L-16 charging voltages [RE-wrenches]

[David Palumbo, Independent Power & Light]

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Wrenches,

Allan's charge voltages listed below look good. Of course the temperature of
the batteries needs to be considered.

I do take issue with the statement on equalization though. The definition of
an equalized battery is, all the cells are equally charged. This can happen
at voltages lower than 15.5v (nominal 12v bat) although that works too. I've
been working with deep cycle bats for 20 years and have seen plenty of sets
have long service lives without ever going over 15v. It depends on many
factors. I have found that if the battery bank receives a full charge at
least once every seven to ten days then the need for an "equalization
charge" with an elevated voltage is typically not needed.

Living and working on off grid systems in the North East, where we usually
have many cloudy days in Nov. and Dec., I saw many people running their
generators too many extra hours every month performing EQ charges. I did
some testing and experimenting with various battery banks and found that
much of the extra gen run hours was not necessary and wasted allot of fuel
and gave off grid pv systems some bad publicity (too much running of noisy,
polluting generators). The caveat is that you must have a well designed
system and pay attention to an accurate (and well programmed) amp hour meter
to insure that the systems batteries are getting a full charge every week to
ten days. Mr. Surrette told me years ago that in his view a fully charged
battery was in fact an equalized battery. He recommended charging voltages
of 14.6 to 14.8v, temp compensated.
When in doubt test each cell with a hydrometer, or refractometer.

Of course if you have a situation where the system is poorly designed, or
people are abusing it etc. then the elevated EQ voltage may be necessary.

Dave

<<From: Allan Sindelar [mailto:allan at positiveenergysolar.com]
Geoff,
30 volts isn't an equalizing charge. I generally shoot for 31-31.5, which is
easily achievable with C/10 if the batteries are in good condition.

Here's Trojan's spec for their L16s: See
http://www.trojanbattery.com/Tech-Support/BatteryMaintenance/Charging.aspx
Table 2. Charger Voltage Settings for Flooded Batteries
        System Voltage
      Charger Voltage Setting 6V 12V 24V 36V 48V
      Daily Charge 7.4 14.8 29.6 44.4 59.2
      Float 6.6 13.2 26.4 39.6 52.8
      Equalize 7.8 15.5 31.0 46.5 62.0

----- Original Message -----
From: "Geoff Greenfield" <Geoff at Third-Sun.Com>

finally - and this could be a separate thread - the US batt
website/instructions call for charge current at c/10 and charge voltage at
2.583 per cell!  That is 30.966!!!! and then hold for 2-4 hours!!!! What????
Their float spec was 26.04 Volts (2.17/cell).  I know that "cycled" batts in
scrubbers in the different universe of grid fed chargers are different, and
we often "modify" these parameters to find a balance between health of the
batt, what the RE system can provide, and watering chore frequency...  but
these numbers seem off the charts.  I would equalize at 30!

WRENCH SURVEY:
Please share your set points for L-16s (T-105s?) KS-17s (Surette/IBE) and
gells/AGMs - this I think would be very useful info.>>

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