Tonk Posted January 26, 2007 Share Posted January 26, 2007 how bigger alternator can u run on a single veebelt before you have to convert to serpentine belts? 120 amp possibly? Quote Link to comment Share on other sites More sharing options...
simonr Posted January 26, 2007 Share Posted January 26, 2007 how bigger alternator can u run on a single veebelt before you have to convert to serpentine belts? 120 amp possibly? Possibly? As a rule of thumb, you can stick 10Hp through a 13mm V belt without it complaining too much. That's 7.5kw A typical AC pump can take 10Hp to drive - Although many have two belts, many do not. 120A is only 2.4kw. Even if the alternator were only 60% efficient, that's still only 4kw worth of mechanical drive. However, the other things you are driving with the same belt, combined with the inefficiency of the alternator could easily conspire to make it unhappy! I would try it! Si Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 26, 2007 Share Posted January 26, 2007 Don't MOD lumps have many-V (not poly-V) lower pullies to drive things like 24v alts? Could be worth a look rather than drive everything from one V? Quote Link to comment Share on other sites More sharing options...
pugwash Posted January 26, 2007 Share Posted January 26, 2007 does it matter what alternator you stick on an engine- ie if i found a 150amp 12v truck alternator which physically fitted, would that be ok to use? some of the modern car alternators must be pretty huge- would it be worth trawling a scrappy to find one? Quote Link to comment Share on other sites More sharing options...
Lewis Posted January 26, 2007 Share Posted January 26, 2007 does it matter what alternator you stick on an engine- ie if i found a 150amp 12v truck alternator which physically fitted, would that be ok to use? some of the modern car alternators must be pretty huge- would it be worth trawling a scrappy to find one? No, put anything on, I have a Volkswagen/Audi 140amp to go on the trayback when i make the brackets. Its unlikely you will find a truck with a high output 12v alt though - almost all trucks are 24volt and as such have 24v alts, if they need 12v they just tap off of one battery. If you want a really high output alt then look at some of the american stuff - Licoln town cars (mostly limos) amongst other large SUV's had an option of a 200amp 12v alt, they crop up on ebay fairly regulary for a lot less than bathtub got ripped of by spent on his premier welding alt HTH Lewis Quote Link to comment Share on other sites More sharing options...
webbsite Posted January 26, 2007 Share Posted January 26, 2007 Tonk, I have been running a 120amp Marelli unit for the last 2-3 years with no problems at all. It will slip if the belt is not tightened regularly though. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 26, 2007 Share Posted January 26, 2007 Also (ask Nige how he knows) you can get different profiles and widths of V-belt, I fitted a thicker one on mine to stop it squealing as the stock one didn't like the load when it got wet. Quote Link to comment Share on other sites More sharing options...
SOA 93 Posted January 26, 2007 Share Posted January 26, 2007 Possibly?As a rule of thumb, you can stick 10Hp through a 13mm V belt without it complaining too much. That's 7.5kw A typical AC pump can take 10Hp to drive - Although many have two belts, many do not. 120A is only 2.4kw. Even if the alternator were only 60% efficient, that's still only 4kw worth of mechanical drive. However, the other things you are driving with the same belt, combined with the inefficiency of the alternator could easily conspire to make it unhappy! I would try it! Si Si, previously on your X-eng website you used to sell alternators for Land Rovers and IIRC you stated that running higher than 65A alternators through a single V belt could cause them to catch fire, the belts that is, or at least get way to hot. I think this refered to using them with a winch though. I think you will struggle to find many car manufacturers fitting much more than 70A to 80A alternators on a single V-belt. The advantage with multi-V(serpantine) is you can make the pulley a smaller diameter, you then get higher power at lower revs. A useful bit of tech here http://www.adverc.co.uk/technical/technical-twin.asp Tomorrow I should be picking up a pulley I ordered, its the V8 pulley which is a normal V drive from the crank with a Multi-V driving the alternator, I'm going to see if it will fit or be adapted to fit a 200TDI. As someone has said already if you use a V belt the it is likely it will need regular adjustment. Also if you are using (heavily) the alternator to power winch batteries/winches then it is likely that problems may occur as opposed to just fitting an larger alternator to power a few extra accessories. Quote Link to comment Share on other sites More sharing options...
Lewis Posted January 26, 2007 Share Posted January 26, 2007 As Andy (SOA93) said its mostly pulley dia that gives the most grip - we ran a vehicle at work with a starter/generator - it had a three-phase motor that could crank the engine from cold in 0.25seconds and ran on the FEAD through a 12grove serp belt, the trick to avoid slippage was having the belt tensioner close to the starter/generator and having at least 120degree belt coverage on the pulley, I doubt any alternator could put as much strain on the belt system as this did Lewis Quote Link to comment Share on other sites More sharing options...
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