Battery Voltage

[BakerEdition]

Well I just checked my battery voltage with a meter...used the truck last night..and has been sitting all day..meter shows battery at 11.9 volts? guess its time to replace??

 

[tonydiv]

Just to double check the meter, see what the running voltage is. Maybe you just need a new meter


But if it rings true, then I'd see how many mA the truck draws while sitting, just to make sure that something isn't killing the battery.

Then maybe a load test on the battery before replacing it.

 

[99 Expy]

Is the battery needing to be charged everytime? I usually run them until they need to be charged frequently, but the battery could also be low on water. Pop off the caps and check the level off all the cells.

 

[BakerEdition]

maintenance free...its sealed...

 

[dougmcp]

If your meter is correct, at 11.9v your battery is about 30% charged.
There is a certain amount of loss from parasitic discharge, things like radio memory, alarm etc, but not enough to drop a battery that low.
My battery after 24 hours sits at 12.4v or so.
The low voltage indicates there is something wrong either with the charging system or the battery.
To determine which one, charge the battery completely and let it sit overnight and if the voltage is less than 12.4v I would say it needs replacing.
With a sealed maintenance free battery, the only other way of testing it is with a load tester. Most auto stores like Autozone, Pep Boys, O'Reillys etc. can do this for you at no charge.

Here is a state of charge chart that I created for golf carts which will also work for starting batteries:

 

[BakerEdition]

Well I went and bought a new battery....They tested the old one and showed a week cell and the machine said to replace...So $122.00 later I put in and check battery voltage which was 12.9 and according to my Edge programmer its 14.3 steady...even when you turn the lights on with the A/C and drop it into drive...14.3 So, with my upcoming road trip this following weekend I feel much better....Thanks for all the advise guys!!

 

[GAINMOB]

can i rely on my capacitor for my system to give me reading?

 

[panda24619]

get one of these. (just happened to be on photobucket. mine is red like this) http://t1.gstatic.com/images?q=tbn:ANd9GcRVhYhN0WV1LfhKNGoBsTcyFdAhSQEreGpFFHAyJg1zbso0vqizlVBS47vZ

i took a multimeter to the battery and its 90-95% exact. cause it only dose it to the first decimal. anyways... i have it hooked up to my radio wires. it works the way i want. when i turn on all my electronics the meter goes down. like my lights, radio, a/c, open the door, it even goes down when i roll my windows down. its just 3 wires. HOT, IGNITION, & GROUND. thats it. its easy to do too. didnt take more than 5 mins to install. and my steering wheel covers it when im driving. i just look around the steering wheel or i turn it to see what my volts are. i do that so my edge can have one more slot to monitor stuff. haha

 

[GAINMOB]

why do i need one like that? i have a capacitor the gives me a read out...i'm just asking if thats a good source to use for battery voltage or do i also need to use a meter...it stays in the 13.xx range until i really crank it up and bang it...so when stereo is off it stays constant...

 

[panda24619]

i see what you mean. as for accurate? idk. take a reading from the cap and go to the battery with a multi meter and see if its the same. if it is then its accurate. but i say to get one of those cause you can keep an eye on the volts while driving and not have to go to the back to see it.

 

[GAINMOB]

gotcha...i'll do it up when i hit the states

 

[Thermo]

As for the accuracy of the capacitor volt meters, I would call it mediocre. I'm sure some are better than others, but they are not putting in high quality things like what you would find in a multimeter. Granted, the $15 multimeters are probably no better and are using the same sort of circuit. But, I would still trust the multimeter more than the cap reading. if you need to get a gauge, find someone with say a Fluke multimeter and then compare the reading on the Fluke to what you get. The Flukes are accurate to within 0.1% if not more accurate (depending on the range). The one I have is accurate to within 0.005%. But then, it is a $200 Fluke, so, you get what you pay for. But, it does everything I need plus more.

 

[GAINMOB]

THERMO...as discussed in previous threads...i'm making that trip up to your spot...

 

[Thermo]

Freeway, you say when, I should be open to make a few projects happen.