Death of a Battery

[phantom power]

Among other things, the comments at the end remind me of my stint working with satellite engineers. Measuring and managing battery capacity is, unsurprisingly, a Huge Deal for any spaceborne system. Measuring battery capacity is actually pretty hard, as it evolves over time and depends on what's going on structurally inside the battery, which is somewhat statistical in nature. This guy's experience is an example of that in action. I imagine that engineering for the ability to reliably measure capacity is at least as important as the more familiar metrics like the capacity itself.

All the metrics looked great. The 2.7-year-old lead acid batteries in my off-grid photovoltaic system appeared to have settled into a consistent mid-life performance. Monthly maintenance (equalizing, adding distilled water) promised to keep the batteries in prime condition for some time to come. Based on cycle depth, I expected another 2.5 years out of the present set of batteries. Life was good.

Then, during my absence over the course of Thanksgiving weekend, one of the batteries expired. No forewarning. Just gave up. A previous post expressed an overall disappointment in batteries, now reinforced by this sudden nosedive.

In this post, I’ll show the metrics on my system detailing the demise of “Battery E.” The gruesome graphics are intended for mature audiences.

... lots of high quality excel plotting porn ...

I suspect that I am missing something here, and that a new battery in an otherwise old set may work itself out in some non-destructive way. I am still adapting to my reduced-capacity PV reality, and meanwhile needed a bloggable topic that I could cover quickly, even if the saga is incomplete. I still need to do some research, and perhaps comments will help set things straight.

I have written before about the disappointment inherent in batteries. Now I have another personal example. Just when I had decided that my batteries were in their prime, crash. In our forced migration from fossil fuels over the coming century, large scale implementations of solar and/or wind are likely to transpire only in connection to energy storage solutions. With storage comes headaches, even for technologies as mature as lead-acid. Batteries will fail, and seldom at convenient times. I liken my recent experience to driving a car without a gas gauge. How tolerable will this situation be to our demanding society? Big adjustments ahead…

http://physics.ucsd.edu/do-the-math/2012/12/death-of-a-battery/#more-1320

[wtmusic]

1. After I saw "lead-acid" I had to read no further.

My do-it-yourself EV conversion was running fine, then one day in 2009 I woke up to the sound of the charger beeping. The car's windows were fogged with acidic vapor, and 10 out of 14 batteries had boiled over. $2,000 worth of deep-cycle batteries were toast.

As I later learned, it's due to a cascade effect from connecting batteries in series that were never designed to be. Resistance across the chain creates sulfate buildup on the plates which quickly spirals out of control. Almost impossible to prevent this from happening.

[Yo_Mama]

2. I didn't know this

Glad I read this post. Thanks for the info.

[phantom power]

4. interesting, so if you keep them parallel it's less of a problem?

[wtmusic]

5. Yes but you don't have enough voltage that way.

Lots of power but only 12 volts. The car goes. very. slowwwwwly.

[hunter]

3. Lead acid batteries are evil.

They are the weakest link in any off-the-grid solar installation.

Most inverters are crappy too.

Both batteries and inverters will randomly transform themselves into toxic waste without any obvious fault or provocation.