Alternator charging while at idle? - Toyota FJ Cruiser Forum
Misc. Technical Discussion For all technical info that doesn't have a category

Reply
 
LinkBack Thread Tools Display Modes
#1 (permalink) Old 01-20-2009, 03:55 PM
Forum Regular
 
HyperX's Avatar
 
Join Date: Oct 2008
Location: Cary, Il
Posts: 185
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Lifetime Supporting Member
(Thread Starter)
Alternator charging while at idle?

So my 2003 4runner would go through batteries once a year - dealer said that I dont drive enough (6 mile round trip commute to train station a day). I finally solved the problem by installing a solar panel that was a 2W trickle charger. Currently on same battery for 3 years. For the hell of it, I installed one on the FJ (sunsei is the company that makes it). But my question is, does the battery get charged while car is in idle? Dealer is telling me car has to be in motion - which makes very little sense. 5 speed vehicles, 45 mph is no more than idle in 5th gear.

Does the FJ have a better alternator than the 4runner (4th gen)? and does it charge battery at idle?

2008 FJ Crawler (ARB FJ Cruiser through DSI), 3 inch OME Lift, 305/65/17 Pro Comp Tires, ARB Black Bumper, Warn Winch, NUVI GPS, reverse cam

2010 Chevy Silverado Crew Cab LTZ 4x4
2008 C6 Z06 Corvette pushing 500 hp to wheels
2008 AWD Chevy Express Conversion Van (Southern Comfort)
HyperX is offline  
Sponsored Links
Advertisement
 
#2 (permalink) Old 01-20-2009, 04:35 PM
Forum Master
 
CanadaFJ's Avatar
 
Join Date: Sep 2006
Location: Calgary, Alberta
Posts: 1,252
Mentioned: 2 Post(s)
Tagged: 1 Thread(s)
Quoted: 1 Post(s)
Re: Alternator charging while at idle?

If the alternator is turning, then the battery is charging - but, if at idle, and if you have every electronic/power accessory on that you can think of within your FJ, then yes, the charging may not be able to meed the demands of the load. Note also that the FJ will only charge the battery if it needs it, which helps to protect the battery from being overcharged. (Most vehicles will have some sort of protection for the battery to prevent overcharging. Now if they would only do something to prevent the battery from completely discharging........ )

Slàinte mhor a h-uile là a chi `s nach fhaic!

For so long as 100 men remain alive, we shall never under any conditions submit to the domination of the English. It is not for glory or riches or honours that we fight, but only for liberty, which no good man will consent to lose but with his life. - THE DECLARATION OF ARBROATH, 1320

Mods: Nuvi 350 GPS, XM Satellite Radio, Yaesu FTM-10R Mobile Ham, VE6RAO
CanadaFJ is offline  
#3 (permalink) Old 01-20-2009, 04:45 PM
Forum Veteran
 
Join Date: Sep 2008
Posts: 590
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Re: Alternator charging while at idle?

I dont know if the alt of the Fj is better than 4runner. But i know that the alt charge youd be getting will be better than at running (12-12.5V idle vs. 13-14V running) as compared to idling. On a side note, vehicles with incorrect pulleys, electrical issues, low idle speed (one or combo) can result to very little charging to battery when idling.

If your 6mile commute doesnt involve more than 15mins of driving (considering traffic lights, traffic in gen., etc...), it may require more time to charge.

If your commute is more than 15mins and the fact that your battery still did not last longer than 1yr tells me theres something wrong with your battery or alt. I personally would take them both out and bring to your nearest auto shop to get them both tested.
lilx10 is offline  
#4 (permalink) Old 01-20-2009, 04:53 PM
Forum Superstar
 
DEWFPO's Avatar
 
Join Date: Nov 2006
Location: High in the Rockies
Posts: 6,344
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Lifetime Supporting Member
Re: Alternator charging while at idle?

Quote:
CanadaFJ previously said: View Post
If the alternator is turning, then the battery is charging - but, if at idle, and if you have every electronic/power accessory on that you can think of within your FJ, then yes, the charging may not be able to meed the demands of the load.
X2.

Like you said, the 5AT likes to keep the engine at a low rpm in each gear to maximize mpg. Sometimes that is only 1,000 rpm. The alt. in the Fj is rated at a max of 140 amps (at it's rated rpm). I haven't seen a curve for the alternator so I don't know what it puts out at idle in gear (550 rpm) but it should keep your battery charged. That is provided your not crawling along at 550 rpm, foot on the brakes (lights), headlamps on, front defroster on high, rear-defroster on, wipers going, the boombox cranked up and only a 3 mile crawl.

DEWFPO

2007 FJ, 5AT, Sun Fusion Yellow, CQ, UP, GY, RB, 2Q, EL, VS.

Engine Block Heater, '08 Cyclone Pre-Filter, Dual horns, Phillips Osram 70W/65W H4's, RockBlocker and 3M Clear Film, Toyota RearSight Backup Camera.

"Enjoying the Journey"

"Wanted - young, skinny, wiry fellows, not over 18. Must be expert riders willing to risk death daily. Orphans preferred"
Original newspaper add placed by William Hepburn Russell, founder of the The Pony Express

Last edited by DEWFPO; 01-21-2009 at 02:56 PM.
DEWFPO is offline  
#5 (permalink) Old 01-20-2009, 06:03 PM
Forum Master
 
Join Date: Jun 2008
Posts: 931
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Re: Alternator charging while at idle?

Battery should be charged with alt running. In small towns, trips are usually 10min or less (3mi city driving) and batteries last 5+ years just like any other battery. Your alt or voltage regulator might be broken.
ducky is offline  
#6 (permalink) Old 01-20-2009, 07:19 PM
Forum Master
 
hpiguy's Avatar
 
Join Date: Nov 2008
Location: Wisconsin
Posts: 1,027
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Re: Alternator charging while at idle?

I drive about 2 miles to work and shut the truck off.

It's hard on the battery and it doesn't really let it charge after the high draw of starting on cold weather.

So about every two months I hook up the charger (automatic shut down to trickle type when charged) and let it run over night.

I've done this on all my cars over the years and I get batteries to last 5+ years, even in this climate.

Maybe you have a constant draw somewhere in the 4runner system. Or maybe you tend to run more accesories or leave stuff on longer than I do. I always make sure everything is turned off before I shut off the vehicle and I never start it with things turned on.
hpiguy is offline  
#7 (permalink) Old 01-20-2009, 07:29 PM
Forum Regular
 
jhaydeno's Avatar
 
Join Date: Oct 2007
Location: Dover, PA
Posts: 288
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Re: Alternator charging while at idle?

I've got to disagree with all three of you. Alternators need to be run up to about 1400 RPM after a start to begin charging ( excite the field). At an 800 RPM idle they aren't doing any charging (no potential difference). This would certainly ruin a battery a year, especially with freezing weather and modern cars that sap voltage 24/7 for alarms, led's, clocks, electronics, etc.. I like the solar charger idea, or make your alt pulley smaller so it runs at higher RPM's.

The ultimate in 4wd is green!
jhaydeno is offline  
#8 (permalink) Old 01-20-2009, 07:35 PM
Forum Veteran
 
FJBinky's Avatar
 
Join Date: Oct 2007
Location: Snowbelt, NY
Posts: 552
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Re: Alternator charging while at idle?

Quote:
jhaydeno previously said: View Post
I've got to disagree with all three of you. Alternators need to be run up to about 1400 RPM after a start to begin charging ( excite the field). At an 800 RPM idle they aren't doing any charging (no potential difference). This would certainly ruin a battery a year, especially with freezing weather and modern cars that sap voltage 24/7 for alarms, led's, clocks, electronics, etc.. I like the solar charger idea, or make your alt pulley smaller so it runs at higher RPM's.
You're correct about the excitation of field but... It really depends on the drive ratio from the crankshaft to the alternator. The crank pulley is much larger in diameter than the alternator pulley (think 10 speed bicycle). At 800 rpm crankshaft speed, the alternator probably is at or pretty close to 1400 rpm.


Integrated rear hitch receiver through a modified All-Pro rear bumper, Demello front bumper with Smittybilt XRC8 winch, Bilstein 5100 adjustables, Toytec rears with ProComps, Rasta front and center skids, Trail-Gear t-case skid, All-Pro high tuck tailpipe, Total Chaos Lower Link Skids, Harbor Freight hitch mounted disposable backup light, SCUBA mod...
FJBinky is offline  
#9 (permalink) Old 01-20-2009, 07:37 PM
Forum Master
 
hpiguy's Avatar
 
Join Date: Nov 2008
Location: Wisconsin
Posts: 1,027
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Re: Alternator charging while at idle?

Quote:
jhaydeno previously said: View Post
I've got to disagree with all three of you. Alternators need to be run up to about 1400 RPM after a start to begin charging ( excite the field). At an 800 RPM idle they aren't doing any charging (no potential difference). This would certainly ruin a battery a year, especially with freezing weather and modern cars that sap voltage 24/7 for alarms, led's, clocks, electronics, etc.. I like the solar charger idea, or make your alt pulley smaller so it runs at higher RPM's.
Boy, then we must own super duper amazing batteries that can run our cars on no charge for months or years at a time.

And those old folks that let their cars idle forever with the heat on high and then drive right home and shut it off must also have amazing reserve power batteries.

And cops must kill a battery per day.

I put on only about 400 city miles a month. Total. Rarely highway. Yet don't go through batteries left and right in any car I've owned.

Like the guy above me explains, the alternator is likely spinning faster then the crank speed and is charging.

Last edited by hpiguy; 01-20-2009 at 07:39 PM.
hpiguy is offline  
#10 (permalink) Old 01-20-2009, 10:12 PM
Forum Superstar
 
mikey's Avatar
 
Join Date: Jun 2006
Location: Edmonton, Alberta
Posts: 8,734
Blog Entries: 1
Mentioned: 5 Post(s)
Tagged: 1 Thread(s)
Quoted: 457 Post(s)
Send a message via MSN to mikey
Lifetime Supporting Member
Re: Alternator charging while at idle?

Your altenator is what keeps your vehicle running, not the battery. The battery is their to hold a charge for when you start, leave your lights on, hazzards etc (anything where the alt is not spinning).
My old K5 Blaer ran with out a battery for a whole summer, I would just use a portable booster pack to get the thing started and I would drive on from there.

Some of the older vehicles needed the rpms brought up so the regulator would engage. I doubt that is even an issue today.

After Monday and Tuesday even the calender says WTF


"It's not easy being Green"
Kermit the Frog
mikey is offline  
Sponsored Links
Advertisement
 
Reply

  Toyota FJ Cruiser Forum > Toyota FJ Cruiser Discussion > Misc. Technical Discussion

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Toyota FJ Cruiser Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome