Tech Tip Tuesday: The Single Biggest Killer of Alternators and Bad Charging Systems
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- Опубликовано: 25 апр 2022
- In this Tech Tip Tuesday, Doug talks a bunch about alternators and pulleys.
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This is spot on. Wifes car was eating alternators quickly, Put a big pulley on the alt and haven't eaten an alt since. Been several yrs.
I’ve street reached her mini van on many occasions it’s definitely putting out a lot of power
One of the most overlooked products on a car. Great video
yep I've went through plenty too
Life lesson right here boys. Good job Doug and the motion crew.👍
Don't forget, Folks-
Changing your pulley diameters also mean your belt lengths change,
and an auto-tensioner only goes so far, either way. Don't lose tension,
and don't over stress that coil spring. Belts are usually measured in mm.
Good call Hubba'. Tip: I get around that by decreasing the "drive pulley" by the same percentage. Problem solved
Thanks Doug. Great info. It’s a bit more critical than people think. Keep up the great work
Another thing which can damage an alternator with a manual transmission is banging through the gears. A lot of modern cars (especially ones with DSG type gearboxes) have a freewheel on the alternator pulley so that when you change to a higher gear the alternator can freewheel faster than the engine and slow down gradually rather than being forced to slow down suddenly. This makes the belt last longer too.
Thanks for sharing so much info! There’s not that many people, or companies for that matter, who are willing to explain why problems occur and the importance of the parts they offer to fix said problems (especially an affordable part that can be used with a stock component)
Motion raceworks for the win!
Great tip again from Motion Race Works. Doug another awesome product that people wouldn't even think of. 💯😂 Aussie Fan 🤟🆒🤣🇦🇺
Love these tech tip Tuesdays lol so awesome
Love watching tech tip Tuesday thanks for all the information. Just ordered a complete fuel system from y’all. Would Like to see a tech tip Tuesday on how to hook up turbo lines to the intake. The route and why it’s that way. And how it works with making boost with a boost controller. It’s all new to me so any info helps thanks. (Hopefully I asked that correctly)
I am so glad you guys are offering these pulleys. Ive cooked plenty of units and even considered having a pulley custom made because no one made them at 3". Thanks Motion!
Good point and a bigger pulley probably won't matter much at idle since stock idle is like 550 and with a decent cam it will probably be like 900 or more
What's the main failure on the alternator is the rotor when you spin it above it's rating the centrifugal force will rip the coil wires away from the slip ring killing the alternator. But also remember if you going to run an underdrive pulley on your alternator on your daily driver you may occur under charging at idle and cruise speeds.
I sddrrss this issue have a peek.
That's exactly what's going on with my 320 a alt from auto tech engineering. First shows 14.8 in idle but starts to drop after a couple mins and actually drops all the way to 12.6 in idle and also as soon as I place the gear in drive without moving or hitting accelerator. It does stay at 14.8 while driving but starts to drop as soon as I come to a complete stop. Also wines and squeals so bad it quickly becomes annoying. Changed to a smaller belt since original belt wasn't small enough on my 11 Toyota Corolla S. Now I think I'm better off putting my 100 a stock alt back on to avoid damaging my new alt.
Hey guys great tech. I would love to see a tech Tuesday on your rear wing. Thanks.
Trouble with a larger pulley on a dual purpose primarily street driven car is a lack of charging at idle and cruise rpm. Amazed nobody has come up with an expanding pulley. Similar to a centrifugal clutch operation, but that allows the pulley diameter to grow a few percent. Brand x, Mr. Patrick has taken care of my alternator needs for the last few years. The hot rod community can learn from the hardcore audio guys. There are better bearings and stators etc available to custom build bulletproof alts, but they are not cheap.
Would really love to see a tech video about vacuum pumps, like when and why you would need one, but thanks for this awesome vid 👍🏽
Great video! Totally sharing this one!
Great video! I upgraded my pullies on my classic mustang and noticed that alternator wasn't happy. I found a calculator online and bought the right size. I did this about 4+ years ago and the alternator has been happy since. My issue was that my underdrive system was cooking my battery because it wasn't charging the battery at idle, traffic jams use to bring me a lot of anxiety lol.
🤣, Yes . Total Discharge Ignition Systems are worrisome .
AWESOME and VERY informative Content!!!👏👏👏👍👍👍
G.M. has made a good drag race pulley for the alternator since the early 70s. Pretty sure the part number is 1942911. Its about 4 inches in diameter.
Awesome I had an aftermarket pulley system and it had a bigger alternator pulley I put the factory one on. Now I know why I'll put the aftermarket one on.
I've read somewhere involving 454 big blocks about buying an entire kit with alternator and crank pulleys to improve fuel mileage.
Great job, I learned a few things. I always thought heat was the biggest killer of alternators, heat from going to full field while attempting to charge a severely discharged battery. Alternators are designed to keep fully charged batteries at that level not bring up drained ones. Thanks again Doug and have a great day.
that just kills the voltage regulator from over current and heat. the winding will be fine unless the battery has been hooked up backwards or you get idiots that dont know how to use jumper cables
Literally fried a alt on my 450ci C6Z spinning to 8200rpm. First mile of driving it almost lit on fire. Got a bigger alt pulley and fixed the issue over last summer
Didn’t know this was a problem until this product was released, once again motion saving the day with proactive soloutions
It's not a problem until it's a problem, I'm sure they wouldn't recommend spending money on their parts unless you are actually having issues with alternator reliability.
@@b.c4066 that’s why it’s a proactive solution, fix the problem before it becomes one
Kyle with Boosted Boyz needs to watch this.. their NSX was eating stock alternators at record pace.
The alternator on my Odyssey went bad and was replaced. The second one didn’t last a day, and had to replaced again. So far,so good
I had a Ford F100 with a 460 B.B. that idled at 400 rpm. Because of the low rpm I had to put a really small pulley on it to achieve 13v. However, when ever I made long hauls across state I always had to bring an extra voltage regulator. Fortunately, mine was external and it was bolted to the fender. Never had a problem with the alternator, though.
Great info!
Over looked that one !! Thank you!!
I've literally watched an alternator explode and a piece of it go through the hood of a camaro from being spun way too fast.
I had a problem with my alternator overheating even under light load and I finally figured out my alternator pulley was too large and the internal fan wasn't running fast enough to cool it.
Awesome advice.
good advise right there guys.
Did this years ago with power master they know how to measure crank pulley x alternator pulley x max RPM's. Tech tip I blue lock tite alternator case bolt, pulley, electrical nuts and more on. I always say do it right the first time and be done!!!
I have went threw a few alternators after installing 25% underdrive harmonic dampener on my. Is powered pontiac g8
It is not just undercharging at low RPM, the regulator will try and maintain the rated output voltage by increasing the field current. That means max current is being pulled thru the brushes and commutator to drive the field, increasing wear there, heat in the regulator and overall heat in the alternator at low RPM when cooling is reduced…
Exactly
Great info.
What you also have to remember is that unless it’s a “ marine” rated alternator and only certain newer style vehicle with an exciter wire it will only function a above 1200 rpm’s or so.
I always used Mercruiser mini alternators rebuilt to charge at 150-200 amp and with ceramic bearings installed.
Marine alternators charge at idle rpm’s .
Mk1-2 vws do this.
Haha you gotta blip the throttle and wake it up.
Don't walk away leaving it idling for 20mins to warm up because you'll come back to a stalled car 😆
Very true.
Interesting 🤔
why would you need 2,400 watts in your car ?
You guys need to start making coyote alternator pulleys!
I rock a mechman 250amp alternator..man its a bad ass unit. Never worry about it ever.
Sweet 🤘🏼🤘🏼
Most alternators are rated at 2,400 RPM. In other words, with the alternator shaft RPM at 2,400 or greater, they will put out their rated amperage. Below 2,400 RPM, the voltage and current will drop. So the bully ratios are set up for the engine at idle the alternator will spin around 2,800. Of course, and you drive down the road or the track, that RPM goes up and provide great charging. As stated in this video, most alternators have a maximum RPM rating as well. So pulley sizing / ratios are vital.
Oh boy, if you think that's a big thing, wait till you figure out what one-way bearings/pulleys are for.
Ford had put gas engine alternators on diesels. Putting ten percent smaller diameter pulley on a 7.3 PSD alt is a great idea.
After you change out the pulley how do you get the right size serpentine belt?
When Mechman made my 250Amp alternator the first question was crank pulley size and redline.
Yeah, I ordered one from ces In Ohio,and later from brand x from Jonathan Patrick and that was his first question too. But also if I needed full output at idle, it was for a daily driver with 200 pounds of stereo equipment. He built me a 240amp alt that would do 85% of max output at idle. 6 years later I sold the jeep with the alternator still going strong. It was a custom built small case denso. Only cost $350. It kept two 1000cca agm batteries at a full charge, and kept up with the jeeps needs as well as a true 2800 rms watt stereo with zero headlight dimming and voltage stayed at 13.8 or above no matter what I was doing.
@@b.c4066 Mine charges 180 amps at 800 rpm. I think it's a large case GM. It was just a tad over $500 polished. I'm running 2 radiator fans, remote A/C condenser with fan, vacuum pump, 2 fuel pumps. electric A/C compressor and electric P/S.
If your car over heats this will help it too. Keeps the fan going and optimized cuz of the current feeding it.
After an engine swap my 1990 Grand Prix started burning up alternators. Months later the headlight circuit went dead.
Pinched wire shorting out was the cause.
Ford spent a pretty penny engineering a fancy alternator for the GT350 because of its high redline RPM. During testing they attempted to reuse the standard GTs alternator but kept having failures.
Vibration was probably their main concern with the undesirable secondary imbalance of a flat plane crank.
Nope, rpm is bigger concern by far.
Can you do
-Wiring dome pressure sensor for terminator x Ls
- wiring duel electric fans with 2 relays on Holley term x Ls for the Holley to control them on a negative trigger
-also how to setup a Mac valve off of dome pressure with boost reference from the turbo non co2 supported
Installed one of these motion pulleys on my road race LS engine cause it would stop charging above 6800rpm like someone threw a switch. Motions rpm chart helped pick the right pulley and charging is good all the way to 8000k.
This is awesome to hear! Glad to hear it helped! Appreciate your feedback and support Philip
Will I need a longer belt if I replace the pulley with a bigger one on my alternator?
First became aware of this on First Gen Z/28’s & asked why is the alternator pulley so big? Wondering what happened to El Toro? Would like to see a TTT on using a mini (gamers) 6 gang switch panel with remote relays? Thx
Great tip! + Those motion pulleys look badass! Thank you!
Thank you!
Holy cow. This makes me think my 4runner probably has an aftermarket pulley size. It hardly charges at idle
I know the aircon shutsdown after a preset rpm limit when going to redline, Does the alternator do anything similar ?
Parts request. Can you guys make these in 8 rib please. Beautiful part BTW.
Man,wish I had seen this video a long time ago,I had a theory,but after doing the math,I'm turning 2600 at the alt,when I'm at 7500rpms,went thru 3 alternators,put a 6k chip in my msd and it stopped... I almost went back to my 7500 chip,glad I didnt. Looking for a pulley for a 5.0 ford asap so I can go back to turning this thing up.
Wow! I used to be an RV hauler. I drove over a million miles in 6 years first a 01 Ford 350 and then a 05 Dodge Ram 3500. Thank goodness for lifetime warranty from Autozone because I went through 2-3 alternators a year. I always thought the pulley was the problem because the engines ran between 2-2200 rpm’s a minimum of 11 hours a day 5-6 days a week. So the batteries would over charge many times. This engines are designed for normal stop and go traffic not to run constantly running over 2200 rpm. This pulley would have definitely help my alternator and batteries.
Now design a water pump for the 5.9 Cummins the pulley is small as well and I had a few water pumps go out especially after mountain passes. The high rpm would tear them up. The 6.7 Cummins has the same design of water pump as the 5.9 but the new 6.7 engines come with 6 speed which run at lower rpm.
My Nippon Denso alternator..in a 1994 Toyota it had 286K miles...i never replaced it....with the 1969 IHC...it still has the stock Delco 65 amp baby...I did replace the field brushes...and the ball and needle bearing.....just for prevention maintenence...
Sure if either of those engines were tweaked to rev higher...I would increase the pulley size....
It seems like some like to add additional loads....and then they play fry the alternator game...
Would a 25% underdrive pulley fix this issue on an LS2?
Tech tip Tuesday: steering columns. Safe and proper install using your universal kits.
I have a 2009 GMC WT, I have an underdrive alternator on my alternator. I am changing the alternator to a bigger amp/hr alternator. I need to remove the pulley, from the alternator, to make this swap. I had my mechanic do the first swap, to the stock alternator; I believe its 60amps. I go camping alot, and I am putting a 100 amp alternator in place of the 60 amp. Is it hard to change pulley's? As I said, my mechanic did the first swap; I want to do this swap myself. Thank you for the advice!
Brad
Do they all turn the same direction if it has a sirpntine belt ?
If it's possible to add a bit of slack in the adjustment so the belt will slip at high RPMs for the A/C and alternator. I've been doing this since the late 60s and I'm surprised these guys didn't already know about it.
I wonder if you can do the same with an ac compressor
Sticking to Alternator's how about a video on building custom brackets. I have a Olds 455 with Fabbed Valve Covers so none of the factory brackets work and I have the Alt on Pass side when it should be DS. I have a setup working but it looks a bit sketchy
What amp rating alternator would you suggest for a twin turbo injected LS drag street car? Loving your tech tips thanks!,
Over 9000
While I can't speak for any of the aftermarket performance alternators (automotive), I can testify to the quality of TRUE marine alternators like those from MerCruiser for their inboard/outboard engines.
These are specifically designed to operate at sustained high RPM while simultaneously taking a beating from rough water conditions. They offer one wire alternators for most Ford and GM case sizes which have premium winding insulation and heavily potted connections and electronics.
Just sayin'
Hey man how about discussing on Tech Tuesday spraying NO2 and water on Intercoolers.
i use a 351 C in my falcon , went to a 4 inch pulley because i hit up to 8500 rpm more than i should . lol . no more alt problems . people dont realize the alt turns four times faster than the engine with the stock pulley! And , u also gain up to 4 hp .
So the belt size will need to be changed?
What about an cog belt drive alternator pulley will that affect your power on your alternator
After sitting in traffic with underdrive pulleys on my rx7, I used to have to push start it from work or gas stations. OHHH, but it rev'd !!
do those pullies work on a dodge/RAM alternators - do you even make anything other than for GM?
how would a guy go about alternator maintenance? I drive to the beach a lot and on the beach. Churn through deep sand. My F150 with the 5.0 has the alternator low on the drivers side of the engine. So i am sure it gets dusted with sand. What are things i can do to help the 500+ dollar thing live? Thank you.
Where do you send the alternator?
Makes perfect sense you only get so many spins you go faster it won’t las as long
Thanks for the vid. Maybe it is a silly question. I have an 1999 Toledo with 1.9TDI diesel engine. I have no working radio in the car. ;-) I have a very low fuel consumption but as a hypermiller I would get better and better. So the question is: I plan to change my factory alternator (maybe 90A) for a greater one (120A from Lupo 3L) and change the pulley of it for a greater one. How can I test whether this lower MRP alternator set will serve enough energy for my electrical system? I guess based on the fact that almost no electrical device on the board it should enough. Sorry for the not engineer-level question... :)
Its a pain when using a spring tensioner and changing pully sizes. Diched the air pump om my 1985 Mustang GT than put a underdrive pulley system on it finding a belt was a shitshow and the belt rubbed between the tensioner and the water pump. Had to modify the tensioner post hole found a belt that gave me 2 in clearance measured and drilled a new post hole with the tension now had 1.5 in clearance a pain but worked. Under drive pulleys on the street you do feel a difference BUT I had to install a flex fan engine running 200f with a 180f stat now runs 190f and my alt is falling on its face anything under 1500 rpm just a toy not my daily driver. A smaller pulley on the alt or a new alt with internal regulator these have more output at lower rpm.
Powermaster alternators are awesome.
I bought one from you guys 3” pulley need help with the belt plz 06 tbss FBO N/A😊
With larger pulley on an alternator, would the slower spin affect its operation?
Yes big loss of charging power at low rpm
I’m putting a smaller alternator pulley on my 2001 gmc because I need to crank just a little more amperage and it’s definitely not a high rpm build me merging on the freeway is about the worst it’ll get
The 2000's modular ford 4.6l suffered from this all the time.
Would you benefit from an underdrive system in general? The reason I'm asking is doesn't the power steering pump suffer from the same problem?
Under spinning the water pump can become a real issue, I would be inclined to do it accessory by accessory
Replace your alternator with a powermaster. They recommend 18k to 20k rpm. I am running the Ati damper and powermaster 8421 alternator with my oem pully. I did have to have it bored from 15mm to 17mm sonit would fit. My output is 175amps
I ran a 7" pull on the alternator on my race car. 8k rpm's is too much on one.
Yeah, this is why my alternator doesn't change at idle. Doesn't start until around 1100rpm.
This sounds the same as an underdrive kit, and at idle and lower rpm’s it doesn’t create enough charge on some vehicles to run properly.
Had that issue with a HO alternator. Original did great but I needed more power due to accessories and electric cooling. The new one kept dipping to 11v at idle, really dragged the electrical system down at stops. Had to return it back for refund and put the previous one back in. I’m sure that thing is so overworked as there’s belt dust on the case and when I hit a puddle on a rainy day I think it slips because the wipers go slow before it dries enough to start spinning again.
I got a 350A autotech engineering alternator wired with big 3 1/0 OFC and 5 extra 8 gauge ground, shes singing like a sewing machine 😎👍
Do you have the alternator pulley chart on the website?
Yes sir it’s on the product listing pages, listed in description here
Cool video but how it ended in my watch list I do not know. I am retired & drive a Crown Vic that rarely sees even 2000RPM.
And all these years I just made fit a GM 100 amp internal regulator an foregot about them !!!
One of those " Obvious " things , that No-One much thinks about . Well Done .
This must be part of the reason why a common mod on old school 5.0s is underdrive pullies. The alternator pulley is one of them. I've never (personally, this is Justin, not my dad) thought of that. I was always curious why we were deciding to undercharge the system at the same time as us building the engine to rev higher, it never clicked until now lol
Interesting. First time I ran my Ls car on the strip, it blew the aftermarket alternator. Was only on there a Year.
That’s likely why, hope this helps
Crank case venting Vacuum vs passive And catch can design
Not so much a 'tech tip' but, How about addressing the difference between the truck, F body and short mount Corvette LS accessories systems and what works best with what...?
Do they make larger clutch pulleys ?
Good question was wondering the same thing