I wonder what you think about the following problem: A car's battery needs to be replaced but the exact capacity battery is not available, though smaller or larger ones are. My feeling is that the battery capacity is matched by the manufacturer with the alternator's charging capacity, so the replacement battery should also closely match the OEM battery's capacity. Is my assumption correct, or it makes not much difference to use somewhat larger capacity replacement battery than the original? I'd appreciate reading your learned opinions.
Car battery matching with alternator
Started by ●October 28, 2014
Reply by ●October 28, 20142014-10-28
On Tue, 28 Oct 2014 11:03:27 -0700, cameo <cameo@unreal.invalid> wrote:>I wonder what you think about the following problem: > >A car's battery needs to be replaced but the exact capacity battery is >not available, though smaller or larger ones are. >My feeling is that the battery capacity is matched by the manufacturer >with the alternator's charging capacity, so the replacement battery >should also closely match the OEM battery's capacity. >Is my assumption correct, or it makes not much difference to use >somewhat larger capacity replacement battery than the original? > >I'd appreciate reading your learned opinions.All you need to "match" is the case size... 24, 24F are typical passenger car sizes. I would tend toward a higher amp-hour rating when replacing... the "capacity" is _draining_, not charging... the alternator regulator will charge the battery as needed. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Reply by ●October 28, 20142014-10-28
"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote in message news:f6nv4ahtpa9svp9orefbijdvfvvk0ir16t@4ax.com...> On Tue, 28 Oct 2014 11:03:27 -0700, cameo <cameo@unreal.invalid> > wrote: > >>I wonder what you think about the following problem: >> >>A car's battery needs to be replaced but the exact capacity battery is >>not available, though smaller or larger ones are. >>My feeling is that the battery capacity is matched by the manufacturer >>with the alternator's charging capacity, so the replacement battery >>should also closely match the OEM battery's capacity. >>Is my assumption correct, or it makes not much difference to use >>somewhat larger capacity replacement battery than the original? >> >>I'd appreciate reading your learned opinions. > > All you need to "match" is the case size... 24, 24F are typical > passenger car sizes. > > I would tend toward a higher amp-hour rating when replacing... the > "capacity" is _draining_, not charging... the alternator regulator > will charge the battery as needed. > > ...Jim Thompson > -- > | James E.Thompson | mens | > | Analog Innovations | et | > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > | San Tan Valley, AZ 85142 Skype: skypeanalog | | > | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | > | E-mail Icon at http://www.analog-innovations.com | 1962 | > > I love to cook with wine. Sometimes I even put it in the food.Also need to match the terminal configuration. And maybe the holddown method.
Reply by ●October 28, 20142014-10-28
>I wonder what you think about the following problem: > >A car's battery needs to be replaced but the exact capacity battery is >not available, though smaller or larger ones are. >My feeling is that the battery capacity is matched by the manufacturer >with the alternator's charging capacity, so the replacement battery >should also closely match the OEM battery's capacity. >Is my assumption correct, or it makes not much difference to use >somewhat larger capacity replacement battery than the original? > >I'd appreciate reading your learned opinions.The matching of total battery capacity, to instantaneous maximum charging current available from the alternator, is not as critical as you seem to feel. Basically, the battery capacity is going to give you a measure of how much starting power you can pull out of the battery (over a prolonged period of cranking) before the voltage starts to drop. Larger is (again, to a first approximation) better. Once you start the car, the charge control system (alternator and control logic) is going to supply current to recharge the battery. Typically, these systems are designed as (fairly crude) "constant voltage" supplies - the alternator output is allowed to float upwards to higher voltages, but is limited by the control system to no more than around 14.4 volts (nominal). If the battery is heavily discharged, the battery will draw about as much current as the alternator can supply; the alternator's voltage won't reach 14.4 and the limiting won't occur. Once the battery is largely recharged, its terminal voltage will rise and it will draw less current from the alternator, and the charge-control system will prevent the alternator voltage from rising above 14.4 volts. If you put in a higher-capacity-than-before battery, then (if you don't deep-discharge it) starting the car will draw out a smaller proportion of the battery's stored charge. Its terminal voltage won't drop as much as would be the case in a smaller battery. It'll probably draw just about the same amount of recharge current as a smaller battery would, though, and so the alternator won't really "notice" a difference. Under conditions of really deep battery discharge, the higher-capacity battery might be able to "take" more current than your present alternator can supply. I don't believe this is harmful, though... the alternator's output voltage will simply drop (due to e.g. resistive loss in the alternator windings) and this will automatically reduce the current into the battery to what the alternator is capable of supplying. The same thing happens with your current battery, if the vehicle is idling and the alternator isn't running very quickly... its output voltage drops, the headlights dim a bit, and everything balances out. Unless there's something really unusual about your car (I believe), replacing an OEM battery with a new one having even twice the capacity shouldn't present any sort of problem (other than the physical size of the battery).
Reply by ●October 28, 20142014-10-28
On Tue, 28 Oct 2014 14:21:12 -0400, "Tom Miller" <tmiller11147@verizon.net> wrote:> >"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote in >message news:f6nv4ahtpa9svp9orefbijdvfvvk0ir16t@4ax.com... >> On Tue, 28 Oct 2014 11:03:27 -0700, cameo <cameo@unreal.invalid> >> wrote: >> >>>I wonder what you think about the following problem: >>> >>>A car's battery needs to be replaced but the exact capacity battery is >>>not available, though smaller or larger ones are. >>>My feeling is that the battery capacity is matched by the manufacturer >>>with the alternator's charging capacity, so the replacement battery >>>should also closely match the OEM battery's capacity. >>>Is my assumption correct, or it makes not much difference to use >>>somewhat larger capacity replacement battery than the original? >>> >>>I'd appreciate reading your learned opinions. >> >> All you need to "match" is the case size... 24, 24F are typical >> passenger car sizes. >> >> I would tend toward a higher amp-hour rating when replacing... the >> "capacity" is _draining_, not charging... the alternator regulator >> will charge the battery as needed. >> >> ...Jim Thompson >> -- >> | James E.Thompson | mens | >> | Analog Innovations | et | >> | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | >> | San Tan Valley, AZ 85142 Skype: skypeanalog | | >> | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | >> | E-mail Icon at http://www.analog-innovations.com | 1962 | >> >> I love to cook with wine. Sometimes I even put it in the food. > >Also need to match the terminal configuration. And maybe the holddown >method. >Yep, you might be a sick puppy and own one of those crap GM cars with batteries with side terminals >:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Reply by ●October 28, 20142014-10-28
On Tue, 28 Oct 2014 11:21:12 -0700, Tom Miller <tmiller11147@verizon.net> wrote:>>> ...snip.... > Also need to match the terminal configuration. And maybe the holddown > method. > >told by mechanics: larger battery as long as it physically fits in there. hold down method! EXACTLY, envision an autocrash and that 50 pound battery becomes a projectile with lethal strengths.
Reply by ●October 28, 20142014-10-28
On Tue, 28 Oct 2014 11:03:27 -0700, cameo wrote:> I wonder what you think about the following problem: > > A car's battery needs to be replaced but the exact capacity battery is > not available, though smaller or larger ones are. > My feeling is that the battery capacity is matched by the manufacturer > with the alternator's charging capacity, so the replacement battery > should also closely match the OEM battery's capacity. > Is my assumption correct, or it makes not much difference to use > somewhat larger capacity replacement battery than the original? > > I'd appreciate reading your learned opinions.Actually, alternators are usually sized to the electrical load that the car designers think the car will present -- cars with little electrical equipment can get by with smaller alternators, cars with lots of electrical equipment need bigger alternators. You'll find camper trucks out there with alternators up to 100A (or more: 100A in a 4-wheeled road vehicle is where my brain fuzzes over). The car has a dingus called a "regulator" in it somewhere (these days it's usually built into the alternator). This holds the voltage from the alternator to a reasonable value for battery charging, regardless of the speed of the alternator, the condition of the battery, or the electrical load. This, in turn, means that as long as the charging system is in good shape you can have a wide range of battery capacities and be perfectly fine. The bottom line is: if you get a battery the correct physical size for the car, you should be OK. Even if you go much larger, you should be fine. If you go much smaller the battery may not have enough oomph to start the car, but if you're getting the correct sized battery then that probably won't happen. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Reply by ●October 28, 20142014-10-28
On Tue, 28 Oct 2014 14:21:12 -0400, Tom Miller wrote:> "Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote > in message news:f6nv4ahtpa9svp9orefbijdvfvvk0ir16t@4ax.com... >> On Tue, 28 Oct 2014 11:03:27 -0700, cameo <cameo@unreal.invalid> wrote: >> >>>I wonder what you think about the following problem: >>> >>>A car's battery needs to be replaced but the exact capacity battery is >>>not available, though smaller or larger ones are. >>>My feeling is that the battery capacity is matched by the manufacturer >>>with the alternator's charging capacity, so the replacement battery >>>should also closely match the OEM battery's capacity. >>>Is my assumption correct, or it makes not much difference to use >>>somewhat larger capacity replacement battery than the original? >>> >>>I'd appreciate reading your learned opinions. >> >> All you need to "match" is the case size... 24, 24F are typical >> passenger car sizes. >> >> I would tend toward a higher amp-hour rating when replacing... the >> "capacity" is _draining_, not charging... the alternator regulator will >> charge the battery as needed. >> >> ...Jim Thompson >> -- >> | James E.Thompson | mens | >> | Analog Innovations | et | >> | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | >> | San Tan Valley, AZ 85142 Skype: skypeanalog | | >> | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | >> | E-mail Icon at http://www.analog-innovations.com | 1962 | >> >> I love to cook with wine. Sometimes I even put it in the food. > > Also need to match the terminal configuration. And maybe the holddown > method.All done by going into your local auto parts store and telling them what car you have. If they're competent, what comes across the counter should fit right in and work just fine. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Reply by ●October 28, 20142014-10-28
On Tue, 28 Oct 2014 13:30:29 -0500, Tim Wescott <seemywebsite@myfooter.really> wrote:>On Tue, 28 Oct 2014 14:21:12 -0400, Tom Miller wrote: > >> "Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote >> in message news:f6nv4ahtpa9svp9orefbijdvfvvk0ir16t@4ax.com... >>> On Tue, 28 Oct 2014 11:03:27 -0700, cameo <cameo@unreal.invalid> wrote: >>> >>>>I wonder what you think about the following problem: >>>> >>>>A car's battery needs to be replaced but the exact capacity battery is >>>>not available, though smaller or larger ones are. >>>>My feeling is that the battery capacity is matched by the manufacturer >>>>with the alternator's charging capacity, so the replacement battery >>>>should also closely match the OEM battery's capacity. >>>>Is my assumption correct, or it makes not much difference to use >>>>somewhat larger capacity replacement battery than the original? >>>> >>>>I'd appreciate reading your learned opinions. >>> >>> All you need to "match" is the case size... 24, 24F are typical >>> passenger car sizes. >>> >>> I would tend toward a higher amp-hour rating when replacing... the >>> "capacity" is _draining_, not charging... the alternator regulator will >>> charge the battery as needed. >>> >>> ...Jim Thompson >>> -- >>> | James E.Thompson | mens | >>> | Analog Innovations | et | >>> | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | >>> | San Tan Valley, AZ 85142 Skype: skypeanalog | | >>> | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | >>> | E-mail Icon at http://www.analog-innovations.com | 1962 | >>> >>> I love to cook with wine. Sometimes I even put it in the food. >> >> Also need to match the terminal configuration. And maybe the holddown >> method. > >All done by going into your local auto parts store and telling them what >car you have. If they're competent, what comes across the counter should >fit right in and work just fine.Yep. I just jump start, drive to Batteries Plus, and wait in the air-conditioned waiting room ;-) ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Reply by ●October 28, 20142014-10-28
"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote in message news:konv4ahpd2pm3qscr7a48n60mj5g1njivk@4ax.com...> On Tue, 28 Oct 2014 14:21:12 -0400, "Tom Miller" > <tmiller11147@verizon.net> wrote: > >> >>"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote >>in >>message news:f6nv4ahtpa9svp9orefbijdvfvvk0ir16t@4ax.com... >>> On Tue, 28 Oct 2014 11:03:27 -0700, cameo <cameo@unreal.invalid> >>> wrote: >>> >>>>I wonder what you think about the following problem: >>>> >>>>A car's battery needs to be replaced but the exact capacity battery is >>>>not available, though smaller or larger ones are. >>>>My feeling is that the battery capacity is matched by the manufacturer >>>>with the alternator's charging capacity, so the replacement battery >>>>should also closely match the OEM battery's capacity. >>>>Is my assumption correct, or it makes not much difference to use >>>>somewhat larger capacity replacement battery than the original? >>>> >>>>I'd appreciate reading your learned opinions. >>> >>> All you need to "match" is the case size... 24, 24F are typical >>> passenger car sizes. >>> >>> I would tend toward a higher amp-hour rating when replacing... the >>> "capacity" is _draining_, not charging... the alternator regulator >>> will charge the battery as needed. >>> >>> ...Jim Thompson >>> -- >>> | James E.Thompson | mens | >>> | Analog Innovations | et | >>> | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | >>> | San Tan Valley, AZ 85142 Skype: skypeanalog | | >>> | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | >>> | E-mail Icon at http://www.analog-innovations.com | 1962 | >>> >>> I love to cook with wine. Sometimes I even put it in the food. >> >>Also need to match the terminal configuration. And maybe the holddown >>method. >> > > Yep, you might be a sick puppy and own one of those crap GM cars with > batteries with side terminals >:-} > > ...Jim Thompson > -- > | James E.Thompson | mens | > | Analog Innovations | et | > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > | San Tan Valley, AZ 85142 Skype: skypeanalog | | > | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | > | E-mail Icon at http://www.analog-innovations.com | 1962 | > > I love to cook with wine. Sometimes I even put it in the food.Yep. Bought it new in 2004. Never again will I buy another GM product. It is a real piece of shit. Did I say GM is crap? GM is crap.
