Sourcing high power alternators

[madlabs]

Hi All,

I'm looking to upgrade the alternator on my lawnmower/alternator battery charger. Right now I have a Delco 7122 that I can get 50A out of. My engine is a 5.5HP, so I should be able to easily get 100-150A out of it. Right now I run the motor not far above idle. The motor is a horizontal shaft, which makes it a little harder to connect to.

So, what I'd like is an alt that has the same mounts as a Delco 7122, with an output range of 150-200A, with an external reg.

So far, all I have been able to find has an internal reg. So, does anyone know how to work with an internal reg to get equalizing voltages? Or know where to get one with an external reg?

As predicted by this group (and the laws of physics enforcement dept.) it takes quite a while to put a substantial charge into the bank.

Thanks!

[bob g]

are we talking a 12 volt system?

its doubtfull your 5.5 hp engine will make 150amps

100amps maybe...

look for a 110-555jho prestolite- leece/neville alternator

it is a large frame alternator, with front and rear ball brgs for long life

a regulator that is piggy back mounted and doubles as the brush cover.

http://www.prestolite.com/literature/alts/PP1131_110-555.pdf

from the graph it will need to turn 2200rpm to make 100amps, but figure on

2500 to account to a hot rating.  very important to pay attention to direction of the fan rotation.

so run your engine at its full 3600rpm gear down to ~2500  about a 2:3 ratio

your best served by either dual A belts of good quality or a serpentine belt

forget aluminum pulleys and cheap single belts it aint gonna happen.

the alternator shaft size is 7/8" which is common off the shelf stuff if you

go with dual A belts, check surpluscenter.com for pulleys.

btw, these alternators are common on hd trucks, available on monthly sales at hd truck dealers such as navistar, peterbilt, kw, freightliner etc. for about a buck and amp, so figure about 160bucks or so, which is cheap for a new hd alternator without a core charge.

if after you get it, it doesn't work out for you as you would like, let me know

these alternators are capable of some interesting things.

also if you are handy you can pick these units up for next to nothing maybe 5 bucks for scrap, when they fail as they sell new so cheap no one will rebuild them. no money in it.  usually it is just the brushes that wear short, and they are servicable from outside the case a 5 minute job at most.

bob g

[madlabs]

Bob,

Thanks for the link, that alt looks like it would bolt right on. I'm afraid that with the direction of my motor that the fan won't be going the right way. I've had to put an external fan on my current setup to keep the alt cool enough. Hopefully that will work for this alt as well.

So, the one thing about the alt you linked is that it is an internal reg type. Is there a way to bypass that? The max volts of the internal is too low for equalizing, no?

Thanks for the help Bob!

[bob g]

yes the regulator is mounted on the rear of the alternator

4 screws and it is off, exposing the 1/4" male spade connectors to

the brushes

take the new one off, find an old one and strip out the potted electronics

then you have the necessary rubber boots, and a cover to seal up the brush

and slip rings nicely, save the new regulator for a backup unit.

my business parnter connected on end to end direct drive onto a 6.5 hp honda clone

it charges very well, but i have never checked its max output. end to end the fan turns the right way for proper cooling

btw, they make a bi directional fan for the 140amp units and below, sure to find one

at a local rebuild shop

bob g

[bob g]

i would like to add a few more comments that might be helpful

i have spent the better part of 35 years modifying alternators for other purposes

early on i spent a lot of time with delco alternators, because they were common as

dirt and nearly as cheap to come by.

about 20 years ago i came across a motorola large frame alternator, which was bought

by leece neville and now prestolite and has morphed over the years from around 90amps to 160amps

the differences between this unit and any delco alternator are stark, in just about

every aspect the large frame 110-555 is much more suitable for modification for various duties.

its efficiency is significantly better than a delco and will make power at much lower speed.

many folks rain on using alternators for these projects because they don't work well, especially the windpower guys,, because they insist on using either the cheap

and plentiful delco or similar small frame alternators that quite frankly aren't worth the effort to mess with at all for anything but what they were designed for.

point being,  automotive alternators are not all equal, some show promise if applied properly in certain applications.

it just seems wrong to condemn all automotive alternators based on experience's with

small frame units and the delco's especially.

just my opinion of course

bob g

[RogerAS]

I agree with everything Bob has said. I have one of the 160 amp units hooked to a small diesel doing exactly what you are attempting. It is over 2 years old and seems as good as ever. I have gone through several delco units and a few higher amp Ford models. None of those compare.

One way around the internal regulator, which is what I have done, is to drill two small access holes into the brush holder and solder wires directly to the brush leads. After the wires are in place a dab of silicone will keep dirt out of the guts via these holes. Use these new wires to supply power to the field coil via the control method of your choice. I use the dashboard lights dimmer rheostat from an old Ford Ranger. This will leave the regulator intact and will have no effect on those electronics.

One way to get the air flow right in the absence of a reversed fan is to rig up a bracket so that the alternator sits the opposite way from its current arrangement. It's not as hard as it sounds. However a high volume external fan will work, but this is a parasitic power drain.

Good luck.

[Ungrounded Lightning Rod]

Good ball bearings solve one of the biggest downsides to alternators - bearing lifetime.

The other major downside is excitation power requirements - especially for wind.  That isn't such a big deal when you're driving them intermittently with a fuel-driven motor (or contunuously, with good bearings, from a water powered turbine with enough drive to spare).  For a "wild" prime mover like a wind turbine the excitation comes off both your total output and cutin speed - and excitation requirements are highest when speed is lowest, just when power is precious with a wind turbine.

Third downside is brush replacement requirements.  But if you're willing to replace 'em every couple years you should be in fine shape.

A fourth is the high RPM requirement for both generation and cooling fan drive.  Again not a big deal if you're running with a gas motor or a water turbine with a rpm boosting drive.

[bob g]

for wind applications i "think" the 110-555 "might" work in certain situations

one would need a large prop, a step up gear (not nearly as much so as for delco's)

and some decent wind speeds, someone with a prevailing wind and perhaps a ridge where the windspeed is accellerated as it goes over the top...

under those conditions one could get some really good numbers from the 555, certainly comparable with many homebuilt machines

where you lose is the excitation current requirments as alluded to, but

the 555 has a relatively low excitation requirement for what it is capable of delivering.

as for brush replacement, there are few that are anywhere near as simple to access

and replace than the 555 alternator, could be done in place on the tower very easily.

not sure i would go to the effort to fit one to a windmachine, but given the choice of having to use an automotive alternator, you betcha it would be the 555, at least there would be a fighting chance of making some good power.

bob g

[madlabs]

As always, a wealth of information! Thanks for all the help. Now I just need to order one and see what I can do with it.

[madlabs]

Bob,

Got one of the 110-555's but they substituted another model instead of the JHO, so I had to send it back. I have another one coming.

Anyway, a question about the brush/field terminals. Does it matter which one you tie to ground, or is one already tied to ground? I have dug through the forum archives and on the net but can't figger it out.

Thanks!

Jonathan