one wire automotive alternator

[DirtMerchant]

 I have an electric start 6/1 and also have a 94amp automotive one wire alternator, I am interested in mounting the alternator for charging the start up battery, anyone have experience using a one wire alternator on a Listeroid? I am concerned that it needs to be "goosed" into producing voltage? I have an 8 inch, an 11 inch and an 18 inch pulleys that I can use to drive it but am wondering what the correct approach is? High rpm so it does not need a goose to get it started charging?

[Tom]

Realistically for charging a starting battery, if you're running a generator and making AC already, a small AC battery charger will be much more efficient. It will also likely be more reliable. If you need to charge a battery bank for an inverter or not running an AC generator go with the alternator and a serp belt around the flywheel.

[DirtMerchant]

 I do have a 12v fan for the radiator as well,  I light the idea of the tail lamp to slow the fan down. I also want the option of charging my battery bank using the alternator on occasion instead of using the ST through the inverter. Sounds like I need to use the 18 ich pulley and see what it produces. Not really interested in maximum output, just need to cover the fan and starter.

 

[ronmar]

How long do you run the generator?  If long duration, I am with Tom as a small battery maintainer is way simpler and more efficient.  If you are running infrequently, the larger alternator may be desireable to makeup for the starter drains during the shorter runs.  When you were talking about pulley sizes, were you refering to alternator pulleys?  If so, I would reccomend running the SMALLEST pulley you have, or perhaps even smaller.  Most auto alternators are designed to run in the thousands of RPM.  A 6/1 flywheel runs at around 630-650 RPM, so an 8" pulley driven off the 24" flywheel is only going to get you around 1800 RPM.  That may not be enough to get the 1 wire alternator to self start.  Somewhere in the area of 4" might be better.  An undersped alternator that is heavilly loaded will also not cool properly  I have an alternator I was going to play with on my 6/1 and I am planning on using the stock automotive pulley that is on it which should turn it in the area of 4300 RPM directly off my flywheel with a long serpentine belt... 

Also be aware that a thirsty battery or some other large 12V load can take all that alternators output.  That 94A alternator at full load is going to demand close to 3HP from the engine, which may effect other output capabilities...

Good luck

[DirtMerchant]

 I have solar and wind power for charging the battery bank, the 6/1 is just going to be run for topping off the battery bank on occasion and for the occasional heavy load, ie running the washer , dryer (propane), well and furnace all at the same time, potentially a few hours a week from the ST head, the 12v alternator would be primarily just keeping the starter battery up to snuff and powering the fan, however I am going to wire it to a (through a switch) proper regulator for charging the battery bank as a backup if the ST is not working for some reason, otherwise the batteries can be topped off by the inverter/charger being powered by the ST.

 

[ronmar]

The old rule of thumb for 12V alternators is 30A per HP, or around 3HP for 94A.  I have always thought that number might be a little conservative.  Using the more acknowledged 2HP per KW figure which applies to small AC generators pretty well, the 94A is around 1.3KW or around 2.6HP required. The 12V alt can be significantly less efficient than an AC generator such as the ST. The actual engine load is probably somewhere betwween these two numbers.  On a 6HP engine it is still a significant % of the available power though.

If I were setting it up as a backup charging source for the St-inverter/charger, I would go with a larger alternator, say closer to 200 A(or 250A with a controllable regulator to run cooler).  This would still keep the starting battery topped when running and drive a fan, but would allow you to apply the full engine HP toward the battery charging if needed.  With the ST - inverter - charger conversion losses, you might find that a driven DC alternator with programmable charge controller might even be more efficient at charging the batteried directly... 

At any rate, good luck...

[veggie]

The one thing that swayed me to go with a Leese alternator instead of my AC-head+Battery charger was the issue of HZ.
Running my AC head at 60hz and the engine at 650 rpm made more KWs than I needed to charge the batteries, so in a way, it was inefficient and wasteful.
With the DC Leese unit I really don't care what rpm my engine runs at as long as it has enough power to drive the alternator at the required load levels, which currently equates to around engine 480 rpm (2600 rpm alternator speed).
I do admit that Auto/Truck style alternators may not be the most efficient method, however the improved fuel consumption at these lower rpm's makes up for some of my losses.

veggie

[DirtMerchant]

  When you were talking about pulley sizes, were you refering to alternator pulleys?  If so, I would reccomend running the SMALLEST pulley you have, or perhaps even smaller.  Most auto alternators are designed to run in the thousands of RPM.  A 6/1 flywheel runs at around 630-650 RPM, so an 8" pulley driven off the 24" flywheel is only going to get you around 1800 RPM. 

I thought the OP was talking about the pulleys on the engine not the alt. I presumed the alt pulley would be left the standard 2-3" and the driving pulley changed.  I also think an 8" pulley on the alt could be a problem.  It may well not be enough to get the alt to self energise as they normally do and it may need the field wire connected.
In any case, with an 8" pulley the output would be low as it would be below the speed an alt would normally  see at engine idle on a vehicle.

  That 94A alternator at full load is going to demand close to 3HP from the engine, which may effect other output capabilities...

Yes the pulleys for the 6/1 not the alternator, I will be using the stock 2 or 3 inch pulley on the alternator,  but I can go anywhere from 8 inch to 18 inch on the 6/1 to drive the alternator (V Belt), I should probably just sit down and do the math to spin the alternator at 1800 -2000 rpm to get a decent charge out of it, just wondering what others have done and how it worked for them.



Do you think it would be that much?
I figured 2.5 Hp but there are variables. I was also factoring 50% alt efficiency. Do you think that is reasonable or too high?

I have 2x  80A alts on my lister and they certainly will bog it down.  I calculated about 1.5 Hp each but now i'm not sure how I got that figure and I can see it's too low..  It makes sense why they are pulling the engine down though.
 I was wondering before if my engine wasn't up to par but it's more my maths that is lacking! 

[ronmar]

The math is easy, divide the smaller pully into the larger pully, like 3" into 18" = 6X you then multiply the engine RPM by that first answer to get the alternator RPM at those pully sizes.  If you are going to put any kind of load on the alternator, I would go higher than 2000 RPM for better cooling.  If your alternator pulley is around 2"+, then the 11" pulley you mentioned will give you around 5X RPM increase or about 3250 RPM out of the alternator with the engine making 650..  If the alt pully is closer to 3", then the 18" pully would give you 6X or around 3800 alt RPM.