lead acid battery specifications

Thread Starter

denison

Joined Oct 13, 2018
55
Hi, I have just bought a new 5A/h battery from dry power. Cannot contact them because message I get is server misconfigured.
Part of the specifications on the battery is that the standby use is 13.5-13.8v. Cycle use is 14.4-15v. I take this as meaning it wont harm the battery if you have a charging voltage equal to the cycle use? I have found that after disconnecting the charger the battery voltage immediately drops from the cycle voltage. My understanding then is that the battery voltage will then drop to the standby use and then hold at that voltage?
When I got the battery the voltage was only 12.6v which is below the standby use. I assumed that the battery needed charging.
I connected it to a 13.86v source. The charging time was 4.5 hours and the initial current was 0.378 amps dropping to 0.107a at the end of the charging period.
After disconnecting the charger I watched the no load voltage of the battery over a period of time. It started at 13.42v (already below the standby use) to 12.99v 15 hours later.
Is this battery faulty as it does not hold at the standby voltage? Or perhaps I needed a longer charging time? The web site of dry power is of no help in this regard.
The battery is to hold an electric gate lock shut. The operating current (momentary) is 1.2 amps and continuous current 175ma.The jaycar catalog quotes a 12v 4.5A/h battery as having a 20 hour rate of 200ma.
When I used the battery to operate the lock the voltage immediately dropped to 12.76v. 6 hours later the voltage had dropped to 12.31v. So there is no way this battery is going to hold the lock closed all night.
Today I am going to see another battery supplier who states the batteries are fully charged when you get them. I will check the voltage and see if it is at the srandby voltage stated on the battery.
 

sagor

Joined Mar 10, 2019
108
"Standby use" is the charging voltage when the battery is not used much, in "standby" all the time (only comes into use rarely). Cycle use is a charging voltage when the battery is actually used on and off, going through one or more cycles that discharge the battery.
Most lead acid batteries will remain around 12.6-12.8V when they are not being charged, not "standby" voltage - that is still a charging voltage, not an idle battery voltage..
The other key is, what is the 20 hour discharge rate or "your" battery? Quoting some other vendor's rate does not mean your battery is the same, though usually they are similar for the same capacity and battery chemistry...
 

TeeKay6

Joined Apr 20, 2019
382
Hi, I have just bought a new 5A/h battery from dry power. Cannot contact them because message I get is server misconfigured.
Part of the specifications on the battery is that the standby use is 13.5-13.8v. Cycle use is 14.4-15v. I take this as meaning it wont harm the battery if you have a charging voltage equal to the cycle use? I have found that after disconnecting the charger the battery voltage immediately drops from the cycle voltage. My understanding then is that the battery voltage will then drop to the standby use and then hold at that voltage?
When I got the battery the voltage was only 12.6v which is below the standby use. I assumed that the battery needed charging.
I connected it to a 13.86v source. The charging time was 4.5 hours and the initial current was 0.378 amps dropping to 0.107a at the end of the charging period.
After disconnecting the charger I watched the no load voltage of the battery over a period of time. It started at 13.42v (already below the standby use) to 12.99v 15 hours later.
Is this battery faulty as it does not hold at the standby voltage? Or perhaps I needed a longer charging time? The web site of dry power is of no help in this regard.
The battery is to hold an electric gate lock shut. The operating current (momentary) is 1.2 amps and continuous current 175ma.The jaycar catalog quotes a 12v 4.5A/h battery as having a 20 hour rate of 200ma.
When I used the battery to operate the lock the voltage immediately dropped to 12.76v. 6 hours later the voltage had dropped to 12.31v. So there is no way this battery is going to hold the lock closed all night.
Today I am going to see another battery supplier who states the batteries are fully charged when you get them. I will check the voltage and see if it is at the srandby voltage stated on the battery.
Why not charge the battery at the suggested 14.5-15V overnight before deciding it's not a good battery? After charging, let it rest for an hour and then measure the voltage. It should be somewhere above 12.6V. Then check capacity (at 175mA) again. Note that battery voltage varies with temperature; the specs are likely measured at about 25C. Further note that capacity will decline with use (only the manufacturer can tell you how much). A fully discharged 12V lead acid battery can have a terminal voltage (no load) as low as 10.8V. Finally, the battery ought to be "topped off" every once in a while; for more info, try https://batteryuniversity.com. It is common practice to choose a battery capacity much larger than calculated.
 
Last edited:

crutschow

Joined Mar 14, 2008
23,335
Yes, the normal fully charged battery voltage with no load is about 12.6V.
The higher voltages are for charging.
A lead-acid battery is typically charged with its maximum recommend charge current (constant-current) until the voltage reaches about 14.4V.
Then the charger is switched to apply a constant charge voltage of about 13.6V to maintain the battery charge (trickle charge).
 

Picbuster

Joined Dec 2, 2013
982
Hi, I have just bought a new 5A/h battery from dry power. Cannot contact them because message I get is server misconfigured.
Part of the specifications on the battery is that the standby use is 13.5-13.8v. Cycle use is 14.4-15v. I take this as meaning it wont harm the battery if you have a charging voltage equal to the cycle use? I have found that after disconnecting the charger the battery voltage immediately drops from the cycle voltage. My understanding then is that the battery voltage will then drop to the standby use and then hold at that voltage?
When I got the battery the voltage was only 12.6v which is below the standby use. I assumed that the battery needed charging.
I connected it to a 13.86v source. The charging time was 4.5 hours and the initial current was 0.378 amps dropping to 0.107a at the end of the charging period.
After disconnecting the charger I watched the no load voltage of the battery over a period of time. It started at 13.42v (already below the standby use) to 12.99v 15 hours later.
Is this battery faulty as it does not hold at the standby voltage? Or perhaps I needed a longer charging time? The web site of dry power is of no help in this regard.
The battery is to hold an electric gate lock shut. The operating current (momentary) is 1.2 amps and continuous current 175ma.The jaycar catalog quotes a 12v 4.5A/h battery as having a 20 hour rate of 200ma.
When I used the battery to operate the lock the voltage immediately dropped to 12.76v. 6 hours later the voltage had dropped to 12.31v. So there is no way this battery is going to hold the lock closed all night.
Today I am going to see another battery supplier who states the batteries are fully charged when you get them. I will check the voltage and see if it is at the standby voltage stated on the battery.
Batteries are chemical things but there are several things to know.
a: working voltage (nominal voltage) 12V
b: maximal charging voltage theoretical 16 V approx in practice normal given by producer between 13.8- 14.5V.
c: max charging current very important. If current is to high the batt will warmup and could start producing hydrogen. The pressure goes up in a closed battery. ( safety valves are present however; no good to batteries life cycle).

When fully charged it will show value under b.
The chemical process will stabilize (no load) and the voltage will drop to just above the 12V. Normal .

When a load is applied the next will happen:
The internal resistance will go up ( chemical process) so the output will go down (Ohms law).

When this battery reaches the 10.5 V the chemicals are not able to maintain the capacity.
Remove the load and place a voltmeter you measure a higher voltage again Ohms law reason your voltmeter has a very high internal resistance in compare to the battery.

The common used calculation capacity/ current (Amp/H)/ amp is the operational time is theoretical correct but in real live u should
multiply this by 0.8 approx. ( lowest voltage producing full power / nominal value).
The current goes up when the voltage drops. Power= current x voltage

Conclusion your battery is NOT defect.
Advice: do not charge above the 13.8 volt.
Higher voltage is useless it will not increase the power but it has a negative effect on batteries life time.

Picbuster
 

TeeKay6

Joined Apr 20, 2019
382
If you do that, it will take a very long time to charge a discharged battery.
Batteries are chemical things but there are several things to know.
a: working voltage (nominal voltage) 12V
b: maximal charging voltage theoretical 16 V approx in practice normal given by producer between 13.8- 14.5V.
c: max charging current very important. If current is to high the batt will warmup and could start producing hydrogen. The pressure goes up in a closed battery. ( safety valves are present however; no good to batteries life cycle).

When fully charged it will show value under b.
The chemical process will stabilize (no load) and the voltage will drop to just above the 12V. Normal .

When a load is applied the next will happen:
The internal resistance will go up ( chemical process) so the output will go down (Ohms law).

When this battery reaches the 10.5 V the chemicals are not able to maintain the capacity.
Remove the load and place a voltmeter you measure a higher voltage again Ohms law reason your voltmeter has a very high internal resistance in compare to the battery.

The common used calculation capacity/ current (Amp/H)/ amp is the operational time is theoretical correct but in real live u should
multiply this by 0.8 approx. ( lowest voltage producing full power / nominal value).
The current goes up when the voltage drops. Power= current x voltage

Conclusion your battery is NOT defect.
Advice: do not charge above the 13.8 volt.
Higher voltage is useless it will not increase the power but it has a negative effect on batteries life time.

Picbuster
"do not charge above the 13.8 volt."
13.8V will not fully charge the battery and will reduce battery life if done consistently.
 

nsaspook

Joined Aug 27, 2009
6,278
I would always include the adsorption phase of charging after bulk before the float cycle in a test of battery capacity (to be sure we are at 100% SOC). I normally calculate the end of adsorption phase by with a end-amps set-point at the fixed adsorption voltage.
https://www.victronenergy.com/upload/documents/Adaptive_charging_how_it_works.pdf

http://support.rollsbattery.com/support/solutions/articles/428-state-of-charge-charging-flooded-lead-acid-batteries
The most important part of the charge cycle is the absorption charge. Since the bulk charge only recharges the battery bank to an 80% level, the absorption charge completes the charging cycle. Most chargers on the market have a timer that allows the user to adjust the duration for the required time to return the battery to full charge. In order to set the correct time, a simple calculation is required. With the help of the 20 AH capacity, you can figure out the remaining charge required for the battery bank using the following equation:
 

crutschow

Joined Mar 14, 2008
23,335
I missed a charging stage in my discussion.
Below is the recommended three-stage charging sequence as discussed at the Battery University site.
I think the "topping charge" is the same as the "absorption charge".
They determine the end of the topping charge by monitoring the current and going to the trickle-charge voltage when the topping-charge current drops below a specified level.

Voltages are per cell, so multiply by 6 for a 12V battery.

upload_2019-10-7_10-54-24.png
 

Picbuster

Joined Dec 2, 2013
982
"do not charge above the 13.8 volt."
13.8V will not fully charge the battery and will reduce battery life if done consistently.
Disagree about life.
Lifetime traction batteries is about 3 -5 years (start current about 200Amps -300 Amps) charged to 13.8V each
When charged to 14.5++ volt 2-3 years. Same brand batteries.
We sold thousands of them over the last 10 years.
Never charge to 100% however; your are free to do so.

Picbuster
 
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