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


All but one of my light bulbs (75w pump house warmth) is either CFL
or
LED. My electric bill is $40/mo, and I have a new timer for the
electric water heater. Once I get the new solar panels installed,
I'll also have a 24v 900w element going into that water heater,
replacing one of the two 240vac energy suckers. The timer will come
on for one hour, if necessary, each day before I get up. I'm not
going to feed the grid because that means I'd have to get a net
meter.


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.
I'm still experimenting with how to best use them. I think the answer
is to recharge them to the solar controller's lower VRLA/AGM voltage
cutoff setting so they don't release gas indoors, and then schlepp
them outdoors after the blackout ends to top off and equalize them per
the maker's instructions at the higher voltage that mixes the
stratified electrolyte by bubbling. That's one of those inconvenient
solutions only the inventer would tolerate, and impractical for
batteries heavier than Group 31.

When recharging quickly from a generator I feed my unregulated,
Powerstat-controlled homebrew 35V 15A power supply through the solar
controller's panel input to make use of its automatic charge cutoff.

My filler-cap batteries don't bubble noticeably at the 13.6V AGM
cutoff. The "book" calls 14.3V the threshold of significant gas
generation. I can't judge the rate by just looking but 14.0 to 14.3 is
where the bubbling becomes continuous, and also where fine acid mist
comes out. I couldn't see well enough through the spattered food wrap
to describe bubbling as more than "substantial" at 14.8V.

I've run a gas generation test in ?? company's lab on their
lead-acid batteries. While I can't reveal details the results were
similar.

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.

--jsw