Specific Gravity Testing

SPECIFIC GRAVITY TESTING

(dealers without midtronics)







The SI (System International) measures the strength of the battery electrolyte as density in grams per cubic metre (g/m cube) @ 25 degrees C
This can be measured by means of a battery hydrometer which measures the battery electrolyte specific gravity (density)
Temperature correction is necessary if readings are taken at anything other than 25 degrees C

Test procedure.
- Remove all battery cell covers or caps, and visually inspect to ensure sufficient electrolyte is present, do not top up any cells before testing. If topping up is necessary then you must charge the battery fully then remove any surface charge before continuing with this test.
- Squeeze the bulb of the battery hydrometer and insert the tube into the first cell (No 1 Cell) and draw the battery electrolyte out of the cell and into the hydrometer.
- Allow for any air bubbles to disappear and the float level to stabilize before reading the value displayed by the level of the fluid on the float. Then enter this figure onto the battery report form for cell No 1.
- Repeat the above operation for the remaining five cells and enter the readings onto the battery report form. Battery Report Form (Diagnosis)

Results:
- Compare the six cells for consistent readings regardless of what the readings are they should ALL be similar. A significantly lower/higher reading in one cell indicates a bad cell and the battery must be replaced.

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VOLTAGE READING UNDER LOAD @ 2000rpm

Connect the red positive lead of a 3.5 digital multimeter to the battery positive terminal post and the black negative meter lead to the negative battery terminal post.
- Start the vehicles engine and leave to idle for a few minutes.
- Switch on electrical loads: Heated front and or heated rear screens, headlamps on main beam and the heater blower on full speed.
- Increase the engines speed to 2000rpm.
- When the rpm as remained stable for a few minutes read the voltage on the multimeter.
- Enter the reading obtained on to the battery report form. Battery Report Form (Diagnosis)