replaced 8D's with truck batteries

[Tin Lizzy]

replaced those awful big bulky 8D's with a couple of used batteries from a truck. Not sure what they came out of but 1/2 the size of the 8D's and my bus starts without a boost for the first time in two years.
It was so sweet to plug in block heater the day before and just have it fire up!
Next step hook up wires to my new square headlights and see how they work

[JackConrad]

My understanding is that 2 "truck" batteries (AKA group 31) will spin your engine as fast as 2 new 8D, BUT will not spin it as long. If it is cold, use the block heater prior to starting and you should have no problems. Has worked for us for 6 years.  Jack

[DavidInWilmNC]

On a related note...
I replaced the 8's that came in my MC-8 last year with a new pair, so I'd hate to not use them.  I don't currently have anything for house batteries.  I'm thinking of adding a pair of group 31's for starting with the 8's available (with a flick of a swith for the combiner relay) if needed.  I still have the OTR heat & A/C, so I'm sure I'll need the reserve of the 8's when idleing, etc.  My question is how well will a pair of newer 8D's work for deep cycle / coach use?  I have a 60 amp three-stage charger that should at least keep them charged properly.  Thanks for any insight.

David

[TomC]

Even though deep and starting versions are made of the 8D, using them as deep cycle will work.  Even though the 8D might have close to the same CCA as a 31, the reserve capacity on the 8D is much more. Translated, do your trick of using the 8D for deep and buy a couple of 31's for starting.  The Interstate 950's are good.  Keep with the highest CCA since 31's are made from 750 on up.  Good Luck, TomC

[NJT5047]

I've been using two 8Ds for house batteries for 3 years without any problems.   I don't run them down below about 12V, and keep'em charged with a DR2424 inverter/charger (70 amp 3 stage).  This spring will be the house batts 4th season. 
Don't let them go dead, don't heavily discharge them, use a good charger, and they'll do quite well.   
An issue may if using a ton of 12V from a center tap.   My equalizer apparently manages this issue.  But, I don't have a lot of 12V demand either.  Some lighting, 12V fridge uses tiny bit of power for the electronics, that's it.  Entertainment is all 110 VAC.
We don't boony for weeks, but we do use the bus frequently at Bluegrass festivals for 4 days without AC power.  No problem...no air conditioning either unless the generator is running.  A benefit in my coach is LP.  Fridge, range, hot water, and some heat are all LP.   My bus is built similar to an RV.
If you use an inverter to operate a fridge or other 110V items, don't let the batteries go below the high 11V range (individually) and you should get good service from the 8Ds.   You would get better service from a raft of golf cart batteries...but?  How long do you wish to camp sans power?  Batteries have a finite life even if impecably cared for. 
Calculate your loads and estimate if your 8Ds would suffice...for a satisfactory period of time.  If you plan to be on a pole most of the time...the house batteries are moot.  You could use a lawn mower battery (two lawn mower batts?)...as long as the bus is running, or you're plugged up.   
JR   

[H3Jim]

and don't forget, a solar panel will make your batteries last a lot longer, as it will keep them fully charged.

[DavidInWilmNC]

Around here, we have Autocraft (from Advance), Energizer (from Sam's), Penn (from Carquest), and Caterpillar (Triple T).  Most have a one year warranty, with the Penn having a 6 month.  None of the Super Walmarts here carry 31's or golf cart batteries.  From the above list, Sam's seems like it will be the easiest to get replaced, if need be.  Does anybody have any experience with these brands?

Thanks.

[DrivingMissLazy]

A deep discharge is generally considered to be in the 1.75 volts per cell range. For a 12 volt battery this is 10.5 volts, for a 24 volt system 21 volts. If you are only discharging to something between 11. and 12, you are not really doing a deep discharge and probably doing little if any damage to your batteries.
Richard

[jjrbus]

Dave I buy my bus start batterys grp31 and my toad batterys from WalMart. Are they great batterys? I dunno but I can replace them 7 days a week almost anyplace in America.  The bus batterys are 5 years old, no problems. The toad battery I had to replace after 1 year under warrenty, its been in there about 3 years now. The golf cart house batterys are from sam's (becuse they are cheap). Mine lasted 4+ years, but I abuse them badly! So they must be good!!! WalMart sells a nothern and southern battery. With the northern battery being heavier, If you can buy your batteries in the north you will get a heavier battery. I also buy my toad tires from Wallys for he same reason.

[Sean]

... Autocraft (from Advance), Energizer (from Sam's), Penn (from Carquest), and Caterpillar (Triple T).  ...  Does anybody have any experience with these brands?

Almost all batteries in the US are made by only a small handful of companies.  The "private label" batteries are usually one of the standard formulations with exactly that, a label, slapped on, although some companies, such as Sears for their Die-Hard brand, set very specific standards for their private label products.

Of those you listed, Autocraft is made by GNB, Energizer is made by Johnson Controls, and CarQuest is made by East Penn.  I do not know who makes the Triple-T/Caterpillar battery.

You can look almost any battery up on Bill Darden's excellent list: http://www.uuhome.de/william.darden/batbrand.htm

Regarding using "8D's" as suggested:  First off, "8D" is a physical size (just like, for example, "Group 24"), and does not say anything about battery construction or intended use.  8D size batteries are available in several styles, as are Group 31 and a couple other common sizes.  By contrast, many BCI group sizes are only available as start batteries, and several large industrial sizes (for example, L-16) are only available as traction or deep-cycle batteries.

If you have 8D starting batteries, they aren't any better to use as house batteries than any other starting battery -- just bigger.  So having an 8D start battery is roughly the same as having about three Group 24 start batteries.  If you've already got 'em, fine, go ahead and use 'em.  But, if you are looking at buying new batteries, you are better off with ones designed for the intended use, both in terms of the dollar cost over the lifetime of the system, and in terms of how much weight you will haul around for the power delivered.

There are many, many great web sites that discuss battery technology and construction (and some really bad ones, too), and I don't want to duplicate that here.  There are dozens of variables, from basic construction and chemistry (Flooded lead-acid vs. gel vs. Absorbed Glass Mat) to plate thickness and surface area that can optimize a battery's characteristics for one or more intended uses.  Just as a quick guide, there are probably five types of batteries that folks on this forum will encounter:

• Starting.  This is for just what it says, starting engines.  Optimized to deliver high current for a very short period of time, then to be recharged at a medium rate from a single-stage charge source.  Performs this task extremely well, but does not handle long term (deep cycle) discharge tasks well at all.
• "Marine."  There is not wide-spread agreement among manufacturers on this term, and one often sees batteries also marked "RV/Marine."  Unlike a true deep-cycle battery, the marine battery is also expected, routinely, to start engines.  So this is a hybrid type of battery, where the manufacturer has attempted to balance the battery's engine-starting performance with the ability to do sustained-discharge work.
• Traction.  This is a type of deep-cycle battery intended primarily for, as the name implies, turning motors for tractive effort.  Examples are golf carts and fork lifts.  The battery is optimized for all-day use, with fairly high current loads in an on-off intermittent fashion for the whole day, down to a high depth-of-discharge.  Intended to be recharged overnight by high-quality, high-current two- or three-stage chargers, and to deliver hundreds of deep-discharge cycles.
• Telecommunications or UPS.  These batteries are optimized to spend their whole lives on a float charger, being called into actual service only very occasionally (two or three times per year).  They will handle heavy depth-of-discharge, but will not deliver very many cycles.
• "House."  This type of battery is purpose-built for RV and Marine house battery usage.  Again, there is not widespread agreement among manufacturers on this terminology.  Lifeline is a good example of this type of battery.

Note that batteries of each type are available in several different packages and constructions.  There are, for example, AGM starting batteries and AGM traction batteries, just as there are flooded-cell starting batteries and flooded-cell telecom batteries.

What battery you choose to use for your house system will depend on many factors, including where you will put them, how you will charge them, and, often, what you can get for a decent price.  Ideally, you would use a house type battery for your house system, but sometimes it works out differently.  Traction batteries make excellent house system batteries, and you may find the the L-16 form factor, which is almost exclusively available as a traction battery, fits into your battery area in such a way as to deliver more performance than, say, 8D house-type batteries.

Telecom/UPS batteries, which are really not very good candidates for house service, are often available for free as take-outs (it costs the carriers real money to dispose of these batteries in conformance with environmental regulations), and it may suit you to have sub-optimal but nearly free batteries and replace them with more nearly free batteries as needed.

Anyway, to try to wrap up a very long story, starting batteries, even if they are enormous (such as 8Ds) make the very worst house batteries.  They are very heavy for the real power delivered, they can only be discharged to around 50% before real, irreversible damage occurs, and they have lower cycle life in deep service.  None of which means anything at all if, for example, you already have a bunch of them that you'd like to use, or you have a great source for free or cheap ones, etc..

If you are starting from scratch, and have to pay real money for your batteries (and to replace them periodically), then it pays to do the research and the calculations based on how you will actually use them.

-Sean
(who has eight size 8D AGM "portable power" batteries on which he got a great deal, and who starts his bus with a pair of group-24 Ever-Starts from Wal-Mart)
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