What kind of Batteries (Was-HELP!!!Starter Woes)

[Fred Mc]

Well, it appears as though my problem with starting was the batteries. Took BOTH 8d's in today for testing and the one that tested weak(but OK) last time didn't register at all today in a load test.(the guy said probably a bad connection inside the batterY). And the one I didn't have tested before tested no good today. So that sounds pretty definitive. I'll know for sure once I get new batteries. I wasn't looking foreward to taking the starter out AGAIN.

Which brings me to my next question. 8d's here(Canada) are about 220 each. Group 31's are about 130 each and I would need 4.

Given that Group 31 is a size designation, why can't I use regular 900cca batteries providing they fit. Is there something special about group 31's. I can get 900 cca at Costco for $75. Am I missing something?

Thanks

Fred Mc.

Changed spelling in title to help with search and archive function--- Your Friendly Neighborhood moderator!

[Stormcloud]

I'm thinking much the same way.... my 2-8Ds are slowly fading. I plan on replacing them with 4 (connected in series and parallel to achieve 24volts) batteries from Wal-Mart (850CCA each) They will fit nicely in the battery trays, and are a helluvalot lighter and cheaper that the 8Ds; much better warranty too. The only glitch for me is that I still use the factory bus air when travelling and I've seen suggestions elsewhere on the board that I should likely stay with the larger batteries.

Suggestions and opinions always welcome!

Mark

[TomC]

I replaced my 2-8D's with two 950cca size 31's.  I have a 12v system and a 8V-71 that cranks very well with these batteries.  If they get low, I can electrically jump the deep cycle batteries for a helper with my jumper solenoid.  The reason for size 31 is that they are the batteries most all trucks and buses use, so replacement should be easier.  With you living in Canada, I too would run 3 batteries if it is 12v and 4 batteries if it is 24v.  I'm using Interstate batteries.  Good Luck, TomC

[belfert]

If you don't have road air you might be able to get by with just two group 31 batteries.  My understanding is the extra batteries are to keep the A/C blowing when the alternator isn't providing enough juice at idle.

TomC, why four batteries with a 24 volt coach?  Two batteries in series will provide 24 volt.

I bought my group 31 batteries from a local Ford/Sterling truck dealer for $62.50 each and they are 1200 CCA.  I was suprised the price hadn't gone up since lead went up in price last year.

[Chris 85 RTS]

Two group 31's start my 24V bus with a 6V92TA no problem.  Belfert is correct about the road air.

[Sean]

FWIW, we use two EverStart Group 65's to start our coach.  They've been working fine for two years, came with a good warranty, and were about $60 apiece at Wal-Mart.  But all they ever have to do is crank the starter -- YMMV.

-Sean
http://ourodyssey.blogspot.com

[jjrbus]

Really good question, on why use groupp 31's?  After doing due diligence I opted for 2 group 31's for my 6V71 auto. NO problems for the last 5/6 years. I also have a selector switch so I could add my house batteries if ever needed. Unless you keep the bus air there is no reason to use 4 group 31's or the 8d's. Unless of course that is the way you want to do it! Or you are one of our Alaskan friends.

[Stan]

I don't think using 8D batteries had anything to do with the A/C since the A/C shuts off automatically whenever the alternator voltage drops (such as engine idle). 8D batteries simply provide more cranking time if an engine is hard to start for whatever reason (cold weather, driver error, ect). House batteries were not available as backup on the bus when it was built.

[H3Jim]

Stan,

your bus may be different, but my bus air conditinler does not shut off when at idle or the voltage drops.  While the compressor itself (electric clutch) does not draw much, those 2 big 1 hp condensor fans and the circulation fans keep right on going and draw big amps.  You might be able to get by with only two group 31's if you have bus air, but they will have shorter lives as a result. 

The big drawdown and fast dumb regulator charge up with heat up the bats a lot more, cause more outgassing etc.  generally shortening their life.

There is no magic about two 8 Ds, vs 4 group 31's. Its all about amp hours, and the general battery type and construction.

[Stan]

H3Jim: I thought all bus A/C systems were interlocked like the MCIs as even 8Ds would only last for a few minutes with all the A/C motors, instation lights and running lights on. You would be looking at close to 200 amp load on 24 volts and that wouldn't allow much time for a commercial bus lunch stop without deep cycling start batteries.

I agree, nothing magic about 8Ds, just high amp hour batteries that can be replaced with multiple smaller batteries. Size 24 will work if you have enough of them. Under ideal conditions, two in series might start your engine.

[gus]

Nobody answered the question about using other series batteries with the same CCA as Group 31??I would like to know this also. I bought both start and house Group 31s last year and remember doing a lot of research before getting them.

I remember clearly why I got the house 31s but don't know why I got the start 31s? I got rid of the 8Ds because I was tired of lifting all that weight and the poor warranty.

It appears to me that CCA and Reserve Amps are the key factors for start batteries but I hope one of the battery experts will come up with the answer.

[Sean]

Gus,

I thought I answered your question when I said I was using Group 65.

To answer in more detail:  It depends.

First off, will you have an alternate means to start the coach?  For example, we have eight 8D house batteries, and a solenoid to connect the house and chassis systems.  Normally, this solenoid closes only when the alternator is charging, but I have a manual override that I can use to force the systems to bridge.  That will allow us to start the coach using an assist from the house batteries, if ever the group 65's let us down.  I don't think I would go with a battery that small without this emergency start system in place.

When it comes to starting batteries, you are correct that the relevant metrics are CA, CCA, and Reserve Capacity (by contrast, house battery capacity is more appropriately expressed in AH at 10, 20, and 100 hour rates).  "Group Size" has absolutely nothing whatsoever to do with a battery's performance or capacity -- it is only a measure of the physical size of the case.  (Before anyone jumps on me about this:  of course I realize that an 8D battery of the same manufacturer, construction, electrolyte, etc. will generally have more capacity than, say, a 4D -- the key here being "all other factors equal").

I have seen Group 24 batteries from one manufacturer with higher capacity than Group 31 batteries from another manufacturer.

So, no, there is no particular reason to buy any specific BCI group size other than space considerations, so long as the battery you are looking at has at least the CA, CCA, and Reserve Capacity that you need.  However, I would not reduce your reserve capacity unless you have an alternate means of starting than just the chassis batteries alone.

We opted for the Group 65 because it met our cranking amps requirements, yet was cheaper and had a better warranty than the Group 31 (not to mention that Wal-Mart generally does not carry Group 31 in its stores, excepting Sam's Club, to which we do not belong).

As for the discussion about 8D's and blowers:  I think there is some confusion. Stan, the only thing that will cause the blowers to cut out is a total failure of the alternator to put out charge (also makes the "Not Gen" light come on).  So, for example, your blowers will cut out when the engine is not running, or if the alternator fails.  That definitely does not mean that the alternator is putting out enough charge to run the blowers and all the other loads on the coach, which is where 8D batteries come in:  they have enough reserve to get you through periods of low idle, or other times of low (but not zero) alternator output.

-Sean
http://ourodyssey.blogspot.com

[buswarrior]

Hello Fred Mc.

That price for 8D sounds a little high. Find out where big transit near you gets their batteries. Closer to $180 here in Toronto area.

Group 31 are attractive alternatives because of the supply and demand equation due to the truckers using them. Drives the prices down, also why Walmart won't play in that game, don't want the warrenty issues with commercial use.

Those of us in the frozen north MUST maintain or exceed the stock battery requirements because what the COLD WEATHER does to battery capacity. If you start off with less, you end up with a lot less when the temps go off below freezing and beyond.

2 8D's will start to struggle down below 0 F degrees, block heater, Webasto or whatever...the cold saps the strength of the lead acid battery.

Now, if you want to talk battery wamers....

happy coaching!
buswarrior

[TomC]

Belfert- two 31's in series will create 24v.  If you're from Canada or other cold winter weather, you might consider using 4-31's (like all trucks with sleepers do) for the extra capacity to crank when it is cold.  Since most deep cycle systems for the camper part of the bus is 12v, you won't have the luxury of having a jumper solenoid.  Good Luck, TomC

[Stan]

Sean: I hope bus warrior has more experience with fleet use on MCIs but my experience is that at low idle and high load on the alternator it doesn't put out enough voltage to hold in the relay connected to the R terminal. That relay turns on the NOT GEN light and drops out the A/C system. I had one MCI with belt driven alternator and one gear driven and they both acted the same.