COACH BATTERIES

[hippieforever3]

> "The extra connections in a six volt system negatively impact
> reliability and efficiency,"
>
> On my two six volt Trojan T-105's, I have a "00" wire six inches long
> connecting the negative and positive to make it 12 volts.
>
> Please explain the "negative reliability and efficiency impact" of
> this "extra connection."

Two 6 volt batteries have:
two connections from terminals to plate frame
two connections from "00" wire to cable connector
two cable connector to terminal connections

more than one 12 volt battery. All subject to ohmic loss, corrosion and
vibration.

A universal premise in reliability is, the more elements the lower the
reliability.

Regards,
GPSGary

[hippieforever3]

> If you deep discharge your lead acid batteries like you suggest you
> will destroy them. That type of cycling is for Nicad and other types,
> not lead/acid.

As lead/acid batteries discharge below their "natural" cell potential
their operating characteristics enter a zone of increased internal
resistance. At some point (before damage) the current they will supply
to a resistive (incandescent) load drops to NEAR zero. The lower the
current through the incandescent load the higher its resistance will
also be.

I admit, I should have clarified that you don't leave the incandescent
load on forever. A few hours after the bulbs dimmed would be ideal.

Under no circumstances should really low resistance loads (like cables)
be used to help with the discharge.

Regards,
GPSGary

[hippieforever3]

> As others have pointed out, there are some technical issues with
your comments. I think if you research the topic you will find a
steady stream of "Lead-acid is not subject to memory' on technical
sites. Rule-of-thumb is to avoid discharge below 50% whenever
possible. I wouldn't personally go so far as to say a 100% discharge
will destroy a battery, but it will definitely shorten life.

I misused the term memory for simplicity but you guys are sticklers
for details.

Please read:
http://www.udel.edu/igert/pvcdrom/BATTERY/charlead.htm


> One other issue is this part:
> >Price vs. performance vs. reliability.
> >Two $75 55ah 12 volt batteries will be more reliable than one $150
> >100ah battery but take up twice the space
>
> As you noted correctly "sheer lead volume determines capacity" so
it is not possible to have a 100AH battery that is the same size as a
55AH battery unless the latter has an extreme amount of wasted space.

Yes atomic physics makes "sheer lead volume determines capacity" true
but characteristics like charge and discharge rates determine "useful
capacity". A good example is that a well designed and built battery
with EXACTLY the same lead weight may have double the "cranking
capacity" as a poorer designed and built battery.

Charge and discharge rates and efficiency are also effected by design
and workmanship.

After looking up the prices of the super premium DEEP CYCLE (don't
buy ANY that aren't deep cycle) and doing a cost benefit analysis, I
would recomment the following;

Buy enough good quality, (not necessarily the highest quality or
price) 12 volt deep cycle batteries that you can start the coach if
one battery shorts a cell (99% of all failures) and replace your
batteries on a periodic rotation basis WHETHER THEY FAIL OR NOT.

EX: If you buy 48 month warrantee batteries and you have 4 replace
the oldest one every year. If you can start the coach on three
batteries, you have a 100% redundant system. Reliability exceeds
99.99% by mathematical proof.

The cost benefit method would be to figure the cost per ampere hour
(a pretty good indicator of overall $ to performance) and then buy
the lowest total cost batteries that have sufficient cranking power
capacity to start the coach with a 10% margin, WITH one battery out
of the system.

I'm guessing that this would result in a system of $100-175 12 volt
batteries, maybe adding one additional spare somewhere.

Regards,
GPSGary

[Don Bradner]

On 8/9/2008 at 10:08 PM hippieforever3 wrote:

>I misused the term memory for simplicity but you guys are sticklers
>for details.

>Please read:
>http://www.udel.edu/igert/pvcdrom/BATTERY/charlead.htm

OK, I read it. I only see confirmation that 100% discharge is a bad thing. What
are you thinking it says?


>Yes atomic physics makes "sheer lead volume determines capacity" true
>but characteristics like charge and discharge rates determine "useful
>capacity". A good example is that a well designed and built battery
>with EXACTLY the same lead weight may have double the "cranking
>capacity" as a poorer designed and built battery.

True, but that's equating "useful" with cranking, when our most-common concern
is total capacity, for house use. You used AH in your 55/100 example, and that
is not cranking capacity. You will not be able to design 100AH in the same
amount of space that you would use for 55AH, no matter how good the design.


Don Bradner
90 PT40 "Blue Thunder"
My location: http://www.bbirdmaps.com/user2.cfm?user=1

[Henry Jay Hannigan]

GB:
While u r an "Engineer with a certificate"............a better answer
would have been as follows:
"The OHMS in a seven inch "00" cable is such a small RESISTANCE that
the CURRENT LOSS is probably negligible."

Instead u had to DEFEND YOUR RIDICULOUS STATEMENT WITH GOBBLY GOOK.

Regards,
Hank
90SP36





--- In WanderlodgeForum@yahoogroups.com, "hippieforever3"
wrote:
>
> > "The extra connections in a six volt system negatively impact
> > reliability and efficiency,"
> >
> > On my two six volt Trojan T-105's, I have a "00" wire six inches
long
> > connecting the negative and positive to make it 12 volts.
> >
> > Please explain the "negative reliability and efficiency impact"
of
> > this "extra connection."
>
> Two 6 volt batteries have:
> two connections from terminals to plate frame
> two connections from "00" wire to cable connector
> two cable connector to terminal connections
>
> more than one 12 volt battery. All subject to ohmic loss, corrosion
and
> vibration.
>
> A universal premise in reliability is, the more elements the lower
the
> reliability.
>
> Regards,
> GPSGary
>

[birdshill123]

I am not an engineer ( nor did I play one on TV) but what you are
suggesting goes against avery article I have ever read. Some were
written by battery mfr. engineers. You are never supposed to mix old
and new battreies in a battery bank! 6 volt golf cart batteries will
give you longer life than any common wet cell deep cycle 12 volt. They
are sturdy and made to handle frequent discharge. There is a reason why
most coach mfrs. use the 6 volt batteries. It would be cheaper to
install the 12 volts. Every solar seller also recommends the 6 volts. I
think you are way off on this one, Notwithstanding any engineering
degrees!

Bruce

1988 FC35 ( 6 -6volts)
2008 Monaco ( 8 -6 volts)

[hippieforever3]

> While u r an "Engineer with a certificate

Forget the certificate ... 30 years experience tells me (and Mil
Specs too) that the more connections there are the more there are to
fail. EVERY ADDITIONAL CONNECTION HAVE A FINITE PROBABILITY OF
FAILURE.

> "The OHMS in a seven inch "00" cable is such a small RESISTANCE
that
> the CURRENT LOSS is probably negligible."
>

The resistance in the wire is negligable, the resistance in the
multiple added connections that can loosen or corrode is not.


> Instead u had to DEFEND YOUR RIDICULOUS STATEMENT WITH GOBBLY GOOK.

But thanks for your input anyway.

Regards,
GPSGary

[jim riordan]

CAN WE BEAT AN ISSUE TO DEATH OR WHAT!

hippieforever3 wrote:

OK, first my bonafides.

I have an electrical engineering degree and worked in quality and
reliability in electronics over 30 years. While I'm not the world's
foremost expert in wet storage batteries. I have had some experience
with the quality and reliability of "backup" electrical sources.

ALL known types of rechargeable electrical storage devices (batteries
included) have "memory". The ability for the battery to absorb, store

and discharge energy is related to how much energy was stored and
discharged in recent cycles. It's very much like flexibility in
humans, if you don't slightly over stress your joints occasionally
over time you lose flexibility. You can reduce failure and extend
useful life by totally (over) depleting the battery bank once a month
or more. A perfect way to do this in an RV type application is to run
the air-conditioner until the batteries were clearly struggling then
turm on incandescent lights and leave them on for 6-12 hour AFTER you
can't see the filament glowing. Switch off all loads and use a good
REGULATED low charge rate charger, not the alternator and regulator.
Actually a trickle charger would be perfect.

Now this is not a very practical routine but the closer you could
come to the deep, deep discharge and slow full, full charge the
longer your batteries would last.

In the most basic lead storage
battery, the more lead the more
overall storage capacity so in a crude sense the heavier the battery
the more ampere-hours, unless the weight is in the case not the lead.
While shear lead volume determines capacity from the standpoint of
physics, performance is determined by configuration. The thinner the
lead plates are the faster they will charge or discharge (cranking
power). The thinner the plates are the more the battery might be
prone to failure from environmental factors like temperature and
vibration. Here is the dilemma preventing you from picking the best
battery using a scale.

One really good indicator of battery quality is the case and
terminals. Is the case a heavy thick walled rubber compound or is it
a nice thin walled high performance polymer? At the factory the cost
differential is at most $2. What they are charging retail is some
indicator of value. If you can see the plate structure, what does
the
workmanship look like? Check the materials of the terminals and the
seals. On almost all batteries the top is a separate piece. Check the
joint construction and workmanship. ANY inconsistency or voids is a
sign of lower quality craftsmanship. Check a couple of different
sizes and cases from the same manufacturer.

There is absolutely no inherent reason why 6 volt golf cart batteries
should be more capable of better handling numerous charge and
discharge cycles than 12 volt batteries although the design of any
battery will impact that and it may be a valid argument that
batteries specifically designed for full charge / discharge
applications will last longer. There are however 12 volt batteries
designed for these same cycles and the extra connections in a 6 volt
system negatively impact reliability and efficiency.

As a general rule you should get better performance and life from
sealed batteries. Typically
they will be newer designs, often made on
more modern production lines and there is far less chance that the
electrolyte will become (even slightly) contaminated or non-optimal.

Price vs. performance vs. reliability.
Two $75 55ah 12 volt batteries will be more reliable than one $150
100ah battery but take up twice the space. You can limp in on one of
the $75 cheapies and with proper care ONE of them will last longer
than the $150 battery. Will four $37.50 six volt batteries outperform
either of the other options ... Nope, if one of those four fail,
you're walking.

If you're looking at spending $500 or more on batteries, in a none
emergency replacement, it might be worthwhile to contact the
manufacturer and get the detail specs and reliability data on the
models you are considering.

Happy to help if you have questions.

Regards,
GPSGary

[hippieforever3]

> OK, I read it. I only see confirmation that 100% discharge is a bad
thing. What are you thinking it says?
>

I admitted I was unclear. 100% discharge is unhealthy but some deep
cycle batteries are designed for up to 80% discharge. As a general
rule, batteries will last the longest and provide the best service if
they are used close to the limits of their design.

It's a little like atheletes, If they never strain a little they get
weaker. If you over stress them they get damaged.

> True, but that's equating "useful" with cranking, when our most-
common concern is total capacity, for house use. You used AH in your
55/100 example, and that is not cranking capacity. You will not be
able to design 100AH in the same amount of space that you would use
for 55AH, no matter how good the design.
>

That would be true if batteries weren't made in standard sizes.
However to offer choices to the marketplace, manufacturers will stuff
the guts of a 100ah battery into EXACTLY the same case as a 55ah
battery.

The reason that the 55ah batteries exist at all is that when you buy
a new car it comes with a battery and most car manufacturers will do
almost anything to save as little as $0.50 in their costs. They
aren't equipping your new car with one ounce more lead than they have
to.

Regards,
GPSGary

[Gardner Yeaw]

GPSGary,
What you may be unaware of is that we Bird owners know that part
of the regular maintenance routine is to clean and inspect the
battery terminals. We have been round and round with the battery
situation and found, through practical experience, what works best
for us. If I were designing a space craft it would be very high on
the list to minimise the points of failure, but that is a different
situation. Using deep cycle six volt batteries cabeled up in a
series/paralell configuration has proven over time to be the right
way to go in an RV. Theory aside, practical experience has proven
the concept to be correct.

Gardner
83FC35





--- In WanderlodgeForum@yahoogroups.com, "hippieforever3"
wrote:
>
> > While u r an "Engineer with a certificate
>
> Forget the certificate ... 30 years experience tells me (and Mil
> Specs too) that the more connections there are the more there are
to
> fail. EVERY ADDITIONAL CONNECTION HAVE A FINITE PROBABILITY OF
> FAILURE.
>
> > "The OHMS in a seven inch "00" cable is such a small RESISTANCE
> that
> > the CURRENT LOSS is probably negligible."
> >
>
> The resistance in the wire is negligable, the resistance in the
> multiple added connections that can loosen or corrode is not.
>
>
> > Instead u had to DEFEND YOUR RIDICULOUS STATEMENT WITH GOBBLY
GOOK.
>
> But thanks for your input anyway.
>
> Regards,
> GPSGary
>