Correct modern replacement for R79S battery for late '69 car

[Charles C.]

Hi. My late 1969 would have had a side-post R79S battery. There doesn't seem to be a reproduction of that specific battery. Regardless, I was going to install a modern replacement.

I found this: ACDelco 78AGM Professional AGM Automotive BCI Group 78 Battery

https://www.amazon.com/s?k=ac+delco+78+battery&crid=1MUZE4IX9O3CQ&sprefix=ac+delco+78%2Caps%2C235&ref=nb_sb_ss_i_4_11

Can people please confirm if they believe this is the right/best replacement for judging (and life) or if there is something better?

Thank you very much.

Gene Cook

[Edward D.]

Re: Correct modern replacement for R79S battery for late '69 car

So far as I know there is no reproduction of the R79 battery. You can get a repro of the R89 used in 1970 and later from Restoration Battery. This is a "correct looking" Delco side post that is actually a modern AGM battery internally. Still, they are relatively expensive and you may need to wait to get one. If function is paramount, you can get a decent side post battery for about $100 at any local battery supplier. I like the Duracell lead/acid batteries since they are black and work well. Note that AGM (Absorbed Glass Mat) batteries (the type in the repro Delcos) are not tolerant of overcharging which can happen with an old charging system. The old fashioned lead acid batteries are much more tolerant of this and are recommended with an original voltage regulating system.

[Patrick H.]

Re: Correct modern replacement for R79S battery for late '69 car

I believe that exact same battery is sold at AutoZone with their labels. I have it in my 2008, as I specifically wanted to use an AGM battery.
I’ve had no problems with it.

To get judging points (50%) I think you’d have to get a black cased Delco, which will likely be a lead acid battery.

[Edward D.]

Re: Correct modern replacement for R79S battery for late '69 car

The reproduction black cased Delco batteries are NOT lead/acid batteries. They are modern AGM batteries inside a reproduction Delco casing. Literally its a whole modern battery inside a reproduction casing. There is NO repro Delco lead/acid battery made by anyone period. If you want lead/acid (cheaper and more forgiving of overcharging) then get a cheap battery store battery. In fact, the cheaper the better, the lowest cost batteries have fewer and thicker plates than the "premium" higher amp batteries and will recharge better and last longer. Higher cranking amps in a battery is not always a good thing, it means more thinner plates that will degrade sooner. You don't need any more cold cranking amps than the original OEM spec calls out. Don't get me wrong, AGM batteries are great, but old charging systems can kill them by overcharge which is their weakness.

[Patrick H.]

Re: Correct modern replacement for R79S battery for late '69 car

The reproduction black cased Delco batteries are NOT lead/acid batteries. They are modern AGM batteries inside a reproduction Delco casing. Literally its a whole modern battery inside a reproduction casing. There is NO repro Delco lead/acid battery made by anyone period. If you want lead/acid (cheaper and more forgiving of overcharging) then get a cheap battery store battery. In fact, the cheaper the better, the lowest cost batteries have fewer and thicker plates than the "premium" higher amp batteries and will recharge better and last longer. Higher cranking amps in a battery is not always a good thing, it means more thinner plates that will degrade sooner. You don't need any more cold cranking amps than the original OEM spec calls out. Don't get me wrong, AGM batteries are great, but old charging systems can kill them by overcharge which is their weakness.

Ed,

If you’re referring back to me in your post, please reread what I wrote.

To garner the 50% originality judging points for a service replacement Delco, I would suggest that one buy the latest black-cased “currently sold at local dealers“ ACDelco battery. These are lead acid batteries.
The gray one shown in a previous post is AGM, and I believe made in the USA. I would suggest that it may not get the 50% originality credit.

In neither of my posts have I yet mentioned or referred to reproduction batteries.

The AGM in my 60 year old car is 15 years old. No harm done by the charging system in that one.
And the repro ACDelco that I bought for my 72, one of the first with AGM and not lead acid, lasted over 10 years.

Patrick

[Edward D.]

Re: Correct modern replacement for R79S battery for late '69 car

Patrick,
You are quite correct in that A/C Delco makes a nice lead acid battery in R78 size, side post,in a black casing. And this is likely to be the best one can get in a good functional lead/acid. But they are not "original appearing" nor are they R79 which you can't get anywhere so far as I know. I was referring to the original appearing expensive "Delco restoration" batteries (not made or sold by GM Delco) which are all actually AGMs internally. Sorry for the confusion.

[Charles C.]

Re: Correct modern replacement for R79S battery for late '69 car

Thank you all for your feedback--this has been exactly what I needed. Take care.

Gene

[Joe L.]

Re: Correct modern replacement for R79S battery for late '69 car

Hi. My late 1969 would have had a side-post R79S battery. There doesn't seem to be a reproduction of that specific battery. Regardless, I was going to install a modern replacement.

I found this: ACDelco 78AGM Professional AGM Automotive BCI Group 78 Battery

https://www.amazon.com/s?k=ac+delco+78+battery&crid=1MUZE4IX9O3CQ&sprefix=ac+delco+78%2Caps%2C235&ref=nb_sb_ss_i_4_11

Can people please confirm if they believe this is the right/best replacement for judging (and life) or if there is something better?

Thank you very much.

Gene Cook

Gene------


Curiously, a Delco 78VPGHR battery carries a longer free replacement warranty than the 78AGM (42 months versus 36 months). It also has a higher cold cranking amps (800 versus 740) and a higher reserve (140 versus 115). In addition, it has an all black case (like the original battery).