Higher vehicle voltage in the winter...? Chevy trucks

Post by Pj » Sun Mar 23, 2003 5:49 pm

Ok, I have owned three Chevy's, and noticed this in all three (89 Corsica, 94 S10 Blazer, 97 Suburban).

During the cold winter months, vehicle voltage (as reported with the Garmin GPS3+ and dash gauge), the voltages seems to run 13.7-14.0, however, now in the spring time it will start around 14.0 and then gradually work its way down (usually within 15min or less) to a steady 13.4-13.6 volts.

What's the deal? I can take into accout battery/temp conditions, but when the truck is running on a highway 8-12 hours straight, I would think the voltage would level off lower, as I would assume the battery would be near 100% charged.

KitN1MCC · Post by **KitN1MCC** » Sun Mar 23, 2003 6:41 pm

maybe it is more effient at a lower temp

when my truck stars when it is cold it had lovoltage for a min then goes righ up

Nand · Post by **Nand** » Sun Mar 23, 2003 7:26 pm

jim · Post by **jim** » Sun Mar 23, 2003 9:01 pm

The ambient temp has nothing to do with charge rate or voltage...I mean....there is no sensor as in a Motorola charger. Some Mopars DO have a battery temp sensor, but it doesn't have much authority on charge rate.

The reason it charges higher when cold is that GM's alternators use very undersized rectifiers and regulators. When the semiconductors are cold, they are more efficient and current/voltage is up. As things heat up, voltage drops with efficiency like any semiconductor. On a cold morning you'll see low/mid 14's. As the engine warms up over 1/2 hour, the efficiency drops, as does the voltage. This is why the Northstar and several other cars have water-cooled alternators that have a coolant jacket that carries 220 degree engine coolant through them. If 220 degree coolant cools an alternator, just imagine how hot they really get inside.

GM also has a tendency of using a VERY small gauge wire on everything today. Did you notice the #10 or #8 B+ lead on a 120 amp alternator? It's too small. Did you notice the #22 wire on headlights? Too small. #8 wire on a 160A alternator will drop off rapidly on a heavy charge. This is why I always run a redundant alternator to battery cable on C/K trucks when building a squad or other commercial conversion.

GM's new alternators are rated for intermittent charge current, also. 15 years ago, a 120A alternator would do 120A all day. Today, GM's "CS" and other cheapo alternators rated at 120A (or whatever) will do that only for minutes then overheat. This is why if you have a dead battery you must charge it fully berfore starting the car or the alternator can (usually will) burn out if you jus boost the battery enough to crank the engine to life. The overcharge condition will kill an Imapla alternator in no time after a jump start.

007 · Post by **007** » Mon Mar 24, 2003 9:28 pm

I'll buy that....I've noticed that with all three of my Chevy cars ('89 Beretta GT, 98 Lumina LTZ and my '02 Impala LS). They were/are nicely equipped and all had 105A alternators. All three cars would start with a high voltage output (14.1-14.5v) at start, then fall within 10-20 min, depending on ambient temp, driving speed (underhood airflow) etc.

Since I am installing 3 100w X9000's and the rest of my lights in a few weeks (mostly LED), this is a good time to upgrade the rest of the wiring. I already am going thru the car adding additional chassis ground straps, in addition to different spark plug wires to bring the LS to the 9C1 RFI UN9 package.

Other than the complete K55 radar in it's case with cert. for cheapo $$, I found 60 feet of new 2ga. wire (2-30ft pieces) at a swapfest for $15 yesterday, so guess what I'm running to the trunk from the 100A breaker under the hood

Maybe I should use a piece from the alternator to the battery.....

How about a good aftermarket high-output alternator? Any suggestions that won't put me in the hospital from sticker shock? I am even considering the stock 125 amp unit.

Here's a question: If I get the 125 amp Delphi, will my car be able to bump up the idle under load or is that a 9C1/9C3 BCM thing only?

jmr061 · Post by **jmr061** » Mon Mar 24, 2003 11:49 pm

I have a 200 amp alternator from Vital Alternators down in TX I believe. It is in my 97 Lumina. Bracket and alternator cost like $800. Probably a little more than you want to spend.

Jason

jim · Post by **jim** » Tue Mar 25, 2003 10:42 am

If you can get a Leece-Neville to fit, go for it!

The #2 will be great for what you're doing.

007 · Post by **007** » Tue Mar 25, 2003 10:59 am

I perused the Vital website quite a while ago, and found it to be rather vague in detail. $800 is a little steep, but for a bullet-proof 200A alternator, it may be worth it. Do you have any comments/complaints about yours, Jason?

Those Leese-Neville units are sweet, but I think they are a little too big for my application (size-wise). I may call them and see if something may work, anyway. I think the 340A unit may be a bit much, huh?

jmr061 · Post by **jmr061** » Tue Mar 25, 2003 11:01 am

Your best bet is to call Vital and see what they have for your vehicle. I am pretty sure the on Vics the alternator is a direct bolt in. I have had really good luck with mine. Since the Impala is a standard police vehilce now they might have a direct bolt in application for that.

I had to call them to get info on mine.

Jason

007 · Post by **007** » Tue Mar 25, 2003 11:21 am

I just called Vital, and he is faxing me up some drawings and info on the 200A unit.....I'll look at them at get back here with some info later.

Macon Sparks · Post by **Macon Sparks** » Tue Mar 25, 2003 2:34 pm

Try these guys:

http://www.wranglernw.com/

I have their dual battery setup in my Ram

I installed a Vital in an FD BC Truck a while back and it worked great but the cooling fins were noisey at speed. They said they were working on fix for that.

KitN1MCC · Post by **KitN1MCC** » Wed Mar 26, 2003 7:40 pm

well you guys could trye joe's auto electric II in middletown ct. they are well know in the nortth east. ask fro jon