I agree with kimmer- you needed to get your battery voltage up to at least 12.6 volts. Batteries start to sulfate when they are discharged below 12.4 volts, so I would disagree with the suggestion that 12.3 is good. If you are concerned about the health of a battery, have it load-tested at an auto parts store. Many will do that for free and it might save you from buying or replacing a battery sooner than needed.

Your underdrive pulleys may not be allowing your alternator to properly-maintain voltage in your battery. We recommend typical alternator output to be in the range of about 13.7-14.7 volts. I'm beginning to feel like I need to start suggesting that anyone who buys underdrive pulleys should also purchase a battery maintainer at the same time.

When it does come time to buy a new battery, you probably don't need to overbuy on cold cranking amps. You live in Tennessee, not Toronto. Cold cranking amps are measured at 0°. If it's that cold outside, you probably won't be driving your Corvette anyway. As long as you meet or exceed the engine's requirement for cranking amps, you should be fine in that regard.

seabright, thanks for posting the link to that website. You'd think “experts” would know the difference between AGM and gel batteries. Optima has never manufactured gel batteries and I have yet to see a gel battery from any manufacturer in an automotive application. We explain the important differences between the two technologies in our Power Source blog.

Jim McIlvaine
eCare Manager, OPTIMA Batteries
www.pinterest.com/optimabatteries

 

I am standing in the garage now and battery is at 12.7 with car off. Car was just driven. I started the car and alternator is putting out 14.4. Fan kicked on and battery is 14.1-14.2. Alternator same.

 

Red89- you are correct. Website shows $115. The receipt they have me when I replaced under warranty showed $84.95. Not sure why.

 

115 is the going price that's what I paid too.

 

I keep thinking of more data to offer. I drove to post office this morning and all was well. When stoping at a red light with fog lights on and turn signal the volts showed 11.9-12.1. When cruising at 35-40 mph volts showed 14.0. I think I read that there is a .3 lower difference between actual and what the dash shows. Is this correct? My measurements I posted in reply to Optima were with a DVM. Dash showed a little lower than the meter. I think the pulleys definitely have a negative effect on charging. When cruising and I put the signal on it blinks normal but as I slow down for the turn so does the signal. If the system is not charging well due to pulleys would buying a charger/tender be something I could do to recharge the battery periodically if it continues to show the issues of the old battery?

 

The readings are with a new pep boys alternator and a new red wire. 6 month old d gold battery.
Idle=14.1 volts
cruising at 40 mph 14.4 volts
all lights on and idling 14.2 volts
stopped with turn signal in drive 14.1 volts
key on position not running 12.0 volts

 

The pulleys must be killing my charging when at idle in gear. I did a search and read a lot of posts saying that this is the case with under drive pulleys. Can the idle be set higher manually or is it ECM controled? It idles at 500-600 in gear at a stop. Also no one answered if the battery can just be recharged if the volts get low due to pulleys not charging good over time. Or is it going to just keep killing batteries? I may be looking for some stock size pulleys soon!

 

I just did a minimum idle setting yesterday and it sets the idle to 600. You could probably adjust the throttle open a tad to gain 100 rpm(700) But you would have to readjust the tpi sensor at that point to .54 because after you manually move the throttle forward the tpi would read .75 or something . The car would not know your foot is off the gas.I don't know if that would work but it seems possible.
Not to change the subject but what are underdrive pullys and why do I need them.

 

If your 12V reading was from your digital gage, and not direct from the batt, the reading will be lower due to a small voltage loss as the current passes through the ignition before it is displayed.

 

That's why I'm wondering if the dash readout is way low. With a VM my battery is 12.7 but dash shows 12.0 with just key on. That's a big swing. As for under drive pulleys I have a crank and alternator pulley that make the accessories run at like 23% less than usual to free up hp. The previous owner put them on. The problem is they can cause your alternator to not put out proper voltage.

 

Dash voltage is lower than a direct batt reading, but only by .5V max.

 

Did you get your cable tight? If needed you can buy a new Lead insert/Bolt at any parts house, I just replaced mine on an 95 C1500. The inserts flatten out over time, and make a poor contact.

 

Good suggestion, Mike.

 

I corrected the loose connection with a washer between bolt head and cable.

 

I see you replaced your red wire on your car, I was wondering if you had a diagram or could post a picture of how it routes? I need to replace mine and i'm going with a bigger gauge wire. I will be running the new wire differently for simplicity and ease and the old wire is just going to be taken out and I don't really want to just pulled it out with force so I don't mess anything up.

Thanks if you can help or if not

EDIT: Nevermind on that haha I just realized that I could leave the old wire on there anyway since I am re-routing the new one to make it easier. Stupid me sometimes.

 

Maybe when the original buyer of the battery bought it, it was either cheaper or at a discount.

I'm gonna try and buy one with the next 20% coupon I get so instead of $115 it will be about $90.

 

The battery is losing charge overnight. Yesterday it was 12.7 with car off and today 12.3-12.4. Started car and volts go to mid to high 14's until warm then it fluctuates between 12.9-14.1. I turned on the AC and turn signal at it was still about the same. I'm guessing the DVM reading should be steady and not jumping from high to low to high. Do I have a parasitic loss going on? How do I find a culprit?

 

My car even with a terribly bad battery when running will charge at about 13.5v-13.9v with all lights, radio and AC on. Do you know how to check for parasitic loss? If not best place to look is on youtube, there is a load of videos showing you how to.

The dropping down in overnight could be a parasitic draw so I would look it up on youtube and check to see if you have one.

 

The volt reading should be steady...... not moving high to low to high. That could be a sign of a poor connection where you used a washer to provide a secure connection. Check the cable ends, replace, if worn.

You still may have a parasitic draw, but a loose connection will not help.

Using an amp meter between the batt post and cable end will show if there is more than a 30 miliamp draw (+/-) which is normal.

An excessive draw, 1 amp +, can be identified by pulling fuses and watching the amp meter respond.

 

I was pulling around 4 amps! Hunted down the fuses and it was the CTSY/CLK. Left fuse out and ran car. With engine hot, it was charging at high 13's to 14's and dropped into low to mid 12's with all lights on and turn signals while in gear with brake on. No more erratic volt readings as before steady readings and they only changed with introduction of more amperage or reduction of. Car charges at steady 14.1 with rpms at about 1800-2000. I let it run for a good 10-15 minutes and parked it. Checked battery and it charged up to 12.8. Going to check again in morning to see if it is holding. The lower than normal volt reading although better than what it was doing, I attribute to the under drive pulley on the alternator. I am going to find a stock one to put on if the current changes do not keep the battery charged properly. I think the old Kenwood stereo I had in my garage that I installed in the car when I bought it in May could be the culprit. More experimenting to come. I need to get my heat and AC back online! They are apparently on that circuit.