House battery question

[Danny]

Getting ready to buy the house batteries.  What are the pros and cons of each (marine deep-cycle or 8D Deep-cycle)?

As always - thanks,

Danny

[DrivingMissLazy]

Look here: http://www.busconversions.com/bbs/index.php?topic=3071.0

ELECTRICAL SYSTEMS AND BATTERIES

Richard

[Dallas]

Pro's:

I can lift and carry Group 31 or Group 27 Marine Batteries.

I like the Ah of the 8D's.

Con's:

8D's weigh in at around 150 pounds each. I would just as soon not have to move them.

Marine batteries are a compromise between starting and deep cycle batteries.
------------------------------------------------------------------------------------------------------------------

You may want to think about using Real deep cycle batteries, something like L-16's (12V) or T-105, T-145, T-160 (6V)

good luck,
Dallas

[DrivingMissLazy]

I also found that the warrenty on the 8D's was generally not as good as that on the smaller physical size batteries.
Richard

Pro's:

I can lift and carry Group 31 or Group 27 Marine Batteries.

I like the Ah of the 8D's.

Con's:

8D's weigh in at around 150 pounds each. I would just as soon not have to move them.

Marine batteries are a compromise between starting and deep cycle batteries.
------------------------------------------------------------------------------------------------------------------

You may want to think about using Real deep cycle batteries, something like L-16's (12V) or T-105, T-145, T-160 (6V)

good luck,
Dallas

[cody]

I have 2 golf cart batteries in my bus, they are huge and I'm not looking forward to the day I have to pull them out and replace them, they have been in the coach the 3 years I've had it and all I've needed to do is clean the posts and add some water now and then, I don';t even know what kind they would be called but they sure do a great job.

[Jerry Liebler]

Danny,
     The biggest questions are: How many amp hours?  12 volt house or 24?  Do you want the monthly chore of adding water?  How big is your budget?  Others have done lots of research and found that if you'll properly maintain them (water and charge) The T105 golf cart flooded cell is the most cost effective, They are 6volt batteries at about 200 ah.  If floor space is at a premium for them and you can use heavy batteries that are 16" tall the L16s are the choice, again 6volts per but about 400 ah. they have the same footprint as the T105  If you can afford them sealed L16 are a great choice but they cost about $400 each and weigh about 125 pounds each, 4 of them gets you 800 AH of 12 volt capacity.  The 8Ds are 12 volt and not a true deep cycle battery but many are in use and work well.  With any deep cycle battery it's life is much greater if only the top 1/2 of it's capacity is ever used so you'll want to recharge them after using about 1/2 the rated capacity. Marine deep cycles aren't a good choice their cycle life is compromised by the design trade offs that allow use as starting batteries.
Regards
Jerry 4107 1120

[Danny]

If a person got 4 - 6V golf cart batteries, would you wire two in series and then the set in parallel to get it up to 12V? 

Danny

[Jerry Liebler]

Danny,
    That's the general concept.  The batteries should all be the same age and as close to identical as possible.  In an effort to keep them all the same, throught their life of many charge and discharge cycles, the wire size and length should be the same when one traces the path from one load connection to the other through either of the paralleled pairs.  The Trace inverter manuals show several arangements that provide the equal length.
Here is my crude attempt to draw one of the arrangenents .
Load +---!---+  bat 1  --!
             !                    !
             !      !---------!
             !      !
             !      !+ bat 2  -------!
             !                             !
             !----+ bat 3  --!        !
                                  !        !
                      !--------!        !
                      !                    !
                      + bat 4  -------!---- load - connection

Regards
Jerry 4107 1120

[Sean]

Folks,

Let's not confuse battery type with battery size (which is also different from capacity).

Asking "What's better, marine or 8D?" is like asking "What's better, 92 Octane or 15 gallons?"

I don't want to irritate anyone by repeating here information that is readily available either in the archives of this board or other bus boards (e.g. BNO), or at various other excellent resources such as:
http://www.phrannie.org/battery.html
http://www.windsun.com/Batteries/Battery_FAQ.htm
and many others.

However, and with due deference to my good friend Jerry, I'd like to note that any type of battery, to include starting, deep-cycle, marine (which is a type of battery that, by definition, attempts to compromise between starting and deep-cycle performance), traction, float-service (emergency back-up batteries), AE (Alternative Energy), etc. can be made in any size, such as Group 31, 8D, L-16, etc.

It is a fact that most batteries in, for example, BCI Group Size 24 will be starting batteries, while most batteries made in size L-16 will be traction batteries.  However, there are a number of sizes, notably 8D and Group 31 (among others) that are very popular form factors for a number of different uses.

One can find 8D batteries that are pure starting batteries, strict deep-cycle batteries, marine batteries, and even traction batteries (especially in EV usage) as well as AE batteries.  And one can find "marine" batteries in a wide range of BCI group sizes and including 8D.

FWIW, as stated elsewhere in many places, I believe "marine" batteries are never the right ones to use in a motor coach.  Use starting batteries for starting, and use AE, Traction, or "deep-cycle" batteries for your house systems.  What size (form factor) you choose depends on many factors, including how much capacity (in amp-hours) you need or want, what the shape of the battery compartment will look like, how much weight you want to carry, etc..  Lastly, within "type", you will often be faced with a choice of technology, to include "traditional" flooded lead-acid (which, BTW, includes many "maintenance-free" batteries that are really flooded cells, just without user-accessible caps), gelled-electrolyte, Absorbed Glass Mat (AGM), and even Lithium-Ion (yes, there are AGM starting batteries, just as there are flooded deep-cycle batteries).  Choice of technology will be driven by ease of service access, availability of proper venting, laziness of the owner, and other factors.

Choosing the right batteries is one of the often-overlooked "critical" decisions in how well your coach will perform, especially if you spend considerable time away from shore power.

Good luck on your research.

-Sean
http://ourodyssey.blogspot.com

[ChuckMC9]

"What's better, 92 Octane or 15 gallons?"

Sean - as always, masterful.

And a great quote, to boot!

[Jerry Liebler]

Sean,
     No need to defer, I agree fully with your statements, just didn't write those details in my previous post in interest of brevity and clarity. 

Danny,
    I'd like to add to what Sean said about the need for lots of consideration in choosing batteries, it's a choice many regret later.  Two attributes of the house bank are often regretted later so consider these extra carefully. Wet vs sealed; many choose wet for cost and wish for sealed soon after, you'll live with the choice for 10 years or so so think hard.  Capacity; many wish for more than they started with, batteries do loose capacity over their life, this is often not taken into account,so best to choose a capacity safely above what you think you'll need.
Regards
Jerry 4107 1120 

[Ncbob]

What is the recommended charge level for AGM Batteries?  I normally try to keep my lead/acid starting batteries at 13.6 with the occasional run to 14.6 if they've sat untapped for a while....then let them settle back to the 13.6

The AGM's are a different matter...what's the good word guys?

NCbob

[Sean]

You should set your charger to the parameters recommended by the manufacturer of your particular batteries  -- every AGM is a bit different.

I am in the middle of changing out batteries right now, so I happen to have the specs handy on my brand new Trojan 8D AGMs, which require a bulk setting of 14.1 and a float setting of 13.5.  My old Xantrex AGM batteries wanted the same float, but a much higher bulk setting of 14.4.

If the required settings are not stamped right on the batteries, you can usually find them on the web site of the battery manufacturer.

-Sean
http://ourodyssey.blogspot.com

[niles500]

Sean - did you get a good deal on the Trojan's ? - I will be interested in seeing how they work since the next time these Lifelines crash I'm leaning towards Trojan's - Thanks

[Sean]

Niles,

I'm sworn to secrecy on what I'm paying.  Infinity is happy to sell me any of a number of batteries, but they do a ton of business with Trojan and so were able to give me a better price on those.  (To explain: I get special pricing from Infinity due to a long past relationship, and I'm paying installation and fabrication labor on top of the price for the batteries.)  I think Infinity's street price on these is $418ea.  Right now, we're crossing our fingers that we can make them fit -- they are just enough larger than the Xantrex units we took out, that it will be a tight squeeze, and we'll have to rotate four of them 90 degrees from the original plan, as well as make new hold-downs and jumper cables.

If the Trojan 8D's can't be made to fit, we'll go to Discover 4D's.  They actually have a higher 20-hr rating (245 AH) in a smaller package, but they're also another $35-$40ea.  BTW, Discover also makes an 8D size with a whopping 290AH 20-hr rate.  Pricey, but worth it if you have limited space or are trying to pack more AH into an existing rack.

FWIW, I consider $1.65 per AH (@12v, 20-hr rate), exclusive of tax, shipping, installation, etc. to be a rock-bottom price on deep-cycle AGM batteries, $1.75-$1.85 per AH to be average pricing from Internet and discount vendors, and roughly $2 per AH to be the going rate for bricks-and-mortar vendors, also known as MSRP.

Current status of the project, as always, will be on our blog.  That's also where I'll be posting about how they are working out, as we develop some experience with them, so stay tuned.

-Sean
http://ourodyssey.blogspot.com