Author Topic: Switch to Group 31's in Engine Compartment?  (Read 6004 times)

Offline Midwilshire

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Switch to Group 31's in Engine Compartment?
« on: February 19, 2014, 04:38:01 PM »
I'm interested in reading the experiences of anyone who has switched from 8D to Group 31 start batteries and moved them to the engine compartment.   I searched the archives, and the last on-point thread was in 2007 and mentioned that heat may become an issue.  Looking for current views on the project by those who have done it.  Thanks in advance.
Michael & Gigi
1978 MCI-5C "Silverliner"
Full-timers in the DC area

Offline muldoonman

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Re: Switch to Group 31's in Engine Compartment?
« Reply #1 on: February 19, 2014, 04:46:00 PM »
Don't know about the MCI's but my Prevost seems to be happy with them there. 

Offline Lin

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Re: Switch to Group 31's in Engine Compartment?
« Reply #2 on: February 19, 2014, 05:38:23 PM »
I switched to 31's but put them in the same compartment.  No problems
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Offline Dave5Cs

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Re: Switch to Group 31's in Engine Compartment?
« Reply #3 on: February 19, 2014, 05:48:08 PM »
we have 4, 6 volt house bats back there on the passenger side on a rack that are fine after 3 years.
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Offline bevans6

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Re: Switch to Group 31's in Engine Compartment?
« Reply #4 on: February 20, 2014, 03:51:46 AM »
The only reason I can think of to not do it is if you use a high current load from the start motors up in the front of the bus.  The two obvious ones might be the OTR heater motor (60 amps) or the AC condenser motor (80 amps).  You will feed the bus via the existing 4/0 cable that runs from the engine compartment firewall to the master disconnect switch, and that would be fine for even those loads.

Brian
1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Allison MT-647
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Offline garhawk

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Re: Switch to Group 31's in Engine Compartment?
« Reply #5 on: February 20, 2014, 04:31:51 AM »
Most all passenger cars and trucks have their batteries up front in the engine compartment with no ill effects.

My Eagle has two 8Ds in the engine bay with no problems. 

It would seem to me that the temperatures reached in an engine compartment are not a deterrent to long battery life.
gary t'berry
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GMC RTS 102"  40er (in progress)

Offline Ed Hackenbruch

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Re: Switch to Group 31's in Engine Compartment?
« Reply #6 on: February 20, 2014, 04:36:00 AM »
I thought about putting mine back there when i switched over but my generator was back there at the time so i just used the existing battery compartment up front. No problems and am going on about 7 years like that.
1968 MCI 5A with 8V71 and Allison MT644 transmission.  Western USA

Offline TomC

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Re: Switch to Group 31's in Engine Compartment?
« Reply #7 on: February 20, 2014, 07:18:24 AM »
I use 2-Interstate 950cca size 31's to start my 8V-71. If I do have a problem, I can hit the dash switch to jump to the 2-8D Lifeline AGM batteries. I have started the bus on the deep cycle when the starting batteries went dead. Size 31's are so much easier to handle then the 8D's. Virtually all big rig trucks use size 31 batteries. 2 on medium engines (6.7 and 8.9 liter), 3 on non sleeper day cabs, and 4 on sleeper trucks. All U.S. trucks are straight 12vdc (compared to my truck that is 12vdc with 24vdc starter). Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.

Offline Seangie

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Re: Re: Switch to Group 31's in Engine Compartment?
« Reply #8 on: February 20, 2014, 08:20:04 AM »
I've got 3x 31s right next to the starter.  Makes sense for me. Cable replacement is less costly and quicker.  It makes sense to have the batts next to the highest load with the least amount of resistance. 

-Sean


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Offline Lin

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Re: Switch to Group 31's in Engine Compartment?
« Reply #9 on: February 20, 2014, 02:08:28 PM »
From everything I've seen posted, it seems that there is no harm in moving the batteries to the back.  But since no one seems to have any problems using that from the original compartment, why bother?
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Offline Emcemv

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Re: Switch to Group 31's in Engine Compartment?
« Reply #10 on: February 20, 2014, 04:23:43 PM »
What do you guys think about group 31's for my 8V92T 450HP? Does this have higher compression? Should I stick with the 8D's?

Bruce
Bruce & Nancy Fagley
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Offline Midwilshire

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Re: Switch to Group 31's in Engine Compartment?
« Reply #11 on: February 20, 2014, 06:30:13 PM »
But since no one seems to have any problems using that from the original compartment, why bother?

I'd like to use the front compartment for my two 8D AGM house batteries. 

The alternative is to place the house batteries where the old AC condenser used to be in the center of the bus, but I was considering that space for my inverter and thought I should keep the inverter separate from the batteries.  The only problem I see now is that it might turn out that I need more than 2 8D batteries for the house system, in which case, I'll have to put them in the condenser bay with the inverter anyhow. 

I'm open to suggestion.
Michael & Gigi
1978 MCI-5C "Silverliner"
Full-timers in the DC area

Offline BeastMaster

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Re:
« Reply #12 on: February 20, 2014, 06:30:34 PM »
I use two group 31's in my 102c3 with 8v92 T. Still in original battery bay. Have had no problems.

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Offline Seangie

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Re: Re: Switch to Group 31's in Engine Compartment?
« Reply #13 on: February 20, 2014, 07:54:59 PM »
Mike - Ill throw this out there for feedback as I'm not sure this is the correct answer.  My understanding is that only lead acid batteries need to be seperated from the inverter as they boil off hydrogen gas but AGM batteries do not boil off hydrogen gas so in theory...you could put them in the same bay as the inverter.

Although you may have to print up an AGM only warning sticker as someone down the road will end up replacing the AGMs with Lead Acid batts. 

-Sean

Fulltiming somewhere in the USA
1984 Eagle 10S
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we live in a van (Eagle 10 Suburban)
Driving through the night
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Offline Lin

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Re: Switch to Group 31's in Engine Compartment?
« Reply #14 on: February 20, 2014, 10:05:35 PM »
If you use AGM batteries, you can put them anywhere and in any position except upside down.  My AGM's sit right in between the generator and the inverter in the same bay.  Also, the closer the inverter is to the batteries the better.
You don't have to believe everything you think.