Battery Light

[Jon Klein]

Hi guys. My battery light has been on since I got my 91 SHO. It has a new alt. new batt. new cables. It charges at between 15.1 and 15.6 at idle. my Batt tests at 12.3 to 12.4 with the car off. the light doesn't flicker or get brighter or go off ever. any ideas? No codes either.

 

[llamaking122]

Hi guys. My battery light has been on since I got my 91 SHO. It has a new alt. new batt. new cables. It charges at between 15.1 and 15.6 at idle. my Batt tests at 12.3 to 12.4 with the car off. the light doesn't flicker or get brighter or go off ever. any ideas? No codes either.

correct me if im wrong 15.1-15.6 is pretty high. usually theyre 13.8-14.1

 

[raff18]

14.75 running voltage is normal
check the little single wire running to the alt

 

[llamaking122]

Well ive never heard of it that high. But that doesnt mean its not true. Both my 92's charge between 13.8-14.1

 

[rubydist]

The voltage regulator is bad - the light will illuminate if the system voltage goes over somewhere between 14.5 and 15.0 V, so over 15 will light it for sure.

 

[llamaking122]

The voltage regulator is bad - the light will illuminate if the system voltage goes over somewhere between 14.5 and 15.0 V, so over 15 will light it for sure.

thats what i was thinking. cant it ruin the batt by over charging?

 

[Jon Klein]

ok so my alt is bad? that sucks cause this ***** is new.

 

[Jon Klein]

how much damage can i do by driving it like this?

 

[Siman]

well im not 100% up on SHO wiring diagram but electronics theory its more than likely something with a transistor not saturating all the way or a capacitor is over charging before it reaches saturation before it discharges in a DC converter at least but you wont really be able to tell without a oscilloscope and a long drawn out map of the cars wiring. in theory if the battery is constantly spiking its extremely harmful to the bat. Most of my electrical experience though comes from computers and and micro CPU architecture though... if anything arcs though and shorts it will fry a good amount of resistors and other components. but i come from a world were .1 Volts means life and death of a machine.

 

[SHOZ123]

Over voltage on the battery will cause it to boil the acid. Be sure to check the electrolyte level and top off to the bottom of the well sights with distilled water. Do not over fill. It should still be good unless this has been going on for a long time.

Could also be a bad ground or connection at the alternator.

 

[bubba]

Yeah getting a reman, is it or miss, I would take it to have it rebuilt! they seem to last long than the reman'ed for some reason!

 

[rubydist]

15.1 likely won't do much damage to the battery, especially in the winter, but 15.6 is pretty high. Then there is the question of how accurate your voltmeter is....

What happens when the rpms get up to 2000 or 3000? Does it go higher than 15.6 or does it limit it there?

I'd say your battery will likely survive the winter okay like this, but when it gets warm out you are going to have problems, but the further over 15V you are, the sooner your battery will puke.

 

[AREA 91]

Hi guys. My battery light has been on since I got my 91 SHO. It has a new alt. new batt. new cables. It charges at between 15.1 and 15.6 at idle. my Batt tests at 12.3 to 12.4 with the car off. the light doesn't flicker or get brighter or go off ever. any ideas? No codes either.

You have a bad voltage regulator.
Time for a new Alt,

 

[ForcedSHO]

Dealing with the same issue. Two reman alt's and two bad voltage regulators. Looks like I may buy a new regulator or a new alt altogether. Regulator's were $80-$100.

 

[llamaking122]

just have the whole thing rebuilt

 

[shocar]

Make sure you don't have a short somewhere. I had an issue with my 92 where an aftermarket security system wire was shorting out which caused a chain reaction. The battery boiled, the alternator light would come one. I screwed around changing alternators and it turned out just to be a simple bare wire shorting out from the battery to the alarm system.

 

[medgraphsho]

I just replaced my alt. with a reman last week.... so far so good

 

[stangeater]

I've owned 3 shos, all for a long period of time, and never had an alternator go bad! Guess I've just had good luck.

 

[Jon Klein]

You are lucky. I've had seven and they've all needed alts. I've never had this problem though. Rubydist to answer your question it never changes. Which I thought was also odd because I've never come across that. 15.1 all day long.

 

[The Guru]

how much damage can i do by driving it like this?

You will get tired of changing batteries but that's about it.