"Larry Jaques" wrote in message
...
On Fri, 11 Mar 2016 20:20:05 -0500, "Jim Wilkins"
wrote:

"Larry Jaques" wrote in message
news
On Thu, 10 Mar 2016 19:25:29 -0500, "Jim Wilkins"
wrote:


That's a case where I think the economics favor grid power, because
of
the high cost and limited cycle life of vented deep-cycle batteries.

That it does, but what happens when (not if) the grid goes tits-up?

We return to the 1800's and DIY steam power, the Good Old Days. But I
suspect that a deteriorating, unreliable electricity supply as in
India would switch the helplessly codependent Greenies from blocking
construction to screaming about their NEEDS!! before it did more than
annoy the more technically competent of us. This neighborhood bands
together and shares resources, one generator serves three houses. I
contribute 100' extension cords and repairs to carbs and electrical
systems, and one of my Coleman gennys has spent almost its entire
operating life powering the house across the street.

https://en.wikipedia.org/wiki/2012_India_blackouts
"The nation suffers from frequent power outages that last as long as
10 hours."

How often are you equalizing? The last article I read said that it
drops battery life considerably if you do it very often. I think
the
article was in HomePower mag. No equalization can drop the life,
too,
so there's a balance.

Every manufacturer's advice is slightly different, and a battery's
behavor changes as it ages. I think the least damaging method that's
still adequate is to charge at 1% to 2% of the 20-hour-rate capacity
until the voltage rises to 14.8V for flooded or whatever the maker
says for AGMs. I charge unmarked ones to 14.4V at less than half an
amp.

Usually I use an unregulated rectifier + capacitor charger adjusted to
the individual battery with a Variac. The cap I added to the charger
stabilizes the voltage and current meter readings. "Dumb" rectifier
chargers automatically taper down the current as the voltage rises.
The next time I walk by I check the meters and turn up the Variac.

One is a 1970's Schauer charger with a small 3 Amp Variac added in,
the other a homebrew that puts out 0 - 35V at up to 15A, with a 1/10
Farad filter cap. Since they don't have an output regulator they
aren't susceptible to damage from battery voltage being fed back into
the unpowered circuit if the AC is interrupted. You can protect a lab
supply from that with a series diode but then the voltmeter will be
useless.

I don't equalize vehicle batteries very hard unless the hydrometer or
charging behavior reveals a weak cell. The smaller colored-bead type
is enough to show significant differences and works better on small
riding mower batteries with small caps and little free liquid..

If they are sulfated / corroded / whatever and won't accept current at
14.4V I apply 15V to 16V and keep an eye on the current, which is
typically under 100mA until they start to recover, then it rises and
may need to be limited due to the otherwise excessive charging
voltage. This is the case where a Smart Charger gives up, but a smart
user can salvage the battery. These numbers are all from makers' data
sheets. I just pick the more conservative ones and procedures that can
safely be left unattended.

My 5-year-old HF '45W' kit supplies 0.6A per panel, making it good
current-limited source for gently conditioning batteries. I made an
LM350 variable regulator to fine-tune the charging voltage and
current. An LM338 will pass more current, I chose the LM350 to protect
some nice 3A meters I found.
http://www.eleccircuit.com/adjustabl...a-using-lm338/
D1 protects IC1 from higher voltage on the output than input, as I
mentioned above.

Active, adjustable current limiting is conspicuously absent from
commercial battery chargers. I've read that "Pulse" desulfating is
really only a cheap substitute for building in a current limiter. At
Segway I learned how to use a lab-type adjustable power supply to meet
almost any battery charging requirement except fast-charging NiCd and
NiMH. The problem is that it requires a careful, attentive and well
informed user such as an electronic lab technician, NOT the average
mechanical engineer.

stratified electrolyte by bubbling. That's one of those inconvenient
solutions only the inventer would tolerate, and impractical for
batteries heavier than Group 31.

Why not vent them well rather than schlepping? MUCH less work.
Enclosed battery space, right? Fan on the inside, window to the
outside? For a more exciting removal of the hydrogen, just burn it
off. (Disclaimer: Kids, don't try this at home.)

I need to do something better with my solar battery set. The
original
is outside in a box, which means it chills in the winter and boils
in
the summer. Maybe I'll build a foam-insulated cover for it, with
vents, then figure out a better solution for the larger battery set
on
the new panels when I do get them. Battery watering sets aren't too
expensive, and auto-fill beats frequent checking. Cheap insurance.

When I rebuild the tool shed I plan to leave space for battery shelves
in a separate cabinet on an outside wall. I've had too much trouble
containing liquids like hydraulic fluid to assume I could safely
control invisible hydrogen. I don't have or plan to acquire nearly
enough batteries to fill it so the remaining space will probably be
for lawn and garden chemicals.
..
How much of an actual problem has the temperature swing been for you?
Batteries work well enough outdoors in cars here, where the temps run
from +100F to -10F. When I lived an hour further north it sometimes
dropped to -30F.

Being able to watch and limit the charging current spares me from the
uncertainties of voltage-controlled charging. I use the
voltage-vs-temperature table only to determine state of charge and
know when they are fully topped off..

Good idea. Generators are also more costly than grid power.

I once figured about half a buck per KWH. My system is for standy use
only, but I need to test it and exercise the generators.

The Interstate battery I put in the truck in 2002 receives a top-off
charge every month or two and is still in good condition, judging by
the electrolyte gravity and the time it will run the headlights
without dropping too far.

13+ years? Not bad. I just replaced my Tundra battery last year,
so
I got 9 on the original.

Did you do anything to maintain it?
I caught one cell on my truck battery dropping out a few years ago and
began charging it and checking the level more often. It seems to have
recovered.

...
I wish LiFePO batteries were 10x cheaper now. I'd get a few KW of
those instead of LA. Tesla keeps making strong drops in pricing on
their battery tech. A couple 10kw modules would be nice, eh?

A friend is getting a quote from Solar City, which is connected to
Tesla. When the engineers come by I'm going to find out as much as I
can about the technical possibilities. Their site is useless.

Segway stores large pallets of Lithium batteries at the factory. The
fire department's practice response for a large Class D fire next to a
river was awesome.
http://www.fire-extinguisher101.com/class-d-fires.html

I needed to use a very reactive Lithium compound for an organic
synthesis and a helpful grad student came over to break off a chunk
from the rock-like mass in the can. As soon as he tapped the chisel it
burst into brilliant crimson flame and all we could do was pull down
the fume hood door and watch it all go up, then go request another
can.

--jsw