Please make sure that
IF the technicians are testing the battery without the aid of a conductance DMM.
And are simply using the old method of:
1. Measuring the open circuit voltage (OCV). The battery needs to be drained of the surface charge for at least 60 seconds prior to testig. Then, they can measure the voltage. There will be a difference of 0.10 volts due to temperature extremes.
100% = 12.80
75% = 12.50
50% = 12.20
25% = 12.00
0.% = 11.90
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2. Specific Gravity: When the technician takes a sample of the electrolyte (acid) all cells should be 1/8" below the vent well. If it is not, then ensure that he only fills to that level.
Each cell should be measured, and not simply referenced to one cell. Below is the specific gravity which will tell you the acidic strength content.
100% = 1.265
75% = 1.225
50% = 1.190
25% = 1.155
0. = 1.120
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3. Load Testing: If your technician intends to load test the unit using a carbon pile battery. Then the battery
MUST be fully charged, prior to testing.
Load testing a unsaturated battery which is at a minimal voltage threshold will damage the grids plates within the battery.
Once the battery is fully charged. The unit which he is using must be set to load the target battery at half the CCA of the battery which is indicated on the top.
ie. 500 CCA / 2 = 250 amps
The battery would then be load tested for no longer than 15 seconds. He will then wait aprox 2-3 minutes to see if the battery recovers.
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4. Qualification: Any of the three tests can be fooled, and if the technician does not know what to see, or understands the reading. You can be stuck with a battery which does not hold a charge.
If upon load testing the battery and the OCV reaches or exceeds 12 volts within a few seconds. This indicates that the battery may be damaged.
If the OCV reaches 12 volts gradually, then it indicates that the battery is used up, or near its service life.
A well maintained SLI battery will only provide a consistent service life 5 years. If you use and purchase higher end batteries such as those AGM deep cycle batteries, you can expect to see at least 6-7 years of service.
The importance of the above information is that, many auto shops will simply disqualify the battery to make a sale.
Either you are present, or bring the unit to a technician you trust, and is known to be fully competant.
The only measuring tool which is 100% accurate in determining a batteries service life is that which used conductance measuring techniques...
Regards
EVIL Teken . . .