Recomendations: How to set up an extra battery for my system

[commsirac]

No, what you brought up originally was that temp effect the batt.?

It certainly does, both the open cell voltage and most importantly the voltage under load, starting ability.

Now read your chart, and you can clearly see that even if the battery went from almost -20 degrees to almost 50 degrees C the battery voltage will change LESS THAN 0.15 volts.?

Yes, that is open cell voltage. The only interest in open cell voltage and temperature is assessing the level of charge of the battery. An open cell voltage of 12.3V tells us the battery is half spent.

So a 12.3 battery will start a car regardless of temperature.?

No. If its a battery where 50% charge is still big compared to the starting demands of the car possibly. If its a battery on the way out 50% may not cut it, or if the temperature is low the voltage when cranking will be affected greatly too.
Its clear to me you have no idea on the terms open circuit voltage and closed circuit voltage under load. You are right the open circuit voltage varies only slightly with temperature, however, this is not the case with the voltage underload. Im only concerned with getting the car started!

I have included your original statement below

Well, actually its Kopper69's, however, it supports what Im saying, so Ill stand by it too!

Anything to add?

Please read all the information carefully.
If you really want to improve your understanding in this area, I am willing to help, however, you are not going about it the right way.

the bottom line is that the device that isolates the battery from the load at 11V is going to be useless if a battery is completely discharged at ~11.8V.
Ive given you a figure of 12.3V can be dicey. I didnt pull that out of fresh air, or even need to go to the link I found for you and others.
Its from the experience of dealing with keeping five cars on the road for the last 30 years in cold and warm conditions.

 

[VNV6VENGEANCE]

The only thing worthwhile to this thread is the suggestion to upgrade your alternator if you want to add a second battery. If you really want to talk **** about temperatures creating fluctuations in batt voltage go do it on a thread where it can supply help to someone that needs it. All he needs to know is how to get the job done.

Whats with all these keyboard warriors on here...? People come on here to learn about their rides not to listen to your crap. You guys must have better things to do...surely there are cannons lying around that you could install on your rides...?

 

[Immortality]

All he needs to know is how to get the job done.

surely there are cannons lying around that you could install on your rides...?

thats becoming a major problem with this site. people ask a simple question and you get bombarded by people who say your wasting your time, it isn't worthwile and a whole lot of technical **** that isn't important

cannons on commodores....... fairly sure no members on this site would admit to that

 

[kopper69]

The only thing worthwhile to this thread is the suggestion to upgrade your alternator if you want to add a second battery. If you really want to talk **** about temperatures creating fluctuations in batt voltage go do it on a thread where it can supply help to someone that needs it. All he needs to know is how to get the job done.

Whats with all these keyboard warriors on here...? People come on here to learn about their rides not to listen to your crap. You guys must have better things to do...surely there are cannons lying around that you could install on your rides...?

If a dual battery switch setup is employed there is probably no need for the added expense of upgrading your alternator as the alternator is only ever charging one battery. If you put the two batteries in parallel, you would need to look at upgrading your battery, but as I said above, not a good option.

 

[Tasmaniak]

I am SOOOOOOO going to get flamed for this. Get two brand new batteries that are identical same brand, size, same CCA and all the other what nots and simply parallel those bitches together.

I feel the heat coming on already.

Just to add fuel to the fire and I'm not joining anysides... I had a similar discussion with a gentleman similar to this 4months ago. He told me my car would NOT under any circumstances start if the battery is below 12.5 well I know that this was a crock and he said to bear in mind that we are in Alaska and yadda yadda yadda....long story short.

I deliberatly left my interior light on in my car. Came out the next day and measured the voltage at the battery. 12.14 Figured that I was screwed and was definetly going to need the isolated battery to start this. Thought I would try anyway...Removed as much load from the battery as I could, turned the key cranked slowly for a split second and then fired up. Battery has a build date of 5 years ago so I can only presume it's been service for at least four years.....here in Alaska.

So status...
12.1 Volts
4 year old battery that has been in hard service
-30C
Vehicle started...after a hard crank.
3.0L V6 Engine 9.3 compression ratio
Oil Viscosity 5w20 (this plays a part as well, don't forget that!)

I have some more gasoline for the fire if you folks want? LOL

Bear in mind, this is ONE vehicle....

 

[commsirac]

The only thing worthwhile to this thread is the suggestion to upgrade your alternator if you want to add a second battery. If you really want to talk **** about temperatures creating fluctuations in batt voltage go do it on a thread where it can supply help to someone that needs it. All he needs to know is how to get the job done.

Whats with all these keyboard warriors on here...? People come on here to learn about their rides not to listen to your crap. You guys must have better things to do...surely there are cannons lying around that you could install on your rides...?

Yeh, and their are self righteous experts that come along and claim only what they post is relevant.

Did you read the requirements of the person? Did you read kopper 69's replies, doesnt agree with yours.

And its not my fault if some creton wants to take me on about the perils of a device that wont isolate the battery till it drops to 11V and then doesnt know when to quit!

 

[commsirac]

I am SOOOOOOO going to get flamed for this. Get two brand new batteries that are identical same brand, size, same CCA and all the other what nots and simply parallel those bitches together.

I feel the heat coming on already.

Just to add fuel to the fire and I'm not joining anysides... I had a similar discussion with a gentleman similar to this 4months ago. He told me my car would NOT under any circumstances start if the battery is below 12.5 well I know that this was a crock and he said to bear in mind that we are in Alaska and yadda yadda yadda....long story short.

I deliberatly left my interior light on in my car. Came out the next day and measured the voltage at the battery. 12.14 Figured that I was screwed and was definetly going to need the isolated battery to start this. Thought I would try anyway...Removed as much load from the battery as I could, turned the key cranked slowly for a split second and then fired up. Battery has a build date of 5 years ago so I can only presume it's been service for at least four years.....here in Alaska.

So status...
12.1 Volts
4 year old battery that has been in hard service
-30C
Vehicle started...after a hard crank.
3.0L V6 Engine 9.3 compression ratio
Oil Viscosity 5w20 (this plays a part as well, don't forget that!)

I have some more gasoline for the fire if you folks want? LOL

Bear in mind, this is ONE vehicle....

that's impressive at -30C, what does it prove? that with ~ 50% charge the car will start and most likely the battery is still in top condition.

 

[Tasmaniak]

Actually, a 4 year old battery in Alaska is close to the end of it's life span. Most batteries here don't see it past the 5 year mark. Forgot to add the strange part. It showed a charge of 12.14 but when I got to work I tested the gravity and had an average of 1.13 which as we both know...means by battery is dead as a door nail. But then I'm not sure what effect frozen cells have on the gravity reading. Several of the cells had quite an accumulation of ice in them.

What does it prove? Absolutely ****ing nothing....was just adding. Read the last line and then untie your knickers dude...I said "this is ONE vehicle"

 

[kopper69]

Just to make a note here, battery voltage is not a good indication of battery capacity or charge. Although it is very helpful in diagnosing a faulty battery or getting a rough idea of the state of the battery, you cannot tell the definite state of the battery simply by the batteries voltage.

evil inside's post on the previous page does give an example of this. I am impressed that the car started in those conditions, but another battery with the same voltage or maybe even higher in the same conditions would not have necessarily started the car - even if it was the same type/age/whatever.

 

[BOGANV8]

Before going down the path of a second battery maybe try chucking in a YELLOW TOP OPTIMA

Best money can get i have had mine in for 2 years never ever ever ever missed a beat.. I went away one weekend to a 4wd comp to watch in my commo 2wd access.. That night i played my stereo for over 5 hrs at a loud enough volume that you could enjoy it and also ran a engel fridge freezer to keep the JIMMY cold..

Didnt start my car all weekdend till Fri 10pm till Sun 4pm and it started fine so yeah might be something to look at first investing in a really good battery YELLOW TOP OPTIMA :bow::bow::bow::bow: These are also sealed too so you can mount one in the boot, back seat, where ever and no stinky gas......