What are the specs around power saving for the MC75? Specifically at what percentage of battery does the radios start shutting down. IE: At 20% the HSDPA and WLAN radios are switched off. This is in response to a request for information from a customer who has run the batteries down and now the HSDPA data session is closed and does not come back up without user intervention.
Battery Levels and Power Saving// Expert user has replied. |
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Ugh. Looks like I may not have been explaining things very well. Let me coordinate with the Platform team and Electrical design people to come up with a document that describes how this works.
WLAN turning off may well not depend on battery power, but I have noticed that below about 20%, it performs pretty sluggish: slow, easily looses coverage, etc.
Just to make sure I have this correct, the 3.2V value is measured from the main battery? Does the backup battery level have any influence over the value? We have seen cases where the radio will not turn back on once the device is back on charge after both batteries have been depleted. This device required a cold boot to unconfuse the Wireless Manager. Symptoms included the green radio LED flashing but Wireless Manager reporting the phone was off. There was no response from Wireless Manager when clicking on the phone.
For a 1.5x battery, the threshold is 11%. It is not customizable and can not be turned off. Note: this is an instantaneous value. So, if there is a large current draw and the voltage dips, the modem will detect that and turn off. This condition should not be seen during normal operation, however as the battery gets closer to the 11% value, the greater the opportunity for this condition to occur.
CORRECTION..... Sorry, I spoke to soon. Although this feature can not be turned off, it can be configured. CHANGING THE SETTINGS IS NOT RECOMMENDED!! THE PERFORMANCE OF THE TERMINAL WILL BE AFFECTED AND THERE IS LITTLE GAIN USE TIME. If you navigate through Start->Settings->System->Power->Runtime, you'll be presented with three options. These are known as the Battery Reserve Options. The normal setting is the 11% discussed before. Less is approximately 8% and Minimum is approximately 4%. There will be very little improvement in use time since the slope of the discharge curve of the battery is already steep once the 11% threshold has been reached.
Wow, this topic has really sparked a bunch of discussions! I don't think it was clear what was being asked and then the answer wasn't clear either. So, let me try to make it right... The modem will turn itself off at 3.2V. Power to the modem is driven by a regulator and not the battery itself. This 3.2V value can not be changed or turned off. At no time during testing was the modem found to turn itself during normal operation. The settings that I described in a previous post, change the values in which the entire terminal will suspend. This will keep the radio powered longer only because the terminal will maintain normal operation for a longer period of time.
The WAN radio is the only radio that will shut down as the battery power drops below a certain threshold. Keep in mind that this is an instantaneous value that shuts the radio down. So, if a transmission causes a dip in voltage the radio will turn off even though the battery power seems to remain at an acceptable voltage. WLAN does is not dependent upon battery power.
Thanks George, two things;
1. Is this value threshold able to be shared with the customer?2. Is it customizable, or able to be switched off?