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I Hate Batteries
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engrguy42:
Thanks T3sl4co1l, but the only "degree of irrationality" I'm implying is for those who have made up their minds that they can't even comprehend how some can find the whole issue of batteries to be an annoying PITA, and instead have decided that what they personally like or have found useful should apply to the entire universe.

But as you so clearly highlight, this is a very complex topic and depends on a lot of things, including technical stuff that requires a ton of research (if you're willing to go down the detailed technical rabbit holes), personal levels of tolerance, usage patterns, equipment capabilities, and on and on.

As with most things in the universe, there is no "right" answer here, although we humans tend to want to believe otherwise. It depends. The only irrationality I'm implying is for those who can't comprehend that.

Personally, I'm tending towards trying the $20 universal charger and getting some rechargeables. It's a coin toss. I like the idea of having a combination charger that also does 9V batteries for those annoying smoke detectors as well as C cells for my flashlight. But maybe the device is crap. Who knows. There's no right answer.   
engrguy42:
Anyway, so I just ordered the Bonai universal charger and a handful of 9V and AAA rechargeables. Shoot...I forgot to order the C cells for my flashlight  |O

Though I guess it will be a while before I find out how well this charger performs. Won't get here until April 30.
paulca:
Long post but not worth a thread.  Sorry to hijack.

My car wouldn't start.  Chug, Chhhhuuuuug, chu...  click, click.

I jumped it with my marine battery off the solar panel.  First question.  Why did the car struggle to start, even with a fresh off the charger, fully charged 100Ah marine battery claiming 900 cranking amps?

My guess.   2 meters of jump leads and crusty oxidized terminals, causing enough voltage drop that over 200Amps they were unable to keep the voltage up.

Second question.  Why did the battery go flat?

Social distancing I have been in the house, working from home for "I don't know anymore Wilson, how long has it been?", "A month", said the ball, eyeing him carefully, 'Don't want your human going nuts after all.', he thought.

4 weeks with only a trip to the shop each week.

60Ah starter battery that's 3 years old, has done regular 1 hour commute and a bunch of "social, domestic, leisure and pleasure" driving.  Must have well over 2000 cycles on it with most around 10% depth of discharge.  One or two longer sit up periods a year with DOD maybe 30-40%.

So it's done it's time, never been properly flattened.  Now stand it up for a week, go to the shop, stand it for a week... repeat.

If the battery can't really start a car below 50% charge level, say, 30Ah divided by a week of 168 hours is around 185mA to drain it 50% in a week.  ~2 Watts.

A modern car won't draw that, so it didn't die in a week, it took 4 weeks. 

Why didn't driving it charge it?
Start versus running charge.  The crank current can spike to 400amps (unmeasured for my particular car), but using 300Amps for 3 seconds we get 900 amp seconds.  Higher on a cold engine than a warm one.
Assuming, the charge current of the running engine is 4 amps.  900 amp seconds divided by 4 amps equals 225 seconds. (COBOL version)
Add in some inefficiencies and call it 5 minutes.

Assuming your battery is low and the charge phase will be "bulk" as soon as the engine is started.  1 start requires 5 minutes of running to charge it.  A 10 minute drive to the shop to try and charge the battery and a 5 minute drive back.  Gives use 15 minutes of charge and 10 minutes of draw.  5 minutes charge is only 300 amp seconds a third of a start.

So over each week the start, stop, start, stop trip to the shop did very little to charge the battery and the slow continious draw of less than 0.5W drained the battery to where it could no longer crank a cold engine.
engrguy42:
BTW, attached is an image of the universal charger I ordered, and its from a company named Bonai, but it appears there's also an older (?) maybe rebranded version by EBL. I checked youtube for reviews and I only found a couple for either of those, neither of which has any detail.

I'm kinda surprised nobody here has mentioned it and it doesn't appear to be too popular at least in youtube terms. Though as I said, Amazon shows over 900 positive ratings between 4-5 stars.

Seems to me that having the ability to natively charge and discharge AAA, AA, C, D, and 9V batteries is somewhat unique (and very useful, IMO) based on what I've seen.

Anyone know anything about these? Seems certain that spec-wise they're about what you'd expect for many Chinese rebranded, low end devices, and I'm sure the spec monkeys would immediately balk at them (y'know, off by 0.354 femto amps at 305 degrees C   :scared: ), but I'm expecting for most users they're probably fairly useful.
magic:
Does it have proper charge termination or just a dumb timer?

(The latter might still be better than some very old chargers where you were the only timer :palm:)
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