automotive battery question

[JHZR2]

Originally Posted By: GreeCguy
Originally Posted By: JHZR2
You can't play the games you are with paralleled batteries. Both must remain at the same state of charge, depleted the same way, and retain a good impedance match. This is essential so that you don't put one into reversal or create other unsafe scenarios which could cause a hydrogen vent and explosion.


So are you saying the weaker battery could drain the other? Seriously, help me understand. I have a bunch of old batteries from different vehicles and different machines. They are different ages, etc. Would one end up killing the other?


It's complex. You have two things going on - impedance and capacity. Impedance determines the voltage drop under load. A higher impedance battery (which is a function of cell size and design, age, chemistry degradation, etc) will see a higher voltage drop for a given current demand compared to a lower impedance battery. Thus if load is "shared", one will have to put out less current than the other, so voltages stay matched. As you deplete the two, one battery can go into reversal, so the cell goes from +2V to 0V to negative, and then the fun really starts. One battery can also charge the other, current can flow from one into the other at too high of a rate, causing overheating, even fires. Capacity is also related here. Batteries age automatically as a fact that they are a chemical system. So from the time of manufacture, batteries are degrading, with impedance rising and capacity dropping. The low capacity battery is a liability as it will drop and reverse, or else have the issues above. I've seen the effects of mismatched batteries in applications as benign as UPS for computers. Lead acid batteries can and will burn. You don't have sophisticated enough equipment to match and charge them properly.

It may work in practice for a bit, but you'll be damaging the batteries, and putting yourself at risk.

 

[eljefino]

Take the alt apart and do the bearing. It's easy. You can get a bearing shipped to your door off amazon for under $4.

Measure the bearing, or, shoot, get the number off of it. Could be a 6203.

 

[SHOZ]

When working at the industrial battery factory they always would try parallel charging/discharging whenever a new engineer came in. Our circuits fro charging were 90 cell max and usually 80 cells. It would always undercharge some cells and over charge others all being the exact same cell size. Way too much individual variance for long term life.

 

[supton]

Dumb question. Why not a float charger and a really long extension cord? I presume this is lightly used. Screw the charger to the hood, and park close enough to reach the extension cord.

 

[JHZR2]

Originally Posted By: SHOZ
When working at the industrial battery factory they always would try parallel charging/discharging whenever a new engineer came in. Our circuits fro charging were 90 cell max and usually 80 cells. It would always undercharge some cells and over charge others all being the exact same cell size. Way too much individual variance for long term life.


Exactly. This is why battery management systems have resistive balancing.

A recent article in journal of power sources indicates that a 20% impedance mismatch! which is easily obtained in manufacturing variances! yields a 40% lower cycle life. OP is cycling so it doesn't bode well.

He could get one big battery, or for this application, even better would be deep cycle. But by the time money and energy is spent, he could have replaced the alternator.

 

[DoiInthanon]

Great news Greasy. The guys at the Barber Shop are willing to help. I am sure it will make catching the right boa a cinch. Of course, the more hands the better when it comes to getting the serpentine belt in place. Some have large families, so the preacher is going to lend us the church bus, providing he can drive it. Can't believe so many people can leave hearth and home for Florida right smack dab in the middle of the winter.

Don't worry about feedin them. They are going to bring their traps, guns, and fishing stuff. They can take care of themselves. We are going to meet at the 4way stop at noon. Be sure to PM me your address soonest. Your buddy, Jim

 

[GreeCguy]

Originally Posted By: DoiInthanon
Great news Greasy. The guys at the Barber Shop are willing to help. I am sure it will make catching the right boa a cinch. Of course, the more hands the better when it comes to getting the serpentine belt in place. Some have large families, so the preacher is going to lend us the church bus, providing he can drive it. Can't believe so many people can leave hearth and home for Florida right smack dab in the middle of the winter.

Don't worry about feedin them. They are going to bring their traps, guns, and fishing stuff. They can take care of themselves. We are going to meet at the 4way stop at noon. Be sure to PM me your address soonest. Your buddy, Jim

Jim, I can't thank you and your barber shop buddies enough. I'm putting fresh straw in the barn so don't worry about sleeping arrangements. The house across the street just went up for sale but the last family took the wheels so if you and yours decide to stay there, be sure and bring an extra set as we can drag it across the street and hook up the power to my power pole. Water might be a problem but there's always the cement pond at the abandoned house on the other side of my house. We could probably get our snakes from there unless you're dead set on a boa as I'm sure that one only has cottin mouths, (this might actually be a good thing as we could catch a few of them and have your preacher lead a good snake handling service Sunday night). Be sure and bring skitter repellent as I want to treat you guys to a night out at our local hot spots and the ladies in these parts simply cannot resist the smell of "Deep Woods Off." I'm having a strong hankering for some possum and taters so be sure to bring plenty of shot, that way there will be plenty to go around. I've already set up a few dates with neighborhood gals who promise a good time as one just got her store bought teeth which they can share between the bunch of them. Meet me by the water tower where the Piggly Wiggly used to be before it burnt down.

 

[DoiInthanon]

Greasy, We are having a little problem here in town. Seems the word has got around and a large crowd has gathered at the 4way stop. Most of them were told they could "come with" by some that were at the Barber Shop. Help me out here and get me your address.

The last PM had Ukiddenme, FL in it. The preacher put that in his PMS thingy and didn't get a match or something. Please try again. Otherwise I'm afraid we will have to get another bus before the 4way stop gets shut down. Listen, I gotta run. Seems like things are gettin a little onruly down there. Sheriff says I need to get out of town

 

[GreeCguy]

Jim, I am so embarrassed. I just shared your exciting news with "Thunder the Wonder Pig" and she says there's no way you can sleep in our barn as our outlaw in-laws are coming to town and plan on using the very barn I had promised to you and yours. They won't be leaving till the big spring thaw and with temps predicted to be in the low 70's by the end of next week, who knows when that will be. Is it possible you could hold off the crowd at the four way till sometime this summer? BobbieJoeImagene said she'll put her teeth back in the jar and hold 'em till you arrive so as not to get them all nasty and cruddy with peanut brittle and such till you and your buddies arrive. Trust me, it will be worth the wait.

 

[steve20]

Hey GreeCe---take all those dead auto batteries (maximum of 5 per visit) to Advance Auto Parts----they will give you 5 bucks each --you can easily pay for your alternator with a dozen dead auto batteries