[shabz]

My GV start and runs fine - until the battery voltage drops a little.

It'll be at 11.9 - 12.1 volts, after running the radio for a while with the car off etc.

So what happens next is when i start the car (cranks over fine even with slightly lower voltage) i get an ear piercing squeal from the belt! (alt belt i think). This last for about 10 seconds and then goes away....

My question is - why would the belt squeek just for 10 secs or so, and ONLY when i've drained the battery a little??

[royce]

more electrical power the alt is creating the more mechanical power it neds to do so, which then is more resistance to teh belt so more likely to slip

after the 10 seconds or so it likely starts to gain traction

[89_tintop]

Cause the alternator is working harder to to charge slightky dicharged battery...

Which in turn puts more load on the engine.

Have you checked the tension of the belt??

Edit: ... missed it by that much

[shabz]

Yeah the belt tension is fine, and the belt isn't worn or cracked etc....

I get a squeal occasionaly when i turn the a/c on, just as the clutch engages for a split second - but with the alternator my thinking is that its always connected. Even if there is more load on the alt to charge up a slightly discharged battery, the same mechanical power is being used? I'm not sure it all seems strange to me...

[Rusho]

Lube it up. You can buy spray on belt stop squeek stuff. Band aid fix though

[steak_knife]

Rusho wrote:

Lube it up. You can buy spray on belt stop squeek stuff. Band aid fix though

No no no no no no

I watch a shit mechanic diagnose glued belt's as a seized eng because of that "belt grip" shit, it's glue in a can.



Soap or dry lube for belt's.. or just adjust the bugger, Gv belt need to be FT, or thay slip..

[shabz]

steknig wrote:

Rusho wrote:

Lube it up. You can buy spray on belt stop squeek stuff. Band aid fix though

No no no no no no

I watch a shit mechanic diagnose glued belt's as a seized eng because of that "belt grip" shit, it's glue in a can.



Soap or dry lube for belt's.. or just adjust the bugger, Gv belt need to be FT, or thay slip..

Thanks stekky, yeah i've got a stick of dry tube so i'll give that a shot...but its strange how it only happens when the battery has dropped a little.

Could it possibly be a sign of something more serious do you think? Worth worrying about?

[steak_knife]

royce & tintop are on the money, the alt may not turn on for 4 to 10 sec's after start up, but when it does it has to go hard to top up the battery.
Gv's NEED good battery's, for that matter all efi eng's do. A lot need's 12v to run, & the starter draw's alot away on start up..

Help??

[shabz]

Makes sence.

I'll give the dry lube a shot, and hopefully soon i'll have the dual battery in - won't have to worry about discharging the main battery.

Thanks for the explanation fellas

[Moph]

Guaranteed the guys have the right explanation ... I'm running a 110A Falcon alt off a single V-belt and when I load it up (4x55W HID spotties; 130W high beams; fridge; radio; heater; etc) it squeals like a stuck pig if cold. Give it a minute or two for the rubber to warm up and the battery to take some charge and it's fine because the load on the alternator is less / grip of the warm rubber is more.

x2 on the Belt Grip ... horrible stuff. Works for a couple of minutes but seems to worsen the problem thereafter.

[MacDaddy]

Everyone has explained it very well....
Even though you think the belt is tight enough, its not, hence slipping and squealing..., it sounds to me like the belt is not ok, and has hardened some, and become shiny inside... i would spend a few dollars buy a new belt, as i think your old belt is letting you know its not ok anymore...

[Jester]

also the new EPDM multirib belts (over the old neoprene), they dont tend to crack or glaze, their grooves just tend to get wider, so the belt may be worn out, i know gates has a depth gauge to put across to check these belts cos when they get too wide in the grooves they bottom out on the pulleys not getting adequate traction

http://www.repcotrade.com.au/go/news/ti ... epdm-belts

theres an official explanation, (yeah its from ripco but hey)

[TZAR]

http://www.repcotrade.com.au/files/dmfi ... uction.pdf


http://www.repcotrade.com.au/files/dmfi ... onents.pdf

good stuff to read on multirib belts

[jonno_racing]

i have put some permextex aviaon fluid on my belt once... band aid i know but works spot on!!!
i get it all the time, 4pk belt on a 6pk altinator.. not much you can do, i replace the belt when i change the oil

[shabz]

Interesting read on the repco site - will have to check the belts again tomorrow!

[2stroker]

shabz wrote:

Yeah the belt tension is fine, and the belt isn't worn or cracked etc....

I get a squeal occasionaly when i turn the a/c on, just as the clutch engages for a split second - but with the alternator my thinking is that its always connected. Even if there is more load on the alt to charge up a slightly discharged battery, the same mechanical power is being used? I'm not sure it all seems strange to me... :roll:

I think this is a fairly common belief, but as some of the others have said the load on your engine actually increases with output demand, when you spin the alternator by hand on the bench it is nothing like how much force it needs to spin it when it is actually making amperage.

Typically, when an alternator is working at full output, it will require approximately one horsepower for every 25 amps it produces. As such, a 100-amp high-output alternator will require up to four horsepower to operate at maximum output.

I would say even if your belt looks ok, replace it and tighten the new one to spec.

[96coily]

v x A = w
13.5 volts x 100 amps = 1350 watts
= 1.35 kW or 1.8 horsepower

This of course doesn't take into account losses. The first law of thermodynamics says that energy is conserved in any process involving a thermodynamic system and its surroundings. Frequently it is convenient to focus on changes in the assumed internal energy (U) and to regard them as due to a combination of heat (Q) added to the system and work done by the system (W). Taking dU as an infinitesimal (differential) change in internal energy.
Also the second law of thermodynamics is an axiom of thermodynamics concerning heat, entropy, and the direction in which thermodynamic processes can occur. For example, the second law implies that heat does not flow spontaneously from a cold material to a hot material, but it allows heat to flow from a hot material to a cold material. Roughly speaking, the second law says that in an isolated system, concentrated energy disperses over time, and consequently less concentrated energy is available to do useful work. Energy dispersal also means that differences in temperature, pressure, and density even out. Again roughly speaking, thermodynamic entropy is a measure of energy dispersal, and so the second law is closely connected with the concept of entropy.

So the belts squeaks huh