In the spirit of service:
A vehicle battery is really a storage tank for electricity.
The head which we call voltage or electrical pressure (depth
of material stored) tries to force the material (electricity)
to flow out of the tank. In order to add to the amount in the
tank sufficient pressure must be applied to force the material
back into the tank. In order to charge, recharge, whatever,
the battery we must apply a sufficient voltage to do two things:
1) Overcome the physical resistance
of the battery.
2) Over come the battery voltage present.
In a fully charged battery the
physical resistance of the battery is low because the electrolyte
(acid and water) is at the highest concentration so it is easier
to pass current (electricity) through the battery. That is to
say, it is easier with respect to the physical resistance of
the battery. In a dead battery, the electrolyte is close to
pure water so the resistance is high and it is hard with respect
to physical resistance to pass current through the battery.
As a battery is charged or
maintained some of the current flow through the battery will
not contribute to charging the battery but will simply act to
break down some of the water into hydrogen and oxygen. This
is why the water level will need to be topped up from time to
time in many applications.
During charging of a dead battery
the physical resistance of the battery is high but progressively
(but no in a directly linear ratio) becomes lower. During charging
of the battery, the battery voltage becomes progressively higher
but again, not in a directly liner ratio.
What this all means is that
water will be consumed during all charging whether it is due
to use of a charger or when being done by the bike's charging
system. The higher the charging voltage beyond the more voltage
which will be available to overcome the physical resistance
of the battery and the battery's voltage so a higher current
flow will result (faster charging rate) This is good during
recharging because charging will happen faster as we have a
higher voltage to push current into the battery but can become
an issue once the battery is fully charged.
When the battery is fully charged
it will have a high voltage (12.8 volts is a fully charged battery)
plus it will surface charge (a light charge with no real capacity
present on the surface of the plates) up to 13.2 or 13.4 volts
in some cases. This surface charge will act to reduce the current
flow through the fully charged battery even further reducing
over charging however unless something else intervenes some
overcharging will occur. Over charging will do the work of breaking
down water and heating the battery. In modern automotive systems
a temperature sensor is present to measure battery temperature
(old ones went buy voltage regulator temperature) and will act
to reduce charging voltage when the battery is warmer. It is
necessary to reduce charging voltage as the battery temperature
becomes higher because higher temperatures mean that the electrolyte
expands, is in lower concentration and so battery voltage/physical
resistance falls slightly. Unless
charging voltage is reduced the higher voltage will result in
over charging, more heating and water loss.
The KLR charging system is
not very complex and it lacks the ability to reduce charging
voltage as the battery temperature rises so on long rides; at
higher temperatures we can expect to see water use. It is useful
to measure system voltage across the battery when the battery
is fully charged at a few temperatures. This recorded information
can help to determine if you regulator is beginning to malfunction
or perhaps the battery is on the way out.
When charging a battery by use
of a battery charger here are some suggestions:
1) Do the charging according
the reference charts which give the charging rate and time according
to cell specific gravity, temperature and battery capacity.
2) Simply do what your bike
does, connect the charger, connect a voltmeter across the battery
in parallel with the charger. Why the voltmeter? Just make sure
that the battery voltage does not exceed the bike's charging
voltage, in other words keep the charging voltage below 14.5
volts. Periodic checks to ensure that the battery temperature
stays under 125 F, not more than warm to touch will keep you
out of trouble. What do if the voltage rises above 14.5 or so?
Easy! Connect some sort of resistance between the charger and
the battery. Handy resistances are an old headlight sealed beam.
Too high a voltage? How about a tail light bulb, then? An old
sealed beam or tail light bulb will give three different charging
rates. Method two is the one I use and recommended to students
as is required no reference and simply duplicates what the bike
A final recommendation: Do not
connect the charger's leads directly to the battery! Connect
one charger lead to the battery and then connect a jumper wire
to the other battery terminal. Now connect the jumper wire to
the charger. I like to have something to screen me from the
battery when charging in case it explodes. You won't like having
one explode close by, trust me on this one! Monitor the voltage
closely for a bit and then periodically after that and all will
be well. When finished charging, switch off the charger, then
disconnect the charger from the jumper lead. Now
disconnect jumper lead and charger from the battery. Why? Connecting
and disconnecting to the battery will create spark at the first
connection disconnected and the last one connected. We don't
want that spark to be close to the battery and maybe ignition
the hydrogen/oxygen mixture produced by charging.