Sealed Lead Acid Batteries: how to detect when they are exhausted?

[edaenrico]

Hi,

this thread is about Sealed Lead Acid Batteries. They are used in small UPS systmes.

this thread is NOT about car's batteries because those are not sealed.

Is there any way to detect when such a battery is exhausted?

Enrico Migliore

 

[atripathi]

By measuring terminal voltage. If terminal voltage is < threshold, you may want to treat your batteries in fully discharge state.

 

[andre_luis]

Enrico,

Are you concernig about the battery life-cicle period reached ?
If yes, take a look here : https://www.edaboard.com/threads/211083/


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[enjunear]

Many good articles on this website, but I'd start with this one.
**broken link removed**

 

[BradtheRad]

Assuming you want to know whether it's useful life is over...

A sealed battery is a question mark.

Shine a light around it, through it, etc. Try to spot the acid inside. Acid level is one clue.

Or shake the battery and listen for acid sloshing.

A deep-cycle lead-acid battery can give several years of useful service. (If it's not mistreated.)

If it's a gel cell then the useful life is about 3 or 4 years. (Although my experience with them was in the 1990's).

(1) Check its voltage. There are tables which tell State of charge (SOC) for lead-acid type.

(2) To see how much life it has, you must charge it and draw current.

(3) See if it will pass the charging current. This will tell you if it has high internal resistance (bad sign).

(4) Watch whether its voltage rises as charging continues. (If it doesn't rise over 13V then it may be deteriorated, or has a shorted cell).

(5) Disconnect charger after a few minutes. See if battery voltage stays elevated for a few minutes. (If it drops quickly then it can't hold a charge.)

(6) Test to see if it will deliver enough current to do the job at rated current for longer than a few seconds.

(7) Reconnect charger long enough to give it a full charge. Then see if it will deliver the required current for a time that meets the battery's Amp-hour rating.

 

[edaenrico]

Hi BradtheRad,

thank you for your complete and clear answer.

Enrico Migliore

 

[andre_luis]

There are some alternatives to measure battery status faster.
An inovative study obtain monitoring as internal electrode impedance :



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[BradtheRad]

There are some alternatives to measure battery status faster.
An inovative study obtain monitoring as internal electrode impedance :

This is a new one on me. Seeing how easily a range of AC frequencies goes through a battery, and that tells you what condition it's in without too long a wait.

Seems like an unlikely method. However the paper provides evidence. Looks like there's something to it.

I also remember when I was assembling a home power system 12 years ago, finding out that sulfation is a problem with lead acid batteries. And I saw devices advertised to be able to remove sulfation by...

... by sending rapid DC pulses through the battery, at a frequency which was kept a secret.

 

[spiba]

1) check the year of manufacture.
2) if the battery service life is nearing its end check as below.
3) Connect the UPS and with multimeter check if the voltage is above 13 Volts on mains without any load and in charging position. If not allow to charge for few hours as per rating of battery
4) Assuring the above now switch of the mains and observe the voltage without any load . It should be above 12V.
5)Now with 50 % of rated load applied if the voltage falls rapidly and reaches below 10.5 V in no time almost indicates the end of service life. Repeat again the FAILED battery will charge to 13V and discharge to 10.5 V in no time confirming the end of service life.

 

[ggmssr]

Hi,

this thread is about Sealed Lead Acid Batteries. They are used in small UPS systmes.

this thread is NOT about car's batteries because those are not sealed.

Is there any way to detect when such a battery is exhausted?

Enrico Migliore

You are wrong car battery can also be a gell/glass (sealed)!!!! But very expensive!

 

[Tipu606]

these days lots of car batteries are maintenance free sealed lead acid type
no need to add distilled water to top up

 

[ggmssr]

these days lots of car batteries are maintenance free sealed lead acid type
no need to add distilled water to top up

This is Ca/Ca technology.

Sealed Lead Acid Gell also used in car and other devices. This type of batteries is very expensive Gell/Glass Tech.
There is 180Ah gell battery. For car 55Ah cost about 300eur.

 

[tpetar]

Measuring voltages on battery terminals, monitoring temp and voltage curve while charging, also time of charging, monitoring and measuring internal resistance of battery.

24h after battery fully charged voltage should be 12,72-12,73V for good and new battery.

 

[andre_luis]

Measuring voltages on battery terminals, monitoring temp and voltage curve while charging, also time of charging, monitoring and measuring internal resistance of battery

It still is not clear if Enrico is searching for a way to detect if lifecicle device was reached, or if he wants just to gauge current charge status.


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[tpetar]

Maybe Enrico buy new battery and left us alone here. :smile: