• How does the PowerTrac differentiates between charge, discharge, and open/idle events?
The PowerTrac unit continuously monitors the battery current and uses the measured current to identify the battery state. When the measured battery current exceeds the “Open Circuit Limit” (default value is 5A, i.e. when the battery current is ≥ 5A or ≤ -5A) the battery state changes. For example, if the battery was setting idle (open event) and then goes in use where the current draw exceeds 5A, the PowerTrac will terminate the open/idle event state and start tracking the new discharge state until it terminates. Note that the unit may not show the new state (i.e. discharge) until a set time is elapsed (typically 30 seconds) to ensure that the new state is a valid one.
• Why would one needs to track idle/open states?
Tracking open/idle states could become handy for a number of reasons:
1- Identifying actual utility of the battery
2- Identifying periods of high use and low use
3- Identifying opportunities for fast charging (extended idle times)
• Does the PowerTrac log open (idle) hours while it’s not connected to a battery?
No, the unit needs to be connected to a battery or power source to log any data.
• Will PowerTrac lose its data when disconnected from the battery?
No. PowerTrac data is saved in a non-volatile memory that will keep all data intact until the unit is re-powered for later download.
• Can one download data to the Palm from a PowerTrac if the unit is not connected to a battery?
No. The PowerTrac needs to be connected to a battery or an external DC power source (minimum 10V) to perform a download.
• What happens if the battery voltage goes below 10 volts?
If the battery voltage drops below 10V, the PowerTrac MAY APPEAR to be working but may not log events and communicate accurately with the Palm software. The battery or supply voltage needs to be increased above 10V for proper operation to resume.
• Will the PowerTrac drain my battery?
Not likely. The PowerTrac only draws an operating maximum of 20 milli-amps at 10 volt input and 10.7mA at 48V input.
• Memory Rollover: What happens to the new events after the maximum number of events that can be saved is reached?
When PowerTrac memory becomes full (reaches 2048 or 2726 events depending on the firmware revision), new events will start overwriting the oldest events (first in - first out or roll-over). For example, with a 2048 event memory, event 2049 will overwrite event 1, event 2050 will overwrite event 2, and so on. The global events counter will show the actual total number of events logged including the erased ones. Note that the cumulative data, such as total charge, discharge hours and amp-hours since installation are not affected by the memory rollover.
• My “Present Current” reading is incorrect. What should I do?
1. Review the “Admin Settings” and verify the proper values are installed for such settings as shunt size, number of posts, etc… These have an effect on the current readout. For example, if the number of posts is listed as two and there is actually one, the present current will read double the actual measurement.
2. Verify the current reading with a clamp-on current meter (see note below). If the values between the PowerTrac reading and the current meter differ by more than 10 amps you may need to re-calibrate the shunt by using the PDA’s “Shunt Calibration” utility in the PowerTrac pull-down menu.
Note: If a clamp-on meter is not available, a multi-meter set on the milli-volt scale can be used. Measure the voltage across the shunt (Vd) and apply the formula “Amps=Shunt Size*Vd/50” to find the total current. If the shunt size is 500, the amp-readout will simply be 10*Vd.
• My “Present Temp” reads “– 41”, why?
1. Check for damage to the Temperature sensor ring lug and temperature sense wiring from the ring lug to the PowerTrac.
2. Verify that the connector that holds the sense input leads inside of the PowerTrac enclosure is not unplugged. This cannot be repaired in the field and must be returned to Power Designers for repair.
• The unit does not log any events, why?
Verify the shunt leads are connected properly. PowerTrac monitors the battery current and if it exceeds the “Open Circuit Limit” (default value of 5A, i.e. when the battery current is ≥ 5A or ≤ -5A) the state changes. If the shunt is not connected, the unit will never see a change of state from charge/discharge to open or vice versa and therefore will not log any data.
• The PowerTrac unit doesn't log any Open events, why?
There may be two causes for this: Either the shunt has not been zeroed (as part of the installation process) or the idle current exceeds the programmed “Open Circuit Limit”.
1. If the shunt has not been zeroed and calibrated, do so using the shunt calibration utility in the Palm software.
2. Auxiliary loads, such as cooling fans, controls, lights and guidance systems draw additional current from the battery and can cause the measured current to exceed the "Open Circuit Limit". You can correct for that by increasing the “Open Circuit Limit” using the Palm.
• The unit measures 550A all the time, even while the battery is idle, why?
The current shunt location is probably incorrect. Note the shunt should replace the last intercell connector and should not be more than 2V nominal above the negative battery terminal. Having the shunt incorrectly installed (e.g. replacing other intercell connector within the battery) will cause the current sense circuit to saturate cause erroneous readings of 550A. Note that for battery stacks where the cell voltage is greater than 2V (e.g. 6V or 12V modules), the shunt must be placed in series with the negative cable (past the negative battery post) to prevent damaging the PowerTrac current sense circuitry.
• The unit does not measure any current during a charge or discharge events, why?
There are two possible causes for this:
1. Verify shunt installation: If using a clamp-on shunt, verify that there is a good solder joint between the shunt post and the battery post. If the shunt is not installed properly, a cold solder joint may result where the inside edges of the shunt post are distinctly visible (not fused with the solder/lead weldment). Cold solder joints are caused by melting the lead/solder bar into the shunt post holes without directly heating the shunt post itself. A proper install requires even heating of the brass block part (not the fins) of the shunt and the cell post before adding solder to joint. Cold solder joints result in high resistance contacts causing arcing in case of single post cells or diverting the battery current to the remaining intercell connectors with multi-post cells.
2. The current and temperature sense connector inside of the PowerTrac enclosure has been unplugged. If that is the case, this unit must be returned to factory for service.
• The unit measures negative amps during charge and positive amps during discharge (Charge and Discharge events are reversed), why?
The current sense leads are swapped on the shunt. Reverse the connections of the shunt sense leads and re-check. The PowerTrac shunt leads should always be attached with the black lead closest to the battery negative post.
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