This coach (8.3) has always been a quick starter. However, recently I had to rely on the boost switch to get the same kind of satisfying start. I took them to O'Reilly's and one of them was shot. These babies are three years old. This is the second time Optimas have let me down so no more for me. I replaced them with O'Reilly Quick Start 34/78PMRS. They are 800 CCA and run about $145. You can always get some kind of discount if you ask.
I was thinking about adding a third battery as my rack has plenty of room. However, in order to do so I'd have to relocate my fuel filter so two it is. Now, all you have to do is threaten to turn the key and it fires right up!
jor
Jor, I'm sure you will be happy with the batteries you selected. This is another from Oreillys that is the next level up and about $50 more and is AGM with about 6% more cold cranking amps. I've used AGM batteries for chassis batteries for over 10 years and I have been very happy, I especially enjoy never having to check or add water and I do not miss the corrosion caused by the electrolyte. Two group 34 AGM batteries have worked fine for my 6C8.3, with that 1,500 cold cranking amps. The Oreillys Platinum grp 34 is mfg by East Penn as are their AGM8D batteries. The Cummins marine spec for our 6C8.3 is 1,250 cca., and 1,500 cca for ours, so two group 34 batteries should be fine.
https://www.oreillyauto.com/detail/b/platinum-5003/more-powersport-30734/battery---automotive-16864/battery---best-fit-16245/7272aa5cfedd/super-start-platinum-battery-group-size-34/34plt/4742696?q=Superstart+platinum+34&pos=0
I have similar batteries in my 8.3, 2 of them and it starts fine but I don't use it in the winter unless running it out to my mechanics shop for some work. It started fine at 19 degrees with 2 agm Napa batteries style batteries. I have no preheater or glow plugs so it impressed me! Unless a lot of winter use I think 3 is a waste.
We have 3 Optima Red Tops in our U300 CAT....9 years old and they spin the Kitty "right now"
H
I fired them when they stopped manufacturing product in the USA. Battery weight dropped 20%. Quality even more. Shame
Scott
With lead/acid batteries, the heavier the better. Check the weight in the specs for the battery you are interested in. Johnson Controls has been manufacturing batteries for many outlets like Autozone, O'Reilly, etc but in mid 2019 they were taken over by Clarios. I don't know much about a quality change since the takeover. Here is a big list of battery supplier and the company that makes their batteries: Lead-Acid Battery Manufacturers and Brand Names List 2020 (http://jgdarden.com/batteryfaq/batbrand.htm)
Pierce
Jor, do you have a link to the O'Reilly Quick Start 34/78PMRS?
https://www.oreillyauto.com/detail/b/premium-4988/more-powersport-30734/battery---automotive-16864/battery-12836/d6cf089e3164/super-start-premium-battery-group-size-34-78/3478prm/4742367
https://www.oreillyauto.com/detail/b/platinum-5003/more-powersport-30734/battery---automotive-16864/battery---best-fit-16245/7272aa5cfedd/super-start-platinum-battery-group-size-34/34plt/4742696?q=34+agm&pos=0
I was using a spare deep cycle (1100 cca ) that I had bought just before we converted to lithium. Well I couldn't take it anymore cause that thing barely spun her over and I REALY didn't want to damage the starter so I switched them out.
Even though I'm not a regular Walmart shopper I find it hard to resist there prices on Rotella 15/40 and batteries actually. I love the 3 year replacement warranty. I have switch out a few in the past that I abused by leaving a vehicle sit way long before starting. Anyway, 3 batteries at 800 cca each REALY spins her over now and I no longer worry about the amp gage dipping when I turn on lights or wipers,, plus I can leave the radio on 24/7 too. If they don't last 3 years,, boom ,free replacement.
Ps. The one in the Vette just past 5 year mark......
Had the same thing happen to me with the Optimas,think they are overhyped.shopping now for 2 replacements.
Our 3 Autozone Duralast 24 series and now 31 series have lasted about 10 years (24 series) Just over $300 11 or 12 years ago and $300 total last year for the 31 series. I checked the weight on the 31 series to get the heaviest made. Other brands also made by Johnson Controls are also good. Not sure about the future with new ownership.
Spun like a top hot or cold 12 years ago and does the same today with never a boost solenoid used (except one time).
Ask for 10% discount if buying three.
Pierce
Two Interstate group 34's, spin our Cat, any time any where, deep cold-temp or hot.
For the engine start batteries I go with simple lead/acid. The batteries are exposed to the elements so no problem with gassing.
I bought 3 about 7 years ago at Costco, never a problem. around 900 CA each, spins the M11 like a top.
I can replace these about 2-3 times for what the AGM start batteries would cost, but so far have not replaced them yet.