OT-ish: alternator question

About what percentage of an alternator's (made mostly of metal!) max
output do you think it could put out continuously without drastically
shortening its life? The other day I put an alternator on a guy's truck
that had so many extra lights (metal filaments) the alternator was
putting out around 80 amps at idle. And that's without his trailer (I
think it'll add roughly 25-30A) hooked up. It's a 160A alternator, but
that still seems far too high for continuous use. He cooks about one a
year.
So what would you say is a good ballpark number?
Reply to
B.B.
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The stock small-frame GM high output alternators are good, optimistically for about 1/3- 1/2 rated output. With the modified "cool" case, 1/2 to 2/3. Thermal mass, heat-sink area, and airflow are the 3 big problems. A 160 large-frame Leece Neville will likely run 90+% rated output 'till the cows come home.
Reply to
nospam.clare.nce
Actually, Leeces are what he's cooking. (: But I'll go ahead and use the 1/3 to 1/2 figure.
Reply to
B.B.
The big problem is the internally mounted regulator modules can't take the heat, but they sure save on manufacturing cost.
John
Reply to
John
You might try using a bigger pulley on the altenator.
John
Reply to
John
[...burning alternators up...]
Did you mean smaller? I can't see how using a larger pulley would help as that would further slow the cooling fan. Either way, the place I work is on a downhill slide right now, so we're lucky is we have any pulleys at all. On the last five alts I've changed I've had to reuse the old pulleys even though a couple were obviously worn out.
Reply to
B.B.
If an alternator is putting out around 80 amps at idle - it probably means that the vehicle has a "throw (a relay will develop a "short" and most of the current that the alternator puts out goes directly to that relay). I can tell you that the one system that uses up the most current in a vehicle that is working correctly is usually the AC system. This consumes around 25-40 amps (never 80). The best way to try and find the "short" is to first find the system that is consuming the most amps and then finding the individual relay or "short" that is causing the "throw". Unfortunately there is not an easy way to go about finding the short without good test equipment. Also, you can disconnect relays one at a time while the vehicle is off and hold it up to your nose and smell it. A bad relay has a distinct smell (electrical fire). A bad ground to the system is also a possibility. Take the vehicle to an electrical repair place or go out and stop the Snap-on or Matco or Mac Tools guy and tell him that you would like to purchase a "power probe". This in my opinion is the best and fastest way to find a short in a vehicle. Last time I bought one it cost around $100.00. Good luck -carlos castillo SF Auto Electric Supply
ps. don't change pulleys. Alternators are manufactured to turn a certain speed and when you toy around with the physics of it's engineering, you are taking the alternator above and beyond what it was capable of doing. Just for the record - a smaller pulley turns the alternator faster. A bigger pulley turns the alternator slower. Bigger pulleys are used on race cars that rev way too high for altenator bearing speed capacities. Smaller pulleys are used on farm vehicles that are at constant idle
Reply to
charlesjohncastle
Interesting claim. The only electrical part in most AC systems is the wire that runs the AC compressor clutch, and that circuit is usually fused at 7.5 or 10 Amps (and typical draw when engaged is about half that.)
Of course there's also the blower motor and maybe some remotely controlled vents/doors but they're all used for heating/ventilation too.
I'm not saying you're wrong - I've heard the same claim by many others - but out of my ignorance I can never figure out what draws all that current other than the little circuit that engages the compressor clutch.
Tim.
Reply to
Tim Shoppa
The electric radiator and A/C condenser cooling fans usually located behind the radiator at the front of the car can easily draw this current in stop and go traffic on a hot day.
I agree that the compressor clutch and the internal circulationg fan combined would draw in the range of 10 to 15 amps.
Wolfgang
Reply to
wfhabicher
[...]
Nah, I confirmed that the bulk of the load is his extra lights. He had about 80 (not a typo) additional lights strung all over the tractor, plus 60 or so more on his trailer. He had all of his extra lights strung through five different switches scattered all over the dash because all together it literally blew the original switch out of the dash. Scorch marks were still there. No relays in his extra lights--at least according to him. Mishmash of incandescent and LED. With 'em on, 80A draw. With them off, 17A. Most of that 17 was the headlights. I left the A/C off while testing his system because, as you mentioned, it draws a shitload. (IME, around 7-12Amps, depending on if the fan kicks on) His headlights wouldn't shut off when the ignition was on. BTW, I picked up a craftsman Amp Clamp AC/DC. Was about $40 and works great. Reads within about five amps of someone else's Fluke. Just saddled with a cheap plastic housing, so I have to be kind of delicate with it. I'll probably spring for the nice one eventually. After this one breaks.
Reply to
B.B.
Can you get clamp ammeters with a metal housing? If so, I'd be very interested to know the brand and price. I've searched but have never been able to find one.
Chris
Reply to
Christopher Tidy
This kind of thing has never made sense to me. I mean why all the stupid lights. Especially when a single one of them being out could be enough to get you a ticket from a pissed off DOT man.
Wayne Cook Shamrock, TX
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Reply to
Wayne Cook
I read a (non-fiction) book about some folks who outfitted an off-road truck and drove it from the nothernmost tip of Alaska to the southernmost tip of South America. In most of central and south america, the roads are not exactly built to interstate standards, and in fact many of the roads they travelled were realistically no better than one-lane dirt trails.
When two vehicles come in oppositte directions, the TRUCK WITH THE MOST LIGHTS WINS THE RIGHT-OF-WAY.
The driver with the lesser lights has to pull over and wait a while until he can see again.
The lighting they had on their truck was truly awesome - not just a bunch of indicator lights like the OP in this thread, but massive and multiple focused beams of searchlight intensity.
Tim.
Reply to
Tim Shoppa
5-10 amp clutch, 15-35 amp evaporator fan, and 25-50 anp condenser fan. The fan current range depends on how it is set up. My TransSport has rear air - so TWO evap fans, and when the AC runs, both the engine cooling fan AND the Condenser fan run. The controlls are basically vac operated, with a small power draw for control splenoids and the "processor"
Reply to
nospam.clare.nce
I don't believe a metal housing would work, as the clamp meter uses an inductive pickup. The metal housing would shield the sensor. The options seem to be limited to cheap plastic, or not cheap plastic. I've seen only various grades of plastic and one oddball with a fiberglass housing.
Reply to
B.B.
[...]
Actually, there's a way around it. At least, according to TxDOT. If all of the extra lights are on a separate circuit and switch from your headlights, it's OK for them to be burned out. But if they come on along with your headlights then every one of them becomes a "marker light" and must function properly. But agreed, the excess lights look stupid.
Reply to
B.B.
B.B. tells us:
80A draw. With them off, 17A.<
A W55 marker lamp pulls just under 1/2 amp and an LED marker assembly can draw up to .6 amps (in the 12 & 24 LED units I've found on-line). 80 X .6 = 48 amps (not too close to the 63 amp figure) so I'd guess he's got a high resistance short (or shorts) somewhere.
dennis in nca
Reply to
rigger
Ok. There's another bit of info I didn't know. The problem is that it's impossible for anybody to keep up with all the regulations.
Wayne Cook Shamrock, TX
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Reply to
Wayne Cook
I don't know. Excess can be cool if you do it right. It reminded me of this:
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Chris
Reply to
Christopher Tidy
So do adding "special effects" to the output of a CB radio.
But many do.
Ive maintained (over the radio) that the use of special effects, is overcompensation for inadequate penis size.
(insert Tarzan yell followed by Oh God Oh God, yes! Yes YESSSSS~)
Lights are likely the same way.."big watch, small penis" syndrome
Gunner, who wears a large watch...sigh
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Reply to
Gunner Asch

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