When the pack gets that old, the runts start cutting into your range. You need to determine now much capacity each battery will provide.
To do this without disassembling the car, you need to; 1. Verify each battery is fully charged. This is done by measuring each battery voltage and pack current at end of charge. If battery voltage gets above 14.5 volts and the current is less than an amp, then it is very close to full. In a long series string, Optimas can be left on overnight at half an amp charge rate. This is a long slow equalization. If the batteries are healthy, some may go over 16 Volts. If some do not come up to 14.5 overnight, drive the car a couple miles and repeat the treatment. If certain batteries don't come up, they need to be equalized separately to avoid damage to the others in the string. If you have wires (or direct access) to each inter battery connection in the pack, this can be done through those wires and you won't need to disassemble the pack. 2. Put a fixed load on the battery and monitor the discharge. 25 amps is a common load because it simulates a Reserve Capacity test. Use whatever load you have available. Headlights, heater, blowers and on board accessories can work just fine. Stop the discharge when the first battery Voltage discharges to 10.5 volts. Multiply the discharge rate times the discharge time to get the capacity of that battery. If you are discharging the pack, this battery is the first to fully discharge and will be damaged if the pack is discharged any further. 3. Let the pack rest 8 to 12 hours. Measure and record the open circuit voltage of every battery. This will indicate the approximate capacity remaining in each of the batteries that did not drop to 10.5 volts. <12.0 Volts indicates about 0% remaining 12.2 Volts indicates about 20% remaining 12.4 Volts indicates about 40% remaining 12.6 Volts indicates about 60% remaining 12.8 Volts indicates about 80% remaining This is a relative number based on the first battery to discharge. These numbers show the relative state of charge for this test only. This is meant to show which batteries are low and which ones are high. Comparing subsequent tests will give misleading results. 4. Repeat the previous three steps to see if the capacity improves on a second test. If the capacity improves significantly, repeat until capacity stops increasing. If the test in step 3 shows all the batteries are very low, then the entire pack is low. If the test in step 3 shows a few batteries are very low, then the runts have been identified and you should replace the runts and retest the pack. I have done this and doubled the capacity of the pack by replacing only one battery. > Best to setup each battery with some extra wires (fused on the positive > terminal) back to a junction so that you can remotely check each battery (and > if necessary provide separate/individual charging). You must fuse EVERY wire with >200 VDC rated fuses to be safe. > Generating a pallet of dead > batteries every 3 years is out of the question! Recycling is good. Replacing them (time and material cost) is bad. Joe Smalley Rural Kitsap County WA Fiesta 48 volts NEDRA 48 volt street conversion record holder [EMAIL PROTECTED]
