own regulator control to recharge other voltage vehicles like golf carts, electric fork trucks, or whatever up to around 110V or so. I just wish I could figure out a way to make it work in a small, light, and economical package. Considering all the time and various doodads, pulleys, switches, guards, dolly, etc, I cannot see how you can make one cheaper than $300-500, even without adding your time to the cost. Well, I have 3 engines floating around that would be canditates, as well as about 5 alternators. And if I want to buy an old Delcotron I can get one for $50 or less. I have an old set of bed-rails stashed in the shop, so if I can't put one together for under $100 their's something drastically wrong. I also have an engine that's WAY too big - but have a generator that would be a good candidate for a 24 volt system, or a welder, that would be about the right size for that 13HP Kohler. Toal investment in all 4 motors is ledd than $75. A used quality charger will cost you only $100 and will work great. |
#34
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Gas powered battery charger.
"Wes" wrote in message ... "Mach1" wrote: Build a good cage around the alternator. At 10,000 rpm there could be pieces going into earth orbit. The ratio of the crank pulley to alternator pulley on cars is ~2:1. Almost all IC auto engines can hit 5000 rpm before rev limiting takes place. Just out of curiosity, has anyone ever had an alternator blow up from rpm? Wes Did have a tile saw lose an armature piece. No blowup but the brushes disappeared. |
#35
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Gas powered battery charger.
"Calif Bill" wrote in message ... "Wes" wrote in message ... "Mach1" wrote: Build a good cage around the alternator. At 10,000 rpm there could be pieces going into earth orbit. The ratio of the crank pulley to alternator pulley on cars is ~2:1. Almost all IC auto engines can hit 5000 rpm before rev limiting takes place. Just out of curiosity, has anyone ever had an alternator blow up from rpm? Wes FWIW, my car idles at 800 rpm, readlines at 7500. without measuring, I'd agree with the aprox 2:1 ratio of diameters, so that suggests that on my car at least, the alternator must be OK at 15K RPM. |
#36
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Gas powered battery charger.
On Feb 9, 7:42 am, "Bill Noble" wrote:
FWIW, my car idles at 800 rpm, readlines at 7500. without measuring, I'd agree with the aprox 2:1 ratio of diameters, so that suggests that on my car at least, the alternator must be OK at 15K RPM. True, but there is no need to speed up the alternator in this case. With equal sized pulleys and the engine running at 3000 rpm, the output will be the same as if it were in a car with the engine running at a very high idle. Alternators will charge batteries when the car is at a low idle. Dan |
#37
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Gas powered battery charger.
On Sun, 8 Feb 2009 20:55:40 -0800, "Calif Bill"
wrote: "Wes" wrote in message ... "Mach1" wrote: Build a good cage around the alternator. At 10,000 rpm there could be pieces going into earth orbit. The ratio of the crank pulley to alternator pulley on cars is ~2:1. Almost all IC auto engines can hit 5000 rpm before rev limiting takes place. Just out of curiosity, has anyone ever had an alternator blow up from rpm? Wes Did have a tile saw lose an armature piece. No blowup but the brushes disappeared. Common on commutator motors and generators - but alternators are not built that way. |
#38
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Gas powered battery charger.
You have to watch the Ford units: the early ones had positive ground,
many of the later ones had external voltage regulator. I just prefer the Delco units for ease of install for odd ball applications. David Lesher wrote: Some good ideas here. As suggested, you can hang an alternator off a rotary lawn mower, and it's already got its own wheels. And there are LOTS of abandoned lawn mowers. Take mine, please! Now, if you find one with electric start.... But I also like the link to the guy selling the fits-all mounting plate. In any case, you do want the alternator with an integral regulator. It's also lots easier if you have a battery on the unit; both to provide the needed excitation to the field and a low impedence load to the alternator. The smallest lawn tractor battery will do. There's a wide variety of alternators available at the auto boneyard; case size is pretty much an indication of max. output.... If I recall, Ford did things the opposite of GM, regulating the top end of the field vice the bottom, but that shouldn't matter much. |
#39
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Gas powered battery charger.
if you want something really small, my local has new gas string trimmers
for $50. Tiny engine, ~34 cc, about a horse, nice little centrifugal clutch, About 10 pounds with gas tank. Direct couple to a junkyard Delco, should be able to get it under 25 pounds, fit in a 12"x8"x8" space. RogerN wrote: wrote in message news:d82ffccf-fad7-4a08-a367- ... A good idea, BUT....work out how much motor power you would need to get the alternator up to 70 amps...not a small motor....and coupling it to the motor is no trivial matter either - but thats OK, no way could you charge a battery at 70 amps anyway...let us know how you get on, if you have the bits lying around then it would be fun - btw, you would need to work out pulley ratios to get the alternator into its power band without revving the motor to blazes - and some sort of governor..(only if your obsessive...) Andrew VK3BFA. I was thinking about something like a 3hp Briggs & Stratton that already has a governor. IIRC, those engines have a maximum RPM around 3600 so if I used a pulley twice the diameter of the alternator pulley it would give me up to 7200 RPM on the alternator. All my autos that have tachometers show from 2000 to 2600 rpm at 60mph. The engine pulley looks (haven't measured yet) to be 3 to 4 times the diameter of the alternator pulley. That would spin the alternator maybe 6000 to 10,000 rpm. In my car when I have the lights and heater on, at idle the lights dim and the fan slows, when I get over about 1200 rpm things pick back up. For experimenting, I could get a used lawn mower and cut the engine hole pattern in a flat plate. Then cut holes for mounting the alternator and install pulley and belt. It would be ideal if I could find a mower with a deck flat enough to mount the alternator, kind of like a riding mower mount. It would be nice to find a smaller lighter motor maybe perhaps a chainsaw engine or good weed eater engine. RogerN |
#40
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Gas powered battery charger.
What's that Lassie? You say that RogerN fell down the old
rec.crafts.metalworking mine and will die if we don't mount a rescue by Sun, 8 Feb 2009 03:17:57 -0600: I've been thinking about mounting an automotive alternator on a small gasoline engine to make a portable battery charger with respectable output. The purpose would be to charge auto batteries when there are no outlets around. Of course you could do the same thing with a generator and battery charger but I think you can get perhaps 70 amps or more from an alternator. It would have been nice this winter when we had the ice & snow storm and the battery was weak on the seldom driven 4WD diesel truck. Also could be useful for camping and boating, could recharge the trolling motor battery on the lake, etc... RogerN You want the booklet "alternator secrets". I think I got mine from Lindsey publications. I built just what you described without it, but it would have been easier with it. I put a large pulley on the engine shaft to add flywheel mass. The donor engine was from a lawn mower, and it was hard to get started with out the blade attached. Keep the RPM up to keep the torque down. The engine shaft bearing wasn't made for a side load. I used a large delco alternator with a built in regulator. Grab the right kind of auto AC compressor and you can have portable air too, if you have a horizonal shaft engine. -- Dan H. |
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