triplblk91conv

I want to replace the battery in my 1991 vert. It has a Delco group
75 size in it right now. Is there room to replace it with a group 78?
I believe it is about 1 1/2 inches longer. Will it fit the tray and will the
hold down fit and work properly? If so I would like to put in this one:

https://www.amazon.com/dp/B00LCFHMNU...=IQ4GUOOUULVD8

Any problem using an AGM battery?

Dan

antfarmer2

I would stick with the proper battery it is a tight fit.

blynch67

size always matters, lol

tlong

Costco Interstate half the price and the correct size.

Hot Rod Roy

I have a Series 78 in my '84. The hold down clamp fits fine, but mods are needed to the bottom tray and the angled brace at the top inside corner of the battery area. The bottom tray needs the end stops trimmed, and the top angle brace needs a small notch. The battery cables fit just fine!

Now I have plenty of reserve cranking capacity!! (I should admit that I got the Series 78 by mistake!)

Klondike

I think keeping corrosion off the cable ends and grounds and using a battery Minder/desulfator during long idle periods makes a larger difference in the health and longevity of a battery than size.
I don't like trickle chargers. They slow-cook and boil dry a battery over time. I got a battery MINDer (brand) at Northern tools for about $45.00. It holds the battery at full charge and de-sulfates the plates while the car sits idle for long periods. Sulfide build up on the plates on idle batteries is what makes them get old and weak.

triplblk91conv

Ya, it is not so much the size, Delco and most other brands don't make an AGM battery in the 75 size. Delco and others make a 78, and I'd like to
stay with a GM/AC Delco brand. I dont want an Optima.

antfarmer2

And you decided to butcher the car instead of getting the proper battery?

THE 383 admiral

Jeesh to much sun on the farm??? Butchered the car??? you trim the battery Tray. the support brace corner. can be crushed in about a 1/2 x 1" long. to keep the battery from rubbing. RE-paint the small area. even the OE battery is VERY close to this notch OR dent mod. GM should have made this clearance in the 1st place.

I have had NO issues with my optima red top.

Paul Workman

on BOTH counts.

My (Walmart) 75 series battery lasted 7 years; full power - winter or summer - with the help of a Battery Tender (smart charger - NOT a "trickle charger"). I might have it still, like the 13 year old Walmart 75 in my wife's C3, I had not had a "little" accident which may well have resulted in the battery becoming instantaneously "open" internally.

antfarmer2

If you have to cut it to make it fit. It is your car to each your own.

Hot Rod Roy

So, are you saying your '94 is totally original, with absolutely no improvements?

The OP asked about putting a Series 78 in his car! It's so easy to criticize!

antfarmer2

Not criticizing just stating my opinion. And yes my car is 100 percent stock. Other than maintenance and repair items that are as close as I could find.

73n95

The biggest battery you can fit in there the better. Most newer cars are such that only a single size fits properly, with the correct hold downs, terminal orientation and height. Costco no longer sells their own brand at a great price. They have switched to Interstate brand (I think) and are about the same price as everyone else. I just bought a battery at Walmart for my old van. Just about anything would fit. Their Value line is about half the price, carries a one year replacement warranty and has plenty of CCA's. My experience with new batteries is that anything over a year is a gift. The Delco in my new Chevy was close to $200 from Chevy, lasted 2 years and kaput! While it was replaced under warranty I doubt I'll buy another. That said the original battery in my 2003 Saturn is still holding a charge and starts the car. The battery actually outlasted the alternator. In fact, it outlasted the whole damn car! +1 on the battery tender. While it probably won't make any difference on your daily driver the ones that sit for weeks on end really should have the assistance of a tender just to save the load on the alternator.

Cliff Harris

Two Optima red tops died within 2 years so I decided I didn't want to deal with that brand any more (and the price went WAY up).

During a recent search I found that series 75 AGM batteries are no longer available (I had a DieHard Platinum -- made for Sears by Odyssey). No series 75 Interstate battery available either.

I ended up with an AutoZone DuraLast. I figure I'll just replace it when it dies and save the aggravation of dealing with batteries made out of unobtanium.

desertmike1

I totally agree..

The Gold top DuraLast batteries give me excellent performance and durability.

tlong

I just bought an Interstate 75 from Costco a month ago. They're all over Google. Great battery. Hope to get 7 years like the AC Delco.

hcbph

I put a Walmart Everstart Maxx in mine this last year. Decent warranty, highest CCA I could find in a 75 and the price was reasonable. No complaints here.