Trouble with batteries.

[makemineatwostroke]

If you live in the cold country keep the 8d's never to much battery when it's 20 below some will say that's what engine heaters are for true but you are not in your shop all the time,like Teebird said not for the AC that was what the large alternators were for

[Highway Yacht]

I changed out my 2 8D batteries 2 years ago with 2 Group 31 batteries. I always shut both my 24V and 12V master switches off when the bus isn't in use. I've not had any problems with enough juice to crank the 6v92TA yet. As stated above, the reason I went with Group 31 batteries was both PRICE and WEIGHT of the batteries.

[Blacksheep]

Well with that said, my personal opinion is most everyone that converts a bus to a motorhome usually removes the bus a/c and it's huge blowers which required the high capacity 8D's. To start the bus and run the few running lights, the monsterous 8D's are just not needed and if your motor needs their cranking capacity to turn it over then I would think it's time to look at your motor! Usually DD engines don't require a lot of spin so there's really no need for the large batteries!
BS

[tekebird]

Blacksheep, you are welcome to your opinions but I can assure you that the battery size has absolutly nothing to do with the A/C or heater blowers or other motors involved with those systems.

I can also assure you that two brand new *D's will be drained of every ounce of energy in less than 30 minutes if using them to run these motors.

you do what you want and why you want....but your reasoning is flawed.

I have spun a DD with a large yard tractor battery ( just to see if it could be done) (mid summer)......it spun but not quite fast enough to start....and it killed the battery in one crank......

a small car battery can start a DD in warm temps too......I've done it.,

if your resoning is correct why not go down to sears and buy the 30.00 die hard and run that.

a DD needs significant ammount of battery power to crank long and fast enough to fire....keep in mind there aint no plugs, or glowplugs.....it fires through compresssion of the atomized fuel alone......not fast or long enough....no fire.

tru alot of folks go to the 31's but it is a money and size/wt managability issue for 98% of it.....  most bus converters are "cheap" and buying two or three 31's is cheaper than 2 8's.

Now there are people with 31's living and running in colder climates, most have 3-4 31's which brings up the juice power some....but if whn you need to do some multiple cranks in cold weather........a 31 does not compare to 8D performance.

not only is your engine cold which then requires a longer starting crank...... but your batteries are cold too which means they are at a fraction of thier peak power.

Again.......has nothing to do with the A/c my freind.

[tekebird]

Volume of batteries

Grp 31  approx 835 CI
8D                   2296 CI

so basically it takes just shy of 3 Grp 31's to give equal performance of 1 8D

Optimum Operating temp for lead acid batteries is about 77 degrees (OATS)

In a perfectly new battery you lose roughly 10% of it's capacity for ever 10 degrees of temp decline

this is why some people start having cold start issues when it's not really cold out.

between cold soaking the block overnight and cold soaking the batteries themselves this effect can be magnified

[tekebird]

some other stats to save you from looking them up.

31 900CCA, RC 195, # of plates 120 (max)
8d 1400CCA, RC 380, # of plates 180 ( max)

RC=reserve capacity is in minutes and is based on a 25amp draw.

[jjrbus]

If you live in a place so cold you need 8D's to start you really need to move, or at least head south sooner. If you have a standard you could park on a hill.
When planning an electrical system it is always an option to crosstie the bus and house batteries, a selenoid or selector switch can be used. Simple fast and cheap.
By the by, page 7-16 of the MCI5C manual, under batteries, section C says.

   It can, for a limited time, furnish current when electrical demands of the electrical equipment exceed the output of the generator??

[tekebird]

has anyone bought 31's lately?  I just did a quick online price search and they were not cheap 180.00 and up thats what I paid for my last 8's a few months ago

[tekebird]

that was a DEKA 31. and the good one ( three different capacities.)

found an interstate model for 89.99

[Stormcloud]

The 8Ds in Papabus were failing....almost always needed a shot of ether for the first start of the day. If it didnt start by the 3rd try, out with the battery chargers.

So, I replaced the 2 8Ds with 4 x Eveready Energizer auto batteries from Wal-Mart. Around 850 Amps each and 7 years warranty for about $79.00 each.
They said they didn't care what the batteries were installed in (for warranty purposes).

Gives me about 1700 cranking amps at 24 volts. It whirls the old 8V-71 like theres no tomorrow. It never started so good.

Just my way.

Mark

[Sojourner]

FWIW....I have 1974 MCI 8 with 8/71 NT, 740 automatic. I had it stored in 1990's at Warren, Michigan area for 3 years. I changed 8-Ds for 2 new group 31 @ 970 CCA because it was old and improper care. Even with 8-Ds in cold climate it won't start. Same thing....with the high ampere 31group batteries, which I already knew it won't. However, by plugging block heater for 45 minutes or more.....it starts within 2 revolutions during 20°F. That with the group "high ampere" 31s batteries. Never had a problem since.

Most all new class 8 trucks are using group 31 batteries.
Intercity and transit buses use 8-D because of the large blower motors along with 270 amperes alternator. While stopping to pick-up or drop-off passengers as well traffic stop in idling mode to cause power drainage from batteries until it on fast idle or traveling to put back electrical energy that was lost.

Remember only buses use extra large 270 amp alternator.....
1)   class 8 trucks are using 100 to 145 amps alternator unless it for emergency vehicle.
2)   And group 31 weights about 70# & 8-D are 170# each.
3)   Before purchase, get the highest CCA (cold cranking ampere) in group 31.
4)   All cold wet cell batteries are weaker than 75°F ones.

The big motorhome are using group 31.

BTW....by having already equips 270 ampere alternator on your bus is a big plus for running large inverter while traveling with A/C on. And if your batteries are fully charged, the extra large alternator uses no more power to turn than a smaller one except during engine acceleration.

FWIW

Sojourn for Christ, Jerry

[Blacksheep]

"Intercity and transit buses use 8-D because of the large blower motors along with 270 amperes alternator. While stopping to pick-up or drop-off passengers as well traffic stop in idling mode to cause power drainage from batteries until it on fast idle or traveling to put back electrical energy that was lost."

HMM, I guess I WAS mis-understood unless Sojourner is too!

I know when I owned my Eagle, the 2 NEW 8D's let me down more times then they got me going, and after re-wiring the WHOLE bus with NEW wiring from front to rear, it came down to changing the 8D's to 3 group 31's and NEVER had a problem afterwards! While re-wiring, all of the a/c components and blowers were removed and it was the opinion of the PRO mechanic doing the work to switch to the 31's. His opinion... the 8D's were not needed because the a/c junk was removed! The alt was also replaced with either a 100 or 150 amp single wire Leece-Neville alt. Again, the large original alt. was not needed due to the removal of the a/c junk!  At that time I removed a LOT of weight, gained a LOT of room, and gained a peace of mind when I went to start up and go!

BS

BS

[tekebird]

I agree the alternator is large for the blower needs, I don't know about everyone elses units, but my large bus alternator works fine at idel providing more than adeqaute power without the need to draw from the batteries.

I suspect a major reason for grp 31's becoming more common in trucks and large motorhomes as well as some buses, yep some today come with 31's.....is strictly a cost issue

I have only ever had 8d issues with my 4104...... it would go through a set about every two years when my folks had it......no battery shutoff.  Whe I got it I put two small solar panels on the rear roof air and trickle charged the coach batteries directly.  Got better than 6 years out of those with pretty limitied bus use the last 4 years.

Lost one cell in one was the only reason they were replaced.

my MC-8 8d's are 6 years old and will happily start the coach in temps in the mid 30's.......two cranks with no block heat (parking area did not have electric one day I needed the bus)

I am not saying 31's won;t work.....as I said you could gang together some motorcylce batteries if you wanted to......they simply just do not have as much capacity or reserve ( read numerous crank cycles) and have a lower cold temp performance.

too each their own.....it's your bus......

[Don4107]

My thoughts on 8Ds vs group 31s.  Remember they (the thoughts) are worth just what you paid for them.     Sold batteries in my business.  Most familiar with agricultural and fire service, NOT bus service.  Ag and fire service is somewhat like many converter bus uses, long periods of inactivity.

My experience is that 8Ds:
1. Have limited warranty coverage, they are assumed to be in commercial service, usually 24 months max.
2. Tend to go TU sooner that the typical group 31. Why? Don't know fer sure.  Inactivity? Basic design?
3. If you take 2 (You should) group 31s to replace each 8D cost difference is not that great.
4. 8Ds will give you or exacerbate that hernia.
5. Many trucks with BIG diesels use 4 31s for above reasons.
6. The one draw back is that it takes more cables and therefore more potential connection problems.
7. Offsetting #6 is that group 31s with top post connections means a few wing nuts to remove.
8. If you use 4 31s and one gives up you are only down 25% of your cranking power. 
9. You will spend less quality time with your Chiropractor if you use 31s.
10. If you live in/play in warm places and use your block heater you can get by with less batts.
11. If you choose option #10, I would suggest a battery crossover if your house and chassis batts are same volts.  No matter how many batts if start and house batts are the same volts I want a crossover and a separate gen start batt.  Paranoid? You bet.  Murphy visits often.
12. Still not cranking, rebuild the starter!

Batteries come in all quality levels.  Shop with your arms not your eyes.  Simply put, the heavier the battery the better. (more lead) Pay for the lead not the fancy label or brand or advertising. There are only a few manufactures who make them all.  In a bus national warranty coverage counts. 

What batts are going to be spinning the 8V71 in the new rig? Can't resist being different so a few Optimas. Provided, of course, I have any bucks at all left after finishing the conversion!!  Doubtful!!  May have to park on a hill!!

Don 4107

[luvrbus]

Guys,it takes very little amps to start a DD 2 stroke like 950 above 32 or 1250 below 32 degrees at 24v but if you don't have the reserve to go with the amps the engine is not going to start.I have owned heavy equipment for 30 years and even the small JD backhoes 310s had 2 group 31 batteries and it was a 276 cu in engine no a/c or blowers with 90 amp alternators the Cat  heavy equipment always had 2 8ds or 8 group 31 batteries and again no big blowers or a/c. Jerry is right about the trucks using group 31 my haul trucks had 4 on each side.In Phoenix the buses run 4 group 31 batteries and have no problem. but if you don't have a good reserve on your batteries soon or later it will get you and 2 group 31 is not enough in my opinion if you ever run out of fuel with no priming pump it will be luck if 2 group 31 batteries last long enough to get going.I use 2 8d in my bus and they last about 6 years never had one go bad in less than 5 years  and I go from the AZ  heat to the cold in Idaho each year. but everyone does what they feel is best for their needs and that is the way it should be