From: John De Armond
Subject: Battery Myths
Date: Fri, 15 Aug 2008 05:22:26 -0400
Here is an interesting paper by an engineer at SAFT, one of the international
major battery manufacturers. It dispels many myths that are floating around
about battery banks.
From: John De Armond
Subject: Re: Battery Myths
Date: Sat, 16 Aug 2008 20:28:50 -0400
On Fri, 15 Aug 2008 17:00:11 -0700, Gar <email@example.com> wrote:
>John.. could you summarize what he said for me/us??? I read about 2
>paragraphs and knew it was waaaay over my head...
Easy. Pretty much every bit of conventional wisdom about batteries in series
or parallel not working is myth. Batteries can be operated in parallel,
series or series-parallel without problem. Unequal size batteries can be
operated in parallel. Batteries of different ages can be operated in either
series or parallel. A bad battery in a series string can be replaced without
Tom J: That paper is just as applicable to your series/parallel 12 volt
system as it is to a 500 volt system. You have 12 cells. It doesn't really
matter how they're divided into physical cases.
These myths are perpetuated by the many "experts" on the web, few if any have
ever tried what is supposed to be so bad. Few, if any, have ever been around
industrial battery banks either.
I learned about battery truths first by being the responsible plant engineer
for several large (250 volts, approx 100,000 amp-hours) standby battery banks
in a nuclear plant and later, by simply trying things on my own. TVA sent me
to a nice school on battery management and I paid attention.
Others learn the same thing in similar ways. Off-gridders have a bad battery
and out of financial necessity, replace only that battery instead of the
dozens of batteries that may comprise their bank. When everything works fine,
the light comes on, so to speak. EVers find out about replacing a weak
battery in a series string pretty much the same way and for the same reasons.
Yet the myths persist.
I very much doubt that a paper written by a major battery company engineer and
presented to his peers will have any effect on the myths but I thought I'd
pass along the info anyway.
Incidentally, here's an ancient book on batteries that is still highly
The book talks quite a bit about Edison or Alkaline batteries. These are now
more commonly known as nickel-iron batteries. Absolutely wonderful batteries
that got pushed to the side, mainly by Edison's greed. 100 year old batteries
that Edison's company built are still in service, still at full capacity and
still having an indefinite life expectancy. Chrysler used them in its
experimental TEvan electric van but otherwise, they've been ignored.
As usual, the ChiComs are filling the void. There is currently one importer
of ChiCom NiFes and he's being greedy too. As soon as the second importer
comes on board... I'm looking forward to being able to buy my first and
lifetime supply of NiFe batteries for my RV sometime in the near future.
The only "problem" with NiFes is that they use a goodly amount of water.
Gassing is part of their normal operation. Most modern batteries (the Eagle
Picher batteries in the TEvan for example) have automatic watering systems.
That turns it into no big deal. Just add some distilled water to the tank
occasionally and otherwise forget about 'em.
One other brief comment. The book talks about the Delco 32 volt lighting
plant. My great-grandfather has one of those on his fairly large farm in
Alabama. I recall it from my childhood. He held out when TVA and the REA
came to town, considering them to be yankee meddling and/or communism,
depending on which mood he was in :-)
The lighting plant actually worked very well. Automatic start and stop, based
on the state of charge of the battery bank as measured by an electromechanical
amp-hour meter (similar to but better than an E-meter). Smart charging
similar to what we do today, only implemented with relays. A high enough
voltage to avoid having to run very large wiring but low enough not to present
a shock hazard.
He ran his house, the dairy barn and the milking parlor on the system. He did
operate it on manual, however, thinking that he could manage his batteries
better than that fancy automatic control (probably because he didn't
understand it.) He'd crank it in the morning and run it until it cut off.
One of my most vivid memories from that time was watching him listen to his 32
volt Delco radio in the evening. Often as not, the batteries would be near
exhaustion. As the volume decreased with the dropping voltage, he'd move his
chair closer and closer to the speaker until at the end he had his head
half-way in the speaker :-)
When he died, great-granny had it all replaced with "government power". And
then took great offense when they "dunned" her. That is, sent her the first
power bill :-) I sure wish she'd tucked all that stuff away in a barn
somewhere. Delco plants in working order are worth a bundle these days.
Another example of the old saying, "There really isn't anything new under the