I need to buy a new battery for my Fiero....Used to be I would buy either Diehard or Interstate....Not sure now....Diehard has....died.

What are your thoughts and experiences on car batteries?

Interstate is still around, and I've had better luck with them than anything else. Tried Optima several times, the last one in my STI, I had to buy a special charger/reconditioner to keep it in good health while the car was parked most of the time at the start of the pandemic when it started to noticeably deteriorate.

https://www.optimabatteries...hargers/digital-1200

I left the Optima in the car when I traded it in for the Model S.

Save the receipt and be sure to take advantage of the pro-rated warranty. THAT is what has saved me more money than anything over the years on car batteries.

FYI Advance Auto sells Diehard batteries.

DH Interstate and more made by one company.
See my Cave, Battery

But JC sold battery div to someone else now and closed most/all US plants.

You may hate Walmart but their best one is cheaper then most and has 3 year Replacement warranty. Not Prorated from hard to read date codes.
If loses receipt then have serial # and obvious date label on it and still return w/o a pain in the a.. at any store.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 12-20-2021).]

I second Ogre's statement about the Walmart batteries. Their best ones (Everstart MAXX?) have been good for me in several vehicles, (one in my 88 GT right now) and on one vehicle I had to claim on the replacement warranty twice, and the process was quick and easy, no questions. Also can't beat the availability since Walmart is everywhere.

But Walmart or otherwise, the next battery I buy will probably be an AGM (Absorbed Glass Mat) type, for higher capacity, longer life, and more rugged (and spillproof) construction. But these are usually about $100 more than a similarly sized standard lead acid batteries, and do have some downsides.

quote Originally posted by cvxjet: I need to buy a new battery for my Fiero....Used to be I would buy either Diehard or Interstate....Not sure now....Diehard has....died. What are your thoughts and experiences on car batteries?

I bought my 86 Fiero SE in July 2001 with 53k miles on it and at that time it already had a new battery tray installed. Since then I've replaced the battery tray twice due to battery fumes rotting them out and I'm now at the 73,00 mile mark. So my thoughts on batteries is forget the acid filled batteries since in my case they're doing more damage to the car than road salt would if I drove in those conditions.

One day I was under the Fiero doing some work and noticed my original starter appeared to be brand new and spotless. Further investigation discovered a pinhole in my fuel line sending an invisible mist of fuel onto my starter. Other words I could only detect it by feel on the back on my hand. By the way SS fuel lines also rust. So I replaced the fuel lines and got rid of the 3rd rotted out battery tray. A few years ago I did the 3800SC swap and relocated the battery up front under the pass headlight. I Por_15'd that entire corner and fabricated a battery tray out of plate aluminum. So far so good.

I recently replaced my Cadillac AC-Delco battery which is installed in the trunk and noticed it had a vapor tube attached to it that lead outside of the vehicle. My replacement battery was a Die-Hard and it had the same battery provision for external venting. This may be a good option for the rear mounted Fiero battery if one is made that will fit. No more battery trays and fuel lines getting rotted out or worse. Just find a better place to vent it.

So my thoughts would be to consider getting a non-acid type battery or a battery that can be vented away from critical engine and chassis & electrical components. Save your vehicle.
End of rant...

ps: It amazes me how the Fiero battery trays rot out so quickly while sitting within inches of a ventilation panel. The fumes from sulfuric acid are lighter than air right?

Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

On our Fieros the rain falling on top of the battery washes the acid residue down onto the battery tray and structure. On my '73 mach1 (5.0 FI engine) I put the battery in a plastic container (Used in boats). My Fiero has the battery mounted up front on a FIBERGLASS battery holder...and of course there is no rain falling....Under the hood!

The smartest thing Pontiac could have done is to just make a plastic platform with a drain tube to down below the chassis......


I have a Deep cycle marine battery in my boat (CVX-20 Jet)....I did not charge it for 5 months last winter and it still was able to turn the engine over (Yes, I should have charged it a few times) I wonder if I could use a deep cycle battery for my Fiero.....They actually show one that is the right size (75) and with the side poles......But it is almost $300!

[This message has been edited by cvxjet (edited 12-19-2021).]

quote Originally posted by Spoon: I bought my 86 Fiero SE in July 2001 with 53k miles on it and at that time it already had a new battery tray installed. Since then I've replaced the battery tray twice due to battery fumes rotting them out and I'm now at the 73,00 mile mark. So my thoughts on batteries is forget the acid filled batteries since in my case they're doing more damage to the car than road salt would if I drove in those conditions.

That sound like the alternator and/or wiring to them has problems and over charging the battery.

When true, Using AGM may help and hind the real problem.

Also Many people don't drive enough and that wreck the battery. AGM are better but can die for same reason.
Low batteries causes many problems like Dead Cell(s) etc. then any charging can boil the battery and more headaches.
You don't want to see a battery under 12v as is. Repeated under 12v is worse. For this time of year, low battery can Freeze very easily and self destroy. You might jump or charge after but damage is done and can cause worse problems.

When I don't drive the Fiero for a week I have Battery Tender attach so stays full charge. More so when weather is cold.
When warm, don't need it on any charger 24/7.

Originally posted by theogre: That sound like the alternator and/or wiring to them has problems and over charging the battery.

Thanks theogre for your response. I was going to mention that but felt I was long winded enough. My wiring and alternator, charging system was functioning properly according to my instruments. I did upgrade to the CS-130 along the way. And my first experience with an overcharging battery was in 1972 when one blew up in my face when trying to jump start my 67 GTO from my aunts car. Sounded like a bomb went off!! It was the first time I saw a topless battery bubbling away with the engine still idling. Fortunately no eye or body injuries but a lesson well learned. It was her battery that was overcharging due to a bad external voltage regulator that seemed to be common in those days.

Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

quote Originally posted by cvxjet: I need to buy a new battery for my Fiero....Used to be I would buy either Diehard or Interstate....Not sure now....Diehard has....died. What are your thoughts and experiences on car batteries?

I agree with the Ogre, and when I was a kid, decades ago, my Dad gave me some advice on battery buying. He said that there are three levels of batteries in many cases. Good, better and best. He told me to always buy the "better" one. When I asked him why, he told me that battery casings are always the same size per a given type. The difference is the plate size. To get more CCA and available current, makers increase the size of the plates. This puts them closer to the casing walls. As batteries age, they shed materials off the plates, and those materials pile up at the bottom of the battery and can eventually short plates together which kills the battery. So why not buy the cheapest, I asked. He said that the CCA will be less and in Northern Utah winters, CCA means a lot. So, I have always bought the "better" batteries and have had excellent luck with them. What Dad said to me made sense and he was an electronics whiz, so I took him at this word.

eti engineer,
Isn't just about CCA...
Better units has more Reserve Time making battery run longer to backup ECM and so on w/o car being run everyday or if alt dies while driving so car can get home or parked somewhere safe. Turn off everything you can when that happens and often drive 1/2 hour or more w/o damage to the battery. Charge the battery ASAP on a "slow" charger {Charger rated 6 to 10a max} and make sure dead alt isn't a leach now. Dead SI and some others a famous for drain a battery. I've had the alt die several times over the years on different vehicles and drove home because I use better batteries.

See cave for meaning of CCA etc.

And not just size of plates but many other plate details make better starting battery vs Deep Cycle or some "hybrid" in between both class.
Is why Optima batteries has/had 4 types of AGM. Standard Wet batteries have about same regardless case color. Many "Marine" batteries have always been a "hybrid" that start engine and safely run some lights w/ engine off besides having different terminals.

quote Originally posted by cvxjet: The smartest thing Pontiac could have done is to just make a plastic platform with a drain tube to down below the chassis......

In building the perfect project car, Pontiac did the next best thing; they left the fun of making the plastic platform to the car owner!

Plastic platform with drain channels and drain holes:


Installed in the car with tie-down rods and a steel flatbar over the top:


Yes, my Fiero has a drain tube, and it terminates about 1/4" below the rocker panel.

Find a place that sells 'branded' DEKA.

quote Originally posted by steve308: Find a place that sells 'branded' DEKA.

Deka is made by East Penn Manufacturing near Philly PA. https://www.eastpennmanufacturing.com/
Good product but hard to get in many places for several reasons... highlights:
1. few stores carries them and many open "9 to 5" or less or closed for a given day.
2. many of those are independent stores and not listed if use Google et al to find Deka batteries.

Example: Only 2 near me I know of...
One not shown in Google has/had very short hours. Don't even know that store is still operates. "Recently" got new signs so maybe.
Other is listed by Google but open 7:00 am - 5:30 pm Mon - Fri, 9:00 am - 3:00 pm Saturday, Closed Sundays. I go there to buy other battery types.

Now I could go to East Penn locations but have to drive a lot more and have same open hours issues. Both "here" are in other states and 50 to 100+ miles round trip.

So if/when in a hurry then often out of luck.

That's why I said Walmart above. Yes, AA AZ and others also have more hours and open 7 days too.
But Walmart sells A Lot of batteries so very rarely you get one sitting on a self for Several Months or even longer. Last one was made 1 month or little more before I got it.
If one those stores is out of stock, others near by often will have right battery.
Means often can still get one in 1 to 3 hours to go to work late or next day. (Often faster then calling AAA or other "road assistance" people too.)

Late to the party but I put an interstate from Costco in mine... The first one was defective they swapped it out 6 months later no issue or hassle. Been great since.

I just mounted a battery tray from Archie up front.
Stay with the Fiero size battery with a V8 coming later, or go larger.
I have tons of room for much larger battery.
Or, should I ask, any disadvantage ?

I have three vehicles with optima batteries and am very happy with them.
One is about a year, another is 4 years and the one (on my fiero) is 7 years.

quote Originally posted by gatorfrey: I just mounted a battery tray from Archie up front. Stay with the Fiero size battery with a V8 coming later, or go larger. I have tons of room for much larger battery. Or, should I ask, any disadvantage ?

I went with the stock (Group 75) battery up front in same setup; I did not like having a welding cable energized running next to the fuel tank, so I installed a Ford-style separate starter relay so the wire is only energized when starting. To run the car, etc I ran a AWG 8 wire....I actually ran it in the Schedule 40 tubing with the GROUND wire- and installed a 40 amp fuse up front...If I ever got high-centered it would (Hopefully) short that wire to the ground wire and blow the fuse (Rather than me and the car)

Added note; The spare tire (Actually from a Subaru to fit 12" brakes) holds the battery in place- any larger battery and the spare wouldn't fit.

Here is a diagram of what I did;

Most People putting battery in front never watch Fiero crash test videos on YT for years or don't understand what happens.
In super short, The entire front compartment is a Crush Zone.
Especially Watch view from the bottom and see Spare Tire and wall/well attach to getting Crushed to the front firewall... And that's just hitting a Wall...

But other vehicles have Front Mounted batteries when made...
And those setups have been design and tested to resist battery shorting out in a crash.
Even with them, many tow operators remove the battery cable(s) on wreck cars to avoid fires during towing or storing after. SOP for many "junk yards," not just one open to public, is disconnect or remove the battery on everything. (And for many years now also prevents many Airbag and related problems too. I bet someone is publishing data for properly disconnecting E-car batteries for same reasons.)

whatever battery brand you get, get the traditional post and change the cable ends instead of those threaded ones, or get new cables all new cables

and also the GND wire, add one to the rear deck lid mounting bolt, and replace the one that goes to the frame with something beefier and make sure any corrosion is cleaned up
a plastic body car, you need good GND's

quote Originally posted by theogre: But other vehicles have Front Mounted batteries when made... And those setups have been design and tested to resist battery shorting out in a crash.

On that topic, the Fiero ECM supplies 12 VDC to turn on the fuel pump relay.

This is contrary to the usual way of switching loads (such as the injectors), which is to provide a path to ground via an NPN transistor or N-channel MOSFET.

With the usual switched-ground method, in a crash, if wire between the ECM and fuel pump relay coil is pinched and shorted to ground (i.e. the spaceframe), then the fuel pump relay will stay energized, potentially pumping fuel into a fire.

By doing it the GM way, if the relay coil wire is shorted to ground, the relay turns off. This is safer in a crash.

I modified my Fiero to use a switched-ground fuel pump relay coil, and I am realizing that it was a mistake.

Folks,
Battery shorted can dump 200 to 300 amps or more and easily start a fire. Just to run the Starter draws 120 to 140 amps when everything is 100% normal. Iffy parts can easily draw 180-200 amps. (And all parts Hate this. See my Cave, Electric Motors)
A "crushed" battery can dump a lot of amps too.
Even big Welding cables can light up fast when you have a battery short. These big cables may make worse problem in a crash because will try to stay shorted longer then 4 or 2 AWG cables. (Most B-cables are Metric wire size but doesn't matter for now.)

quote Originally posted by ZaraSpOOk: whatever battery brand you get, get the traditional post and change the cable ends instead of those threaded ones, or get new cables all new cables and also the GND wire, add one to the rear deck lid mounting bolt, and replace the one that goes to the frame with something beefier and make sure any corrosion is cleaned up a plastic body car, you need good GND's

Changing to Top Post battery for Fiero isn't a good plan. And Not good for many other models either.
For OE Fiero location just drop the vent can short the battery. Need to add + post insulation but even that can have problems. For Fiero and more is just not much Clearance for either.
If battery comes loose for any reason, very easy to short out the battery. Post Insulation often doesn't work when hit repeatedly driving on bad roads let alone a wreck.

For Fiero Front Batteries often have problems w/ top post types for other reasons, similar or same problems as any front mount side terminal for Fiero.

I had one of universal top and side terminal batterys in my Fiero because that all the store had at the time so I know there is a clearance and other problems. I kept both top posts cover w/ insulation came on and built in handle to keep the vent off of them.

Yes, New Battery cables are good. For Side Terminals... Use Only ACDelco sets. Not lead battery ends come w/ most aftermarket cables.
ACdelco has "updated" OE battery ends and Better because can remove the plastic cover and coat metal w/ brake or silicone grease to stop "water" eating them.
I avoid "Generic" ends even for tops post battery.

[This message has been edited by theogre (edited 12-22-2021).]

quote Originally posted by cvxjet: .......Diehard has....died.

and so close to Christmas too

[This message has been edited by 2.5 (edited 12-23-2021).]

I suppose I should post a pic, but it's cold out, my top post battery doesn't even come close to the vents
the nice thing is, easy to jump if needed, easy to add extra GND wires, in fact just about everything is easier
and as for coming loose due to bad roads, I find that's one good thing about the GM design, if you have the bolt and battery holder in place and snug, it ain't going anywhere

it is just my suggestion, your car, do what you want