COACH BATTERIES

[Michael]

Very interesting Thread. Being an Electro-Mechanical Technician for
Motorola for 25 years has taught me several things, as well as owning
bus conversions for over 20 years.

1) The definition of a Technician - an Engineer's only link to
reality.

2) KISS - Keep It Simple Stupid.

3) The nice things about "standards" is there are so many to choose
from. :-)

I'm no battery expert but do know a thing or two about keeping
equipment running for long periods of time. Some designs have built
in weaknesses (series circuits), and some have built in redundancy
(parallel circuits). So 12v parallel systems are superior if you
view them from a "survival" stance. Sure you can throw more money
and more batteries into a 6v battery system, but then there's my
point.

Some batteries do have memory, some don't. Some can be damaged just
by charging with your engine's alternator, some don't. The more
expensive and high tech the battery, the more expensive and high tech
the maintenance and charging system. Thin plates on starting
batteries, thick on deep cycle, etc I do say stick to one or the
other; hybrids do both fair but is not specialized as the starting
and deep cycle.

I'm not a fan of putting thousands of dollars in battery banks, huge
inverters, and special chargers just to avoid running a generator to
use my AC's down the road. That's what generators were designed to
do. What our Engineer friend was trying to say is that ANY
connection is not as good as a straight wire. And if the straight
wire is not the correct gauge even it can be an issue.

Running 20 amps on an inverter is at least 200+ amps on the DC side.
I'm not going into details about efficiencies, etc.. but it is
probably more like 220+ amps. At those currents even a small bit of
corrosion, dirt, wrong wire size, or any other contaminant that might
cause resistance is devastating. Do you realize it would only take a
resistance of .005 ohms to loose an entire volt! It's very easy to
have that kind of resistance and not be able to find it, especially
with the added connections of a 6v system.

Running multiple batteries in a series/parallel config is superior to
running the 12v counter parts in parallel... IF..IF.. you only look
at performance! If you do believe it is the BEST choice then you too
are living in an ideal Engineers' world! There are Mean Time Between
Failure (MTBF) numbers that needs to be looked at. Even if the 6v
golf battery is superior to a cheap 12v deep cycle it does make
itself vulnerable simply by design. A bad 6v battery will bring you
down. A bad 12v battery simply needs to be removed and you can go on.

If you compare EVERY THING, the cost, size, weight, and design
limitations it doesn't make 6v batteries very appealing in my book
for the small spaces available on the older coaches. Plus, unless
you have special needs (long dry camping or running an AC) then your
bank will only be a few batteries.

Using cheap Walmart MAXX-29 batteries for $76 a piece allows you to
have 3 batteries in parallel for a rating of 375 ah. The cost is
low, the space and weight are low. The area the battery consumes is
636 cu in each. The 6v equivalent (2 batteries) has an area at
closer to 4003 cu in, over 6 times more area and how much more
weight? How much more cost? I know you can try to justify cost over
time, but with the prorating on batteries these days, we're just
renting them anyway so that has little meaning now.

Bottom line is for most people who will not take the time to do the
proper maintenance, invest big dollars in expensive
monitoring/charging systems, or have special needs, then 12v parallel
systems ARE superior to their 6v counter parts.

Hope I didn't put too much fuel on the fire?

Michael & Tami
63FC35 - "Freedom Bus"
78FC35 - "Putz'n Around"
82FC35 - parts
82 GMC RTS
Mesa, Az




--- In WanderlodgeForum@yahoogroups.com, Ron Thompson
wrote:
>
> I can't help but comment on this one.
>
> Old and new batteries mixed would most likely have eddy currents
flowing between the batteries due to deterioration of th internal
currents and would definitely have reducing effect on the AH and
therefore the cranking amps too.
>
> There are good points on both sides of this discussion. No need to
beat each other up.
>
> Oh by the way my qualifications are over 30 years experience
electronics with an engineering background. Not a graduate engineer
but definitely schooled in several good engineering schools. In
summary I was a practical applications electronic tech.
>
> Just my two cents.
>
> Ron Thompson
> 1995 WLWB 42'
>
> hippieforever3 wrote: > 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.
>
> Show me one.
>
> > You are never supposed to mix old
> > and new battreies in a battery bank!
>
> Why??? Please use science, physics or electronics or references.
>
> > 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.
>
> It is very likely that the manufacturers design almost all 6 volt
> batteries to withstand more abuse like 100% discharge, temperature
> extremes and vibration. However if you get a 12 volt battery from
the
> same manufacturer, built to the same design spec and use it in the
> same application, the 12 volt system will last longer and
outperform
> the 6 volt with less maintenance.
>
> Regards,
> GPSGary
>
>
>
>
>
>
> Ron Thompson -Waller, Tx.
> 1995 WLWB 42'Blue Bird
> (cockyfox@...)
>