Actually, I recalled seeing this circuit in the app notes, but only after I replied.
That's the one.
That's the understatement of the week. The problem is there are too many points, here and in the various bits of literature I've read, to study in any reasonable length of time.
I'm more interested in using the different parts to see how they affect the whole thing. I think I am at the stage where it is becoming practical to do that sort of experimentation.
Regards,
Uncle Steve
-- There should be a special word in the English language to identify people who create problems and then turn around and offer up their own tailor-made bogus non-solutions designed to completely avoid the root causes of the situation under consideration. 'Traitor' might be a good choice, but lacks the requisite specificity. One of the problems with contemporary English is it lacks many such words that would otherwise categorically identify certain kinds of person, place, or thing -- making it difficult or impossible to think analytically about such objects. These shortcomings of the English lexicon are representative of Orwellian linguistics at work in the real world.
[snip]
Remembered where I had stashed some ancient data...
These are the TC curves provided to me by GM and Ford back in the day when I designed alternator regulators.
Your regulator should approximate such a TC if you want to hold a reasonable charge on your lead-acid battery.
What information do you actually need fed back to your microcontroller? ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| 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.
What, no NDA? Holy crap! I don't want to have to install plumbing to keep the water level above the top of the plates.
I suspect the thing will charge reasonably quickly with a fixed- voltage set to the float charge level, but I have numbers from 13.1V to 13.5V for the float from different sources. It may depend a little on the battery. For EOC float, it may be easier to specify 50-150mA or so charge current.
Supply voltage, battery voltage, sense resistor voltage, battery temperature. It would be nice to have load voltage and load current as well, but I could do without if I had to since my NAS is a static load.
Serial I/O is one pin since as I'm only doing TX. The ATtiny85 I was trying out has 5 I/O pins if I keep _RESET_, so I'll have to multiplex all those measurements on one A/D channel, which actually simplifies the software a lot. Should be doable, assuming I can make the electronics work properly. I don't know if any extra safety devices or sensors are recommended, but with three select bits available, there are options. Sound reasonable?
Regards,
Uncle Steve
-- There should be a special word in the English language to identify people who create problems and then turn around and offer up their own tailor-made bogus non-solutions designed to completely avoid the root causes of the situation under consideration. 'Traitor' might be a good choice, but lacks the requisite specificity. One of the problems with contemporary English is it lacks many such words that would otherwise categorically identify certain kinds of person, place, or thing -- making it difficult or impossible to think analytically about such objects. These shortcomings of the English lexicon are representative of Orwellian linguistics at work in the real world.
No NDA? You missed the dates. This was 46+ years ago ;-)
"Jerry" Stenklyft was a nice engineer/friend from Anderson, Indiana, who, while visiting Motorola, would come over to my house, help me lay floor tile, then have dinner with us ;-)
He died in 2004 at age 70.
That's what following the TC curve does for you... minimizes water usage.
BTW, the flattening at low and high temperatures is NOT lead-acid physics, it's to keep from burning out head lights when cold, and to minimize dimming when hot. A straight curve is quite adequate for your purposes.
(My ignition system designs work down to 3V cranking voltage ;-)
You're in for a surprise... holding at 13.2V will give you a weenie capability charge.
I still don't understand what you are trying accomplish. Charging a lead acid battery to a proper level is downright trivial with stand-alone simple-minded circuitry. How do you plan to measure battery temperature?
I don't speak micros... I hire that out. I have a long-time buddy in Columbus, OH, who adds any needed digital and bus needs (SPI, I2C, CAN, etc.) to my analog chips and he also does my layouts. He has a Master's from Ohio State and is a whiz at Verilog and VHDL. (Let me know if you have such needs, and I'll provide contact information.)
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| 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.
The lawyers have been busy since that time. 46 years ago farmers could buy dynamite to remove tree stumps on their property. Kids these days would find "Rocket Ship Galileo" utterly alien. Building rocket motors? Radar? Preposterous.
We're all so much safer now that all that icky science and engineering is restricted to licensed and regulated corporate facilities.
Condolences. I suppose he didn't have his head frozen to be stored and tended to by ultra-reliable robots at some autonomous cryogenic facility in the far North.
I should think so. My reading on the matter tells me the key to battery-longevity are gentle charge/discharge curves, minimizing temperature excursions, and of course keeping them fully charged.
Heh. That's a lot of amps.
I haven't decided on a charge voltage yet. Once I sort of have the electronics where I want them, I'll run a discharge/charge cycle and watch what actually occurs. If I start with 15V supply and PWM, the battery voltage can be set to whatever is appropriate given battery state-of-charge. I'm ready for surprises.
I'll tape a thermistor to the case, or maybe I'll use some glue.
This is a good first project with the microcontroller precisely because it is so trivial. I could go out and buy a small UPS for less than a hundred bucks but where's the fun in that? I'll probably write it up afterwards, so you'll be able to see what it looks like then.
I'm just getting started with microcontrollers, but I already know what I'm doing in so far as programming is concerned. It was surprisingly easy to do the serial code; the Atmel part is full of features that make everything super-easy without a lot of external electronics.
Regards,
Uncle Steve
-- There should be a special word in the English language to identify people who create problems and then turn around and offer up their own tailor-made bogus non-solutions designed to completely avoid the root causes of the situation under consideration. 'Traitor' might be a good choice, but lacks the requisite specificity. One of the problems with contemporary English is it lacks many such words that would otherwise categorically identify certain kinds of person, place, or thing -- making it difficult or impossible to think analytically about such objects. These shortcomings of the English lexicon are representative of Orwellian linguistics at work in the real world.
[snip]
Think Detroit, -20°F, parked outside overnight. I've observed 4V myself :-)
I'd still go a buck regulator (with a limited current capability), and fudge in the TC curve. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| 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.
Oh, you were referring to the battery chemistry hysteresis. I would never have imagined that car batteries dropped out that much.
This Atmel application note describes a development board using such a circuit. I suppose a buck regulator is common in these applications.
Regards,
Uncle Steve
-- There should be a special word in the English language to identify people who create problems and then turn around and offer up their own tailor-made bogus non-solutions designed to completely avoid the root causes of the situation under consideration. 'Traitor' might be a good choice, but lacks the requisite specificity. One of the problems with contemporary English is it lacks many such words that would otherwise categorically identify certain kinds of person, place, or thing -- making it difficult or impossible to think analytically about such objects. These shortcomings of the English lexicon are representative of Orwellian linguistics at work in the real world.
No, no! While cranking a cold engine.
Yep. Just replace the output bank of capacitors with your battery.
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| 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.
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