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Forum Index : Other Stuff : Big alternator
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shawn Senior Member  Joined: 30/03/2010 Location: New ZealandPosts: 210 |
I have bought a 24volt 95 amp alternator its off a cat wheel loader just wanted to use as backup charging for my 24volt 1000 ah bank when the wind dosn't blow cannot afford solar yet. First question how many hp do I need to run it? ecoinovation are selling 3.5 hp diesal/veg oil moters for 200 bucks!! sod those chinese how can anybody compete? And then the power greedy side of me says put two alternators on with a bigger moter how would 190 amps affect my bank??? please keep answers not two technical so I can keep up thanks. shawn |
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| dwyer Guru  Joined: 19/09/2005 Location: AustraliaPosts: 574 |
Hi Shawn First of all is 24 volts 95 amp alternator need approx 10 hp high torque motor and also those Chinese engine just forget it is the one same as ecoinovationl got is aheap of sh*t metal & noising engine and my 200 metre away neighbour complaining at me hearing like loose like worn out Conrad bearing (still got it) as l have said this before few years ago somewhere in this forum if l were you l would spend extras dollar for better quality diesel engine where spare part are easily available at well known engine dealer. Again l have given you my advise is that you wasting your time and money as l have already made one big mistake is saying to myself "How petty and good looking engine is" and say “Wow” that is cheap soon l brought back home as end all sort of problem fuel line fail, muffler,air filter fell out and engine is dancing all over the workshop (running out of balance ) 
Dwyer the bushman |
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| shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210 |
Thanks for the info thought it would be two small, but 10 hp goodness surely about 5 to 7 hp would run this??? |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
If i remember correctly a standard 40 amp car alt draws about 5 Hp from the motor at 40 amp, so Dwyer is about right. Just remember if you gear the alternator speed up double to get maximum output you are also halving you engine Hp. It is interesting no one notices the drop in fuel / mileage with there big spotlights on and the heater fan and every other accessory that draws power on a car. The wankers with 1/2 dozen LARGE spotlight racked up on their vehicals for what ever reason, make me think "Sucker" you are paying dearly for being a wanker.
Pete. Sometimes it just works |
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Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566 |
shawn; Wrote, surely about 5 to 7 hp would run this??? At 28 charging volts and 95 amps, I get 2660 watts, divided by 746 watts = 3.55 horsepower. Overall Mechanical efficiency, Belts, Pulleys, of 50% would dictate 7.10 Hp. Surely more than 7 horse would be overkill. EDIT; I Have an AC Generator, 4000 watts 240 -120 volt, 60 hz. using a Briggs & Straton single cylinder 8 horsepower gasoline engine. This is continuous rating. Time has proven that I am blind to the Obvious, some of the above may be True? |
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| dwyer Guru Joined: 19/09/2005 Location: AustraliaPosts: 574 |
Hi All Greenbelt EDIT; I Have an AC Generator, 4000 watts 240 -120 volt, 60 Hz. using a Briggs & Stratton single cylinder 8 horsepower gasoline engine. This is continuous rating. OK That your AC generator at 60 hz is running at appox 3600 rpm while Aust is 240 AC 50 hz 3000 rpm as my Chinese made engine running 1900 rpm with two different size pulley and two vee belts to run old Dunlight 1500 rpm 240 volts 2000 watt and just enough puff left and still under 3 hp not 3.5 hp as is misleading and if l do let my Chinese made engine at max 2700 rpm fuel consumption is high so therefore slow down the rpm is help & cut out the engine vibrated so you should leave enough hp to spare and therefore less load on the motor and better than running at max at rpm however if l had 5hp chinse engine running will be good The bad news that Briggs & Stratton is not very good design motor as high on consumption of fuel and lack of toque at low rpm than Honda engine sorry about that. ] dwyer |
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| shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210 |
Thankyou for your time guys its great to run these things over here before I jump in which mostly I do. goodness I must be growing up help  |
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| Robb Senior Member Joined: 01/08/2007 Location: AustraliaPosts: 221 |
Did you see this Shawn? 4 to 5hp for a normal car alternator. |
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| shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210 |
Yes have had a good look thanks just need to work out if mine has a internal regulator or not. have an old 8hp briggs I know these are hard on fuel but the motor was free. |
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