Decrease In Engine Power Due To Electrical Load?

P

psea17

Member
Looking for some insight.

I noticed the other day that when i lower the windows while driving, there's a noticeable decrease in engine power. Even if the windows are all the way down and I press the window buttons and hold them down, I get the same effect. It kind of caught me off guard. It's similar to the effect when I turn on the AC. The engine just seems more tasked. The alternator is original. (240k mi). All windows including the moon roof seem to close pretty slowly as well.

Any thoughts?
 
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Sub'd to follow along. I've noticed the same thing occur on the highway when my A/C compressor kicks in. Haven't wanted to mess with it because the A/C currently works. Interested to see if anyone has ideas. To my knowledge my alternator is also original (223k).
 
Greyhome, AC will definetely cause a decrease in engine performance. The AC compressor requires a few horsepower (say, 2-5), which is easily enough to feel while cruising down the road (when you are using say, 20-40 to cruise at a constant speed).

I'm surprised you can feel a change with the windows. What I can tell you though, is that DC motors draw MORE current when they are stopped, like at the end of the window motor travel. That's actually how the auto-down feature works on the front windows... (it senses excess current draw and turns off, the auto-up has some pinch detection and limit switches for safety instead)

-Charlie
 
psea17 said:
Looking for some insight.

I noticed the other day that when i lower the windows while driving, there's a noticeable decrease in engine power. Even if the windows are all the way down and I press the window buttons and hold them down, I get the same effect. It kind of caught me off guard. It's similar to the effect when I turn on the AC. The engine just seems more tasked. The alternator is original. (240k mi). All windows including the moon roof seem to close pretty slowly as well.

Any thoughts?
Click to expand...

Interesting. Curious as well
 
Brand new battery and oversized alternator. I feel the same lug on the engine when parked or stopped. When the battery is low, it's more pronounced.
 
Our factory Alts are 960w. I can’t see that drawing more than 2hp fully fielded. The AC requires more HP........


Sent from my iPhone using Tapatalk
 
psea17 said:
Looking for some insight.

I noticed the other day that when i lower the windows while driving, there's a noticeable decrease in engine power. Even if the windows are all the way down and I press the window buttons and hold them down, I get the same effect. It kind of caught me off guard. It's similar to the effect when I turn on the AC. The engine just seems more tasked. The alternator is original. (240k mi). All windows including the moon roof seem to close pretty slowly as well.

Any thoughts?
Click to expand...
Have you ever replaced the alternator brushes? If not, find some - probably will need to order since nobody carries them. Mine wore out at about 220k. I didn't experience your symptom, it just failed. I imagine if they're making poor contact it could be not charging well, taxing the alternator.
 
Just to be clear. I'm not talking about the reduction in HP when the AC is engaged. I was just using that situation to describe the situation.

Since starting this thread, I just completed the Big Three+ Rewire. (alternator to battery+, engine block (oem location=beneath oil filter) to battery-, battery- to body (oem location), battery- to frame). The battery to frame was added because I'm running 2ga to an Anderson Plug I located at the rear trailer hitch area. The plug is grounded to the frame. The plug will have two uses: a) charge my trailer's batteries (a BlueSea ACR was installed at the truck's battery to disconnect when the truck isn't running; prevents the trailer from draining the truck's battery) and b) should I decide to use my winch, which will be mounted on a tray that fits into the trailer hitch, it will have all the juice it needs.

My alternator increased output at idle from 13.98v to 14.25v. Very happy. Will report on the window power draw a little later. I have not changed the alternator's brushes. But, I would guess based on the alternator's output, the brushes should be fine.

Appreciate any other insights.
 
psea17 said:
Just to be clear. I'm not talking about the reduction in HP when the AC is engaged. I was just using that situation to describe the situation.

Since starting this thread, I just completed the Big Three+ Rewire. (alternator to battery+, engine block (oem location=beneath oil filter) to battery-, battery- to body (oem location), battery- to frame). The battery to frame was added because I'm running 2ga to an Anderson Plug I located at the rear trailer hitch area. The plug is grounded to the frame. The plug will have two uses: a) charge my trailer's batteries (a BlueSea ACR was installed at the truck's battery to disconnect when the truck isn't running; prevents the trailer from draining the truck's battery) and b) should I decide to use my winch, which will be mounted on a tray that fits into the trailer hitch, it will have all the juice it needs.

My alternator increased output at idle from 13.98v to 14.25v. Very happy. Will report on the window power draw a little later. I have not changed the alternator's brushes. But, I would guess based on the alternator's output, the brushes should be fine.

Appreciate any other insights.
Click to expand...
I'll assure you that, if those brushes are original, they're about finished. Easy enough to check. May not be causing your problem, but a great preventive measure.
 
Glad to see you upgraded the grounds, its a closed loop system so adding more power doesn't help if the grounds are at their capacity. I did a battery to frame to engine block ground on my tacoma and it helped and definitely made it start quicker
 
thennen said:
I'll assure you that, if those brushes are original, they're about finished. Easy enough to check. May not be causing your problem, but a great preventive measure.
Click to expand...

You were right! The alternator was on its way out! Problems persisted. Narrowed it down to a bad positive battery terminal and then foubd that the truck would immediately die when I disconnected the battery.

doing the cs144 mod this week.
 
psea17 said:
Just to be clear. I'm not talking about the reduction in HP when the AC is engaged. I was just using that situation to describe the situation.

Since starting this thread, I just completed the Big Three+ Rewire. (alternator to battery+, engine block (oem location=beneath oil filter) to battery-, battery- to body (oem location), battery- to frame). The battery to frame was added because I'm running 2ga to an Anderson Plug I located at the rear trailer hitch area. The plug is grounded to the frame. The plug will have two uses: a) charge my trailer's batteries (a BlueSea ACR was installed at the truck's battery to disconnect when the truck isn't running; prevents the trailer from draining the truck's battery) and b) should I decide to use my winch, which will be mounted on a tray that fits into the trailer hitch, it will have all the juice it needs.

My alternator increased output at idle from 13.98v to 14.25v. Very happy. Will report on the window power draw a little later. I have not changed the alternator's brushes. But, I would guess based on the alternator's output, the brushes should be fine.

Appreciate any other insights.
Click to expand...

What if the power window relays are wearing out?
 
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