How much current can lead acid batteries safely supply?












3














I have a motor I wish to drive with an 18V lead acid battery. The motor can draw quite a lot of current when stalling and I am worried of overdischarging the lead acid battery. Unlike LiPo batteries with have a maximum current rating, the lead acid battery only stated the "initial current", which is used for charging. The label stated not to short the battery. Hence, may I know what/how to find out the safe current to draw? How will the battery fail if I draw too much current (explode/lifespan decreased/?)? Thanks










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  • How much is 'quite a lot' of current, and for how long do you expect the motor to be 'stalling'? What is the Ah rating of the battery?
    – Bruce Abbott
    1 hour ago










  • Chien Hao Tan - Can you provide a link to the manufacturer's datasheet for the battery? And, ideally, for the motor too?
    – SamGibson
    1 hour ago












  • Usually, if I have a concern about whether the current is acceptable, I would review the datasheet for the battery to see if it has any guidelines about maximum current. I have seen some lead acid batteries that have such. But quite a few don't. Barring that, I can tell you that a typical automotive starting battery can supply at least 100 Amps, or maybe much more in some cases, for 10 or 20 seconds. Unfortunately, construction details of lead acid batteries vary quite a bit. Flooded starting batteries, deep cycle batteries. Gel cells. AGM batteries. They all are different from each other.
    – mkeith
    1 hour ago










  • When you supply the links to the battery and motor, please put them in the body of your question, not in the comment section (in other words, edit your question, don't answer in the comments).
    – mkeith
    1 hour ago
















3














I have a motor I wish to drive with an 18V lead acid battery. The motor can draw quite a lot of current when stalling and I am worried of overdischarging the lead acid battery. Unlike LiPo batteries with have a maximum current rating, the lead acid battery only stated the "initial current", which is used for charging. The label stated not to short the battery. Hence, may I know what/how to find out the safe current to draw? How will the battery fail if I draw too much current (explode/lifespan decreased/?)? Thanks










share|improve this question







New contributor




Chien Hao Tan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.




















  • How much is 'quite a lot' of current, and for how long do you expect the motor to be 'stalling'? What is the Ah rating of the battery?
    – Bruce Abbott
    1 hour ago










  • Chien Hao Tan - Can you provide a link to the manufacturer's datasheet for the battery? And, ideally, for the motor too?
    – SamGibson
    1 hour ago












  • Usually, if I have a concern about whether the current is acceptable, I would review the datasheet for the battery to see if it has any guidelines about maximum current. I have seen some lead acid batteries that have such. But quite a few don't. Barring that, I can tell you that a typical automotive starting battery can supply at least 100 Amps, or maybe much more in some cases, for 10 or 20 seconds. Unfortunately, construction details of lead acid batteries vary quite a bit. Flooded starting batteries, deep cycle batteries. Gel cells. AGM batteries. They all are different from each other.
    – mkeith
    1 hour ago










  • When you supply the links to the battery and motor, please put them in the body of your question, not in the comment section (in other words, edit your question, don't answer in the comments).
    – mkeith
    1 hour ago














3












3








3







I have a motor I wish to drive with an 18V lead acid battery. The motor can draw quite a lot of current when stalling and I am worried of overdischarging the lead acid battery. Unlike LiPo batteries with have a maximum current rating, the lead acid battery only stated the "initial current", which is used for charging. The label stated not to short the battery. Hence, may I know what/how to find out the safe current to draw? How will the battery fail if I draw too much current (explode/lifespan decreased/?)? Thanks










share|improve this question







New contributor




Chien Hao Tan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











I have a motor I wish to drive with an 18V lead acid battery. The motor can draw quite a lot of current when stalling and I am worried of overdischarging the lead acid battery. Unlike LiPo batteries with have a maximum current rating, the lead acid battery only stated the "initial current", which is used for charging. The label stated not to short the battery. Hence, may I know what/how to find out the safe current to draw? How will the battery fail if I draw too much current (explode/lifespan decreased/?)? Thanks







battery-operated lead-acid over-discharge






share|improve this question







New contributor




Chien Hao Tan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question







New contributor




Chien Hao Tan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question






New contributor




Chien Hao Tan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked 2 hours ago









Chien Hao Tan

162




162




New contributor




Chien Hao Tan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





Chien Hao Tan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Chien Hao Tan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












  • How much is 'quite a lot' of current, and for how long do you expect the motor to be 'stalling'? What is the Ah rating of the battery?
    – Bruce Abbott
    1 hour ago










  • Chien Hao Tan - Can you provide a link to the manufacturer's datasheet for the battery? And, ideally, for the motor too?
    – SamGibson
    1 hour ago












  • Usually, if I have a concern about whether the current is acceptable, I would review the datasheet for the battery to see if it has any guidelines about maximum current. I have seen some lead acid batteries that have such. But quite a few don't. Barring that, I can tell you that a typical automotive starting battery can supply at least 100 Amps, or maybe much more in some cases, for 10 or 20 seconds. Unfortunately, construction details of lead acid batteries vary quite a bit. Flooded starting batteries, deep cycle batteries. Gel cells. AGM batteries. They all are different from each other.
    – mkeith
    1 hour ago










  • When you supply the links to the battery and motor, please put them in the body of your question, not in the comment section (in other words, edit your question, don't answer in the comments).
    – mkeith
    1 hour ago


















  • How much is 'quite a lot' of current, and for how long do you expect the motor to be 'stalling'? What is the Ah rating of the battery?
    – Bruce Abbott
    1 hour ago










  • Chien Hao Tan - Can you provide a link to the manufacturer's datasheet for the battery? And, ideally, for the motor too?
    – SamGibson
    1 hour ago












  • Usually, if I have a concern about whether the current is acceptable, I would review the datasheet for the battery to see if it has any guidelines about maximum current. I have seen some lead acid batteries that have such. But quite a few don't. Barring that, I can tell you that a typical automotive starting battery can supply at least 100 Amps, or maybe much more in some cases, for 10 or 20 seconds. Unfortunately, construction details of lead acid batteries vary quite a bit. Flooded starting batteries, deep cycle batteries. Gel cells. AGM batteries. They all are different from each other.
    – mkeith
    1 hour ago










  • When you supply the links to the battery and motor, please put them in the body of your question, not in the comment section (in other words, edit your question, don't answer in the comments).
    – mkeith
    1 hour ago
















How much is 'quite a lot' of current, and for how long do you expect the motor to be 'stalling'? What is the Ah rating of the battery?
– Bruce Abbott
1 hour ago




How much is 'quite a lot' of current, and for how long do you expect the motor to be 'stalling'? What is the Ah rating of the battery?
– Bruce Abbott
1 hour ago












Chien Hao Tan - Can you provide a link to the manufacturer's datasheet for the battery? And, ideally, for the motor too?
– SamGibson
1 hour ago






Chien Hao Tan - Can you provide a link to the manufacturer's datasheet for the battery? And, ideally, for the motor too?
– SamGibson
1 hour ago














Usually, if I have a concern about whether the current is acceptable, I would review the datasheet for the battery to see if it has any guidelines about maximum current. I have seen some lead acid batteries that have such. But quite a few don't. Barring that, I can tell you that a typical automotive starting battery can supply at least 100 Amps, or maybe much more in some cases, for 10 or 20 seconds. Unfortunately, construction details of lead acid batteries vary quite a bit. Flooded starting batteries, deep cycle batteries. Gel cells. AGM batteries. They all are different from each other.
– mkeith
1 hour ago




Usually, if I have a concern about whether the current is acceptable, I would review the datasheet for the battery to see if it has any guidelines about maximum current. I have seen some lead acid batteries that have such. But quite a few don't. Barring that, I can tell you that a typical automotive starting battery can supply at least 100 Amps, or maybe much more in some cases, for 10 or 20 seconds. Unfortunately, construction details of lead acid batteries vary quite a bit. Flooded starting batteries, deep cycle batteries. Gel cells. AGM batteries. They all are different from each other.
– mkeith
1 hour ago












When you supply the links to the battery and motor, please put them in the body of your question, not in the comment section (in other words, edit your question, don't answer in the comments).
– mkeith
1 hour ago




When you supply the links to the battery and motor, please put them in the body of your question, not in the comment section (in other words, edit your question, don't answer in the comments).
– mkeith
1 hour ago










2 Answers
2






active

oldest

votes


















2














Lead acid batteries are fantastic at providing a lot of power for a short period of time. In the automotive world, this is referred to as Cold Cranking Amps. From GNB Systems FAQ page (found via a Google search):




Cranking amps are the numbers of amperes a lead-acid battery at 32 degrees F (0 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12 volt battery).




A car actually doesn't need 30 seconds, normally only a few seconds to start. But 30 seconds means you could give it a few tries before the battery (if it started charged and in good shape) becomes a problem.



Picking one battery at random from Sears DieHard, I found 730 CCA. That's 730 Amps at 12 V. That is a LOT of power.



The end result is that you have to find the right battery combination of:




  • Max. surge current or CCA

  • Total capacity, typically in Amp-hours

  • Size & weight

  • Cost


An 18 V lead-acid battery could be a tiny little thing. Or it could be like a typical car battery, only 18 V instead of 12 V.



If you are looking at a one-off or small production run you may be better off leveraging car battery technology - mature, inexpensive, easy to replace - rather than 18 V or something else more unusual. But that only works if the size & weight parameters work for your particular project.






share|improve this answer





























    1














    The max safe current is the CCA rating for 30 seconds max and 30 second intervals.



    Exceeding this may warp the plates of batteries, boil the electrolyte and with sparks create a safety hazard.



    A car starter will not exceed this rating when sized properly and the voltage will not drop below 7.5V, which is the criteria used for the CA and CCA test. This the power dissipated internally is (12.5V-7.5V) * CCA = Pmax



    e.g. 5V drop x CCA rating of 800A = 4000 Watts of heat for 30 seconds can supply 7.5V * 800 = 6000 Watts of power to the load.



    This is the maximum "safe" power transfer.



    The starting current for a DC motor is 8~10x the "rated current", and is also called the "stall current". This may be calculated or measured with a voltmeter.



    Obviously, this ages the battery faster with frequent max CCA tests and also if the left in an undercharged condition < 11.5V but cars do not typically draw the max CCA rating and the lights do not dim to half power, but if they do then battery may be weak, badly sulphated or simply have high ESR.






    share|improve this answer























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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      2














      Lead acid batteries are fantastic at providing a lot of power for a short period of time. In the automotive world, this is referred to as Cold Cranking Amps. From GNB Systems FAQ page (found via a Google search):




      Cranking amps are the numbers of amperes a lead-acid battery at 32 degrees F (0 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12 volt battery).




      A car actually doesn't need 30 seconds, normally only a few seconds to start. But 30 seconds means you could give it a few tries before the battery (if it started charged and in good shape) becomes a problem.



      Picking one battery at random from Sears DieHard, I found 730 CCA. That's 730 Amps at 12 V. That is a LOT of power.



      The end result is that you have to find the right battery combination of:




      • Max. surge current or CCA

      • Total capacity, typically in Amp-hours

      • Size & weight

      • Cost


      An 18 V lead-acid battery could be a tiny little thing. Or it could be like a typical car battery, only 18 V instead of 12 V.



      If you are looking at a one-off or small production run you may be better off leveraging car battery technology - mature, inexpensive, easy to replace - rather than 18 V or something else more unusual. But that only works if the size & weight parameters work for your particular project.






      share|improve this answer


























        2














        Lead acid batteries are fantastic at providing a lot of power for a short period of time. In the automotive world, this is referred to as Cold Cranking Amps. From GNB Systems FAQ page (found via a Google search):




        Cranking amps are the numbers of amperes a lead-acid battery at 32 degrees F (0 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12 volt battery).




        A car actually doesn't need 30 seconds, normally only a few seconds to start. But 30 seconds means you could give it a few tries before the battery (if it started charged and in good shape) becomes a problem.



        Picking one battery at random from Sears DieHard, I found 730 CCA. That's 730 Amps at 12 V. That is a LOT of power.



        The end result is that you have to find the right battery combination of:




        • Max. surge current or CCA

        • Total capacity, typically in Amp-hours

        • Size & weight

        • Cost


        An 18 V lead-acid battery could be a tiny little thing. Or it could be like a typical car battery, only 18 V instead of 12 V.



        If you are looking at a one-off or small production run you may be better off leveraging car battery technology - mature, inexpensive, easy to replace - rather than 18 V or something else more unusual. But that only works if the size & weight parameters work for your particular project.






        share|improve this answer
























          2












          2








          2






          Lead acid batteries are fantastic at providing a lot of power for a short period of time. In the automotive world, this is referred to as Cold Cranking Amps. From GNB Systems FAQ page (found via a Google search):




          Cranking amps are the numbers of amperes a lead-acid battery at 32 degrees F (0 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12 volt battery).




          A car actually doesn't need 30 seconds, normally only a few seconds to start. But 30 seconds means you could give it a few tries before the battery (if it started charged and in good shape) becomes a problem.



          Picking one battery at random from Sears DieHard, I found 730 CCA. That's 730 Amps at 12 V. That is a LOT of power.



          The end result is that you have to find the right battery combination of:




          • Max. surge current or CCA

          • Total capacity, typically in Amp-hours

          • Size & weight

          • Cost


          An 18 V lead-acid battery could be a tiny little thing. Or it could be like a typical car battery, only 18 V instead of 12 V.



          If you are looking at a one-off or small production run you may be better off leveraging car battery technology - mature, inexpensive, easy to replace - rather than 18 V or something else more unusual. But that only works if the size & weight parameters work for your particular project.






          share|improve this answer












          Lead acid batteries are fantastic at providing a lot of power for a short period of time. In the automotive world, this is referred to as Cold Cranking Amps. From GNB Systems FAQ page (found via a Google search):




          Cranking amps are the numbers of amperes a lead-acid battery at 32 degrees F (0 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12 volt battery).




          A car actually doesn't need 30 seconds, normally only a few seconds to start. But 30 seconds means you could give it a few tries before the battery (if it started charged and in good shape) becomes a problem.



          Picking one battery at random from Sears DieHard, I found 730 CCA. That's 730 Amps at 12 V. That is a LOT of power.



          The end result is that you have to find the right battery combination of:




          • Max. surge current or CCA

          • Total capacity, typically in Amp-hours

          • Size & weight

          • Cost


          An 18 V lead-acid battery could be a tiny little thing. Or it could be like a typical car battery, only 18 V instead of 12 V.



          If you are looking at a one-off or small production run you may be better off leveraging car battery technology - mature, inexpensive, easy to replace - rather than 18 V or something else more unusual. But that only works if the size & weight parameters work for your particular project.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 1 hour ago









          manassehkatz

          28916




          28916

























              1














              The max safe current is the CCA rating for 30 seconds max and 30 second intervals.



              Exceeding this may warp the plates of batteries, boil the electrolyte and with sparks create a safety hazard.



              A car starter will not exceed this rating when sized properly and the voltage will not drop below 7.5V, which is the criteria used for the CA and CCA test. This the power dissipated internally is (12.5V-7.5V) * CCA = Pmax



              e.g. 5V drop x CCA rating of 800A = 4000 Watts of heat for 30 seconds can supply 7.5V * 800 = 6000 Watts of power to the load.



              This is the maximum "safe" power transfer.



              The starting current for a DC motor is 8~10x the "rated current", and is also called the "stall current". This may be calculated or measured with a voltmeter.



              Obviously, this ages the battery faster with frequent max CCA tests and also if the left in an undercharged condition < 11.5V but cars do not typically draw the max CCA rating and the lights do not dim to half power, but if they do then battery may be weak, badly sulphated or simply have high ESR.






              share|improve this answer




























                1














                The max safe current is the CCA rating for 30 seconds max and 30 second intervals.



                Exceeding this may warp the plates of batteries, boil the electrolyte and with sparks create a safety hazard.



                A car starter will not exceed this rating when sized properly and the voltage will not drop below 7.5V, which is the criteria used for the CA and CCA test. This the power dissipated internally is (12.5V-7.5V) * CCA = Pmax



                e.g. 5V drop x CCA rating of 800A = 4000 Watts of heat for 30 seconds can supply 7.5V * 800 = 6000 Watts of power to the load.



                This is the maximum "safe" power transfer.



                The starting current for a DC motor is 8~10x the "rated current", and is also called the "stall current". This may be calculated or measured with a voltmeter.



                Obviously, this ages the battery faster with frequent max CCA tests and also if the left in an undercharged condition < 11.5V but cars do not typically draw the max CCA rating and the lights do not dim to half power, but if they do then battery may be weak, badly sulphated or simply have high ESR.






                share|improve this answer


























                  1












                  1








                  1






                  The max safe current is the CCA rating for 30 seconds max and 30 second intervals.



                  Exceeding this may warp the plates of batteries, boil the electrolyte and with sparks create a safety hazard.



                  A car starter will not exceed this rating when sized properly and the voltage will not drop below 7.5V, which is the criteria used for the CA and CCA test. This the power dissipated internally is (12.5V-7.5V) * CCA = Pmax



                  e.g. 5V drop x CCA rating of 800A = 4000 Watts of heat for 30 seconds can supply 7.5V * 800 = 6000 Watts of power to the load.



                  This is the maximum "safe" power transfer.



                  The starting current for a DC motor is 8~10x the "rated current", and is also called the "stall current". This may be calculated or measured with a voltmeter.



                  Obviously, this ages the battery faster with frequent max CCA tests and also if the left in an undercharged condition < 11.5V but cars do not typically draw the max CCA rating and the lights do not dim to half power, but if they do then battery may be weak, badly sulphated or simply have high ESR.






                  share|improve this answer














                  The max safe current is the CCA rating for 30 seconds max and 30 second intervals.



                  Exceeding this may warp the plates of batteries, boil the electrolyte and with sparks create a safety hazard.



                  A car starter will not exceed this rating when sized properly and the voltage will not drop below 7.5V, which is the criteria used for the CA and CCA test. This the power dissipated internally is (12.5V-7.5V) * CCA = Pmax



                  e.g. 5V drop x CCA rating of 800A = 4000 Watts of heat for 30 seconds can supply 7.5V * 800 = 6000 Watts of power to the load.



                  This is the maximum "safe" power transfer.



                  The starting current for a DC motor is 8~10x the "rated current", and is also called the "stall current". This may be calculated or measured with a voltmeter.



                  Obviously, this ages the battery faster with frequent max CCA tests and also if the left in an undercharged condition < 11.5V but cars do not typically draw the max CCA rating and the lights do not dim to half power, but if they do then battery may be weak, badly sulphated or simply have high ESR.







                  share|improve this answer














                  share|improve this answer



                  share|improve this answer








                  edited 28 mins ago

























                  answered 34 mins ago









                  Tony EE rocketscientist

                  61.5k22193




                  61.5k22193






















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