2001 Gen4 4cyl (5SFE) - base electrical load/reserve capacity?

[jantman]

Hi,

Yes, I'm new here, and this is my first post; but I've looked around a bit, and found a few pieces of useful information.

I just bought my first Toyota last week, a 2001 Camry with the 4 cylinder (5SFE) engine. I'm looking to add some electrical accessories to the car. As far as I've read, the stock alternator should be 80A. I was wondering if anyone can tell me what the base electrical load on the vehicle is? I've checked the FSM and the wiring diagram book, but can't seem to find any mention of either a per-system load calculation, or how the fuses are sized, or any mention of installing accessories and what toyota considers to be an allowable additional drain.

I'd really like to avoid having to shunt every system in the car, one at a time, if there's any way around it, and I'm relatively particular when adding accessories.

Thanks for any advice,
Jason

[RichieRichJP]

I don't think that should even be a concern.
As long as your system is does not exceed the amperage of the alternator, you're fine.
I sold off my system about 4yrs ago so I don't remember all of the parts necessary to exceed the amperage, but I think you'll need a capacitor.
Just remember that running a system putting a larger load on your alternator than what it's rated at will eventually kill it.
My recommendation is if you want to run a huge system in your car, just send your alternator to Mr. Alternator. Search yahoo for it.

[jantman]

Thanks for the advice, but I'm not putting a stereo system in my car. I'm the lieutenant of an ambulance squad, I'm putting in emergency lights, siren, strobes, headlight flasher, and a 2-way radio. The load of everything else on the vehicle is a concern - if my radio stops working, it literally becomes a matter of life and death.

No offense, but "As long as your system is does not exceed the amperage of the alternator, you're fine." is, from an electrical engineering standpoint, idiotic. I already know that if I have the heat, headlights, wipers, and rear defroster on, I'm probably pulling somewhere around 40A. It's an 80A alternator. If you add a "system" to the car that's pulling 80A, and 40A of factory load, you've got a dead alternator and a fried battery too. Simple math.

A capacitor, in simple terms, lets your power source (alternator/battery) deal with spikes in demand. It doesn't magically make the alternator output more current. They might be great for people who need more current just when bass is hitting hard, but they're not useful for any sort of constant load.

So... I'll try again... does anyone have the information needed to do actual engineering work on the Gen 4 Camry electrical system? I have the wiring diagram book, but there's no mention of actual load from the various circuits. I want to be able to know, before I ever connect an aftermarket wire, what the voltage drop at maximum usage will be (< 2%).

[Pvt-Public]

Easy. Hook an ammeter to the car turn on all electrical accessories see what your total amperage draw is. I have looked through the FSM and can not find an answer to what the total draw is. There is no 1 definitive answer since there are different power options offered for different trim levels and geographic markets. We do know that the stock alternator is rated at 80A and the main fusible link is 100A. So after you figure your total draw plus the equipment you plan to add you will know if you need more alternator or not. And if you need a 100A or larger you will need to get a larger capacity fusible link. Sorry if that does not directly answer your question but it is the best I can do with the FSM I have.

[RichieRichJP]

Originally Posted by jantman

No offense, but "As long as your system is does not exceed the amperage of the alternator, you're fine." is, from an electrical engineering standpoint, idiotic. I already know that if I have the heat, headlights, wipers, and rear defroster on, I'm probably pulling somewhere around 40A. It's an 80A alternator. If you add a "system" to the car that's pulling 80A, and 40A of factory load, you've got a dead alternator and a fried battery too. Simple math.

Call me stupid, but I ran a multiple 100A systems in my car for over 5yrs. So where you think logic would apply, really doesn't. In fact, since I pulled the audio shit out of my car about 4yrs ago, I am still running the same alternator with no problems.

[jantman]

Originally Posted by Pvt-Public

Easy. Hook an ammeter to the car turn on all electrical accessories see what your total amperage draw is. I have looked through the FSM and can not find an answer to what the total draw is. There is no 1 definitive answer since there are different power options offered for different trim levels and geographic markets. We do know that the stock alternator is rated at 80A and the main fusible link is 100A. So after you figure your total draw plus the equipment you plan to add you will know if you need more alternator or not. And if you need a 100A or larger you will need to get a larger capacity fusible link. Sorry if that does not directly answer your question but it is the best I can do with the FSM I have.

Yeah that's what my theory is. I don't have a DC clamp ammeter anymore, so I guess I'll have to beg or buy one. Was just hoping that, maybe, someone had already done the work.

Originally Posted by RichieRichJP

Call me stupid, but I ran a multiple 100A systems in my car for over 5yrs. So where you think logic would apply, really doesn't. In fact, since I pulled the audio shit out of my car about 4yrs ago, I am still running the same alternator with no problems.

Ok. Assuming the base load is 20A, I don't really see how your 80A alternator could provide 120A of output.

More importantly, if something in my electrical system fails, it's more than not having music. Most of the wiring work I've done was on Fords - either Ford truck/van ambulances or crown vic police cars. I do my work at or above original factory spec. Hoping that everything works OK isn't really an option. I don't mean to sound like a jerk, but my idea of "installing accessories" (i.e emergency vehicle accessories) means an engineered wiring installation complete with load calculations, CAD drawn schematics, etc. I'm the type of guy who pre-cuts wires to length, because I know the length (within 1-2 ft) of every run I'm putting in the car.

I guess I'm going out to buy a DC clamp ammeter. When I finally finish taking readings, I'll post the results for anyone else who has similar questions.