US Battery Corp... Charging "parameters"

 

I'm setting up a TriStar and Xantrex SW4048 to charge  ( 8 serially
connected) US Battery US250 batteries(6VLead-Antimony).(48V nominal system).

Most recommendations I find, set the charge voltage ( for the absorption
phase) at ~58V.  The US Battery website recommends ~62V. This seemed
rather high to me, so I called their tech support line. They confirmed
that the batteries should be charge to 2.583V/cell (61.992V for 48V
system).

They recommend a C/20 rate until voltage hits that 61.992V, then hold
for 2hours to complete absorption.


So.. before I follow their advice, I thought I'd "poll" the newsgroup
for comments. Is anyone else charging to this high voltage?

thanks

  - jim

  jim washer wrote:

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Jim,

The 61.992vDC (or 2.583vDC/cell) does seem high,
but I think the key is *ONLY TWO HOURS*. If this
charge rate (some of us might call it an
'equalize' charge) were to be held for more time
(up to eight hours in some cases), damage would be
done. Did you ask about the 'float voltage' after
this high rate? I suspect 2.15vDC/cell would be close.

Thanks for specifying 'Lead-Antimony' instead of
the oft mis-applied 'Deep-Cycle' terminology.

--
-- Jack --
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Everything you see is temporary.
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Jack Daynes wrote:

The float voltage is spec'd at 2.17.

They recommend a constant-current equalizing charge of c/20 until the
voltage moves less than 0.2mV/cell measured over a 3 hour period. For
users without a constant current source, they recommend that same 62V
for 4 hours.

  - jim

 hmmm... at 2.17v per cell I suspect you will have to equalize this bank a
lot. This is very low. Our old lead antimony banks used to float about
2.20-2.22v per cell. This was determined by about 20 years of
experimentation to get the right balance of equalization and liquid
evaporation. Ours were held at 20 deg C most of the time.

After getting the system down perfect for 20-30 years the lead calcium came
in and changed everything again...LOL.  Lead calcium can float much higher
without boiling damage. This has almost eliminates equalization cycle
requirements. Those timers have mostly been eliminated.

 I don't think I'm too concerned about this float being too low, as the
battery will ( almost certainly ) be fully charged every day (as there
are few cloudy days here in NV ).

Gymy Bob wrote: