second battery
3rd Gear Member
Joined: Jul 2007
Posts: 992
From:
RE: second battery
the 1st battery doesnt recharge anything. there is current flowing through the wires and when your system needs more power it draws from your batteries. they are then gradually recharged by youre alternator while its running. the 2nd battery just increases your reserve.
Joined: Apr 2008
Posts: 7
RE: second battery
ORIGINAL: PReal
Actually your physics are somewhat right but you arestill 100% wrong in your reasoning.
I have two batteries in my car. I have two Optima 75 series red tops in parrallel in the battery tray. This is overkill, but one of the optimas was free. I jsut wanted to provide some insight into wheter or not I have two batteries.
Here are where your physics are 100% wrong.
1) in a perfect world the static pressure across two vessels in parrel will remian constant and equal. That is a fact. Two car batteries will also remain constant and equal when static. The problem is that your car's electrical system is in no way whatsoever static when your car is running or the stereo is on, it is dynamic.
2) Since we have estabilshed the fact your car's electrical system is dynamic lets consider that effect on our little battery addition. Every battery has an internal resistance to charge related to metallurgy and chemistry of the battery. There is also wire that has resistance leading to each battery.Your charging system will see an equivalent load from the system but the effects on each circuit can be verydifferent. In order to maintain a relativley constant voltage between the battiers your charging system will in turn send current to each battery.If the resistance of the smaller batteryand its wiring is significanly higher then the largerbattery then it will build more heat to achieve thesame voltage level. If the difference is drastic and the battery was in no way designed for that application it could easily overheat and crack or explode. I have personally seen a battery explode on a charger and would never want something like that occuring in thetrunk of my car.
3) If the voltage of one battery in a parrallel system drops, please explain how the other raises the "pathetic" one's voltage. In a parrallel system all batteries are drained at the same rate and basically make one huge battery with a a very high current capacity. You might want to look at that high school physics book and research how batteriesin parrallel and series operate.
4) I'd love for you to explain the differences between primary and secondarycell batteries.
5) Since you are trying to prove your immense knowledge, get a dyno test of that claim on the alternator. I'd love to see a graph of the difference the alt pulley makes in HP on a number of differentvehicles and enigne sizes.If you can determine the precise amount of horsepower your hand exerts to make an alt pulleyturn,then you must be a genius. If you are that smart you shouldn't be driving a V6 mustang or hanging out at such an uneducated forum.
Actually your physics are somewhat right but you arestill 100% wrong in your reasoning.
I have two batteries in my car. I have two Optima 75 series red tops in parrallel in the battery tray. This is overkill, but one of the optimas was free. I jsut wanted to provide some insight into wheter or not I have two batteries.
Here are where your physics are 100% wrong.
1) in a perfect world the static pressure across two vessels in parrel will remian constant and equal. That is a fact. Two car batteries will also remain constant and equal when static. The problem is that your car's electrical system is in no way whatsoever static when your car is running or the stereo is on, it is dynamic.
2) Since we have estabilshed the fact your car's electrical system is dynamic lets consider that effect on our little battery addition. Every battery has an internal resistance to charge related to metallurgy and chemistry of the battery. There is also wire that has resistance leading to each battery.Your charging system will see an equivalent load from the system but the effects on each circuit can be verydifferent. In order to maintain a relativley constant voltage between the battiers your charging system will in turn send current to each battery.If the resistance of the smaller batteryand its wiring is significanly higher then the largerbattery then it will build more heat to achieve thesame voltage level. If the difference is drastic and the battery was in no way designed for that application it could easily overheat and crack or explode. I have personally seen a battery explode on a charger and would never want something like that occuring in thetrunk of my car.
3) If the voltage of one battery in a parrallel system drops, please explain how the other raises the "pathetic" one's voltage. In a parrallel system all batteries are drained at the same rate and basically make one huge battery with a a very high current capacity. You might want to look at that high school physics book and research how batteriesin parrallel and series operate.
4) I'd love for you to explain the differences between primary and secondarycell batteries.
5) Since you are trying to prove your immense knowledge, get a dyno test of that claim on the alternator. I'd love to see a graph of the difference the alt pulley makes in HP on a number of differentvehicles and enigne sizes.If you can determine the precise amount of horsepower your hand exerts to make an alt pulleyturn,then you must be a genius. If you are that smart you shouldn't be driving a V6 mustang or hanging out at such an uneducated forum.
I never got involved in the alternator/HP argument, but I can tell you from dyno graphs (alternator dyno,not engine dyno) that a large case 3G alternator with OEM rotor and stator requires 9HP to drive at 12,000rpm rotor speed and maximum load; and just shy of 3hp to drive with no load (fan and bearing resistance only) at 12,000rpm rotor speed.These tests are performed with a 6rip serpentine belt at standard tension.
This datadoesn't tell you theenergyrequired to acceleratethe rotatingmass of the rotor/fan, nor does it tell you the difference in drag between pulley ratios, but I thought it might be usefull info.
6th Gear Member
Joined: Feb 2006
Posts: 6,936
From:
RE: second battery
hey jerky, THOSE AIN'T LAWM MOWER BATTERIES! The cheapest one you find on there is $200, you must have ahell of a lawn mower and why would you supplement a $70 old cheapo with a $200 200CCA battery?
I did a couple of searches for lawm mower batteries in cars and the only info I find on there was from the lawn mowers recommendation to NOT charge a lawn mower battery with a car as anything more then 2A of current will over charge the battery, and can cause it to heat up, crack and explode. I guess everyone missed the memo..........
Please you guys, go buy a camaro or maybe a cute little import with a big wing...
I did a couple of searches for lawm mower batteries in cars and the only info I find on there was from the lawn mowers recommendation to NOT charge a lawn mower battery with a car as anything more then 2A of current will over charge the battery, and can cause it to heat up, crack and explode. I guess everyone missed the memo..........
Please you guys, go buy a camaro or maybe a cute little import with a big wing...
Joined: Apr 2008
Posts: 7
RE: second battery
ORIGINAL: 07lane40
i believe the point was the OP did not use one of these specifically used batteries and just threw a random lawnmower battery in to act as a large capacitor. which was slightly retarded. yeah a specified battery for this particular install would be acceptable to use. because its for that particular use. a lawn mower battery is for a lawn mower. not a car.
i believe the point was the OP did not use one of these specifically used batteries and just threw a random lawnmower battery in to act as a large capacitor. which was slightly retarded. yeah a specified battery for this particular install would be acceptable to use. because its for that particular use. a lawn mower battery is for a lawn mower. not a car.
He threw the lawn mower battery in to act as a battery, not a capacitor. A high end car audio battery would be much better suited to the application, but the lawnmower battery is still a lead acid battery in the end. It wouldn't surprise me if the flimsy cell conections melted and ruined the battery, but I don't think it's fair to call the guy an idiot, moron, and a safety hazzard.
Thread Starter
2nd Gear Member
Joined: Oct 2006
Posts: 212
From: Michigan
RE: second battery
ORIGINAL: 07lane40
thats like saying if you hook some wires up to one AA battery and hold them to another rechargable AA battery the rechargable one will charge back up. doesnt quite work that way.
thats like saying if you hook some wires up to one AA battery and hold them to another rechargable AA battery the rechargable one will charge back up. doesnt quite work that way.
Thread Starter
2nd Gear Member
Joined: Oct 2006
Posts: 212
From: Michigan
RE: second battery
ORIGINAL: Matt Young
The OP is a little confused about the way a charging system works, but in fairness, so are some other people in the thread.
He threw the lawn mower battery in to act as a battery, not a capacitor. A high end car audio battery would be much better suited to the application, but the lawnmower battery is still a lead acid battery in the end. It wouldn't surprise me if the flimsy cell conections melted and ruined the battery, but I don't think it's fair to call the guy an idiot, moron, and a safety hazzard.
ORIGINAL: 07lane40
i believe the point was the OP did not use one of these specifically used batteries and just threw a random lawnmower battery in to act as a large capacitor. which was slightly retarded. yeah a specified battery for this particular install would be acceptable to use. because its for that particular use. a lawn mower battery is for a lawn mower. not a car.
i believe the point was the OP did not use one of these specifically used batteries and just threw a random lawnmower battery in to act as a large capacitor. which was slightly retarded. yeah a specified battery for this particular install would be acceptable to use. because its for that particular use. a lawn mower battery is for a lawn mower. not a car.
He threw the lawn mower battery in to act as a battery, not a capacitor. A high end car audio battery would be much better suited to the application, but the lawnmower battery is still a lead acid battery in the end. It wouldn't surprise me if the flimsy cell conections melted and ruined the battery, but I don't think it's fair to call the guy an idiot, moron, and a safety hazzard.
1st Gear Member
Joined: Mar 2008
Posts: 100
From:
RE: second battery
ORIGINAL: ttocs
hey jerky, THOSE AIN'T LAWM MOWER BATTERIES! The cheapest one you find on there is $200, you must have ahell of a lawn mower and why would you supplement a $70 old cheapo with a $200 200CCA battery?
I did a couple of searches for lawm mower batteries in cars and the only info I find on there was from the lawn mowers recommendation to NOT charge a lawn mower battery with a car as anything more then 2A of current will over charge the battery, and can cause it to heat up, crack and explode. I guess everyone missed the memo..........
Please you guys, go buy a camaro or maybe a cute little import with a big wing...
hey jerky, THOSE AIN'T LAWM MOWER BATTERIES! The cheapest one you find on there is $200, you must have ahell of a lawn mower and why would you supplement a $70 old cheapo with a $200 200CCA battery?
I did a couple of searches for lawm mower batteries in cars and the only info I find on there was from the lawn mowers recommendation to NOT charge a lawn mower battery with a car as anything more then 2A of current will over charge the battery, and can cause it to heat up, crack and explode. I guess everyone missed the memo..........
Please you guys, go buy a camaro or maybe a cute little import with a big wing...
as much as you ford guys hate us, any import deserves that more than a american muscle[>:]