Battery: Best way to minimize charge loss when parked for extended periods?

[Number Twelve]

no more than 20 Ma would keep me happy. imp

You might be right. Some time ago, I calculated 50 ma would empty a 100 A-H battery in 2000 hours (83 days). In reality, I have never found a sneaky little parasitic failure. They always seem to be more than an amp, sometimes 2 or 3 amps.

 

[imp]

You might be right. Some time ago, I calculated 50 ma would empty a 100 A-H battery in 2000 hours (83 days). In reality, I have never found a sneaky little parasitic failure. They always seem to be more than an amp, sometimes 2 or 3 amps.

@Number Twelve
You obviously understand Electric Theory! You can then probably appreciate that any parasitic current drain anywhere has to be generating heat. Heat is bad news. What kinds of resistances in the system on the order of 10 Ohms or so, can be "eating up" battery energy @1 Amp. is the big question. And why don't things get hot? In my 50+ years of messing with automotive electrical issues, I have never found a low-level parasitic current draw of about 1 amp.

So, what are the A-H ratings of batteries? This I can't address knowledgeably. But I do know, in the past decade, Mfrs have supplied their OEM vehicles more and more with the batteries I like, for example Group 65. A-H ratings have eluded me, and really are needed to do these kinds of calculations. No matter what the critics say, in batteries, BIGGER IS BETTER. imp

 

[Number Twelve]

I could swear you already know I'm an electronics nerd.
1 amp? glove box lamp stuck on
3.5 amps? door lock switch stuck on, being protected by a PTC resistor placed where the heat won't burn the car down.
100 amp-hours used to be the standard, but I've seen ratings like 74 amp-hours lately.

A bit of Googling gets a hundred explanations of what an amp-hour is, but nothing on how many are in a car battery. I guess you have to look up one battery at a time.

 

[imp]

I could swear you already know I'm an electronics nerd.
1 amp? glove box lamp stuck on
3.5 amps? door lock switch stuck on, being protected by a PTC resistor placed where the heat won't burn the car down.
100 amp-hours used to be the standard, but I've seen ratings like 74 amp-hours lately.

A bit of Googling gets a hundred explanations of what an amp-hour is, but nothing on how many are in a car battery. I guess you have to look up one battery at a time.

@Number Twelve
Electronics nerd, eh? Try this one: Set up a bridge circuit using 5 unequal resistors connected to a DC source. Choose any values you like, don't get fancy with reactances, imaginaries, etc. You know the voltage feeding the bridge, obviously. Can you solve for the "imbalance voltage" appearing across the junction of each of the two pairs of resistances in series, without resorting to any nodal theories, Thevenin's, Norton's, i.e., only Ohm's Law?

If too tough, try wiring a pair of three-way switches. I used that question, draw a working three-way diagram on my test when interviewing for Plant Electricians. You'd be surprised how many "Electricians" don't know Jack ****. imp

 

[imp]

You might be right. Some time ago, I calculated 50 ma would empty a 100 A-H battery in 2000 hours (83 days). In reality, I have never found a sneaky little parasitic failure. They always seem to be more than an amp, sometimes 2 or 3 amps.

@Number Twelve
Who else knows? That a 20 amp. fuse feeding a 10-amp. short to ground somewhere, can catch the damned thing on fire? And the "safety valve" never knew.......imp

 

[Number Twelve]

Now you're into thermodynamics...which I have a Florida State Certificate of Competency in.
Any input of energy, properly insulated, will increase in temperature without limit. The only difference between a short that drains the battery and a short that catches on fire is the confinement of the energy.

As for the resistor bridge? I don't ********** with trivial puzzles. I am an analog electronics designer and have plenty to do designing circuits that have a purpose. Right now, there are three waiting for me on my electronics site, but I'm too tired to do them right now, so I'm playing on the car site. I designed a 38KHz smoke detector/servo motor driver circuit today, but this site will not let me upload a .png of it.

 

[imp]

Now you're into thermodynamics...which I have a Florida State Certificate of Competency in.
Any input of energy, properly insulated, will increase in temperature without limit. The only difference between a short that drains the battery and a short that catches on fire is the confinement of the energy.

As for the resistor bridge? I don't ********** with trivial puzzles. I am an analog electronics designer and have plenty to do designing circuits that have a purpose. Right now, there are three waiting for me on my electronics site, but I'm too tired to do them right now, so I'm playing on the car site. I designed a 38KHz smoke detector/servo motor driver circuit today, but this site will not let me upload a .png of it.

@Number Twelve
OK, OK, I didn't intend to get your "hackles" up, you are a busy, gainfully employed person not seeking to sharpen old skills, as I do a lot. Still, you don't come on as more Theoretician than Practicioner. imp

 

[Number Twelve]

OK, OK, I didn't intend to get your "hackles" up,

I'm not all that irritated. I'm just surprised that you don't already know these things about me. I thought we had that conversation. I gots a lotta edecashun and I use it ever day. Figuring out a Wheatstone bridge or a 3 way switch is as common to me as a 3/8ths socket set. I just don't do 'em to sharpen old skills, I do 'em 'cause they come up often enough in my usual work.

 

[imp]

I'm not all that irritated. I'm just surprised that you don't already know these things about me. I thought we had that conversation. I gots a lotta edecashun and I use it ever day. Figuring out a Wheatstone bridge or a 3 way switch is as common to me as a 3/8ths socket set. I just don't do 'em to sharpen old skills, I do 'em 'cause they come up often enough in my usual work.

@Number Twelve
Understood, and agreed. I had no way of knowing your background, educational or otherwise, just reading into your posts. My experience with forums is that not too many Professionals are present, and I obviously ain't one of them. You do have an interesting way of comparing "Bakelite" to "Teflon", though! imp

 

[Number Twelve]

You do have an interesting way of comparing "Bakelite" to "Teflon", though!

I don't remember mentioning Bakelite.
I kinda know what it is, but it's really old!

 

[imp]

I don't remember mentioning Bakelite.
I kinda know what it is, but it's really old!

@Number Twelve
If you've seen one of the old-fashioned telephones, the black ones, the Receiver was made of Bakelite, otherwise knwn as "Phenol Fiber", one of the earliest plastics, real good electrical insulator, solid and strong, threadable for screws. imp

 

[shucker1]

Pool Table balls are made of that stuff. Pretty rugged.

 

[imp]

Pool Table balls are made of that stuff. Pretty rugged.

@shucker1
Seriously? By tradition, pool balls were made of "Belgian Ivory", a substance probably banned today from private ownership. Bet if it made H-bombs work, though, the govvy would have plenty of it.

Never heard of balls made of Bakelite, but why not? Pretty durable. Seem about the right "hardness".

Lucite too soft. How about Hickory? imp

 

[shucker1]

Yup.

It's true.

Have not seen too many "Belgian Elephants" hanging around so I guess that's why they switched to Bakelite....

Might have run out.

 

[imp]

Yup.

It's true.

Have not seen too many "Belgian Elephants" hanging around so I guess that's why they switched to Bakelite....

Might have run out.

@shucker1
Gotta admit, yer keepin' "one-up" on me lately. You do know it can freeze in LA, yes? imp

 

[shucker1]

Lower Alabama?