Battery Problem - Need Help

[olblu66]

My original battery went dead, so I replaced it with an Optima Red Top battery. Within 4 days of the car sitting, the new red top battery went dead. I returned that battery and received another Optima Red Top.

I attached a volt meter between the positive terminal on the battery and the positive cable. It showed 12 volts. Is this normal? I unhooked the single wire to the alternator and it dropped to 6 volts. I pulled all of the fuses but there were no changes.

Something appears to be draining the battery while the car just sits. Any idea on how to check this?

Has anyone ever had this or a similar problem? Any ideas?

[brfutbrian]

just a wild quess totally blind, id start at the ignition switch. later, brian.

[Jim Harding]

The voltage measurement you mention, reading from the positive post of the battery to the 'disconnected' positive lead is referred to as the "open circuit voltage" and because there is no current flow, it is NORMAL to see the "source" or total battery voltage in this case. (I know, the meter completes the circuit, but the current will be minuscule)

Pulling fuses, removing wires, etc. should NOT change the reading until all the connected circuits are removed, at which time the voltage will go to ZERO. It is possible that the reading could be somewhere in between 0 and 12 volts. In this case the 'fault' current in the circuit is due to a very high resistance that is almost equal to the internal resistance of the meter used.
(a VERY small current draw)

A better way the check for a current draw from the battery is to use the ammeter function of the multimeter, or a simple 12 volt test light. Placing either the ammeter or test light in the circuit, like you did with the voltmeter, will indicate the presence of current flowing in the circuit. If there is no current flow, the light will not illuminate or the meter will not indicate any current flow. Depending on what circuits require a constant source of 12 volt power, (i.e. clock, ignition computer, radio memory, stuff like that) a slight (very dim) illumination of the test light is normal or a reading of a few milliamps on the ammeter is normal. If the light is bright or more than a few milliamps is reading on the meter, removing fuses and/or disconnecting wires at this time while observing the light or meter will give you a better diagnosis of what is causing your current draw from the battery.

Electrical gremlins can be frustrating but a slow and deliberate testing procedure can put a 'light' on your problem.

[olblu66]

Jim, thanks for your thorough explanation. The information was very helpful. I plan to use your procedure today. Wish me luck.

Thanks!

[olblu66]

Brian, thanks for your response. I did check the ignition switch and it seemed okay.

Thanks!

[traveler]

I am having the exact same problem with the Optimum battery in my car . In fact , I have two cars with Optimum batteries and both are having the same problem .

I have checked everything I can think of and also have had both cars checked by some very good mechanics and no one has found the problem .


I am changing back to a different type of battery to see if this will solve my problems .

If you find out what is causing your problem please let us know .

I like the Idea of the Optimum battery if it would not go dead on me .

I don't leave my house in my car without carrying a battery supply source to jump start mine because i never know if it will crank or not .

Seems the problem comes and goes . It can sit for days at a time and crank ,No problem . Then for no reason , i can find , the battery will go dead everytime I turn the car off and try to restart a short time later .

Doesn't make much since to me so I am going back to the other type battery to see if this make a difference .

Traveler

[JeepSnake]

Guys, I can't help but wonder about the quality control at Optima. There just seems to be a rash of Optima problems cropping up on the Cobra boards, Chevelle board, and Jeep board that I check.

It took several tries for me to get an Optima that held a charge on the Chevelle back in 2005.

I have two Jeep pals who have given up on Optimas (in the last year) and gone back to regular wet cell batteries in plastic marine battery boxes.

The technology is attractive for protecting vintage sheetmetal from battery acid, but the failure rate doesn't seem to inspire confidence right now.

[nolastyankee]

All,
We bought a brand new Optima for the Spence car and it would never hold a charge. I traced wires for months thinking that it must be the car, not my 'premium battery' that could be at fault. Finally went back to the dealer and it turns out in that short time frame he quit selling Optima because of the number of failures. He was replacing 30%-50% of his batteries on a regular basis. Unfortunately we have an Optima specific battery mount or I would have changed brands. The second battery we bought has worked great. It still makes me nervous though and I am paranoid about not allowing the EFI ECU to stay on for any period of time to avoid discharging.

[eliminator]

I didn't know about all the issues with these batteries. I have one that is 5 years old and has never had a charger on it. Knock on wood......
You never heard of any issues until the last year or so, wonder what happened to them??

[Naumoff]

I know that with the gel batteries they can not take fast charging as it over heats the battery and will burn out cells.
My Jeep ate a few of them.
So if your Optima goes flat remember to trickle charge it on the low amp setting.

Do you have a battery disconnect on your car?
I make sure I disconnect the baterry when I shut the car off. I bought one of the Painless remote disconnects that I have a switch under the dash to operate it.
I have only had one Optima in my Cobra in 3 years.

Good luck on finding your battery draw. I would change the ignition switch if I couldn't find the problem just because it sounds like an intermitting problem and these little ignition switches can go out like that.

[olblu66]

Thinking of swithing batteries back to a interstate.

[RJacobsen]

If these Optima batteries can only be trickle charged are they in danger of being damaged by a high amp alternator?

[Jerry Cowing]

Agree with Tony. The only problem I had with my Optima was when I attempted to fast charge it. It did not like the fast charge and I had to replace the battery. I have accidentally drained mine a couple of times when I forgot to disconnect the battery using one of those battery disconnect keys/switches. My radar detector was still on and it drained the battery. I recharged it several times using the 2 amp setting and have never had a problem. My second Optima has been in the Cobra for 6 years, no problems.

[Naumoff]

If these Optima batteries can only be trickle charged are they in danger of being damaged by a high amp alternator?
Just recalling from memory but
as long as the battery stays below 120*F it should be OK.
Now the question is what is the temp of the battery with a high output alt.?

I will have to look into that as I have had a 140 amp alternator for a year now. I should soon find out.:)

[RJacobsen]

Just recalling from memory but
as long as the battery stays below 120*F it should be OK.


So now we need a Battery temp gauge? :)

[Naumoff]

So now we need a Battery temp gauge? :)

Sure, Why not. :D

My multi-meter has temp sensors I can run back and strap it onto the battery.

[RJacobsen]

Unless Brian has changed this original feature on the "Spence" car, he can just stick a thermometer in it and glance over.:D

http://www.uniquecobra.com/uploaded/nolastyankee/Interior1.jpg

[Naumoff]

I can't see why he would have changed that. It is a little bit of a pain to get to it located in the boot.:)

[olblu66]

Tell me something... Is there supposed to be 12 volts present at the altenator at all times (even with the ignition in the off position)? The only way to kill the volts is with the battery cutoff. Is this right?

Pat

[Jim Harding]

Pat, if you are refering to the larger gauge wire at the alternator, then yes. No other lead (if there are more than one) should be hot with the ignition switch off.

[Naumoff]

Tell me something... Is there supposed to be 12 volts present at the altenator at all times (even with the ignition in the off position)? The only way to kill the volts is with the battery cutoff. Is this right?

Pat

Yes. It is wired to the battery to charge it. Usually they are connected at the starter solenoid.

[Naumoff]

Pat, if you are refering to the larger gauge wire at the alternator, then yes. No other lead (if there are more than one) should be hot with the ignition switch off.

Jim, I didn't see your post when I was posting.

You are so specific.:)

[RJacobsen]

Since we are on the subject, what size alternator is sufficient? Tony has a 140 amp in a car that only has a cooling fan and fuel pump to run, my wife’s van has a 135 amp and has power seat, windows, doors, cooling fans, dual AC, heater, fuel pump, etc. My 65 Mustang had a 40 amp and only an AM radio and heater motor. Seems to me that the only power draw we have is the ignition system, cooling fans, and maybe a fuel pump. Is a 40-65 amp alternator enough?

[Naumoff]

Since we are on the subject, what size alternator is sufficient? Tony has a 140 amp in a car that only has a cooling fan and fuel pump to run, my wife’s van has a 135 amp and has power seat, windows, doors, cooling fans, dual AC, heater, fuel pump, etc. My 65 Mustang had a 40 amp and only an AM radio and heater motor. Seems to me that the only power draw we have is the ignition system, cooling fans, and maybe a fuel pump. Is a 40-65 amp alternator enough?

Rad,
Not at idle speed does my alt. put out 140 amps.

I read an article on cooling systems for muscle cars in Car Craft and the one place you need a high amp output is at an idle so that your fans can run at full speed.
my alt. puts out 90amps at an idle. a little high for my application but at an idle my cars temp does not raise up. I had a 50amp one before and the lights would dim and the temp would creep up at an idle in traffic.:)

you could probable get away with a 100 amp alt.
Don't you have dual fans?

[RJacobsen]

Rod,
Not at idle speed does my alt. put out 140 amps.
you could probable get away with a 100 amp alt.
Don't you have dual fans?


I guess I didn't think about it that way. I was thinking that everything basically runs off the battery and the alternator only has to keep that at full charge. Yes to the dual fan question.

[Jim Harding]

You are so specific.:)

OK Tony, so here I go again :eek::eek:


I guess there are many theories on how to spec a certain size alternator for any given vehicle. The basic theory that a vehicle with a large power demand would require a hefty alternator is true, and vise versa. Here's a little primer on voltage and current (amps):
The 'storage' battery in our cars is there to start the car only. The alternators job is two fold. One, recharge the battery after it has done its job starting the car. Second, supply all the voltage and current demands from all the various electrical devices in the car. Ideally, the battery will not be called on to supply any of the power demands (volts X amps) while the engine is running and up to speed. Voltage output from the alternator depends on its shaft speed; at idle the voltage will be less than when it is spinning faster. The amp meter on the dash will tell you if the alternator is up to its job. If it is reading 'negative', it tells you that the battery is being called on to supply some of the current needs of the car. If its reading 'positive' it means the alternator is doing it's job and also re-charging the battery. A volt meter is not so intuitive. It will measure somewhere around 12.6 volts at rest (engine not running), and should peak to around 14.6 volts when the engine is up to speed. What it doesn't tell you is where the voltage threshold is when the battery starts to supply some of the load. It can be safe to assume that if the volt meter indicates something over 12.6 volts that the battery is not discharging.
OK, so now we know the alternator's voltage can fluctuate due to shaft speed, but what about it's current (amps) output. Let's assume for the moment that the only electrical need on our car is the ignition circuit. And let's also assume that it requires (besides 12 - 14 V) 5 amps of current. That's ALL the current that will be pulled from the alternator, 5 AMPS. It doesn't matter that the alternator is rated at 100 amps or 50 amps, it will only supply what the load demands.
So how big of an alternator do you need? Just enough to supply what your car needs? Just enough and maybe 25% more just to be safe and not over tax the alternator. Just enough and maybe 50% more? That's where the many theories come into play.
Taking a typical Cobra, let’s break down the current needs with everything turned on. Two 60 Watt headlamps will draw 10 amps, 6 type 1157 turn signal/brake lamps (2 in front and 4 in back) will need about 18 amps, a hefty fan will need around 20 amps, a typical electrical fuel pump, another 5, and we can throw in another 5 amps for dash lights, tach, and other miscellaneous stuff. That totals just fewer than 60 amps. That would be the maximum draw from the battery/alternator, and would indicate the minimum size alternator needed to prevent the battery from discharging when driving down the road. Under real conditions, we can trim down the current draw because everything is not usually functioning 100% of the time, so a 60 amp rated alternator should do just fine. If you wish to throw in a safety factor from 25 to 50%, you’re looking at a 75 to 90 amp alternator. Tony’s 140 amp monster is over-kill in my opinion, but he’ll never have a problem supplying his car with power, and the alternator will just loaf along, run cool and probably out live both Tony and his car. :D[thumb]:D

[RJacobsen]

Jim, thanks for the info, that clears things up for me. As for bigger being better? well.. we are talking about Cobras here, I don't think there is a limit on excess.:)

[Naumoff]

OK Tony, so here I go again :eek::eek:


I guess there are many theories on how to spec a certain size alternator for any given vehicle. The basic theory that a vehicle with a large power demand would require a hefty alternator is true, and vise versa. Here's a little primer on voltage and current (amps):
The 'storage' battery in our cars is there to start the car only. The alternators job is two fold. One, recharge the battery after it has done its job starting the car. Second, supply all the voltage and current demands from all the various electrical devices in the car. Ideally, the battery will not be called on to supply any of the power demands (volts X amps) while the engine is running and up to speed. Voltage output from the alternator depends on its shaft speed; at idle the voltage will be less than when it is spinning faster. The amp meter on the dash will tell you if the alternator is up to its job. If it is reading 'negative', it tells you that the battery is being called on to supply some of the current needs of the car. If its reading 'positive' it means the alternator is doing it's job and also re-charging the battery. A volt meter is not so intuitive. It will measure somewhere around 12.6 volts at rest (engine not running), and should peak to around 14.6 volts when the engine is up to speed. What it doesn't tell you is where the voltage threshold is when the battery starts to supply some of the load. It can be safe to assume that if the volt meter indicates something over 12.6 volts that the battery is not discharging.
OK, so now we know the alternator's voltage can fluctuate due to shaft speed, but what about it's current (amps) output. Let's assume for the moment that the only electrical need on our car is the ignition circuit. And let's also assume that it requires (besides 12 - 14 V) 5 amps of current. That's ALL the current that will be pulled from the alternator, 5 AMPS. It doesn't matter that the alternator is rated at 100 amps or 50 amps, it will only supply what the load demands.
So how big of an alternator do you need? Just enough to supply what your car needs? Just enough and maybe 25% more just to be safe and not over tax the alternator. Just enough and maybe 50% more? That's where the many theories come into play.
Taking a typical Cobra, let’s break down the current needs with everything turned on. Two 60 Watt headlamps will draw 10 amps, 6 type 1157 turn signal/brake lamps (2 in front and 4 in back) will need about 18 amps, a hefty fan will need around 20 amps, a typical electrical fuel pump, another 5, and we can throw in another 5 amps for dash lights, tach, and other miscellaneous stuff. That totals just fewer than 60 amps. That would be the maximum draw from the battery/alternator, and would indicate the minimum size alternator needed to prevent the battery from discharging when driving down the road. Under real conditions, we can trim down the current draw because everything is not usually functioning 100% of the time, so a 60 amp rated alternator should do just fine. If you wish to throw in a safety factor from 25 to 50%, you’re looking at a 75 to 90 amp alternator. Tony’s 140 amp monster is over-kill in my opinion, but he’ll never have a problem supplying his car with power, and the alternator will just loaf along, run cool and probably out live both Tony and his car. :D[thumb]:D

Isn't that what I said?:D[thumb]

[Naumoff]

Rod,
I would have done a 100 amp if I would have to do it again. The Powermaster 140amp alt. Is big and on the big block it does not fit betwwen the head and the stock bracket.
I bought a set of double pulleys and moved the alt. out from the head and used the outer pulley groove.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ModsMarch2008009.jpg

[nolastyankee]

Rod,
Sorry for the late reply on this...Yes, we did move the battery to the trunk. I kind of liked the accessibility in the footwell but it was hell on the leg room. The original owner would have likely bolted it to the hood, we went for a battery tray and standard location.

[RJacobsen]

Brian, I was starting to wonder if you would spot that old photo I dug up. I'm sure you have been busy getting ready for Gadsden. Have fun :)

[JeepSnake]

Does anyone know of an alternator source that provides output vs. shaft RPM info on their products?

Much like we talk about having a "flat" torque or power curve, I'm thinking most of us would benefit from an alternator with a similar output curve. In other words, the car may only need 40 amps, but it needs that 40 amps to be available at idle RPM. I'm sure the advertised ratings of alternators are at some elevated RPM level. So we may be buying 140 amps at 2500 rpm in order to get that 40 amps at 800 rpm.

Wonder what kind of ratings are on police cruiser alternators? They must have a serious output at idle to power all the various electronics all day long.

Interesting stuff!

[RJacobsen]

Does anyone know of an alternator source that provides output vs. shaft RPM info on their products?

Much like we talk about having a "flat" torque or power curve, I'm thinking most of us would benefit from an alternator with a similar output curve. In other words, the car may only need 40 amps, but it needs that 40 amps to be available at idle RPM. I'm sure the advertised ratings of alternators are at some elevated RPM level. So we may be buying 140 amps at 2500 rpm in order to get that 40 amps at 800 rpm.

Wonder what kind of ratings are on police cruiser alternators? They must have a serious output at idle to power all the various electronics all day long.

Interesting stuff!

Zack, I would like to know how fast we can safely spin an alternator. We can easily install a smaller pulley to increase output at idle, but what is the limit on alternator RPM? I would guess that 2 to 3 times engine RPM would be normal.

[Naumoff]

Zack,
The Powermaster came with a proof of performance tag.
Output @ idle w/ stock pulley* 91amps
(shaft 2400 dyno RPM)

* output @ idle may be drastically reduced when using power pulleys

Output @ highway speeds 154amps
(shaft 6000 dyno RPM)

[lonnie]

Agree with Tony. The only problem I had with my Optima was when I attempted to fast charge it. It did not like the fast charge and I had to replace the battery. I have accidentally drained mine a couple of times when I forgot to disconnect the battery using one of those battery disconnect keys/switches. My radar detector was still on and it drained the battery. I recharged it several times using the 2 amp setting and have never had a problem. My second Optima has been in the Cobra for 6 years, no problems.

Jerry were you able to exchange the battery or did you have to buy a new one. I fast charged mine and now it's junk.
Lonnie