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Discussion Starter · #1 ·
Well, it wasnt raining yet so i decided to take the cobra for a quick run around the block to try out the new engine. I made it two miles and then the car stalled. I started her back up, a little hesitatin, and all was well. I approached the next stop sign and the car stalls again. Crank crank-nothing, cranking then turns into a slur rur. So, i broke down. Then five seconds later the skies open up and i get absolutely drenched. Luckily i had the cover in the trunk and at least got to protect the interior and new wiring from the rain. It took the tow guy 1-1/2 hours to reach me and it continued to rain the entire time. I tell ya what, these optima batteries have really been crappy to me. That's the third one i have had in the last 3 years to have problems.

However, on a good note(besides the stalling), the car was running awesome. I goosed it just a touch and it took off. The power brakes work great too.
 

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Big Kahuna
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Originally posted by cobrastang:
these optima batteries have really been crappy to me. That's the third one i have had in the last 3 years to have problems.
Hey Cobrastang,

I can't help you with the stalling, but I have been in and around power and sailboats for years and can tell you about your AGM battery. AGM batteries are EXTREMELY sensitive to charging conditions. They can handle 75% of their rating from a charge perspective, but if you give them more than 15.5(Check your batteries specifications), you will burn it up and render it useless in a hurry.

Make sure you are not giving it too much voltage, and use a few sources besides your panel mount meter.

You could also consider a "smart" regulator that has bulk, absorption and float modes that can be set specifically for AGM batteries, and they will last a lot longer.
 

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Big Kahuna
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Originally posted by cobrastang:
I trickle charge them with a special charger.
PS, don't undercharge them either. ;)

A note from an AGM battery manufacturer:

"AGM and Gelled batteries require a charging voltage that does not exceed 14.00 volts (summer temperatures may require even lower voltages). Unfortunately almost all automotive charging systems have a permanently fixed set point voltage that exceeds 14.00 and this spells trouble. Subjecting the batteries to (commonly found) 14.6 volts for a prolonged period will eventually destroy them. Pusher diesel motorhomes normally use truck-type alternators and voltage regulators and most have internal set screws which can be fine-tuned (To lower the voltage set point). Automobiles (pickup trucks) and standard motorhome charging systems can be modified to accept an exterior adjustable voltage regulator. Your local automotive electrical rebuild shop can be a lifesaver if you elect to go that route. For your edification, 14.05 volts is my personal "upper limit" for charging valve regulated batteries."
 

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Still broke & dreaming...
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So wait...if they KNOW that "subjecting the batteries to 14.6 volts for a prolonged period will eventually destroy them", and they also know that MOST automotive applications generate 14.6 volts, why would they design and sell them to the automotive market in first place?!
It seems to me that you would build your product that fits the current (pun intended) market rather than go outside the norm and have to come up with a fix for your product to work without being destroyed. I guess that would make too much sense though...
 

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Big Kahuna
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AGM batteries were not designed for automotive applications. They are normally used for highly specialized applications, like large banks of deep cycle AGM's.

On sailboats, we might have 6-8 AGM's in parallel. we might have a 150 to 200 amp generator to charge them, and they can take it, as long as it is below the rating at a specific temp. The hotter, the lower the voltage they can handle. on a sailboat, we will have a smart charger, along with a temp probe, and it will regulate charging based on the temp of the battery, as well as charge state.

If all that happens, they will last 4-5 years. I have even seen wet batteries last 6-7 years under smart charger conditions.
 

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I bought a "Mustang" battery from Autozone. Going on 3 1/2 yrs without a problem. Pete
 

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Yep, just don't see the attraction of a $100+ battery when a regular one works just fine.

My record for a battery here in AZ was 5 years. I used it in my sandbuggy as a daily driver. No engine heat to cook it and a generator to gently recharge it. It only died after I quit driving the thing and let it sit.
 

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I bought a Gold Top 8 year battery from Autozone back in 1999 and it's still working. It's not a gelcell.
 

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Discussion Starter · #11 ·
That piece is going in the recycling yard tomorron and getting replaced by a standard battery that can be charged/jumped. I think that was the biggest thing for me today-not having a battery that could be jumped-such a pisser.
 

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I'm not one to endorse products, but I have seven cars, most of which sit for long periods of time. I'm pretty good about keeping them charged, kind of fun to do a round robin @-10F!.
Bottom line the only batteries that last are the good old standard Diehard, not the gold or premium, the one for 59.95, Sometimes on sale for 49.99. I have two that are going on over ten years old. The one in my roadster (1014) lasted 8 years. The other thing I like about them is the first time they crank slow will be their last. The one in my daily driver ranger lasted 9 years. I came out one morning and it would barely turn over. I jumped it, drove to Sears, left my truck running while I bought a new battery and went home. Optima was a sponsor on one of my cars, they failed so often, that I would put in a Diehard to race. JMHO
Thanks,
Michael D.
 

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Big Kahuna
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Originally posted by Mike D:
Yep, just don't see the attraction of a $100+ battery when a regular one works just fine.
Mainly that they are sealed and no acid can spill on our precious Cobra's.
 

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Just for some counter point and for the sake of accuracy, I did a little research. As an aside, I have a RedTop Optima battery and it has worked flawlessly for 4 years now. Winter float charging (micro processor controlled unit for $15 on the Internet) has been done of course.

Before people get out of sorts, here is what Optima says about charging their RedTop batteries (note the voltages).

Alternator: 13.3 to 15.0 volts, no amperage limit.
Battery charger: 13.8 to 15.0 volts, 10 amps maximum, 6-12 hours approximate
Rapid Recharge: Maximum voltage 15.6 volts (regulated).
Float charge: 13.2 to 13.8 volts, 1 amp maximum current, time indefinite (at lower voltage).

From their FAQ section

QUESTION

Will my high-output alternator damage the OPTIMA?

ANSWER

No, as long as the voltage is properly regulated. Because the OPTIMA has a very low internal resistance it will accept high current more efficiently than conventional batteries.

PDF of Optima RedTop Battery Specs

I currently can't find anything that says you can't jump start a RedTop Optima battery.
 

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Big Kahuna
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Originally posted by Vacation Land:
Alternator: 13.3 to 15.0 volts, no amperage limit.
Battery charger: 13.8 to 15.0 volts, 10 amps maximum, 6-12 hours approximate
Rapid Recharge: Maximum voltage 15.6 volts (regulated).
Float charge: 13.2 to 13.8 volts, 1 amp maximum current, time indefinite (at lower voltage).
Vacation,

Exactly what I am getting at. Couldn't agree with you more. This is why our fine friend is going through them like bottled water. The standard alternator does not have the ability to manage a charge from bulk to float to equalize. You need a smart charger or regulator to do that. If this guys alternator puts out 15.5 volts and doesn't stop charging till it hits that voltage(and it MAY NOT!), it will cook the battery. Quickly.

On boats, we have Balmar and Aqualine Alternator Regulators, as well as smart chargers when on shore power, along with battery temp sensors. They are also set specificially for AGM batteries, and have the ability to be set for wet or gel as well.

Not to mention soft startup technology to give the belts a bit of time to warm up before being subjected to a 150 amp alternator!
 

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I have an Optima in mine and I have had no problems as long as I have the kill switch off if storing for a long time. For instance for the 3 months it was at the painter, I had the switch off. The day we picked the car up, I turned the switch on, turned the key and it started right up.

On the other hand if I store it for a month or two with the switch on, the battery goes dead. Keep in mind that the computer and certain accessories cause a steady drain of power. Additionally, there could be some very slight ground you are unaware of that is also draingin the battery.
 

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cobrastang,
My battery was NAPA, 1999 vintage with about 35,000 miles on it in the Cobra. It just broke last week with a dead short. No warning what-so-ever.
Guess I really can't complain because it lasted longer than any battery I've ever had!
Take care,
Ron
 

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As my 1 wire alternator puts out less than 15.0 volts, I made the assumption that his did as well. Indeed, that may not be the case for Cobrastang.
 
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