1997 Tahoe - Dual Batteries ?

On Thu, 04 May 2006 21:52:25 GMT, SnoMan > wrote:


>
>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

I've used mis-matched sets too with good results. (No, I didn't set it
up, apparently one battery was bad and the dealer replaced it with
another one, different maker, similar ratings).

The issues of parallel batteries are blown up well beyond what they
really are.

However, when I replaced those mis-matched batteries, I did go with a
couple of nice Optima's.... <g>

PeterD 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.
> >
>
> 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.

I used to run a fleet of electric boats that ran on 12V automotive
batteries.

I ran into mis matched charging with boiling problems all the time when
I tried to charge two batteries in parallel. I would come in in the
morning and one would be just a sizzling away with the other just coming
up to full.

Could be because they were discharged at different rates....

Diesel trucks run them in 24V series don't they?

I still will recommend the isolator setup.

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 Fri, 05 May 2006 09:17:33 -0400, Mike Romain >
wrote:

>I ran into mis matched charging with boiling problems all the time when
>I tried to charge two batteries in parallel. I would come in in the
>morning and one would be just a sizzling away with the other just coming
>up to full.


This is easy to understand why. When you charge them you did not
balance the cyrrent between them. WIth higher charge rates, the lencth
of circut from charge to cells can change the effective voltage and
current delievered to the cell while charging. When it doubt, use a
clamp on current probe to see what circut adjustments need to be
made.. On more thing, while it may not be practical sometimes, it is
best to use a lower charge rate when possible to recharge deep cycle
batteries as it will produce less gassing and extend their service
life.
-----------------
The SnoMan
www.thesnoman.com

SnoMan wrote:
>
> On Fri, 05 May 2006 09:17:33 -0400, Mike Romain >
> wrote:
>
> >I ran into mis matched charging with boiling problems all the time when
> >I tried to charge two batteries in parallel. I would come in in the
> >morning and one would be just a sizzling away with the other just coming
> >up to full.
>
> This is easy to understand why. When you charge them you did not
> balance the cyrrent between them. WIth higher charge rates, the lencth
> of circut from charge to cells can change the effective voltage and
> current delievered to the cell while charging. When it doubt, use a
> clamp on current probe to see what circut adjustments need to be
> made.. On more thing, while it may not be practical sometimes, it is
> best to use a lower charge rate when possible to recharge deep cycle
> batteries as it will produce less gassing and extend their service
> life.
> -----------------
> The SnoMan
> www.thesnoman.com

I was under the impression the RV isolators would balance the current in
the automotive setting so that wouldn't happen in the vehicle either...

I also have seen some that are designed for the deep cell battery charge
as the secondary battery.

If I had a second battery I would use the isolator or at least a blade
switch and do my own isolating....

As it is I have a 7 year old Optima Blue top Marine deep cycle in my CJ7
which is my daily driver and off road buggy. I haven't been able to
pull that battery down even running my winch on full load. I do have a
hand throttle to keep the alternator putting out.

It is the second one in this Jeep in the 7 years though. I broke the
first one from vibration and took this out of my wife's daily driver
Jeep 3 or 4 years ago.

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 Fri, 05 May 2006 15:46:52 -0400, Mike Romain >
wrote:

>SnoMan wrote:
>>
>> On Fri, 05 May 2006 09:17:33 -0400, Mike Romain >
>> wrote:
>>
>> >I ran into mis matched charging with boiling problems all the time when
>> >I tried to charge two batteries in parallel. I would come in in the
>> >morning and one would be just a sizzling away with the other just coming
>> >up to full.
>>
>> This is easy to understand why. When you charge them you did not
>> balance the cyrrent between them. WIth higher charge rates, the lencth
>> of circut from charge to cells can change the effective voltage and
>> current delievered to the cell while charging. When it doubt, use a
>> clamp on current probe to see what circut adjustments need to be
>> made.. On more thing, while it may not be practical sometimes, it is
>> best to use a lower charge rate when possible to recharge deep cycle
>> batteries as it will produce less gassing and extend their service
>> life.
>> -----------------
>> The SnoMan
>> www.thesnoman.com
>
>I was under the impression the RV isolators would balance the current in
>the automotive setting so that wouldn't happen in the vehicle either...
>
>I also have seen some that are designed for the deep cell battery charge
>as the secondary battery.
>
>If I had a second battery I would use the isolator or at least a blade
>switch and do my own isolating....
>
>As it is I have a 7 year old Optima Blue top Marine deep cycle in my CJ7
>which is my daily driver and off road buggy. I haven't been able to
>pull that battery down even running my winch on full load. I do have a
>hand throttle to keep the alternator putting out.
>
>It is the second one in this Jeep in the 7 years though. I broke the
>first one from vibration and took this out of my wife's daily driver
>Jeep 3 or 4 years ago.
>
>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)


By its very nature, a isolator cannot balance the current charge rate
between batteries because in order to do so it would have to have the
alt output sent to it directly and then routed to batteries through
isolator and then the isolator would have to have remote sensing at
batteries to be able to balance charge rate. The best way to try to
crudely balance them with a external charge is to place the positive
lead in the correct terminal of one battery and the negative lead on
the correct terminal of the other one as this will split the circuit
resistance between bot batteries some what (moreso than placing the
charger on one battery only). The higher the charge rate, the more of
a problem it is. On my dual battery setups in vehicles, I always run a
extra wire from alt output to second battery so it receives a better
charge rate without the bigger circut loss and it alos takes some of
the load off on main wire charging circuit too abd in theiry increase
rate of charge to both batteris at a give voltage output becaue if you
charge dual batteries at say 40 amps off of altenato. You will have
some drop in feed wire and more in circut to secon battery. With a
parrallel charge circut, the charge leads see less average load and
less voltage drop at a give load fso more power is deleivered to
battery. I also install a fuse in the extrra lead so that there is
some alt short circuit ptotection.
-----------------
The SnoMan
www.thesnoman.com

SnoMan wrote:
>
> On Fri, 05 May 2006 15:46:52 -0400, Mike Romain >
> wrote:
>
> >SnoMan wrote:
> >>
> >> On Fri, 05 May 2006 09:17:33 -0400, Mike Romain >
> >> wrote:
> >>
> >> >I ran into mis matched charging with boiling problems all the time when
> >> >I tried to charge two batteries in parallel. I would come in in the
> >> >morning and one would be just a sizzling away with the other just coming
> >> >up to full.
> >>
> >> This is easy to understand why. When you charge them you did not
> >> balance the cyrrent between them. WIth higher charge rates, the lencth
> >> of circut from charge to cells can change the effective voltage and
> >> current delievered to the cell while charging. When it doubt, use a
> >> clamp on current probe to see what circut adjustments need to be
> >> made.. On more thing, while it may not be practical sometimes, it is
> >> best to use a lower charge rate when possible to recharge deep cycle
> >> batteries as it will produce less gassing and extend their service
> >> life.
> >> -----------------
> >> The SnoMan
> >> www.thesnoman.com
> >
> >I was under the impression the RV isolators would balance the current in
> >the automotive setting so that wouldn't happen in the vehicle either...
> >
> >I also have seen some that are designed for the deep cell battery charge
> >as the secondary battery.
> >
> >If I had a second battery I would use the isolator or at least a blade
> >switch and do my own isolating....
> >
> >As it is I have a 7 year old Optima Blue top Marine deep cycle in my CJ7
> >which is my daily driver and off road buggy. I haven't been able to
> >pull that battery down even running my winch on full load. I do have a
> >hand throttle to keep the alternator putting out.
> >
> >It is the second one in this Jeep in the 7 years though. I broke the
> >first one from vibration and took this out of my wife's daily driver
> >Jeep 3 or 4 years ago.
> >
> >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)
>
> By its very nature, a isolator cannot balance the current charge rate
> between batteries because in order to do so it would have to have the
> alt output sent to it directly and then routed to batteries through
> isolator and then the isolator would have to have remote sensing at
> batteries to be able to balance charge rate.

Yup, that is the exact idea. The modern isolators get the alternator
output and send it on it's merry way with a load sensing switch. Here
is just one link:

http://www.hellroaring.com/rv.htm

Or you can try to Mickey mouse something like below....

Mike


The best way to try to
> crudely balance them with a external charge is to place the positive
> lead in the correct terminal of one battery and the negative lead on
> the correct terminal of the other one as this will split the circuit
> resistance between bot batteries some what (moreso than placing the
> charger on one battery only). The higher the charge rate, the more of
> a problem it is. On my dual battery setups in vehicles, I always run a
> extra wire from alt output to second battery so it receives a better
> charge rate without the bigger circut loss and it alos takes some of
> the load off on main wire charging circuit too abd in theiry increase
> rate of charge to both batteris at a give voltage output becaue if you
> charge dual batteries at say 40 amps off of altenato. You will have
> some drop in feed wire and more in circut to secon battery. With a
> parrallel charge circut, the charge leads see less average load and
> less voltage drop at a give load fso more power is deleivered to
> battery. I also install a fuse in the extrra lead so that there is
> some alt short circuit ptotection.
> -----------------
> The SnoMan
> www.thesnoman.com

On Sat, 06 May 2006 10:31:31 -0400, Mike Romain >
wrote:

>Yup, that is the exact idea. The modern isolators get the alternator
>output and send it on it's merry way with a load sensing switch. Here
>is just one link:
>
>http://www.hellroaring.com/rv.htm
>
>Or you can try to Mickey mouse something like below....
>
>Mike
>
>
>The best way to try to
>> crudely balance them with a external charge is to place the positive
>> lead in the correct terminal of one battery and the negative lead on
>> the correct terminal of the other one as this will split the circuit
>> resistance between bot batteries some what (moreso than placing the
>> charger on one battery only). The higher the charge rate, the more of
>> a problem it is. On my dual battery setups in vehicles, I always run a
>> extra wire from alt output to second battery so it receives a better
>> charge rate without the bigger circut loss and it alos takes some of
>> the load off on main wire charging circuit too abd in theiry increase
>> rate of charge to both batteris at a give voltage output becaue if you
>> charge dual batteries at say 40 amps off of altenato. You will have
>> some drop in feed wire and more in circut to secon battery. With a
>> parrallel charge circut, the charge leads see less average load and
>> less voltage drop at a give load fso more power is deleivered to
>> battery. I also install a fuse in the extrra lead so that there is
>> some alt short circuit ptotection.
>> -----------------
>> The SnoMan
>> www.thesnoman.com


Calling mickey mouse something that you does not understand does not
prove anything. And the link you show does not balance as I said
becuse the diagraigram they post shows alt hooked to main battery
directly then a jumper wire to secound battery and no abilty to sense
actual voltage at second battery under. The voltage will be lower at
second batteries because of addition circuit loss (the higher the rate
the more the loss) Again the ONLY truew way to balance with a isolator
is to feed alt output ONLY to ALT and they the ouput is sent to two
circuits of equal resistance so that the same relative charging
potenail is sent to both battieres. BTW I have a electrical and
mechanicl engineering background and my way is a lot less micky mouse
that the setup you suggest when it come to balancing the charge loads.
I have in the past design and install power distibution system in
large test bed aircraft and it had to be right because there is not
pulling over at 35,000 feet to fix it.
-----------------
The SnoMan
www.thesnoman.com

SnoMan wrote:
>
> On Sat, 06 May 2006 10:31:31 -0400, Mike Romain >
> wrote:
>
> >Yup, that is the exact idea. The modern isolators get the alternator
> >output and send it on it's merry way with a load sensing switch. Here
> >is just one link:
> >
> >http://www.hellroaring.com/rv.htm
> >
> >Or you can try to Mickey mouse something like below....
> >
> >Mike
> >
> >
> >The best way to try to
> >> crudely balance them with a external charge is to place the positive
> >> lead in the correct terminal of one battery and the negative lead on
> >> the correct terminal of the other one as this will split the circuit
> >> resistance between bot batteries some what (moreso than placing the
> >> charger on one battery only). The higher the charge rate, the more of
> >> a problem it is. On my dual battery setups in vehicles, I always run a
> >> extra wire from alt output to second battery so it receives a better
> >> charge rate without the bigger circut loss and it alos takes some of
> >> the load off on main wire charging circuit too abd in theiry increase
> >> rate of charge to both batteris at a give voltage output becaue if you
> >> charge dual batteries at say 40 amps off of altenato. You will have
> >> some drop in feed wire and more in circut to secon battery. With a
> >> parrallel charge circut, the charge leads see less average load and
> >> less voltage drop at a give load fso more power is deleivered to
> >> battery. I also install a fuse in the extrra lead so that there is
> >> some alt short circuit ptotection.
> >> -----------------
> >> The SnoMan
> >> www.thesnoman.com
>
> Calling mickey mouse something that you does not understand does not
> prove anything. And the link you show does not balance as I said
> becuse the diagraigram they post shows alt hooked to main battery
> directly then a jumper wire to secound battery and no abilty to sense
> actual voltage at second battery under. The voltage will be lower at
> second batteries because of addition circuit loss (the higher the rate
> the more the loss) Again the ONLY truew way to balance with a isolator
> is to feed alt output ONLY to ALT and they the ouput is sent to two
> circuits of equal resistance so that the same relative charging
> potenail is sent to both battieres. BTW I have a electrical and
> mechanicl engineering background and my way is a lot less micky mouse
> that the setup you suggest when it come to balancing the charge loads.
> I have in the past design and install power distibution system in
> large test bed aircraft and it had to be right because there is not
> pulling over at 35,000 feet to fix it.
> -----------------
> The SnoMan
> www.thesnoman.com

Yup, you write/think like an engineer all right.... Why just put in one
simple proven thing, when piles of wires and connectors can do the same
thing 'if' you are a freakin' engineer and have the equipment to
actually balance a load...

Sheesh.

The isolator in the link controls one battery or bank of batteries and
the vehicle's alternator and regulator do the job they are 'supposed' to
do and balance the other battery's load....

Just too simple eh.

Mike

Hey guys I was gone for a while and just got back , forgot all about
posting this. WOW!!!! Thanks for a ton of info , probably I should
just leave my single one in , seems like I might mess something up
because to be quite honest - LOL , I have no clue how to hook the two
up....you guys are FANTASTIC , really sincerely appreciate all these
comments on the subject.....

Tom (ScanDaBands)

On Wed, 03 May 2006 06:54:41 GMT, 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 ?
>
>It's a 1997 Chevy Tahoe LT1500 4x4 by the way