What voltage is considered 100% charge on a typical deep cycle led acid battery

[Yoda]

Moved the trailer to work in it today and noticed my GO-POWER solar display showing 100% charge but only 13.5 or 13.6 volts on the batterys. It was showing a .4 amp charge at the time (single 170 watt panel full afternoon sun) I thought full charge was over 14V. I have 2 -12V deep cycle battery in parallel and solar is connected through the central power panel and not directly to the battery's. These are the same battery's that were drained dead last winter(previous post over a year ago) They worked well moving the slide in and out several times though and no major voltage drop.

Trying to learn here
Thanks - Keith

[Guest]

Yoda,

I believe the final float stage of your charger (for FLA) is 13.8V so with a small load on the system with the switch turned on, this seems reasonable. Not to go off in the weeds but this is why a FLA charger is not the best choice for Lithium batteries which requires constant current, constant voltage at 14.2-14.6V.

Jim

[Calbar]

Yoda full charge is 12.6 volts on a typical lead acid deep cycle battery but could be between 12.5 - 12.8 or so and still be considered fully charged. Best way to confirm is to use a hydrometer to confirm fully charged.

Rob

[Cate&Rob]

According to the attached chart, 12.6V is 100% charged for lead acid. (right side of the chart) 2.1V per cell (2.1 x 6 =12.6)
This reference https://batteryuniversity.com/learn/..._with_voltages says that 2.25V x 6 = 13.5V would be on a trickle charger.

(another) Rob

[Guest]

According to the attached chart, 12.6V is 100% charged for lead acid. (right side of the chart) 2.1V per cell (2.1 x 6 =12.6)
This reference https://batteryuniversity.com/learn/..._with_voltages says that 2.25V x 6 = 13.5V would be on a trickle charger.

(another) Rob

Rob,

Battery university is such a great site where all the answers here would work, depending on the charger.

Jim

[Calbar]

According to the attached chart, 12.6V is 100% charged for lead acid. (right side of the chart) 2.1V per cell (2.1 x 6 =12.6)
This reference https://batteryuniversity.com/learn/..._with_voltages says that 2.25V x 6 = 13.5V would be on a trickle charger.

(another) Rob

Thanks for the correction Rob. Brain cramp this morning before breakfast.

Rob

[mbopp]

And to everyone who is measuring and/or worried about the difference between numbers.....12.6....12.5.....12.7, etc and whether or not their battery(s) are fully charged.....most meters are not 100% accurate. A $29 Harbor Freight meter is not nearly as likely to give an accurate measurement as a high quality DVOM.....such as a Fluke instrument. So my advice is, don't sweat the small stuff. And if you are anal enough that you absolutely have to have the exact...99.9 % accurate number to satisfy that itch, you may have to invest in a quality meter and/or have it calibrated to exacting standards. This is similar to air pressure gauges. One might read 80.5 psi....another might be 82, and another might be 79.5. Unless it is calibrated to be dead on or let's say maybe 1/2 of 1%, you basically get what you get.

The battery monitor in our Imagine quit working. I added a 3-1/2 digit voltmeter from Amazon below the monitor panel. Checking it with my good Fluke, it was way off but I managed to find the calibration pot and adjust it accordingly.

[Guest]

And to everyone who is measuring and/or worried about the difference between numbers.....12.6....12.5.....12.7, etc and whether or not their battery(s) are fully charged.....most meters are not 100% accurate. A $29 Harbor Freight meter is not nearly as likely to give an accurate measurement as a high quality DVOM.....such as a Fluke instrument. So my advice is, don't sweat the small stuff. And if you are anal enough that you absolutely have to have the exact...99.9 % accurate number to satisfy that itch, you may have to invest in a quality meter and/or have it calibrated to exacting standards. This is similar to air pressure gauges. One might read 80.5 psi....another might be 82, and another might be 79.5. Unless it is calibrated to be dead on or let's say maybe 1/2 of 1%, you basically get what you get.

Triplethreat I agree where the voltage levels I listed were with Yoda's Go Power charger connected and what looks like its in the float portion of the charge profile. The voltage levels Rob posted were open voltage and after the surface charge would have dissipated from the battery. We are splitting hairs (engineers do this sometimes), but I wanted to point out the differences in the two measurements.

And your correct in the quality of the instrument being used for an accurate measurement where the Fluke would be far better than anything from Harbor Freight or the Go Power display for that matter.

Jim

[Yoda]

Wow - Thanks folks for the wealth of information. It is greatly appreciated.

So bottom line I am OK and if I go and get the good Lithium batteries I will need a new charger. Speaking of witch I wonder where the dealer put the solar charger unless it is part of the display assembly. Ill haft to look around.

Thanks again

[Jkwilson]

For most conventional flooded cells made by Johnson Controls, East Penn and Exide, the three of which manufacture the majority of batteries in North America even with different labels, full charge voltage with no load is 12.65V. The difference between 12.6 and 12.65 is fairly significant. Trojan is an exception at 12.72V. AGMs, which are lead-acid batteries, generally range from 12.8V to 13.1V for full charge open circuit voltage.

For conventional flooded cells, battery specific gravity measured with a hydrometer is a better indication of charge state and battery condition. A battery can measure good OCV, but have reduced capacity if it needs equalizing, and specific gravity readings can identify this issue.

Not sure what the deal is with BU, as no commercial battery is at full charge at 12.6V.