12 volt SLA battery voltage questions

[Mr. Tone]

I recently purchased a 12 volt spotlight with included charger that doesn't shut off when fully charged. So I was hoping someone here would know what the resting voltage of a 12 volt SLA should be when it is fully charged? Also what is the voltage range/state of charge? Thank you in advance for any info.

 

[alpg88]

post battery capacity, and charger output in ma.

it is like asking which car is faster, this one, or that one

 

[SilverFox]

Hello Mr. Tone,

Lead Acid resting State of Charge voltages

12.65 V = 100%
12.45 V = 75%
12.24 V = 50%
12.06 V = 25%
11.89 V or less = discharged

Resting voltage is taken at room temperature and 12 - 24 hours after the completion of charging.

Tom

 

[cottonpickers]

A minute or two off the charger you should see about 13.5v. Anything over 14.4v while charging is too high imo for a sla.

At rest (left alone for 3 hours) 12.6v or higher is generally considered full.

Any battery reading exactly 12v is basically completely empty. Any battery reading less than 12v at rest (eg 10v or 11v) is shot.

Good practice is not to use more than 50% capacity from a sla before you recharge it. this may be around 12.3v-12.4v at rest (or thereabouts)

 

[Mr. Tone]

Thanks for the info guys, this is exactly what I needed to know. :twothumbs Now I only have to wait until it is dark again!

 

[TinderBox (UK)]

Hi Guys, sorry for opening an old thread.

I bought an car/mains adaptor for my notebook, and i am messing about with it.

I am powering my notebook from a 12volt 7amp SLA battery.

Now the battery voltage without load is 13.05volts , and under load after 10mins it hovering around 12.65volts , my notebook while browsing the net only pulls around 17-20watts according to my wallwart power plug meter.

EDIT : 30mins and the voltage is still at 12.62volts

My question is at what voltage should i stop powering my notebook from the SLA battery as to not cause damage to the battery.

Can the voltages in post 3, be used under load?

Thanks for any help.

John.

EDIT : my car/mains notebook adaptor manual does not give an "Low Voltage Shutdown" voltage , but after googling for a while a lot of invertor and card adaptor use between 10-11 volts for Low Voltage Shutdown

 

[CKOD]

Hi Guys, sorry for opening an old thread.

I bought an car/mains adaptor for my notebook, and i am messing about with it.

I am powering my notebook from a 12volt 7amp SLA battery.

Now the battery voltage without load is 13.05volts , and under load after 10mins it hovering around 12.65volts , my notebook while browsing the net only pulls around 17-20watts according to my wallwart power plug meter.

EDIT : 30mins and the voltage is still at 12.62volts

My question is at what voltage should i stop powering my notebook from the SLA battery as to not cause damage to the battery.

Can the voltages in post 3, be used under load?

Thanks for any help.

John.

EDIT : my car/mains notebook adaptor manual does not give an "Low Voltage Shutdown" voltage , but after googling for a while a lot of invertor and card adaptor use between 10-11 volts for Low Voltage Shutdown

Check the datasheet or search for information from the battery manufacturer. Lead acid batteries vary so much in chemestry, that the actual voltages vary depending on the type. the voltages listed above are resting, which usually means let the battery sit with no load for ~30 minutes and measure. Under lightish load that youre presenting, 11v would be an ok terminating point. Just make sure to not let it sit discharged for a while. If you have a charger which supports it, a peak/cycle charge rather then a float charge would be desireable (~14.5v, depends a lot on chemestry, check the batteries specs to get the exact voltage!) rather then the usual 13.8v float charge.