95 Battery Condition and State of Charge Charts
Always wear eye protection when working
near batteries.
Even a small battery stores a great deal of
energy which can be released during a
short circuit.
The electrolyte contained in batteries is
corrosive.
The following information is courtesy of Ralph Heisy of
Bogart Engineering.
Battery voltage will vary for the same state-of-charge depending on whether
the battery is being charged or discharged and what the current flow is in
relation to the size of the battery.
The chart below will give you an idea of state-of-charge for various battery
conditions in flooded cell lead-acid batteries.
Voltage varies with temperature.
While charging, a lower temperature will increase battery voltage.
Full charge voltage on a 12 volt battery is 0.9 volts higher at 32 deg. F.
While discharging, a higher temperature will increase battery voltage.
There is little temperature effect while a battery is standing.
The following information is courtesy of
AEE Solar.
A hydrometer is very accurate at measuring battery state-of-charge if you measure
the electrolyte near the plates.
Unfortunately, you can only measure the electrolyte at the top of the battery.
When a battery is being charged or dis-charged a chemical reaction
takes place at the border between the lead plates and the electrolyte.
During charging the electrolyte changes from water to sulphuric acid.
The acid becomes stronger and the specific gravity rises as the battery charges.
Near the end of the charging cycle gas bubbles rising through the acid stirs the
fluid to mix it.
It takes several hours for the electrolyte to mix so that an accurate reading can
be taken at the top of the battery.
Always try to take readings after a period of no charge or no discharge.