Alternator stops charging at high rpms
#21
Joined: Mar 2003
Posts: 10,244
Likes: 1,530
From: The City of Fountains
As was suggested, add up the loads. I assume the cooling fan is also ON at WOT, so that can add to the draw as well.
Andrew
#22
Thread Starter
Joined: Nov 2009
Posts: 1,620
Likes: 31
From: THORNTON, PA (NEAR PHILLY)
Thing is I dont know what these items pull. Maybe you guys can give me an idea:
96 Mustang, oe electric system with usual stuff (dash lights, head lights etc)
Holley EFI w/low imp inject.
2 fuel pumps
1 electric fan
Doesn't seem like alot, but could this all me over 100a? Still not sure why power would suddenly drop off at high rpm vs a slower decline in power.
96 Mustang, oe electric system with usual stuff (dash lights, head lights etc)
Holley EFI w/low imp inject.
2 fuel pumps
1 electric fan
Doesn't seem like alot, but could this all me over 100a? Still not sure why power would suddenly drop off at high rpm vs a slower decline in power.
#23
Joined: Mar 2003
Posts: 10,244
Likes: 1,530
From: The City of Fountains
Thing is I dont know what these items pull. Maybe you guys can give me an idea:
96 Mustang, oe electric system with usual stuff (dash lights, head lights etc)
Holley EFI w/low imp inject.
2 fuel pumps
1 electric fan
Doesn't seem like alot, but could this all me over 100a? Still not sure why power would suddenly drop off at high rpm vs a slower decline in power.
96 Mustang, oe electric system with usual stuff (dash lights, head lights etc)
Holley EFI w/low imp inject.
2 fuel pumps
1 electric fan
Doesn't seem like alot, but could this all me over 100a? Still not sure why power would suddenly drop off at high rpm vs a slower decline in power.
I think halogen headlights draw 7.5amps per light.
Andrew
#24
Thread Starter
Joined: Nov 2009
Posts: 1,620
Likes: 31
From: THORNTON, PA (NEAR PHILLY)
Holley 12-1400 dual pumps, factory single 3.8 Ford cooling fan. I figured about 15a for the headlights.
I emailed Doug F from Holley and asked about the apprx amp draw of the following and here's his estimates:
Holley ECU - 10a (mostly wideband pulling)
Injectors - 15a max
Coil - 15-20a
Fuel pumps - 23a
Meth sys (that I don't really run) 10a
I figure the cooling fan pulls ~30a
These items are apprx 108a at WOT. Could be more/less. This doesn't include headlights, the rest of the car whatever that pulls. I have a couple of other modules that are sapping power to (the factory ecu is still in place - I should disconnect it but worried it might cause a check engine/anti-lock light, convenience module, tach adapter and speedo converter box).
Looks like a 105a alternator just may not be enough.
#27
Joined: Mar 2003
Posts: 10,244
Likes: 1,530
From: The City of Fountains
#28
Thread Starter
Joined: Nov 2009
Posts: 1,620
Likes: 31
From: THORNTON, PA (NEAR PHILLY)
B/c I have a hood clearance issue, it's kinda limits my choices somewhat. Current alternator is a AD230 which is basically the same as a CS130D, just newer I believe with some improvements. Powermaster makes one in a 165amp drop-in conf. for my app. This alternator barely clears my hood as-is.
I'd like to get the AD244 in there, but it's much bigger. I actually have one here that came off this motor (this was a pull-out LQ9 from an Escalade) that's rated at 145a. I would have to get a aftermarket relocation bracket for the alt/ps pump to move it down a bit. I don't object to doing that if it allows a better alternator.
New 165a alternator is $250.00. Relocation bracket is $130.00 + 30.00 for a new belt, but I then have a "better" alternator installed, although it has 70k miles on it and its 145a vs. 165a.
Not sure what the best approach is just yet.
I'd like to get the AD244 in there, but it's much bigger. I actually have one here that came off this motor (this was a pull-out LQ9 from an Escalade) that's rated at 145a. I would have to get a aftermarket relocation bracket for the alt/ps pump to move it down a bit. I don't object to doing that if it allows a better alternator.
New 165a alternator is $250.00. Relocation bracket is $130.00 + 30.00 for a new belt, but I then have a "better" alternator installed, although it has 70k miles on it and its 145a vs. 165a.
Not sure what the best approach is just yet.
#30
Thread Starter
Joined: Nov 2009
Posts: 1,620
Likes: 31
From: THORNTON, PA (NEAR PHILLY)
We'll, hooked-up the 145a ad244 that I had laying around, and couldn't close the hood completely due to clearance, but it was latched. Ran the engine up to 6100 and it stayed solid at 14.2 even though alternator shaft speed was over 20k (had the factory 2.25" pulley on there). This is with a well worn used alternator too! Looks like I just didn't have enough alternator after all.
Thanks for all the tips!!
Thanks for all the tips!!
Last edited by 69-chvl; 12-21-2015 at 07:15 PM.
#31
Whatever came of this? I currently have the same issue. Though my 105A CS130D alternator from auto zone has worked flawlessly for 3 years. It suddenly started dropping out completely anytime I go WOT. I don’t think it’s an amperage issue and I changed nothing and it worked great for years. I figured my alternator just crapped out so I got another reman (lifetime warranty).
Could you have shut off the 30a fan and tried a pull to see if it still dropped out? I run the same fan and I know on high it’s an amperage hog.
Thanks
Could you have shut off the 30a fan and tried a pull to see if it still dropped out? I run the same fan and I know on high it’s an amperage hog.
Thanks
#32
Many Alt are computer controlled
"The only known factory LS application where the stock ECU doesn’t connect to the alternator is the ’98-’02 F-body. However, most of the “computer controlled” alternators on these engines can be placed in an automatic mode by wiring their “L” terminal to the dashboard alternator warning light (which would get switched 12 volt power if your car originally did not have one). When the L terminal is connected to a lamp, the alternator will power up and put out charging voltage. This trick works on any alternator with a four terminal connector where the terminals are marked P, L, F (or F and I on the same terminal), and S. The remaining three terminals are left disconnected."
"
At high percentages of TPS (near WOT) the computer controlled alternator is programmed to shut off (go low voltage). this helps save gas and free up power.
"The only known factory LS application where the stock ECU doesn’t connect to the alternator is the ’98-’02 F-body. However, most of the “computer controlled” alternators on these engines can be placed in an automatic mode by wiring their “L” terminal to the dashboard alternator warning light (which would get switched 12 volt power if your car originally did not have one). When the L terminal is connected to a lamp, the alternator will power up and put out charging voltage. This trick works on any alternator with a four terminal connector where the terminals are marked P, L, F (or F and I on the same terminal), and S. The remaining three terminals are left disconnected."
"
At high percentages of TPS (near WOT) the computer controlled alternator is programmed to shut off (go low voltage). this helps save gas and free up power.
#33
This is not computer controlled. It's a 98 1 wire deal with lamp in between field wire. Like I said worked great for years... Now I'm guessing I got a crap remain alternator. Or I lucked out with a good one the first time around.
Relatively low RPM as well... it's down to 12.9v by 5k. Charges fine at 14v+ on startup... 13.3v steady once charged.
Bottom graph/red line is bat voltage
Relatively low RPM as well... it's down to 12.9v by 5k. Charges fine at 14v+ on startup... 13.3v steady once charged.
Bottom graph/red line is bat voltage
#34
Thread Starter
Joined: Nov 2009
Posts: 1,620
Likes: 31
From: THORNTON, PA (NEAR PHILLY)
Whatever came of this? I currently have the same issue. Though my 105A CS130D alternator from auto zone has worked flawlessly for 3 years. It suddenly started dropping out completely anytime I go WOT. I don’t think it’s an amperage issue and I changed nothing and it worked great for years. I figured my alternator just crapped out so I got another reman (lifetime warranty).
Could you have shut off the 30a fan and tried a pull to see if it still dropped out? I run the same fan and I know on high it’s an amperage hog.
Thanks
Could you have shut off the 30a fan and tried a pull to see if it still dropped out? I run the same fan and I know on high it’s an amperage hog.
Thanks
#35
Thats a stinker. Are you using a resistor or light inline to excite the alt? happen to check output voltage at alt plug with key on?
I ordered a little beefier 160a one wire alt to try. Ill keep u posted.
I ordered a little beefier 160a one wire alt to try. Ill keep u posted.
#36
Thread Starter
Joined: Nov 2009
Posts: 1,620
Likes: 31
From: THORNTON, PA (NEAR PHILLY)
Using the factory control wire...it definitely sends out way less than 12 volts. Then I ran another wire with a bulb...no difference. But keep me posted. I don't mind spending money but hate spending money on something that wasn't needed.
#37
Went with this $140 deal
http://www.ebay.com/itm/HIGH-OUTPUT-...9T497m&vxp=mtr
Price is right if it works...
http://www.ebay.com/itm/HIGH-OUTPUT-...9T497m&vxp=mtr
Price is right if it works...
#38
Got off work a little early and was playing with this. I noticed my field voltage was still 11.8v. (with the light in series) I read alot of conflicting information on how much voltage you want on this wire some said no more than 5v. Some say 8ish.. One site claimed as soon as they see more than 5v they are trashed.
So I tried running 5v to it with the idiot light bulb in series. I saw 14.6 after start and it trickled back down to 13.5 with my fans on. Quick pull and it dropped to 13v. Turned trans/rad fan off and made another pull and it stayed at 13.3v. So there is something going on there.
bad pic but you can make it out.
So I tried running 5v to it with the idiot light bulb in series. I saw 14.6 after start and it trickled back down to 13.5 with my fans on. Quick pull and it dropped to 13v. Turned trans/rad fan off and made another pull and it stayed at 13.3v. So there is something going on there.
bad pic but you can make it out.
#39
Please let us know how that alternator does! I'm having a similar problem where my car charges around 13.5 V in the morning, but drops to 12.8 V after engine is at operating temperature and one derale fan on