Minimum battery size for starting

[CountingFireflies]

Howdy -

I'm trying to be frugal with my new battey purchases, and the starter batteries have me perplexed.  I have an 8v92TA, and  I currently have 2x 8D 12V batteries with a Vanner system.  Each battery spec's at 1380CCA.  The 8D's are rediculously expensive.  Given that my engine starts on the first revolution, can I get by with 2x 31 size cells with 800-900CCA?  What's the minimum CCA to get that beast turned over? 


Chris.

[chev49]

I imagine that you can, but i wouldn't do so.

On the other hand, i have moved several busses around that have 8v71,s and the 6v71, and 671, and some cummings, cats and probably a hundred excavators  and backhoes with one or two group 24's depending on the voltage.
Not something i reccomend for over the road use..

[zubzub]

I can start my 6-71 in the fall with one group 31.  I figure 2 31s would probably start you just fine.

[Iceni John]

O'Reilly has 1000 CCA (1200 CA) Group 31s for only $110, and a higher-capacity one for $130.   When my present 8Ds die (one of them is not healthy), I'll use Group 31s instead.   Their lower Reserve Capacity won't be a problem because I'll eventually tie my house batteries to the starting batteries for emergency use.   I decided to use smaller cheaper lighter Group 31s because I used the 8Ds' space for the poo tank, and the only other space for my starting batteries now is not big enough for 8Ds.   When I bought my bus we started it on a cold December day in Fresno CA after it had sat for several months, and one Group 31 started it without a problem.

However, if you're in a colder part of the country, my experience may not be relevant!   YMMV etc.

John

[rv_safetyman]

Our Eagle came standard with 3 group 31 batteries. 

I am of the school where more is better.  As batteries age, they loose some of their capacity.  They loose some of their capacity when cold.  Those can be additive.

If you tired to start your engine at low temperatures, you might have an issue with 2 group 31  batteries.

If you were to loose prime or had some other issue, you would not be able to crank the engine very long with 2 group 31 batteries - especailly if it is cold or the batteries are old. 

I just got my flyer from our local IHC truck dealer and they had group 31 batteries on sale for less than $65.  I have seen them on sale there often.

Jim

[luvrbus]

With a 8v92 and the 42MT Delco stater it takes 1250 CCA amps for a 24 volt system (double for 12 volt),the MT 50 that some 8v92's have they are 1800 CCA just remember CCA are for a few seconds only low amperes or low volts will kill a 42MT or 50MT starter and those are not cheap or easy to change but we all do it different, 4 G31's would be my choice for 24 volt if changing from the 8D's JMO

good luck

[roadrunnertex]

I own a GMC P8M4905A Buffalo 8V/71 and it has 2-8D batterys in series for a total of 24 volts DC.
I just installed 2 new 8D's and it cranks the first try within a half a turn of the engine.
I started to go the group 31 battery's route but decided to stay with the 8D's after talking to a few old bus mechanics who said
better stay with the 8D's in cold weather for starting.
Your choice!
jlv 

[jjrbus]

I was fortunate with the people I was around when I did my electrical system! Most electrical on my bus was 24V.  I cross tied the house system and bus system together with a selector switch, the same could be done with a solenoid.

If at any time the bus batteries were incapable of starting the bus, I could also tie in the house batteries with the flick of a switch.  I used 2 group 31 ( group is only a size not an amperage rating) to start my 6V71. The house were 4 6V golf cart type batteries. I also had a block heater which could be used off shore power or generator. I used the block heater once.

I had no problem at all with 2 31's, but I spent my time in more temperate climates.    JIm

[papatony]

I just left Advance Auto today and they have began carring the 4D&8D in their stores,4D  150.00  8D 179.00 I know this not real cheap but my thoughts are you need more than just starting power you need the storage cap.of the larger batt. for extended power when boondocking. Am I wrong?

[artvonne]

  What about using 4 (or 8 ) T105 trojans from your battery bank for starting.

 

[TomC]

A cheaper way to go would be to use 3-group 27 or even 24 batteries.  You want to be around 2000cca.  Or just use 2-31's and have a solenoid that can jump your house batteries if more juice is needed (I have that and it works great). Good Luck, TomC

[luvrbus]

Wiring 3- 12v G27's batteries is not a good setup for 24v IMO 2 need to be wired in series then 1 has to parallel could work ok for a while I guess never tried it,in my area small town AZ Interstate 8D's are 139.00 at Sams 179.00 for the 5 year warranty 8D's 

good luck

[John316]

8D's starting aren't that bad. Around here, they are about 160, with a five year warranty. Less might work, but you will probably end up swapping them out sooner.

Now, if you are talking deep cycle. Those babies are pricey.

Stick with the 8D's, if you can. Especially with a 8V92.

FWIW

John

[jjrbus]

I just left Advance Auto today and they have began carring the 4D&8D in their stores,4D  150.00  8D 179.00 I know this not real cheap but my thoughts are you need more than just starting power you need the storage cap.of the larger batt. for extended power when boondocking. Am I wrong?

Starting batteries do not make good house batteries.  For house use you want deep cycle batteries.   Google deep cycle batteries and you will learn more than you ever wanted to know.

[Ed Hackenbruch]

About 4-5 years ago my 8D's died and i replaced them with 2  group 31's. My 8v71 fires right off and i have had no problems. When it gets down below 40 degrees i use the block heater to help out. Once or twice it has been frosty out and i forgot to use the block heater and it took a second or two longer to fire off.  The 31's are cheaper and a whole heck of a lot lighter than the 8D's. After getting my fingers caught between the 8D's and the battery box one time and thinking that i had either broken or cut off my fingers, i will never use them again......lots easier on my back too.