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On a one wire mini alternator; in order to maintain a charge on the battery while motor is running; is it necessary to run a bigger pully on the crankshaft side & smaller on the alt side? currently im running 2 3/4" on both sides. Im continuing to have some charging issues. Battery is new as is alternator. Alternator is spinning at same speed as crank pulley. Am i missing somthing? Iv'e asked around however have got no solid answers wether this will or will not work. any opinions or knowledge would be appreciated.
 

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Cantard
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On a one wire mini alternator; in order to maintain a charge on the battery while motor is running; is it necessary to run a bigger pully on the crankshaft side & smaller on the alt side? currently im running 2 3/4" on both sides. Im continuing to have some charging issues. Battery is new as is alternator. Alternator is spinning at same speed as crank pulley. Am i missing somthing? Iv'e asked around however have got no solid answers wether this will or will not work. any opinions or knowledge would be appreciated.
With that size of alt pulley you are going to want about a 6" crank pulley.
 

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On a one wire mini alternator; in order to maintain a charge on the battery while motor is running; is it necessary to run a bigger pully on the crankshaft side & smaller on the alt side? currently im running 2 3/4" on both sides. Im continuing to have some charging issues. Battery is new as is alternator. Alternator is spinning at same speed as crank pulley. Am i missing somthing? Iv'e asked around however have got no solid answers wether this will or will not work. any opinions or knowledge would be appreciated.
Im having the same issue. Its working but its not putting anything out.

I ran a jumper wire from the feild the the power wire when im cruiseing the river and it puts out 15 volts, and then i unplug it after about 5/10 min running so i don't over charge.
 

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this subject has been covered many many times on HB...every1 has a different opinon on what works...i personally run 2 batteries hooked to a Perko 3 way isolator switch...this allows me to use 1 battery for starting & 1 for assys...can chrg 1 or 2 with the flick of a switch...i also have an advantage over alot of people in that i run a "magneto" :)...i learned a whole lot of years ago from drag raceing...so...i only need to spin the starter over & go with no issues about chrging! :)...if everythings rite, it will start on a flashlite battery lol :)...as far as pulleys go...i run a very small 1 on the crank & the normal 1 on the alt...n/p on chrging...just my .02 cents

FastRat
 

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I'm No Expert
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I use the jegs one wire 80amp alt, has a small pully on the front, and my crank pully is 6". One reason i bought this alt was because it energizes at a low rpm (900 rpm). I have had no issues with my setup and i run a MSD 6AL box.

http://www.jegs.com/i/JEGS/555/10101/10002/-1

Unless your running a ton of accessories or have a stereo that your playing all the time you dont need two batterys either.
 

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mo balls than $cents$
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you've gotta run the smaller pulley on the alt., the alt turns almost twice the rpms as the crank, or should be anyways;) if your alt was made to turn on at 1500rpms, when runnin a 1 to 1 ratio on the pulley's, its gonna take 3000rpms to turn it on:)bulb
 

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Boat 502
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At idle what should your volt meter read ? You aren't charging at idle, right ? So when your cruising down the river don't you want to see 14 volts on the gauge so you know your charging ? Now, I'm wondering if I have the same problem ?? I have a mini alt., not sure what size the pulley is, but the crankshaft pulley is 5 3/4''

If you are overcharging would you pop the 30-amp re-setable breaker on the electr panel ?
 

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mo balls than $cents$
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At idle what should your volt meter read ? You aren't charging at idle, right ? So when your cruising down the river don't you want to see 14 volts on the gauge so you know your charging ? Now, I'm wondering if I have the same problem ?? I have a mini alt., not sure what size the pulley is, but the crankshaft pulley is 5 3/4''

If you are overcharging would you pop the 30-amp re-setable breaker on the electr panel ?
30 amp breaker between the alt and battery is wayyyyy to small if that's how your's is set-up, i'll either use some fuse link wire or a big 80-90amp fuse to protect my boat from a shorted alt.. on my tx i used a 90amp fuse , you can get them at most auto parts stores.
your breaker shouldn't be in series with that 30amp breaker, something else is either drawing to much amperage or shorting to ground.
 

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At idle what should your volt meter read ? You aren't charging at idle, right ? So when your cruising down the river don't you want to see 14 volts on the gauge so you know your charging ? Now, I'm wondering if I have the same problem ?? I have a mini alt., not sure what size the pulley is, but the crankshaft pulley is 5 3/4''

If you are overcharging would you pop the 30-amp re-setable breaker on the electr panel ?
You need to excite the field before it will charge and then it will charge untill the regulator says not to charge anymore. I like to see 13+ volts on the meter, but with my mini alt, it is not registering any volts, just showing battery volts until i plug the field excite wire to the power wire and it jumps up and shows a charge. I think i have something going on with my alt, but i have not had a chance to take it in and have it checked out. I bought it brand new and it has never acted like a 1 wire alt, but the people i bought it from swear it is....
 

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Unless your running a ton of accessories or have a stereo that your playing all the time you dont need two batterys either.
i run lites 4 nite time use n a stereo n sometimes a flood/spot lite 4 fishing...thats y i have 2 batteries

FastRat
 

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Boat 502
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30 amp breaker between the alt and battery is wayyyyy to small if that's how your's is set-up, i'll either use some fuse link wire or a big 80-90amp fuse to protect my boat from a shorted alt.. on my tx i used a 90amp fuse , you can get them at most auto parts stores.
your breaker shouldn't be in series with that 30amp breaker, something else is either drawing to much amperage or shorting to ground.
The 30 amp breaker I'm running is very standard set up, its built into the electrical panel. Its not in series w/ the alt to the battery. Its been rigged the same way for 3yrs now with no problems, but it went bad on me last time out and the only change was the mini alt. Could be a bad connection somewhere or maybe the breaker just took a crap ?? Put a new one in and it fired right up. The question is...is it fixed or is it going to happen again ? I hate wiring !!
 

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Boat Nut
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I run a Summit Racing 6.6 inch crank pulley with a Moroso alternator 5 inch pulley. Takes about 1200 rpm to put it on line, once on line it stays at 14v. My Alternator is a Motorola marine one wire.
 

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Discussion Starter #13
Thanks for your input; will experiment with different size pulleys. should get it right; hopefully sooner then later.
 

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B1 Racing
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Mares turn the alternator 2:1. in other words smaller pulley on the alternator. We are turning an east coast electric mini alt. 21,000 Rpms (3:1) on one of our boats with no problems so far. They said it can handle the rpm and so far no problems. You dont want to turn it 1:1 you will not be happy with the results. If its a powermaster alt. keep an eye on it, they make JUNK parts, period.

As far as charging goes (at 2:1) it should turn on just off idle, you can see this with a multimeter, I see it on my data logger very clearly.

Good Luck.

Chris.
 

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V-Drive 4 ever
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i run my alternater Direct off the crank shaft no belt no pulley nothing . rex sells a set up like i have its pricey but nice . its connected with a drive dog rubber isolated pulleys . the cranks spins the same as alternator and charges just fine (now that i got it wired right lol) 2 wire alternator .. dont have to worry bout a stinking belt .. heres a pic of my setup :D
 

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I have a one wire alternator just like the Jegs unit with one of those Moroso 5 inch pulleys and a 6 inch puley on the engine, if I just fire up the boat and let it idle it doesn't charge, have to gun it a couple times but once it comes online it stays charging even at idle.
 

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i run my alternater Direct off the crank shaft no belt no pulley nothing . rex sells a set up like i have its pricey but nice . its connected with a drive dog rubber isolated pulleys . the cranks spins the same as alternator and charges just fine (now that i got it wired right lol) 2 wire alternator .. dont have to worry bout a stinking belt .. heres a pic of my setup :D
very nice looking :)...perhaps u couldnt run a set-up like that in a jet boat for lack of space (rear seat)...do u ever worry about vibration on the crank or front main bearing?

FastRat
 

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V-Drive 4 ever
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do u ever worry about vibration on the crank or front main bearing?

FastRat
no vibration ive noticed and i turn right at 7000 rpm .. the alternator has a drive dog pulley and the crank has a drive dog pulley and there is a big rubber isolator between them that absorbs it no metal touches each other just rubber between then .. its a sweet setup if you have room to run it . ive seen one other boat set up like mine and he mentioned he liked it and has had no problems charging .
 

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E-7 Sheepdog (ret)
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At idle what should your volt meter read ? You aren't charging at idle, right ? So when your cruising down the river don't you want to see 14 volts on the gauge so you know your charging ? Now, I'm wondering if I have the same problem ?? I have a mini alt., not sure what size the pulley is, but the crankshaft pulley is 5 3/4''

If you are overcharging would you pop the 30-amp re-setable breaker on the electr panel ?
At idle, after the alt. has been energised, it should charge 13.6 to 13.8 volts aprox.
Mine does at 850-RPM idle.

You ARE charging at idle, just with very little amp capacity.

14 volts is about as high as you want to see, maximum. Much more will boil the battery dry sooner or later.

BTW, from research into the physics of it on the internet, all you guys worried about "saving hp" running the alt. slower, are MAYBE saving 2HP.
1 is more likely. It depends on the load on it.

They guy with a magneto and nothing but dash gauges, is likely saving about .1HP. POINT 1 that is. 1/10th.

It will take about 3/4HP to make 50A of electricity at 14vdc, double it to get into bearing friction and belt losses.
 
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