is 14.9 volts dangerous?

MrPants · 02-25-2004, 03:41 PM

i just installed my second voltage regulator (took less than an hour this time). i had it at about 3/4 of the way up and the car kept stalling. i cranked it all the way up. it's now running at 14.9V.
i know SoCal says it should be at 14.4 but can running at 14.9 cause any problems?

ae1969 · 02-25-2004, 04:03 PM

uhmmmm was the battery completely dead ?
why was it stalling?

You can cook the battery..... 14.9 is starting to get a little on the high side IMO.

bearone2 · 02-25-2004, 06:31 PM

14.9 is way high. should be around 13.8-9 when the car is at operating temp or shortly after starting if it wasn't a long, labored start.

what was the voltage at the 3/4 setting?

the battery should show 12.6-7 with the engine not running.

you haven't mentoned the age or condition of the battery. if old the alt/vr could be getting overworked.
do or have someone do a highrate discharge test on the batt. if it drops below 10v, the batt is no good.

MrPants · 02-25-2004, 07:09 PM

the battery wasnt completely dead.
i assume it was stalling because the alternator wasnt providing enough voltage at idle. cranking up the voltage regulator stopped it from stalling
the voltage regulator i installed was adjustable. i meant it was about 3/4 of the way to the max

bearone2 · 02-25-2004, 08:08 PM

was the alternator light on when it was running, if so the alt wasn't charging the batt and it needs to be generating at least 1/2v more than batt voltage to turn the lite off and the 5a current draw from the fuel pump was being taken from a batt that wasn't being recharged.

the alternator may not recover an almost dead battery where the older generators could. gen doing dc and the alt converting ac to dc.

charge the batt with a charger, do/have done the hr discharge test and you'll know if the batt is good or bad and i'd venture to say the 3/4 level will give 13.9 or so if the batt is 10v or above on the test and fully charged.

checker and other places can check the opertion of the alt/vr in the car and a good alternator should put out it's rated amps as the system is loaded and the voltage comes down but the batt has to be fully charged.

MrPants · 02-25-2004, 11:05 PM

alternator light hasnt been coming on. its been charging at around 13V for the most part, occaisionally below. the main problem is that its so intermittent i cant get it to repeat the problem when its being tested.
once get the regulator adjusted im sure ill need a charge or a new battery (been putting that warranty to good use)

bearone2 · 02-25-2004, 11:26 PM

get/do the hi rate discharge test on the batt, go to checker, they can test it all for you for free.

hope you're using a good digital vm rather than relying on the vm in the car and check voltage at the battery.

was the 13v with the old volt reg.

on the car i traded for the p-car back in may, i got a penny's batt, with a lifetime warranty,(yeah penny's) back when dinosaurs roamed the earth in '79 and probably got 8 free batteries, the last several from firestone, who picked up the penny's contract. go for the warranty.

me be thinking you gots a bad battry but the 13v on the old vr/brushes tells me the vr is bad and when you jack the new variable vr up to it's max on a questionable battery it's doing it 's job, just at too hi of voltage.

adrian jaye · 02-26-2004, 04:32 AM

I get 14.xx when the car is running (wired in DVM)
I have no problems.

I need to check the stats though

adrian jaye · 02-26-2004, 04:39 AM

Battery voltage or electrolyte density gives information about the charging condition. 100% charging condition with all cells OK corresponds to 12.7 volts.

as to battery charging:
To prevent gassing, a simple charging device with maximum 0.05A and voltage limit 13.8V is sufficient for preservation /maintenance charging.

Rot 911 · 02-26-2004, 10:22 AM

Like another on here said, 14.9 is getting on the high side. I rarely see a regulator putting out much above 14.4 and most are around 13.5-14.0.

SoCal Driver · SoCal Driver's Garage

IceShark Says: 14.2 to 14.4 volts at the battery.

MrPants · 02-26-2004, 03:18 PM

i bought the regulator from iceshark and i think he knows his stuff so i will follow his reccomendations.
thanks guys

IceShark · 02-27-2004, 06:24 AM

With our 20 year old cars and all the questionable wiring conditions, where to set the voltage regulator becomes sort of an art rather than hard science.

But after a few hundred of the regulators in service the target is typically 14.4v at the alt (under minimal load) and 14.0v to 14.2v at the battery after you lose a bit from your wiring from alt to starter and starter to battery.

Running too high voltage problems: First off our Bosch alternators can't make 14.4v once you load them up with about 40 amps of draw. This includes whatever the battery wants to recharge. Second, if the voltage gets too high you can cook the battery recharging. But this really isn't an issue with the 944 because the battery is located behind the main firewall and exposed to the outside air via the hood to windshield gap and our alternators can't shove enough current down the pipe.

So all that remains are other components. They are all designed to run around 14.0v and by the time the current is run through the fuse/relay board and over to the component you will be darn lucky to have 14.0v on tap. Your real downside is your light bulbs will burn a bit brighter and die quicker. The H4 and H3 German bulbs I sell are rated at 13.8v. 0.2v more will make a difference in life but not enough to get worried about.

So, I would crank the regulator down a bit to around 14v at the battery when it is fully charged up and you are in 80*F ambient temps. Then you will be just fine.

TCMdocs944 · 02-27-2004, 11:44 AM

Iceshark

Dont ever leave this board. :-)