1997 Tahoe - Dual Batteries ?

I have a spot for two batteries , only running one right now......350
v8 , what advantages would it be to have two.....how do they hook up
together ?

It's a 1997 Chevy Tahoe LT1500 4x4 by the way

Scan Da Bands wrote:

> I have a spot for two batteries , only running one right now......350
> v8 , what advantages would it be to have two.....how do they hook up
> together ?

Connected with an interrupting relay it could provides power for a radio,
auxiliary heating, etc. with benefits of unlimited use and without risk to
get an empty main battery for starting.

Regards,

Ralf
--
www.omnibusclub.de
Erfinder des Abgasturboladers Dr. Alfred J. Büchi: "Die Abgase,
deren noch inne-wohnende Energie bis dahin vergeudet wurde ..."

In article >,
Ralf Ballis > wrote:
#Scan Da Bands wrote:
#
#> I have a spot for two batteries , only running one right now......350
#> v8 , what advantages would it be to have two.....how do they hook up
#> together ?
#
#Connected with an interrupting relay it could provides power for a radio,
#auxiliary heating, etc. with benefits of unlimited use and without risk to
#get an empty main battery for starting.
#
#Regards,
#
#Ralf
#--
#www.omnibusclub.de
#Erfinder des Abgasturboladers Dr. Alfred J. Büchi: "Die Abgase,
#deren noch inne-wohnende Energie bis dahin vergeudet wurde ..."

If you do this, make sure the 2nd battery is a "marine" or "deep
cycle" battery. They are made to be run completely down. The
"normal" automotive batteries will wear out very quickly if run
all the way down on a regular basis.

/herb

Herb Leong wrote:

> If you do this, make sure the 2nd battery is a "marine" or "deep
> cycle" battery. They are made to be run completely down. The
> "normal" automotive batteries will wear out very quickly if run
> all the way down on a regular basis.

Of course, but sum equipments like auxiliary heating shutting down
automatically in case of low voltage.

Regards,

Ralf
--
www.omnibusclub.de
Erfinder des Abgasturboladers Dr. Alfred J. Büchi: "Die Abgase,
deren noch inne-wohnende Energie bis dahin vergeudet wurde ..."

On Wed, 03 May 2006 09:47:57 +0200, Ralf Ballis >
wrote:

>Scan Da Bands wrote:
>
>> I have a spot for two batteries , only running one right now......350
>> v8 , what advantages would it be to have two.....how do they hook up
>> together ?
>
>Connected with an interrupting relay it could provides power for a radio,
>auxiliary heating, etc. with benefits of unlimited use and without risk to
>get an empty main battery for starting.
>
>Regards,
>
>Ralf

A "better" idea is to parrallel them because you will in effect get
more than twice the battery capacity in normal usage. This is because
the efficency of a lead acid battery increases as the discharge rate
decreases. When starting car, not allow will you have more power
availble but each battery will see half the cranking load and will
beable to delivery power longer and more effecently. I use dual
batteries in my plow trucks and they are in parrallel with no
disconnect.
-----------------
The SnoMan
www.thesnoman.com

SnoMan wrote:
>
> On Wed, 03 May 2006 09:47:57 +0200, Ralf Ballis >
> wrote:
>
> >Scan Da Bands wrote:
> >
> >> I have a spot for two batteries , only running one right now......350
> >> v8 , what advantages would it be to have two.....how do they hook up
> >> together ?
> >
> >Connected with an interrupting relay it could provides power for a radio,
> >auxiliary heating, etc. with benefits of unlimited use and without risk to
> >get an empty main battery for starting.
> >
> >Regards,
> >
> >Ralf
>
> A "better" idea is to parrallel them because you will in effect get
> more than twice the battery capacity in normal usage. This is because
> the efficency of a lead acid battery increases as the discharge rate
> decreases. When starting car, not allow will you have more power
> availble but each battery will see half the cranking load and will
> beable to delivery power longer and more effecently. I use dual
> batteries in my plow trucks and they are in parrallel with no
> disconnect.
> -----------------
> The SnoMan
> www.thesnoman.com

You are very lucky. That might work in an occasional use vehicle, but
not usually in a daily driver.

Normally batteries don't wear evenly and all connections aren't perfect
so they don't charge at the same rate. This usually leads to one
battery out of a parallel set getting boiled dry while the weaker one
stays normally charged. They then discharge differently so every cycle
gets worse.

There is a good reason for the isolator setup. You never kill a battery
by the above scenario or can't start it because you left something on by
mistake or overuse.

I also agree with the marine battery for the second one. Car batteries
can go bad fast if totally run down.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

On Thu, 04 May 2006 12:19:46 -0400, Mike Romain >
wrote:

>You are very lucky. That might work in an occasional use vehicle, but
>not usually in a daily driver.
>
>Normally batteries don't wear evenly and all connections aren't perfect
>so they don't charge at the same rate. This usually leads to one
>battery out of a parallel set getting boiled dry while the weaker one
>stays normally charged. They then discharge differently so every cycle
>gets worse.


Guess what, I have been using dual batteries in some daily drivers too
and I have had none of you suggested problems and I get great battery
life. By spliting the load accross two batteries at all times you can
extend their service life. The chemical process by which a lead acid
battery makes energy sees its efficency decrease with load increase.
If you take a battery that is rated at say 140 minutes reserve (a
25amp load for 140 minutes) you would want to think that dual
batieries would give you 280 minutes when they would likely give you
around 350 or more because the battery with be a lot more efficent at
the reduced discharge rate. THey are not like taking water out of a
bottle where you get the same amount regardless of how fast you pull
it out, with those battiers the slower the rate, the more energy you
can recover.
-----------------
The SnoMan
www.thesnoman.com

SnoMan wrote:
>
> On Thu, 04 May 2006 12:19:46 -0400, Mike Romain >
> wrote:
>
> >You are very lucky. That might work in an occasional use vehicle, but
> >not usually in a daily driver.
> >
> >Normally batteries don't wear evenly and all connections aren't perfect
> >so they don't charge at the same rate. This usually leads to one
> >battery out of a parallel set getting boiled dry while the weaker one
> >stays normally charged. They then discharge differently so every cycle
> >gets worse.
>
> Guess what, I have been using dual batteries in some daily drivers too
> and I have had none of you suggested problems and I get great battery
> life.

As mentioned, you have been lucky. Using two new at the same time
identical batteries gives you a decent chance to pull that off.

Adding a second battery of a different age or make and you can wear them
out too early.

It's a gamble on connections, wear and manufacturing standards....

Plus it is damn hard on the alternator to charge two low batteries at
once....

I would rather recommend and do it the correct way.....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

On Thu, 04 May 2006 12:19:46 -0400, Mike Romain >
wrote:


>
>You are very lucky. That might work in an occasional use vehicle, but
>not usually in a daily driver.
>

Gee, Mike, you're usually right, but I'll disagree on this one.
Millions of diesel trucks use two parallel batteries, successfully,
and have them last just as long as a single battery.

On Thu, 04 May 2006 17:10:52 -0400, Mike Romain >
wrote:

>
>As mentioned, you have been lucky. Using two new at the same time
>identical batteries gives you a decent chance to pull that off.


I have used unmatched sets too. Also long as they are the same type,
ie maintainance free or not and do not mix a deep cycle with a
standard battery in parrallel.
-----------------
The SnoMan
www.thesnoman.com