Hi, For a 12V lead acid car battery, at 12.6V and a measured internal impedance of 9mOhms, is that enough info to accurately estimate the CCA of the battery, or should a battery load tester be used? cheers, Jamie
impedance meter to test car battery
Started by ●December 29, 2019
Reply by ●December 29, 20192019-12-29
On Sun, 29 Dec 2019 16:21:10 -0800, Jamie M <jmorken@shaw.ca> wrote:>Hi, > >For a 12V lead acid car battery, at 12.6V and a >measured internal impedance of 9mOhms, is that enough >info to accurately estimate the CCA of the battery, or should >a battery load tester be used?The latter. -- "When constituencies are small their elected representatives must concern themselves with the local interests of their constituents. When political representatives are distant and faceless, on the other hand, and represent vast numbers of unknown constituents, they represent not their constituents, but special interest groups whose lobbyists are numerous and ever present. Typically in Europe a technocrat is an ex-politician or a civil servant. He is unelected, virtually impossible to dislodge during his term of employment and has been granted extensive executive and even legislative power without popular mandate and without being directly answerable to the people whose interests he falsely purports to represent." - Sir James Goldsmith (Member of the European Parliament) 1933 - 1997
Reply by ●December 29, 20192019-12-29
On 2019-12-29 4:29 p.m., Cursitor Doom wrote:> On Sun, 29 Dec 2019 16:21:10 -0800, Jamie M <jmorken@shaw.ca> wrote: > >> Hi, >> >> For a 12V lead acid car battery, at 12.6V and a >> measured internal impedance of 9mOhms, is that enough >> info to accurately estimate the CCA of the battery, or should >> a battery load tester be used? > > The latter. >Thanks, Also when a car battery can no longer provide enough CCA to reliably start the car but is in otherwise "good condition", are there any disadvantages to putting a supercapacitor in parallel with the battery rather than replacing the battery with a new one? https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878 cheers, Jamie
Reply by ●December 29, 20192019-12-29
mandag den 30. december 2019 kl. 01.39.07 UTC+1 skrev Jamie M:> On 2019-12-29 4:29 p.m., Cursitor Doom wrote: > > On Sun, 29 Dec 2019 16:21:10 -0800, Jamie M <jmorken@shaw.ca> wrote: > > > >> Hi, > >> > >> For a 12V lead acid car battery, at 12.6V and a > >> measured internal impedance of 9mOhms, is that enough > >> info to accurately estimate the CCA of the battery, or should > >> a battery load tester be used? > > > > The latter. > > > > Thanks, > > Also when a car battery can no longer provide enough CCA to reliably > start the car but is in otherwise "good condition", are there any > disadvantages to putting a supercapacitor in parallel with the battery > rather than replacing the battery with a new one? > > https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878 >why bother? just get new one https://youtu.be/h7rTcBanpMk
Reply by ●December 29, 20192019-12-29
On 2019-12-29 4:46 p.m., Lasse Langwadt Christensen wrote:> mandag den 30. december 2019 kl. 01.39.07 UTC+1 skrev Jamie M: >> On 2019-12-29 4:29 p.m., Cursitor Doom wrote: >>> On Sun, 29 Dec 2019 16:21:10 -0800, Jamie M <jmorken@shaw.ca> wrote: >>> >>>> Hi, >>>> >>>> For a 12V lead acid car battery, at 12.6V and a >>>> measured internal impedance of 9mOhms, is that enough >>>> info to accurately estimate the CCA of the battery, or should >>>> a battery load tester be used? >>> >>> The latter. >>> >> >> Thanks, >> >> Also when a car battery can no longer provide enough CCA to reliably >> start the car but is in otherwise "good condition", are there any >> disadvantages to putting a supercapacitor in parallel with the battery >> rather than replacing the battery with a new one? >> >> https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878 >> > > why bother? just get new one > > https://youtu.be/h7rTcBanpMk > >I've actually seen that video (good youtuber), ironically his first sentence gives the answer to your question! (lead acid batteries are a waste of money) cheers, Jamie
Reply by ●December 29, 20192019-12-29
On Sunday, December 29, 2019 at 8:08:26 PM UTC-5, Jamie M wrote:> On 2019-12-29 4:46 p.m., Lasse Langwadt Christensen wrote: > > mandag den 30. december 2019 kl. 01.39.07 UTC+1 skrev Jamie M: > >> On 2019-12-29 4:29 p.m., Cursitor Doom wrote: > >>> On Sun, 29 Dec 2019 16:21:10 -0800, Jamie M <jmorken@shaw.ca> wrote: > >>> > >>>> Hi, > >>>> > >>>> For a 12V lead acid car battery, at 12.6V and a > >>>> measured internal impedance of 9mOhms, is that enough > >>>> info to accurately estimate the CCA of the battery, or should > >>>> a battery load tester be used? > >>> > >>> The latter. > >>> > >> > >> Thanks, > >> > >> Also when a car battery can no longer provide enough CCA to reliably > >> start the car but is in otherwise "good condition", are there any > >> disadvantages to putting a supercapacitor in parallel with the battery > >> rather than replacing the battery with a new one? > >> > >> https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878 > >> > > > > why bother? just get new one > > > > https://youtu.be/h7rTcBanpMk > > > > > > I've actually seen that video (good youtuber), ironically his first > sentence gives the answer to your question! (lead acid batteries are a > waste of money)How much is a supercapacitor that will have a useful capacity at that voltage? -- Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code - https://ts.la/richard11209
Reply by ●December 30, 20192019-12-30
On 2019-12-29 7:59 p.m., Rick C wrote:> On Sunday, December 29, 2019 at 8:08:26 PM UTC-5, Jamie M wrote: >> On 2019-12-29 4:46 p.m., Lasse Langwadt Christensen wrote: >>> mandag den 30. december 2019 kl. 01.39.07 UTC+1 skrev Jamie M: >>>> On 2019-12-29 4:29 p.m., Cursitor Doom wrote: >>>>> On Sun, 29 Dec 2019 16:21:10 -0800, Jamie M <jmorken@shaw.ca> wrote: >>>>> >>>>>> Hi, >>>>>> >>>>>> For a 12V lead acid car battery, at 12.6V and a >>>>>> measured internal impedance of 9mOhms, is that enough >>>>>> info to accurately estimate the CCA of the battery, or should >>>>>> a battery load tester be used? >>>>> >>>>> The latter. >>>>> >>>> >>>> Thanks, >>>> >>>> Also when a car battery can no longer provide enough CCA to reliably >>>> start the car but is in otherwise "good condition", are there any >>>> disadvantages to putting a supercapacitor in parallel with the battery >>>> rather than replacing the battery with a new one? >>>> >>>> https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878 >>>> >>> >>> why bother? just get new one >>> >>> https://youtu.be/h7rTcBanpMk >>> >>> >> >> I've actually seen that video (good youtuber), ironically his first >> sentence gives the answer to your question! (lead acid batteries are a >> waste of money) > > How much is a supercapacitor that will have a useful capacity at that voltage? >Under $40US on ebay (see above link) cheers, Jamie
Reply by ●December 30, 20192019-12-30
On Sunday, December 29, 2019 at 11:13:59 PM UTC-5, Jamie M wrote:> On 2019-12-29 7:59 p.m., Rick C wrote: > > On Sunday, December 29, 2019 at 8:08:26 PM UTC-5, Jamie M wrote: > >> On 2019-12-29 4:46 p.m., Lasse Langwadt Christensen wrote: > >>> mandag den 30. december 2019 kl. 01.39.07 UTC+1 skrev Jamie M: > >>>> On 2019-12-29 4:29 p.m., Cursitor Doom wrote: > >>>>> On Sun, 29 Dec 2019 16:21:10 -0800, Jamie M <jmorken@shaw.ca> wrote: > >>>>> > >>>>>> Hi, > >>>>>> > >>>>>> For a 12V lead acid car battery, at 12.6V and a > >>>>>> measured internal impedance of 9mOhms, is that enough > >>>>>> info to accurately estimate the CCA of the battery, or should > >>>>>> a battery load tester be used? > >>>>> > >>>>> The latter. > >>>>> > >>>> > >>>> Thanks, > >>>> > >>>> Also when a car battery can no longer provide enough CCA to reliably > >>>> start the car but is in otherwise "good condition", are there any > >>>> disadvantages to putting a supercapacitor in parallel with the battery > >>>> rather than replacing the battery with a new one? > >>>> > >>>> https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878 > >>>> > >>> > >>> why bother? just get new one > >>> > >>> https://youtu.be/h7rTcBanpMk > >>> > >>> > >> > >> I've actually seen that video (good youtuber), ironically his first > >> sentence gives the answer to your question! (lead acid batteries are a > >> waste of money) > > > > How much is a supercapacitor that will have a useful capacity at that voltage?Not sure how the battery and supercap will interact. On discharge, the cap will supply current at a decreasing voltage, so the battery won't supply much current until the voltage starts to drop. As the battery voltage starts to drop the battery will drain down. Once the cranking stops and the alternator starts to charge, the cap will still be at a low voltage and will suck up all the current. Do you know if the electronics in the alternator will prevent damage by charging a very high current into a low voltage? Will the current be limited? Will the alternator not try to raise the voltage immediately? I don't really know how the electronics in the alternator is designed. Regardless, I don't see the point. A new battery isn't $100. I get mine at Costco for more like $70, which is more than $40, but not enough to make me want to try to make this work. -- Rick C. + Get 1,000 miles of free Supercharging + Tesla referral code - https://ts.la/richard11209
Reply by ●December 30, 20192019-12-30
Impedance isn't a very useful measure for a couple-second surge into the nonlinear* range of operation. What frequency was the impedance measured at? Around 1Hz would seem to be more relevant. *Actually I don't think it's so much nonlinear at low voltages, but it is for similarly high voltages, so it seems worth noting. That is, you can discharge a battery with say 200A at -3V change, but you sure as hell can't charge at +3V and 200A. On a slightly less related subject, I've had good results floating car batteries. Once most of the charge is done, remaining charge current drops very slowly, like at 13.6V it might be down to 500mA after a day, 300mA after two days, etc. The further down it goes, the stronger the start. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/ "Jamie M" <jmorken@shaw.ca> wrote in message news:qubftk$uds$1@gioia.aioe.org...> Hi, > > For a 12V lead acid car battery, at 12.6V and a > measured internal impedance of 9mOhms, is that enough > info to accurately estimate the CCA of the battery, or should > a battery load tester be used? > > cheers, > Jamie
Reply by ●December 30, 20192019-12-30
On Monday, December 30, 2019 at 12:21:37 AM UTC-5, Rick C wrote:> On Sunday, December 29, 2019 at 11:13:59 PM UTC-5, Jamie M wrote: > > On 2019-12-29 7:59 p.m., Rick C wrote: > > > On Sunday, December 29, 2019 at 8:08:26 PM UTC-5, Jamie M wrote: > > >> On 2019-12-29 4:46 p.m., Lasse Langwadt Christensen wrote: > > >>> mandag den 30. december 2019 kl. 01.39.07 UTC+1 skrev Jamie M: > > >>>> On 2019-12-29 4:29 p.m., Cursitor Doom wrote: > > >>>>> On Sun, 29 Dec 2019 16:21:10 -0800, Jamie M <jmorken@shaw.ca> wrote: > > >>>>> > > >>>>>> Hi, > > >>>>>> > > >>>>>> For a 12V lead acid car battery, at 12.6V and a > > >>>>>> measured internal impedance of 9mOhms, is that enough > > >>>>>> info to accurately estimate the CCA of the battery, or should > > >>>>>> a battery load tester be used? > > >>>>> > > >>>>> The latter. > > >>>>> > > >>>> > > >>>> Thanks, > > >>>> > > >>>> Also when a car battery can no longer provide enough CCA to reliably > > >>>> start the car but is in otherwise "good condition", are there any > > >>>> disadvantages to putting a supercapacitor in parallel with the battery > > >>>> rather than replacing the battery with a new one? > > >>>> > > >>>> https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878 > > >>>> > > >>> > > >>> why bother? just get new one > > >>> > > >>> https://youtu.be/h7rTcBanpMk > > >>> > > >>> > > >> > > >> I've actually seen that video (good youtuber), ironically his first > > >> sentence gives the answer to your question! (lead acid batteries are a > > >> waste of money) > > > > > > How much is a supercapacitor that will have a useful capacity at that voltage? > > Not sure how the battery and supercap will interact. On discharge, the cap will supply current at a decreasing voltage, so the battery won't supply much current until the voltage starts to drop. As the battery voltage starts to drop the battery will drain down. Once the cranking stops and the alternator starts to charge, the cap will still be at a low voltage and will suck up all the current. Do you know if the electronics in the alternator will prevent damage by charging a very high current into a low voltage? Will the current be limited? Will the alternator not try to raise the voltage immediately? I don't really know how the electronics in the alternator is designed. > > Regardless, I don't see the point. A new battery isn't $100. I get mine at Costco for more like $70, which is more than $40, but not enough to make me want to try to make this work. > > -- > > Rick C. > > + Get 1,000 miles of free Supercharging > + Tesla referral code - https://ts.la/richard11209Price depends on the size of that battery. Larger batteries for SUVs, for example, are over $100. But that doesn't change the rest, which I agree with. A battery should last 5+ years. It's a small expense in owning a vehicle. Many places even install them for free. I would not be looking at screwing around with band-aids that could have an undesirable effect on other parts of the system.
