I need to replace the 5 year old 12volt 40lb 800cca 115RC AC Delco battery group 34. My alternator outputs about 80 amps and won't charge the system at equilibrium with full accessories until about 1800rpm and that isnt fixable. I almost feel like I had a working system going, just the battery isnt deep cycle and its age. I'm looking for a good 12V battery for this application. And I'll bring a jump box to the track JIC. Not really considering 16v at this time. Besides needing a new charger, I HAVE READ that 16V should reduce voltage to the fuel pump (mines overkill now), Oxygen sensors, and possibly the Holley data dash. People I know charge the 16V between rounds anyway.

What alternator are you running? The Toyota Denso alternator charges 14.6 volts as low as 600 RPM . For the last 12 years I have had this setup with a single 650 CCA battery and a 91 Toyota truck alternator with zero charging and starting issues

Gus

I have the powermaster 1 wire 95 amp alternator( charges nicely from 1000rpm and up) with a big interstate battery..think its around 900cca
Havent had a battery charger on the car in two years… running elect WP/ Fan/fuel pump/ msd, etc, etc, even after going rounds

I have had great success with the Snyder Motorsports battery. I use two but can get 10 plus starts out of them before the need recharging.

What's the pulley ratio? Needs to be about 1-3 to spin the alternator quicker at low rpm. You could get a bigger alternator. Or go 16V as we discussed and don't look back. I struggled with 12v for 7 years. 16 v is WAY BETTER.
Doug

I was using the 31lb red top batteries for the last 10 years....Probably still will....I am trying out a 47lb XS3400D AGM battery this year....It has a ton of reserve and 1150 CCA ....The red tops work pretty well except for the reserve...So a good alternator is required..Best one I ever used is this one...I can turn everything on, and voltage is rock steady even at idle...

https://www.mechman.com/alternators...85-gm-natural-finish-includes-2-pulleys/

Buy this Alternator: Powermaster #857295-1. One wire, 145 amps at idle 175 amps top end. I just got one for myself. $246 thru Summit.

Mine has had the same optima red top in it since I put the car together 8 years ago. Car sat in the cold all winter, and I didn't even have to charge it this spring....just fired right up.

But power draw is probably a bigger issue than capacity. If you're taking out more than you can put in, it'll die eventually no matter how good of a single 12v you put in.

ALL good replies and i thank you. I'll try to respond to them all here. First, i cannot package a different alternator without major changes. (time) The current pulley ratio puts the alt rpm at it's critical limit...i already did maximize the pulley ratio/custom. I will check out Snyder...THANKS! I was looking at the XS series and specifically the 3400 but now I'm realizing most of these 'good' batteries will require a new charger...even the 12V's So, now I'm leaning towards a single 16V and removing the alt from the car! Then metering the specific circuits prudently.

There is people offering 14V batteries now as well. Would also require a charger but I think they play better with he electronics you already have.

The Powermaster alternators I have seen say,

Yep!

At this point I'm replacing with a fresh non-agm 12V and using a jump pack. The off-season I'll do a light-weight 16V without an alternator....saving prob 30lbs combined.

FWIW we use a single small 14lb Odyssey 12V Battery in the Vette. Starts that 17-1 plus, open spring pressure that would scare most SB with zero issues. We also have a myriad of racepak sensors to include 8 O2's and anyone who runs one knows how much power they rob. It also has a std SM one wire alternator, gotta have the juice for the power windows you know

One wire Toyota alt with big pulley, made sure battery was up before going to races Friday nite and Sunday stayed charged, regular bat in trunk. MSD, fuel pump and fan for water pump. Under 900 rpm amp gauge showed a slight discharge till rpm got up.

Guess I can ad we use a 16V Lithum in the dragster and a House of Payne mini one wire. Really no need for the charger unless its hotlap time and need quick cool down. I ran a lithium and no alternator in the Stratus, both cars have a fair amount of racepak stuff on board 2 O2's on the dragster and 8 on the Stratus.

I have used east coast auto electric alternators with real good luck.

As far as 12 vs 16, there are advantages and disadvantages. On my last build when I saw I had to reduce a bunch of things, and just would really be using the extra voltage for cranking I decided against it.

Sometimes i think people have problems starting, so just default to 16V when in fact the issues are elsewhere in the electrical system. Running proper size cables for alternator, starter etc. are important. I don't use chassis grounds, my whole system grounds back to battery, I firmly believe that helps a lot.

i like deka batteries.

Mine had excellent wiring gauge and connections. The trouble was 15-1 at full timing and an alternator that has questionable output at idle. When you go late rounds in the heat there isnt enough time to fully recover the batteries. You need a better platform to start.
Doug

I couldn't find any such battery. 12V /14lb

I share the same reasoning. I do believe Doug had /has adequate wiring materials. And he helped me with mine so, if anything mine is ignorant overkill in many opinions. This battery was quite old and I did a restoration/ decalcify procedure to it before I ever tried it...I never charged it before this. So the reserve was suspect. I know a 'hillbilly' jumpbox will solve my starting problems for the moment along with new battery and a more tenative 'replenishing' proceedure. It is a fast fix hopefully. Jumped it in the lanes that day (thanks SimonFast!), drove it directly to trailer and loaded it so it had 3? minutes of partial charging. When I got home 2 hrs later, it started 3 times during unloading. I'll have all winter to consider redesigning a different electrical system but, it'll likely be an expensive weight savings.