Let's talk about batteries

[Ronbo]

Thought I'd share some info about batteries and what I know about them...

As you are well aware typical car batteries are basically available in two flavors, standard lead-acid and gel cells...

Lead acid batteries use lead plates and sulfuric acid / water electrolyte. The "cell" generates 2 volts so 12v car batteries have 6 cells in series. When charging hydrogen gas is released through vents in the upper caps, therefore batteries inside passenger compartments (and trunks) should always have vent tubes that run to the outside air. You'll see these (if someone didn't take them off) on corvettes, VW's and other production cars.

With this in mind to add voltage = more cells, to add current = larger plate area + more electrolyte.

Over time the batteries degrade from sulfer deposits that form on the plates and in effect "insulate" them from the electrolyte as well as the acid itself not recovering from the loss of sulfer. This process is actually reversable by applying "pulsed" DC current to the battery, several companies offer conditioners like this one: The Battery Life Saver electronic device Deep cycle batteries are also vulnerable to this condition although they are constructed to reduce the effect. (well, somewhat)

OK, so along comes the gel cell. Lighter, more current by size, sealed (no venting hydrogen), tougher, yet still lead acid. Why?

Since the electrolyte is a gel the plates can now be much thinner as the gel absorbes vibrations that would normaly be transmitted through the liquid electrolyte. Thinner plates means more plates per a given space, more plate area = more current. Also since the electrolyte is thicker it doesn't readily give up hydrogen gas during charge/discharge cycles and the sulfer transfer is minimized as well. Since the hydrogen is staying put we can seal it shut.

Of course I'm skimming over a lot of other "minor" improvements like plate alloys and chemical "tweaks" to the electrolyte. The higher CCA's we see today in standard car batteries is mainly due to improved plate designs. Although IMHO cases have gotten considerablely worse. Almost every battery I see today starts swelling within a year.

I really like the gel cells but they're still very expensive, the above conditioner is a great investment to extentd the life of your batteries. I bought one some time back and ran it on some old batteries that were on there way to the recycle pile. My "toaster" battery tester showed a CCA above what the battery was rated at. These were from my old boat, gave them to a friend. (I'm now boatless) Ran it on my van and the 2yr old battery jumped right back. (the sides are still swelled so it's getting replaced anyway) BTW they're not kidding about the time, I ran it for about a week every evening on the van and for two weeks on the boat batteries.

Like to hear from anyone who has anything to add... The Kirkham will be my first experiance in running a gel cell in a car. I maintained some rather large -48v backup systems at the paging co. I worked for in the past.

[wetdog]

I wheel a jeep when the road ends , a jeep in front of me took a slow roll over nothing radical everyone was okay until...the caps came off the battery and acid burned the two passengers . That was it for me only gel from then on , I have three (optimas) one since 1998 and go out once a month and vroom starts right up. If you are worried about cost interstate battery carries them and ask for the blems ..purely cosmetic ,a scratch or two at a reasonable price . Hope this helps in my opinion you cant go wrong .
WD

[COBRANIP]

Ronbo,
Thanks for the primer, very informative. Do you have any knowledge or opinion about the dry cell batteries usually used in race car applications because of their smaller size and weight? Also, did you buy your Kirkham new?
Thanks, John

P.S. I am also located in Jax. Would love to see your Kirkham some time.

[Ronbo]

Ya, I think the gels are the way to go. The cost is high enough that the pulse conditioner is feasible to invest in.

I'd imagine the racers are using some type of lithium batteries, very light weight, very $$$$, short life span. Lithium batteries suffer irreversable damage from charge/discharge cycles and are usually shot after a couple years.

My Kirkam roller is in route to Jax and due to arrive next week. I've yet to order the engine and trans but should be getting that started next week. I'll try to get some pics posted after delivery. Joe told me it looks pretty sweet and it'll be "killer". (didn't know he knew how I drive)

Sure put a ding in the bank account...

[Ronbo]

I thought of one thing to add concerning batteries and their ratings.

Anymore you typically see car batteries rated in CCAs yet most starters never even approch this value. Starters on V8s run around 200 ~ 300 amps of current. So it really doesn't matter if the battery can deliver 900 CCAs. Granted there is a higher in-rush current for a few milliseconds but the extra couple milliseconds to get the motor up to speed is not an issue.

What does matter is A/hr (Amp hours) this is the capacity of the battery:

100 Ahr = 100 Amps for 1 hour or 1 Amp for 100 hours.

100 Ahr = 300 Amp starter run for 20 mins. or 200 Amp starter for 30 mins.

So in reality a 900 CCA battery with 100 Ahr is really a worse choice than a 600 CCA battery with 120 Ahr capacity.

Freezing temps rapidly drop these values by 30% or more which is why your battery conks out on the first cold day in the winter. If it went completely dead then a plate or connecting strap likely fractured.

[davids]

Optima Gel is the way to go...Mine's 5 years old and and I'm in the Arizona desert..Great battery..Question, when should one think about getting a new Optima?? Please don't say, "When the battery goes dead!" Dave

[Maurice Johnson]

Ronbo, the "which battery is the best" is an interesting problem, as you point out. Your comments about CCA ratings, and their relevance,I agree with. In another post, a few days ago,about wiring a new Mini-starter, I kind of raised this point in relation to why so many Cobras seem to use slave solenoids, when the built in starter solenoid is more than capable of handling the starter load.

I work on lots of large ocean-going sailboats, where the DC amperage requirements to run big inverters is often large ,for long periods of time. This is where Gel Cell technology is most appropriate. A high output, at a steady rate, is this battery's strong point. The problem with Gel Cells is their really fussy about charging rates, requiring strict recharging voltage monitoring, (if not you get swelled sides when the gel releases vapour, expands into gas pockets, the surrounding silica congeals, and you have cavities in the electrolite). If you are going to invest in a Gel Cell, have an alternator shop take a good look at the quality of your regulator. Gell Cells were developed for the military where the installations could be in any configuration,e.g. lying on their side, subject to vibration, and not necessarily checked for fluid levels.
The "absorbed glass mat" battery, AGM,kind of goes back a step to combine the effeciency of flooded batteries, with the ability to take a wider range of charging voltages, without damage.

Thanks for opening an interesting thread.

(Working on aquiring my Unique build. Sorry Comish, without you, its just not the same )

[Ron61]

I have ran the Optima battery in my Cobra for over 7 years with no problems. When I park it I hook a battery tender to it. All that does is keep it at peak charge and once in a while will kick on for about 20 seconds if it drops a little. But it won't charge the battery as it is just what the title says, a Battery Tender. Just monitors it for any drop and charges it back to that level.

Ron

[Dwight]

I bought a gel cell for my Cobra and it lasted 11 months. They exchanged it and that one lasted 13 or 14 months. The third one, less than a year. They gave up and gave me an acid battery that I have used for 3 years. I think I burned one of the gel cells up by charging it to fast. Maybe my charging system in the car was part of the problem. I know they are better batteries but could not get one to last in my Cobra.

Dwight

[Maurice Johnson]

Dwight, your failure rate on the 2 gel cells may have been caused by too high a charging rate as I mentioned earlier. I notice from the members photo galleries that a lot of the engines are fitted with what appears to be Delco-Remy 10SI or 12SI alternators, particularly the 1 wire type. These are excellent peices of equipment, but often come with regulators allowing as high as 14.8 volt output. This is 1/2volt higher than gels can accept without cooking up. They also like to be exercised regularly, and are prone to developing a "memory condition" which is sometimes hard to break them out of. As Ron61 says, his Battery Tender just tops them off with really charging. Unless we have a really good quality battery charger, with battery type selector switch, we need to be careful.

[rlrichins]

This is my first comment on club cobra. This has been a very good discussion and I appreciate all of your input. I am in the process of purchasing parts for my dream car.

[Pete Munroe]

I have had good luck with the Exide Select Orbital. I think this is a gel-cell... round cells and no vents.

First one lasted just under 5 years...10,800 miles.

It was rated at either 60 or 72 months, so it came out a little short, but they pro-rated the replacement for the lost time.

It had been abused. Sat unused for the first year, but was "trickle charged" off and on every month or two.

After the car was up and running it was TOTALLY discharged 3 times due to alternator failures.

After the alternator failures, it was charged at an excessive rate by the replacement alternator...(had to drive it home, always more than an hour away, at night...60+ amp pegged ammeter)...another fried alternator, too.

Finally got a new, NOT rebuilt, alternator with a much higher rating and all has been well two years later.

The battery is located in the right rear fender, so at least it is not subjected to a lot of heat under the hood.

Pete

[Ronbo]

The charging rate is very important even in wet battries and is the primary cause of damage and premature failure.

In the case of our kit cars, you need to be aware of the importance of proper engine / frame bonding. Also heavy gauge wire to match your alternator output. Minimum 10ga (60A) to 6ga in the case of 100A alts.

If the battery's neg. terminal is not connected directly to the engine then a 2 gauge jumper to the frame should be used. Otherwise a 6 gauge wire will provide a good bond for the frame.

In the case of external regulators a 10ga wire to frame or block to reduce voltage drops (floating ground). Also 12 ga. "sample" wire to alternator output.

I am suprised that battery temprature is still not used in lead acid systems as it's a very important reading to catch overcharge conditions as opposed to voltage monitoring. Your battery life would probably double if temp monitoring was used.

[J Persons]

I use an Optima yellow top, and it's about 5 years old, and Cobra is the second car it's been installed in. The alternator is a 95A 3G. I also use a "Battery Butler" float charger, but the battery seems to hold its charge very well, and seldom needs it. This past winter, I forgot to connect the float charger, and after about three weeks, plugged it in. The charger indicated it was charging for about a minute, then went on its standby mode. This tells me that the Optima was still fully charged even after sitting for three weeks.

[Bob In Ct]

My Interstate went into the trunk in 1999. It comes out once a year for cleaning. It's 9 years old now and still starting my SPF. All I do when I put it away is use the cut-off. Why would I want anything else? Batteries in these cars don't even break a sweat.

Bob

[double ugly]

I have two Odyssey dry cell batteries (PC680s) behind the passenger seat. They'll maintain a charge for two years in storage.
http://www.microbattery.com/pdf/odys...tery-specs.pdf
John

[Old Phart]

Originally Posted by davids

Optima Gel is the way to go...Mine's 5 years old and and I'm in the Arizona desert..Great battery..Question, when should one think about getting a new Optima?? Please don't say, "When the battery goes dead!" Dave

When the battery goes dead! Actually, Dave, mine last about 7 years on the average, and I use a battery moniter to see any changes. The Battery Center in Mesa usually has good prices. Bill

[427 S/O]

I've come to the conclusion batteries are batteries, with most of the 'premiums' being mostly a slick sell. I use a stainless steel battery box from a B727, and the only battery that would fit, was a walley world (WM). Going on four years and still cranks just fine.

[badrich]

My beast came with a red top Optima and I've been running it for over five years without a problem. I was so impressed I bought one for my Brand X and the only problem I had was when I recharged it after I left a car door ajar. Too many amps and it blew up. They like about 2 amps much better. Rich