What battery do you use?

[b5blue]

  My group 34 red top AGM battery was bought new April of 2016 and it may be done. The car sat for a few weeks while I patched some paint and such. Today I got the clicking weak battery sound and no crank. My charger read 12.5V with 54% charge. (Charging now.)
  I'm thinking of just getting a "normal" battery? 279 plus tax is kinda steep and Amazon's return policy is not that great if I had issues later. 

[metallicareload99]

I stayed away from AGM batteries for a long time, cause the overall impression I got is that they might not last that much longer than regular lead acid 

but after a string of bad lead acids I'm trying out a super start branded 34/78 AGM. First one showed a persistent voltage loss after the first winter  this second one is holding up better

[Kern Dog]

My group 34 red top AGM battery was bought new April of 2016 and it may be done. The car sat for a few weeks while I patched some paint and such. Today I got the clicking weak battery sound and no crank. My charger read 12.5V with 54% charge. (Charging now.)
  I'm thinking of just getting a "normal" battery? 279 plus tax is kinda steep and Amazon's return policy is not that great if I had issues later. 

Technically, 12,5 volts is much higher than a 54% charge....



That chart is very similar to others that I have seen so it can't be far off. I was surprised to learn a few years back that the percentage of charge is not linear to the voltage. In short, a 12 volt battery at 6 volts was not at 50% charge. It defied logic to me.
The battery in my red car is a standard lead/acid type that will charge to 12.6 and above but will also discharge from sitting. It will crank over cold even down to 12.15 or so despite being 495 cubes. Prolonged cranking if the carburetor is low will run it down fast though if it is below 12.2. The CCA rating is 800 which is much higher than stock. Mopar Action magazine claimed that new batteries in the late 60s/early 70s were under 500 CCAs.
I'm looking to make a switch to a Lithium battery despite the cost. A buddy had a 1000 CCA rated group 24 sized one that weighed 7 lbs! My battery is 40. Mine is also trunk mounted so add in the weight of longer battery cables....I want to see about a battery that is smaller than the group 24 but still with 750 CCAs.
Cheers

[b5blue]

  Yea it's just what the charger's readout said. It pulled up to fully charged up much faster than expected to boot. Still clicking not cranking I jumped the posts on the relay and it cranked.
  The suspect relay will be replaced and I'm likely still replacing the 8 year old battery. 

[Kern Dog]

I thought that there was a published estimate of the lifespan of 12 volt batteries that was something like 3-5 years. That surprised me. The one in our 2015 Challenger conked out over the summer, lasting 9 years. The one in my 2007 truck was about 8 for the original, 8 or so for the replacement too.
My classics...the ones I barely drive seem to be lasting well past the 5 year mark but the one in the red car is only 3 years old and starting to act up.

[b5blue]

My 120amp Denso Alt. puts out about 60 amps @ idle and that has much to do with protecting my battery from working it's butt off. (Like it use to.)

[b5blue]

  Well CRAP. 2nd time an ignition switch has failed me. The "crank position" no longer activates the yellow relay wire. Swapped my truck battery and replaced the relay only to confirm no crank function with my meter. (The reason I replaced ignition switch last time.
  I'll be installing a starter crank push button like I ran with back in the day for 10-15 years. It will sit right next to the manual choke I installed after realizing the electric choke was a waist of time in sunny Fl.
  Time for a new battery though. It drops overnight from full to low 80's %. 

[Kern Dog]

If you can find a NOS or good used OEM ignition switch, you'd be better off than using a new one.

[b5blue]

Yea I'm just not dropping the column AGAIN! Push to start will never quit working. 

[Kern Dog]

I've found that removing the seat really helps for access to the underside of the dash or steering column stuff.
I have a group 24-ish sized battery from the NAPA store. I'd post a picture but every one I have is above the size limit for this site.
I have mine in the trunk. I relocated to the trunk in 2013 based on the thought that by moving it back there, that it improves traction and handling. What I've learned is that while it may have done those two things, it adds weight to get there. I have longer battery cables that run from the engine back to the trunk now. I have a battery box that is slightly heavier than the stock tray.
I've been casually considering a switch back to mounting the battery up front but with a Lithium battery that is smaller than the stock group 24 size.
A buddy of mine has a group 24 Lithium battery that looks stock in size but only weighs 7 lbs! My lead acid battery is 40 1/2 lbs. My CCA is something like 800 @ 0 degrees. His is 700 at a degree I don't recall. I noticed that my battery never goes over 12.6V no matter what I do. His was at 13.08V and when I tried his battery in my car, my starter spun the engine over way faster that ever.
There are people that are leery of using a Lithium battery and I do understand the hesitation. There have been some that are prone to fires and are hard to extinguish. There are newer Lithium designs that are much safer and all of this stuff is getting better and safer as time marches on.
Swapping batteries is a 33 lb difference. When the cumulative weight of the longer battery cables is factored in, A swap to a front mounted Lithium battery could result in at least a 50 lb weight loss.
One thing that I like about a trunk mounted battery is the extra room under the hood. I'd want to see if anyone makes the safe Lithium Titanate design with adequate CCAs while being thinner than a Group 24. In short, I don't mind the length and height but I'd want something thinner so it doesn't crowd the radiator and A.C compressor/hoses like a stock battery does.
I read recently that OEM batteries from our cars were often 400-500 CCAs. The batteries we often use are more powerful that the originals even if we don't have powerful stereos or any additional electrical accessories in the car.

[69hemibeep]

My group 27 restoration battery gave up but it should be an easy fix. When I unscrew the caps I see cables and a smaller battery in there, lithium I'm guessing. Time to cut the bottom out of it.

[timmycharger]

I am not sure of the size but I have been using this Optima red top battery since around 2016.  Mounted in the trunk, this is an old pic as its now enclosed fully but with this setup, spins my 440 with no troubles unless hot then it is a little slower.

Im a big fan of these batteries. My brother in law still has the same yellow top Optima battery that he bought from the auto parts store in 2012 when he was working there, someone brought it in as a core for a new one. It just needed a charge and its been in his 72 Maverick since.

[Kern Dog]

I've had 2 Optimas and neither held a charge as long as a quality Lead-Acid battery. I don't know if this was normal for the design but it was what I experienced.
The Optimas are heavy too.
Lately I have been on a path of shedding weight in the car when parts get replaced.
I shed 14 lbs with a Borgeson steering box, another 14 when I changed to different front brakes which have aluminum hubs, a different spare tire is 21 lbs less than the stock one. I used aluminum parts where I could. I'm at around 3940-3950 right now.

[timmycharger]

Strange you had that experience with the Optima batteries. My Charger sits every winter and fires up every Spring for the last 8 or so years, I don't think I ever charged it once. 

Not worried about weight on my car anymore. 20 + years ago when i was racing it more often, I got it down to 3780lbs after removing the front swaybar, power steering, switching over to aluminum wheels, using a fiberglass hood as well.

Its over 4200 lb per the last time I raced it, but it also now has a Dana 60, Hemi 4 speed with Lakewood blowshield,  power steering, power brakes, the steel hood, steel wheels, front swaybar, a ton of sound deadener and all kinds of extra stuff like electric fans, amp, etc.

Guess I need to just add more power!

[Kern Dog]

I know, chasing weight savings means little to some. Look at the Hellcat Challengers and Chargers....They weighed 4300+ lbs so they just made the engine more powerful to move the car faster.