Battery Charger
(Seal Lead Acid and Gel batteries)
HoangThi Le
October 11, 00
University of Rhode Island Kingston RI 02881
Biomedical Engineering
Introduction: The main ideas of this project was
designed a battery charger converter, which use
for both Acid battery and Gel battery. Lead –
Acid batteries are constructed of lead plates
suspended in a container fill with a mixture of
sulfuric acid and water. This fluid called the
electrolyte reacts chemically with the lead plates
to produce electrical current. Those batteries
have deep cycle, the most satisfactory choice for
most wheelchair users, even the power
wheelchairs. In addition, to selection a deep
cycle type battery is capacity of the battery. This
is measure in ampere-hours, which is determined
by number and size of the lead plates. The more
and the larger plates the higher the ampere-hour
rating. Different models of wheelchair, different
patterns of use, and different users will require
different battery capacities. But, In Zambarano
hospital, they used a power wheelchairs, which
operates 24 V, it means that they required two 12
Volt batteries. Another type of battery used in
power wheelchairs is the gel cell battery. This
battery operates the same as Lead Acid battery.
The advantage of this battery is that person who
travel by air are the most frequent users. The
main disadvantage to gel cell batteries is that
they have a lower ampere- hour rating resulting
in less time operating time on a single charge.
Design: we based all the information and
knowledge we got from Internet, or technical
support for battery charger. What we had been
done: First, we drained the Acid and batteries by
two cars headlights, and television. Then we
measured the voltages drop between those two
batteries: Acid batteries drained until 5-6 V,
which completed drain. Beside that Gel cell
batteries drained until 7- 8 V that fully drained.
Second, we recharged them by a series
connection, and then we measured the voltages
of those batteries. The Acid batteries were got
fully charge slower than the gel cell batteries.
However, the Acid batteries weren’t complete
charge as original, they charged up to 10- 11 V.
This means the Acid batteries have leak resistant
http://www0.delphi.com/disable/wheelchair.html
http://www.4unique.com/battery/battery
http://www.health-e-quip.com/tips/battery.htm
http://www.mywebplace.com/batfaq.htm
http://www.mywebplace.com/batinfo.htm
http://www.usenergycontrols.com/chargerinstall.html
http://www.sunpower-uk.com/battery_chargers.htm
occurs. So we need to refill the chemical in side
a battery to get them full charge.
Present: The best method is to slowly recharge
Acid and Gel batteries using an external constant
voltage, because the electrolyte has more time to
penetrate the plates. A constant voltage
“automatic” charger applies regulated voltages at
approximately 14.4 volts and 10 ampere. But the
“Seal Lead Acid” charger applied approximately
12 volts and 1.2 ampere. By charging different
capacity battery, we need to change the circuit
board of the Acid charger, based on Seal Lead
Acid charging method. The Seal Lead Acid
charger operates by float charging the battery to
13.65 Volts. This is the middle of the proper
float voltage range at room temperature for most
12 Volt Seal Lead Acids. When the charger
detects a charging current of greater than about
165 milliamps, it switches automatically into the
"bulk charge" mode. In this mode, the charger
attempts to pull the battery voltage up to 14.45
volts. This voltage is great enough to equalize
the charge in the battery's cells. At all times, the
charger limits the current output to 300 mA.
When the battery becomes fully charged, its
current drops off. When that current drops to
less than 12 mA, the charger will switch back
from the bulk mode to the float mode where the
voltage will be maintained at 13.65 volts. Thus,
when a battery that is slightly discharged is first
connected, or power is applied to the charger, the
battery will draw enough current to put the
charger into the bulk charge mode. The battery
will be charged, and its cells will be equalized.
Then the charger will switch automatically to the
float mode to maintain the battery's state of
charge at precisely the correct voltage.
Future Plan: Now, this project wasn’t worked,
as we want, because we tried to get more
information from people, who were technical
support for battery charger. Accordantly, to what
they told us that we need to either and more
component to Acid charger circuit board or
replace for a new devices. But where do we may
get the replacement? If we can get a replacement,
the Acid batteries charger will charge both Acid
and Gel batteries.
Ref: http://www.hepi.com/battery/battery
http://www.nyquist.ee. Ualberta.ca/dcbat.html
Lester Battery Charger Co.
Technicians support: (402) 474-1769
US Energy Controls Corporation
Technicians support: 408-274-5700