145 amp alternator enough, multiple fans
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Some alternators just have a problem where they stop working at a certain rpm. Whether it's cheap chinese stuff, faulty internals, deliberate...who knows.
Some OEM ecu's may also stop charging under certain conditions if it is a modern car with what some deem as a smart alternator.
But I've had the exact same alternator, albeit with different regulator or whatever...before it worked fine until it failed one day. Then for whatever reason after it was repaired locally...it stopped charging at 6k. Before it had ran to over 7k without issue. It wasnt the brushes, it wasnt anything like that as I tested and replaced those again myself....it was something else.
I bought the alternator I linked to after all that ******* about and it's bee fine since.
Some OEM ecu's may also stop charging under certain conditions if it is a modern car with what some deem as a smart alternator.
But I've had the exact same alternator, albeit with different regulator or whatever...before it worked fine until it failed one day. Then for whatever reason after it was repaired locally...it stopped charging at 6k. Before it had ran to over 7k without issue. It wasnt the brushes, it wasnt anything like that as I tested and replaced those again myself....it was something else.
I bought the alternator I linked to after all that ******* about and it's bee fine since.
Good discussion, thanks.
Couple questions...…
Is this issue just related to the large scale truck alternator?
Anyway, I ran the pulley diameters on the car I'm having issues with. We are at 18000 alt rpm at 7000 engine rpm which is where it sits most of the run.
Peaks at 19000 rpm.
So we need to either slow it down or buy a fancy high rpm alt.
And sure we need the current, it's a turbo car that has to support high current when the fuel pump hits full tilt.
Second question.....is it only us guys who take detailed data logs who see this?
Ron
Couple questions...…
Is this issue just related to the large scale truck alternator?
Anyway, I ran the pulley diameters on the car I'm having issues with. We are at 18000 alt rpm at 7000 engine rpm which is where it sits most of the run.
Peaks at 19000 rpm.
So we need to either slow it down or buy a fancy high rpm alt.
And sure we need the current, it's a turbo car that has to support high current when the fuel pump hits full tilt.
Second question.....is it only us guys who take detailed data logs who see this?
Ron
yes it's just us who notice it. most see FP drop and throw a boost a pump at it instead of running the correct gauge wire, not overspeeding the rotor.
ron in the logs does it step down the volts like stairs over a few seconds or just drop off a cliff and run on battery voltage?
the stair step down means floating brushes, the drop off means regulator cant hang
TECH Fanatic
Joined: Jun 2003
Posts: 1,869
Likes: 99
There are two things that haven't been mentioned in this discussion.
1) Bearings in alternators 2) Racetronix's suggestion to hook their hot wire kit directly to the alternator.
Bearings:
The most common bearing used in alternators is 6203 series with a 17mm bore ID (shaft size). Every bearing has a maximum rpm limit, among other things. The limiting speed is around 20 to 24K. But that's a very high quality bearing with synthetic shielding on both sides and the best lubricant available. Not cheap China bearings that cost about $3 with no shielding, or metal shielding that rusts, or cheap lubricant.
So even if the rpm of the typical alternator could be increased you still have to account for the bearing rpm limiting factor and bearing life. Heat and dirt kills the life of a bearing and alternators by definition create a lot of heat in an engine bay with temps much higher than ambient. So makes good sense to limit the rpm of most typical automotive alternators to not more than 18k.
Racetronix Hot Wire Kit (attach 10 guage wire directly to alternator).
Not suggesting their instructions are wrong as I am sure they have done a lot of testing. But did they test their high draw pumps to account for what happens when the alternator exceeds it maximum rpm (18k) and takes a dump. What happens then at the pump when voltage drops below 13.5 volts?
1) Bearings in alternators 2) Racetronix's suggestion to hook their hot wire kit directly to the alternator.
Bearings:
The most common bearing used in alternators is 6203 series with a 17mm bore ID (shaft size). Every bearing has a maximum rpm limit, among other things. The limiting speed is around 20 to 24K. But that's a very high quality bearing with synthetic shielding on both sides and the best lubricant available. Not cheap China bearings that cost about $3 with no shielding, or metal shielding that rusts, or cheap lubricant.
So even if the rpm of the typical alternator could be increased you still have to account for the bearing rpm limiting factor and bearing life. Heat and dirt kills the life of a bearing and alternators by definition create a lot of heat in an engine bay with temps much higher than ambient. So makes good sense to limit the rpm of most typical automotive alternators to not more than 18k.
Racetronix Hot Wire Kit (attach 10 guage wire directly to alternator).
Not suggesting their instructions are wrong as I am sure they have done a lot of testing. But did they test their high draw pumps to account for what happens when the alternator exceeds it maximum rpm (18k) and takes a dump. What happens then at the pump when voltage drops below 13.5 volts?
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
There are two things that haven't been mentioned in this discussion.
1) Bearings in alternators 2) Racetronix's suggestion to hook their hot wire kit directly to the alternator.
Bearings:
The most common bearing used in alternators is 6203 series with a 17mm bore ID (shaft size). Every bearing has a maximum rpm limit, among other things. The limiting speed is around 20 to 24K. But that's a very high quality bearing with synthetic shielding on both sides and the best lubricant available. Not cheap China bearings that cost about $3 with no shielding, or metal shielding that rusts, or cheap lubricant.
So even if the rpm of the typical alternator could be increased you still have to account for the bearing rpm limiting factor and bearing life. Heat and dirt kills the life of a bearing and alternators by definition create a lot of heat in an engine bay with temps much higher than ambient. So makes good sense to limit the rpm of most typical automotive alternators to not more than 18k.
Racetronix Hot Wire Kit (attach 10 guage wire directly to alternator).
Not suggesting their instructions are wrong as I am sure they have done a lot of testing. But did they test their high draw pumps to account for what happens when the alternator exceeds it maximum rpm (18k) and takes a dump. What happens then at the pump when voltage drops below 13.5 volts?
1) Bearings in alternators 2) Racetronix's suggestion to hook their hot wire kit directly to the alternator.
Bearings:
The most common bearing used in alternators is 6203 series with a 17mm bore ID (shaft size). Every bearing has a maximum rpm limit, among other things. The limiting speed is around 20 to 24K. But that's a very high quality bearing with synthetic shielding on both sides and the best lubricant available. Not cheap China bearings that cost about $3 with no shielding, or metal shielding that rusts, or cheap lubricant.
So even if the rpm of the typical alternator could be increased you still have to account for the bearing rpm limiting factor and bearing life. Heat and dirt kills the life of a bearing and alternators by definition create a lot of heat in an engine bay with temps much higher than ambient. So makes good sense to limit the rpm of most typical automotive alternators to not more than 18k.
Racetronix Hot Wire Kit (attach 10 guage wire directly to alternator).
Not suggesting their instructions are wrong as I am sure they have done a lot of testing. But did they test their high draw pumps to account for what happens when the alternator exceeds it maximum rpm (18k) and takes a dump. What happens then at the pump when voltage drops below 13.5 volts?
And of course pump performance will be compromised if the alternator dies....but that wont really matter whether it's connected directly to the alternator or the battery. They're still all interconnected and it's either charging or it is not.
That's nothing to do with Racetronix or any other part s supplier. That's up to the cars owner, tuner, whatever to ensure all vehicle systems work correctly and reliably, and where possible have safety features to prevent harm should things go **** up.
