Babnik

I found this paragraph in my owner's manual:

Now I'm no mechanic but I THOUGHT that when the engine was on, anything in the car that uses power, including the seat heaters, draw power directly from the alternator, so the battery is not used at all. The only time power is drawn from the battery is when the engine is not running. So then, I should be able to use the heat seaters non-stop for as long as I like while the engine is running and it shouldn't affect the battery. What am I missing?

Bearcat94

I thought if the alternator cannot supply enough power, the car will draw add'l power/wattage from the battery.

Perhaps at idle the alternator doesn't generate enough power for the seats plus various other elcetrical (Control Sytems, Navi, Radio, etc) systems and so draws from the battery.

Just a guess.

Babnik

Well I once drove for about 4 hours on the highway and had the seat heater on the entire time and had no problems. And my battery is almost 5 years old. Does the alternator generate more power when the car is moving compared to idling?

jvinhj240

I am not sure I am right but i have a 08 Sienna use for work. I have power inverter in there which withdraw alot of power (1000w). I have a laptop , laser printer and couple other scanner that i need to charge it with power inverter. Well, I killed 1 battery in 3months and since then on, I minimize on my charging my other systems when i am not driving. Maybe It doesnt support enought current and kill battery? I dont know but seem related.

pbcmedia

if ur driving ur going to be constantly charging the battery via the alternator... so thats y u didnt have any effects.

now i do believe that if ur idle for a long period of a time i do believe that if you have on your radio, nav, seats, etc.... u do have to use some battery so i c how tht can affect the battery, one way u can tell is to look at ur interior lights and see if they start to dim...

but hey you shouldnt be idling that long anyway its against the law....lol

01tl4tl

here is how the car really works--I dont care about the battery cables off and the car still runs...for a few minutes. Thats an old school alternator quick test, if the alt is working it will support the car without the battery ---at idle

At idle the alternator is putting out barely enough amps to support the computers-fuel injection and basic systems
Above 1700 rpm the alternator can put out massive amps

The car runs on the battery, all power is drawn directly from it
The alternator generates power and the voltage regulator sends that power to the battery to REPLACE what the car is using at the moment, including the extra it needs to recharge after using the starter

So its possible to drain from the battery at idle, then not have enough juice to make the car run correctly--hid lights- 6 hi output ignition coils...
At speed you can run everything without concern--except seat heat on high will cause it to hit the over temp limit switch and shut off until it cools
use high to warm seat and low to operate

01tl4tl

the instruction is really for those who leave the car running to warm up in the morning
Dont turn the seats on high and walk away

01tl4tl

batteries seem to last 3-4 years, if you are lucky 4
If yours is 5 get it checked asap at parts store
A low battery voltage condition will make the car run bad- including bad fuel mileage

chairguru22

This is very good to know... handy info for those in the northeast right now.

YeuEmMaiMai

When it is cold outside I start my car, turn the seat heater on high, and let it run while I am scraping it off.

SouthernBoy

01tl4tl is right. Almost everything electrical in you car runs off of your battery. And the biggest single power consumer is the starter. So you have a very cold morning and you go out to start your car. You turn on your parking lights, your sound system is on, and you turn on your seat heaters. In about a minute or so, the engine is back down to idle speed and the alternator is unable to replace the amperage that has been drawn from your battery. If you have a really short trip to work, your battery and alternator are really going to be taxed. Do this time and again and you will wind up with insufficient voltage to start the car.

01tl4tl also makes a good point about checking your battery and this is something you can do yourselves very easily. Go to an auto parts store or sears and buy a powered (9-volt battery) digital volt/amp/ohm tester for multiple power sources (so you can also use it in your home). I bought mine, a Craftsman, at a gun show for a ridiculously low price. After arrive home from a drive or work, read your battery's voltage (it should be somewhere between 12.4 and 12.8 volts give or take a little). Then wait about an hour or two and go back out for another reading. If your reading has not changed hardly at all, your battery is holding a charge and is most likely fine (do this again the following day before starting your engine if you want). A battery that will not hold a charge can still start your engine but you will see a lot of variance in the voltage readings.

Incidently, my '04 manual TL still has the factory installed battery and reads fine. But my '05 automatic had to have a new battery installed last November after only 3 years 8 months. It stopped holding a charge.

01tl4tl

I would rather people go the the parts store and get a free system test

It will simulate the load used by the starter, check alt output with headlights on at running rpm, test battery cable condition internally and more--all for free!!

Less than 15 minute drive with cruising speed is not enough to recharge the battery

If you are right there cleaning the window with 1 seat heater on and then drive a reasonable distance,,its not really a big deal
Letting the car sit 15 minutes at idle with everything on...not good

When I get stuck in traffic, stop and go, not generating squat for amps out of the alternator, I go to lights park, or off completely-- to save the battery voltage for important things like my stereo enjoyment while sitting in traffic

01tl4tl

the thing to remember is the actual amps being drawn and used by the seat heater specifically
They are essentially pieces of bed electric blanket. Nothing but thin guage (18?) wire sewn into a cloth cover, with electricity pumped thru the wire at 15 amps..the wire is going to get hot!!!!
Its also pulling ALL that juice as long as its on

Tripnbeats

batteries are the alternators rectifiers..... it smoothes current ripple from the alternator as its passed through the battery so theres no damage to electrical components.... it supplies all power to the car and the alternator supplies the extra voltage and amperage as its called on by all other accessories. if the battery stays at 12.6 after u shut the car off its ok the next day it should be down to about 11.2-11.8 if its not and its above....thats fine if its below 11.2 new battery is needed. the car as its running should produce over 14 and no more than 14.8 to have the correct voltage going to any and all components of the car without damage to any circuits.

jweb12

iTrader: (2)

I thought the seat heaters didn't actually operate unless the seat recognizes someone is actually in the seat, whether the switch is on or not. I haven't looked into this so don't kill me here if I'm wrong. I recall turning the seat heater on while my car warmed up awhile back and when I came back, the seat was not warm. Once I was in the seat, it began to warm. Maybe I am mistaken.

Tripnbeats

yea the weight sensors tell the seat heater someone is sitting and its ok to turn on.

blkaspec

interesting read, thanks for the info! i warm up my car and turn on the seat heaters...i wont do that anymore.

J-STEELE

Yup, that's the way mine works. I remembered leaving them on to go back into the house, came back and the seats were still cold. Once I sat in them, heated up pretty quickly. I was gone for a couple of minutes.

PEACE!

Babnik

That explains a lot! I would always turn on my engine and seat heater then clear the snow off my car, thinking that by the time I was done the seat would be warm, but it is always cold and doesn't warm up until I've been driving for a few minutes. I thought the seat heaters were just really slow.

I kind of wish it worked even without someone sitting in it, because I hate sitting on a cold seat.

Babnik

What makes you say that? I realize the TL has a lot more electronic gizmos than the average car but 3-4 years still seems abnormally short for a battery life. My dad's car is 8 years old (he bought it new) and the battery is still good.

Regarding having your battery tested: How do I know they won't say my battery is bad even if it's good just to sell me a battery? That's why I'd rather buy a voltmeter and test it myself.

jweb12

iTrader: (2)

I hear you. It would be nice to be able to have the seat warm while the car is warming up but I'm sure there are safety reasons this isn't the case.

paliknight

this is interesting. idk if its a problem with my seat heaters or not, but it normally takes like 15 minutes for the seat to get warm (while im driving). so im practically half way to my destination before my seat starts to get warm.

Be-in my TL

I think it would be a little hard to get an accurate test with a voltmeter. You'd need a good VAT. Those microvats they use at parts store and shops are fucking useless. It's like using a metric wrench to measure rotors. It's for lazy people.

01tl4tl

the parts store only wants to sell you the part you actually need, and if you dont need anything they tell you and show the results on paper to you if you need

If you dont know anything about cars- get educated before it sees any shop!

To really see whats going on -you need to test each cell of the battery for voltage being equal across them

Ask any ziner- the newer the car the shorter the battery life
It has to do with higher heat in the engine compartment,
and that they make everything as cheap as possible.
8 years ago is not 4 years ago
My 01 needed a battery in late 06, that was lucky 5 years!!

01tl4tl

there's an occupant sensor for the seat heat? I never knew!!!

Makes sense from a fire standpoint, hi temp side of switch runs until it hits temp overlimit switch and shuts off till cooled to a certain level and then back on full
If the limiter should fail, and you are inside the house for 15 minutes getting ready,,

The sound of fire trucks approaching makes you curious as you head out the door....
I hope they wont be blocking my route~