---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 02/15/22: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:52 AM - Re: Battery capacity test (bcone1381) 2. 05:33 AM - Re: Re: Battery capacity test (Werner Schneider) 3. 08:26 AM - Re: Re: Battery capacity test (Robert L. Nuckolls, III) 4. 09:24 AM - Re: Re: Battery capacity test (Alec Myers) 5. 10:26 AM - Re: Re: Battery capacity test (Robert L. Nuckolls, III) 6. 11:08 AM - Re: Re: Battery capacity test (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 04:52:35 AM PST US Subject: AeroElectric-List: Re: Battery capacity test From: "bcone1381" Help me understand how the load test is performed. Lets say I have the HF 100 amp load tester. I charge my 12V 10 AH battery in my shop for 24 hours. Do I hook it up to the Load Tester and start my handy dandy little stop watch? I think maybe I am watching the voltage and waiting for it to go down to a pre-determined level. I am guessing that Maybe my 10 AH battery ought to maintain a good voltage for 6 minutes on this 100A load tester. -------- Brooks Cone Bearhawk Patrol Kit Build Read this topic online here: http://forums.matronics.com/viewtopic.php?p=506047#506047 ________________________________ Message 2 _____________________________________ Time: 05:33:29 AM PST US Subject: Re: AeroElectric-List: Re: Battery capacity test From: Werner Schneider The instruction on the tester say, you load it for 10sec and check the display on the correct scale for CCA for your battery and depending in which scale area it is your battery is bad/weak or ok and it tells as well about compensation if below 7 deg Celsius. CCA is the value a battery can deliver for 30 sec when temperature is 0F until voltage falls below 7.2 Volt As an example the Odysee PC545 stats, CCA to be 185A, so you would at 0Fahrenheit have the capability for 30sec to load it with 185A until voltage drops to 7.2V On 15.02.2022 13:52, bcone1381 wrote: > > Help me understand how the load test is performed. Lets say I have the HF 100 amp load tester. I charge my 12V 10 AH battery in my shop for 24 hours. Do I hook it up to the Load Tester and start my handy dandy little stop watch? > > I think maybe I am watching the voltage and waiting for it to go down to a pre-determined level. I am guessing that Maybe my 10 AH battery ought to maintain a good voltage for 6 minutes on this 100A load tester. > > -------- > Brooks Cone > Bearhawk Patrol Kit Build > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=506047#506047 > > ________________________________ Message 3 _____________________________________ Time: 08:26:48 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Battery capacity test At 06:52 AM 2/15/2022, you wrote: > >Help me understand how the load test is performed. Lets say I have >the HF 100 amp load tester. I charge my 12V 10 AH battery in my >shop for 24 hours. Do I hook it up to the Load Tester and start my >handy dandy little stop watch? > >I think maybe I am watching the voltage and waiting for it to go >down to a pre-determined level. I am guessing that Maybe my 10 AH >battery ought to maintain a good voltage for 6 minutes on this 100A >load tester. Good question. There are TWO qualities of battery performance in which we have an interest. (1) Capacity: a measure of ENERGY the battery will deliver to critical loads in case of alternator failure. I.e. ENDURANCE gaols. (2) INTERNAL RESISTANCE: the ability to deliver energy into a large LOAD, like a starter. Those qualities are somewhat intertwined but not tightly. An AGM battery may well get your engine going while marginal for meeting design goals for ENDURANCE. Accurate quantification of those two qualities is accomplished with two kinds of instrumentation: (1) LOAD tester: a device capable of impressing temporary loads many times greater than your endurance loads while observing rate at which the voltage falls. (2) CAPACITY tester: a device that completely drains the battery at some test-load that is more in line design goals for ENDURANCE. The devices we've been discussing in this thread are LOAD testers. I've long and often suggested acquisition of load testers like the Harbor Freight devices: http://aeroelectric.com/Pictures/Battery_Testers/HF_Variable_Load_Tester_1.jpg and now . . . http://aeroelectric.com/Pictures/Battery_Testers/HF_Fixed_Load_Tester.jpg These devices are used to benchmark your battery's internal resistance by placing a significant load on the battery and observing ability to shoulder that load after a period of time. With the high current, variable tester we apply enough load to reduce the battery voltage to 9 volts (minimum output for cranking) for 15 seconds. We ADJUST the load to maintain the 9 volt reading. After 15 seconds, read the current. (Follow instructions on the instrument for el-cheapo). I've seen new, 18 a.h. svla products start out at 600-700A and still be grunting 500A after 15 seconds. The el-cheapo load meter topic of this thread cannot deliver so robust a load . . . but TO BE SURE . . . if the battery tests 'weak' at a piddling 100A presented by this device, you can be quite sure that the battery is toast. A CAPACITY tester is a different breed of critter. Here's one example of many: http://aeroelectric.com/Pictures/Battery_Testers/CBA2_1.jpg This is a computer driven device that lets you load a battery to some constant current (say equal to your endurance load?) and then count the electrons as you suck them out. http://aeroelectric.com/Pictures/Curves/Battery_Performance/300_vs_50mA_discharge_of_AA_cell.jpg Here's a plot of data I gathered to demonstrate the ability of a particular cell (in this case some Maxell AA alkaline cells) to service a range of loads. If we set 1.0 volts as end-of-useful-life, then a 50 mA load would be serviced TWICE as long compared to a 300 mA load. Clearly, INTERNAL resistance of these small cells has a huge influence on the cell's ability to perform at the heavier load. The bottom axis of that plot is TOTAL electrons delivered. 6x the load tosses off about half of the cell's potential energy. Here's an exemplar plot of an LiFePO4 product. http://aeroelectric.com/Pictures/Curves/Battery_Performance/LiFePO4_Discharge_Characteristics.jpg Here we see that an 8x increase in load produces an energy loss of only 11%. Short Answer: Just starting your engine conducts a practical 'load' test. If the cranking process seems to be sagging, it's TIME to to a CAPACITY test . . . but at some temperature near your bench-mark value and AFTER a significant service by a battery maintainer (topped off). This el-cheapo load-tester is of good value because for $dollars$ that wouldn't take the family to McD's for lunch it does offer useful information on battery condition. But it DOES NOT take the place of measuring your battery's ability to carry ENDURANCE loads as established by your project design goals. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 4 _____________________________________ Time: 09:24:38 AM PST US From: Alec Myers Subject: Re: AeroElectric-List: Re: Battery capacity test Is there any way to measure charge acceptance efficiency, or =9Crechar geability=9D, or is that not a criterion that degrades? Specifically, for a battery whose capacity from =9Cfully charged =9D to whatever discharge threshold is appropriate is x% of nominal, how man y times that quantity of electrons needs to be provided to restore the maxim um charge level it will hold. On Feb 15, 2022, at 11:27, Robert L. Nuckolls, III wrote: =EF=BB At 06:52 AM 2/15/2022, you wrote: > > Help me understand how the load test is performed. Lets say I have the HF 100 amp load tester. I charge my 12V 10 AH battery in my shop for 24 hours . Do I hook it up to the Load Tester and start my handy dandy little stop w atch? > > I think maybe I am watching the voltage and waiting for it to go down to a pre-determined level. I am guessing that Maybe my 10 AH battery ought to m aintain a good voltage for 6 minutes on this 100A load tester. Good question. There are TWO qualities of battery performance in which we have an interest. (1) Capacity: a measure of ENERGY the battery will deliver to critical loads in case of alternator failure. I.e. ENDURANCE gaols. (2) INTERNAL RESISTANCE: the ability to deliver energy into a large LOAD, like a starter. Those qualities are somewhat intertwined but not tightly. An AGM battery may well get your engine going while marginal for meeting design goals for ENDURANCE. Accurate quantification of those two qualities is accomplished with two kinds of instrumentation: (1) LOAD tester: a device capable of impressing temporary loads many times greater than your endurance loads while observing rate at which the voltage falls. (2) CAPACITY tester: a device that completely drains the battery at some test-load that is more in line design goals for ENDURANCE. The devices we've been discussing in this thread are LOAD testers. I've long and often suggested acquisition of load testers like the Harbor Freight devices: http://aeroelectric.com/Pictures/Battery_Testers/HF_Variable_Load_Tester_1.j pg and now . . . http://aeroelectric.com/Pictures/Battery_Testers/HF_Fixed_Load_Tester.jpg These devices are used to benchmark your battery's internal resistance by placing a significant load on the battery and observing ability to shoulder that load after a period of time. With the high current, variable tester we apply enough load to reduce the battery voltage to 9 volts (minimum output for cranking) for 15 seconds. We ADJUST the load to maintain the 9 volt reading. After 15 seconds, read the current. (Follow instructions on the instrument for el-cheapo). I've seen new, 18 a.h. svla products start out at 600-700A and still be grunting 500A after 15 seconds. The el-cheapo load meter topic of this thread cannot deliver so robust a load . . . but TO BE SURE . . . if the battery tests 'weak' at a piddling 100A presented by this device, you can be quite sure that the battery is toast. A CAPACITY tester is a different breed of critter. Here's one example of many: http://aeroelectric.com/Pictures/Battery_Testers/CBA2_1.jpg This is a computer driven device that lets you load a battery to some constant current (say equal to your endurance load?) and then count the electrons as you suck them out. http://aeroelectric.com/Pictures/Curves/Battery_Performance/300_vs_50mA_disc harge_of_AA_cell.jpg Here's a plot of data I gathered to demonstrate the ability of a particular cell (in this case some Maxell AA alkaline cells) to service a range of loads. If we set 1.0 volts as end-of-useful-life, then a 50 mA load would be serviced TWICE as long compared to a 300 mA load. Clearly, INTERNAL resistance of these small cells has a huge influence on the cell's ability to perform at the heavier load. The bottom axis of that plot is TOTAL electrons delivered. 6x the load tosses off about half of the cell's potential energy. Here's an exemplar plot of an LiFePO4 product. http://aeroelectric.com/Pictures/Curves/Battery_Performance/LiFePO4_Discharg e_Characteristics.jpg Here we see that an 8x increase in load produces an energy loss of only 11%. Short Answer: Just starting your engine conducts a practical 'load' test. If the cranking process seems to be sagging, it's TIME to to a CAPACITY test . . . but at some temperature near your bench-mark value and AFTER a significant service by a battery maintainer (topped off). This el-cheapo load-tester is of good value because for $dollars$ that wouldn't take the family to McD's for lunch it does offer useful information on battery condition. But it DOES NOT take the place of measuring your battery's ability to carry ENDURANCE loads as established by your project design goals. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 5 _____________________________________ Time: 10:26:52 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Battery capacity test At 11:23 AM 2/15/2022, you wrote: >Is there any way to measure charge acceptance efficiency, or >'rechargeability', or is that not a criterion that degrades? Absolutely . . . and yes, it is a consideration for battery designers although seldom detailed in battery performance. This it because the energy source used to charge the battery is generally much more robust than the battery . . . whether we can recharge it in say 10 hrs vs 12 hours is not generally a big deal. Further, it's also not of great concern if the energy you get out of the battery is a fraction of total energy pushed into it . But yes, I've conducted a number of tests on batteries wherein total energy to top-off is compared to total energy to end-of-life are compared. This is a measure of the energy conversion efficiency. Numbers on the order of 95% (for long, slow recharge/discharge events and VERY low resistance) to perhaps 75% for hard, rapid cycle. The biggest single influence on energy loss is battery internal resistance. Fast chargers for power tool batteries will often produce a noticeable rise in battery temperature as will hard discharges by say, quickly drilling a lot of large holes. But as the chemistry begins to wear out, internal resistance goes up as does energy loss due to internal heating. So conversion efficiency does degrade along with ability to grunt a load or keep the radio lit up. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 6 _____________________________________ Time: 11:08:43 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Battery capacity test >I am guessing that Maybe my 10 AH battery ought >to maintain a good voltage for 6 minutes >on this 100A load tester. Unfortunately, there are features of the battery and the load tester that would disprove your supposition. Download this document: http://aeroelectric.com/Mfgr_Data/Batteries/Enersys_Hawker/OdysseyPC545.pdf Note the performance figures for various loads. It's a 14 AHour battery when-new if discharged at 0.7 Amps for 20 Hours. (20 Hours x 0.7 Amps = 14 AHours) But look what happens at about 7x that load. (5.3 Amps x 2 Hours = 10.6 Ah) What happened to 3.6 Ah of capacity? It warmed the battery up. It's that pesky internal resistance thing again. Going to the top of the chart we see 128A is good for about 2 minutes or only 4.3 Ah! But if you were using your el-cheapo, HF load tester to approximate this test, it would probably terminate in smoke at less than 2 minutes. That load tester is not cooled well enough to dissipate that much energy for so long. For most of the lead-acid products sold into vehicular and portable power service, their AH energy can realized only if discharged over 20 Hours; a gentle rate that minimizes effects of internal resistance and maximizes availability of chemical energy contained therein. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.