Alternator cycles at cold startup????

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I live in Florida, and it has been extremely cold here lately. I keep one of those Digital Voltage Monitors pluged into my 12v outlet all the time to monitor voltage. In the morning when I start my truck ever since it got cold... when I start the truck the voltage when I turn the key to on is about 12. 4, after I start it usually falls to about 11. 8, then about 10 seconds later the Alternator juisces it up to 14. 1, then the alternator cycles on about 10 sec, off 10 sec, on-off-on etc for 2-3 minutes, then it stays at 14. 1 for the rest of the day?? Anyone else ever seen this. It seems to me to be protecting the alternator from extremely high current draw into cold batteries.

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2001. 5 3500 QC CUMMINS 4X4 Auto. Bright Silver all but leather & pwr seat. Firestone Air Springs w/ Cab controls, Tork Lift Super Hitch & Frame mounted tie downs.

 

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That is your intake manifold heater grid cycling on and off. I see this happen 9 months out of the year.

Should add that it will cycle for approx. 3 minutes at an idle, stays on if idle raised to 1200 rpm and it will quit cycling when the speedo hits 18-20 mph. If you look at the small battery cables going to the manifold you get the idea that they draw a lot of juice. I think someone mentioned 140 amps. Yes the lights will dim.

[This message has been edited by BV (edited 01-04-2001). ]

 

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BV are you saying the manifold heater drags my voltage from 14. 1 down to the low 12'vs with the truck running. I thought it just cycled once before we cranked. If it's night the headlights go dim to bright with every cycle, then it just stops and stays at 14. 1 and everything great.

 

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ALTexp ,the grid heater will keep cycling after started until the intake air temp sensor see's a certain temp (not sure what the temp is) when it dont cycle in colder weather is when you got problems( just been there on my 94 ) air temp sensor was bad and it was 5 degree outside hope this helps

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94 2500 4x4 SLT,auto,182,000 miles,3:54,brilliant blue/silver,tst 250/635 set full forward,star wheel wide open,air box ported,pump turned up 20%,k&n,gauges,cat gutted,
2001. 5 3500 4x4 q-cab slt,auto,6000 miles,3:55lsd,brite silver,stock (for now)both have 12k hitches&15k's in the beds,30ft fourwinds 5er,(MY RAMS) http://albums.photopoint.com/j/AlbumIndex?u=1360183&a=10142301

 

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Yep, Been there... seen that. . Asked the same question the first year I had mine.

Your truck is operating fine. Your just not used to seeing this cause you live in FL.
I see it every morning and evening during this time of year... I hardly notice it.
Actually, its made for some interesting conversation in the truck when I have a newbie in the passenger seat. #ad

 

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Altexp, fellow Southerner! I got beat up by the fellows up north for asking this same question at the beginning of winter! #ad
Not really, but I did get ribbed about it!

Someone gigged me for not reading my manual. I thought, "But I DID read my manual! I did, I did!". Flipped back through it that night, and there it is! Even describes the dimming of the lights! My excuse: Being a southern boy, I ignore any reference to temps below 60 degrees. #ad


Mine will even cycle after the trucks run a while if it's cold enough outside, (34 degrees here last night!). I even plugged my block heater in last night!

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'96 Regular Cab, 116. 5K, SLT 2WD auto 3. 54, Vista topper, Pillar-mounted Autometer Boost/Pyro, transmission temp and oil pressure guages under dash, starwheel spun

 

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Altexp . . yep . . grid heater cycling.

You need to read the section in the owners manual . . or maybe on the visor . . on cold weather operation. There is a section that mentions that this cycling is a large drain on the batteries and that you need to run the engine long enough to recover.

Good luck . . tell Mickey and Minnie hi for us!

Michael

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00 Driftwood 2500 ST QC ISB LB 5spd 3:54 LSD Tow & Camper Groups

my photos

 

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Altexp,
As probably stated in other post already.
Air intake heater have pre and post cycle.

I have found this year even if the pre does not come on (because warm enough air in intake) that the post cycle will come on when the engine/turbo starts sucking the cold outside air in. My voltemeter will also go down to 10-11 when engine first starts up.

When your engine isn't running the heaters will pull that voltmeter down to 8 in pre cycle.
I would rather it pull a lot of juice out of battey when generator/alternator is putting out power.

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Bill Thomas
Missouri Mule - 96 Wht 4X4 ST CC,5 spd, 3. 54, 8 ft bed, 1 ft high cheater boards.
99 Freightliner bl/wht FL60 ISB-5. 9 24v,215 hp,520 tq,6 spd, 3. 59 nsr,16 ft box, 19. 5 tires,Wt/gvw 11,000/23000