Measuring the specific Gravity of Battery Acid
In a maintenance-free battery the acid specific gravity (SG) cannot be measured.
If charging status is not satisfactory, charge the battery once more.
In conventional, non-maintenance-free batteries the SG can be specified with an
acid pipette. The range should be at least 1.25 up to 1.28 g/cm
The SG in a well-conditioned battery has to be equal in all 6 cells. When the
density in the cells is different - the highest and the lowest value – and vary up to
more than 0.025 (25 points), this might be a hint for possible problems in the
cells.
If the SG does not show the same state after recharging the battery, the battery
might have sulphurized. If the value remains below 1.24 g/cm
charging – the battery is discharged and should be replaced. A battery is used up
after approx. 5 – 8 years.
SG of Battery Acid in
3
g/cm
1.25 – 1.28
1.20 – 1.24
< 1.20
Starter Motor Test (for 12 V systems only)
With this test you can easily measure whether the starter motor of the vehicle
does not take too much current from the battery. In some cases currents of about
200 Ampere can be produced and weak the battery.
Before performing this test, the battery load test has to be done and the battery's
condition should be OK. The engine must be at normal operating temperature.
1. Pull the spark plug cables from the spark plug in order to avoid the engine to
get started.
2. Connect the black battery clamp (9) directly to the negative terminal (NEG, N,
-, Minus) of the battery.
3. Connect the red clamp (10) directly to the positive terminal (POS, P, +, Plus)
of the battery. Ensure the connections are good.
4. Now turn the key to try to start the engine.
Operation
Charging State
Charged
Semi charged
Insufficiently charged
18
3
.
3
Step
Perform Measurement
Charging is recommended
Charge immediately
- even after