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From: Bob Lowe (no email)
Date: Wed Jun 02 2004 - 15:36:38 EDT
I posed the question of the value of Pulse Charging to Jamie Surrette, owner
of Surrette/Rolls Battery Company. Following is his reply along with their
bulletin on Charging and equalization. Since they have no axe to grind one
way or the other, I value their advice.
I hope this helps to achieve a better understanding.
Good luck,
Bob Lowe
www.MV-Dreamer.com <http://www.mv-dreamer.com/>
www.CruisingAndMaintainingYourBoat.com
<http://www.cruisingandmaintainingyourboat.com/>
************************************
Bob,
Pulse chargers are tough to comment on. They often claim to "prevent"
sulfation, which is difficult, if not impossible, to test. Moreover,
sulfation must occur during the discharge phase to generate energy. Our
general (public) opinion is that they could be of assistance and will
not hurt. This is a tough one and more product variations are popping
up all the time.
Attached is our bulletin on charging and equalizing.
Regards,
Jamie
ROLLS BATTERY ENGINEERING
Salem, Massachusetts, USA Ph 1-800-681-9914 Fax
(902) 597-8447
P.O. Box 2020, Springhill, Nova Scotia
The positive power choice
Bulletin 605, Preventive Maintenance, Charging and Equalization
This bulletin describes preventive maintenance and recommended charging
procedures to maximize battery life. The leading cause of premature battery
failure is improper charging and poor battery maintenance.
Equalization is very important and must be performed correctly but only as
required.
Preventive Maintenance
When a battery is first received the cell acid levels should be checked and
the battery should be put on charge. After removing from charge the
specific gravity readings of each cell should be recorded and kept for the
life of the battery.
Preventive maintenance involves, at a minimum, checking the cell electrolyte
level for correct acid volume once a month and equalizing once every six
months. The cells should be watered back to the original acid level which
is < - = below the bottom of the vent well (tube inside the battery cell
with slots on each side). Distilled water is preferred but local water (not
chlorinated) maybe acceptable if it is not hard or does not contain high
iron levels.
A recommended preventive maintenance program can be summarized as follows:
1. Water each cell to original level as required.
2. Equalize as required or once every six months.
3. Record the specific gravity readings of each cell every three
months.
Occasionally cleaning the battery terminals and case / cover is a good
practice and recommended. A weak solution of household baking soda and
water can be used to neutralize any spilled acid (100 g per liter or 4 Oz
per pint). Make sure the vent caps are securely tightened and NO soda
solution gets into the battery cells.
Good record keeping is stressed as review of these records can help to
determine the health of the battery and can prove invaluable if system
problems develop.
State of Charge and Charging
The truest measure of a batterys state of charge is the SPECIFIC GRAVITY of
the battery acid. The following shows the approximate state of charge at
various specific gravities at 77:F / 25:C.
% Charged Specific Gravity % Charged
Specific Gravity
100% 1.255 1.275 25%
1.1651.155
75% 1.215 1.235
0% 1.130-1.110
50% 1.200 1.180
Hydrometers can be difficult to use and at best accurate to +/-0.005 points.
Please see Bulletin 606 for correct hydrometer use.
We recommend a three step charging procedure. Recommended voltage settings
are as follows:
(Volts per cell) 12V
24V 48V
Equalization 2.58 -2.67(max) 15.5-16.0 31.0-32.0
61.9-64.1
Absorption / Bulk 2.37-2.45 (max) 14.2-14.7 28.4-29.4
56.9-58.8
Float 2.20-2.23 (max) 13.2-13.4
26.4-26.8 52.8-53.5
To calculate the correct settings for another battery bank voltage divide
the total nominal voltage by two and use this number as a multiplier. For
example a 18V system, 18/ 2 = 9, equalization preferred = 9 x 2.58 = 23.2 V
CAUTION: The ideal float voltage is the lowest voltage setting that will
maintain the battery at full charge. The higher the voltage the more water
the cell will consume. The minimum equalization voltage is highly
recommended unless it is suspected a sulphation problem exists.
Equalization
Equalization is required to mix the battery acid and bring every battery
plate to an equal charge. Equalization should only be performed when
required or once every six months. Equalization is required when the cell
specific gravities vary from highest to lowest by +/- 0.015 (1.245 1.260
at full charge).
The exact particulars (such as charging time and currents) are dependent on
the charging system. However, the point is to bring the batteries up to the
equalization voltage and continue charging for 1-2 hours at a low current,
without excessive heat. The final or finishing charging current should be
3-7% (we recommend 5%) of the 20 hr capacity in amps. If battery temperature
exceeds 125:F the battery should be taken off of charge and allowed to cool
before equalization is continued. When two consistent specific gravity
readings are taken a half hour apart the battery is equalized.
It is recommended to water the battery cells before or half way through the
equalization. This is to assure the water is completely mixed into the
electrolyte.
Caution: If you have HYDROCAPS remove during equalization.
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