Safely disabling the heater

Discussion in 'Panasonic' started by ransu, Oct 16, 2011.

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  1. ransu

    ransu Notebook Enthusiast NBR Reviewer

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    I have a bunch of CF-18mk1s that need to operate in deep freeze. Changing HDs to SSDs.

    Has anyone figured out how to disable the HD heater circuit so that its happy ie. thinks the temp is OK?
     
  2. Alex

    Alex Super Moderator

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    I would not bother (I left the heaters in place on my ssd's)
    Read the specs on your ssd
    I bet it's not designed for use below 0
     
  3. ransu

    ransu Notebook Enthusiast NBR Reviewer

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    Need to use them in -20C (actual operating in -20C, not just storage). The reason for the question was that during field testing the laptop in freezing temperatures it appeared to have a reduced battery life. Don't know if this is due to the heater element or a characteristic of the litium battery.

    I quickly examined the heater element and measured the resistance to be 2 ohms. No switches, sensors or other electronics visible. Must be using the HD's internal temp sensor. So not so simple to disable.

    Need to figure out how to measure the voltage current while in operation. If the element uses the battery voltage (7v) directly, that would be 24W and would drain the battery in 2 hours. If 12V then in 1 hour.

    Need to actually leave it in the freezer overnight and start and see what happens.

    All major SSD manufacturers indeed site 0-70 as operating temp. Probably some chip spec on the board. I doubt they've actually tested what the low is.

    There are only two I found so far that go below:
    Model: KF2502MIS 32G Industrial line IDE PATA SSD -20C + 70C
    Shenzhen New KingFast Storage Technology Co., Ltd.

    Model: STRP-25 (IDE/ Parallel ATA) Operation Temperature -40℃ ~ +85℃
    Solid State Drive, SSD, Military, Aerospace, Marine, Industrial, Embedded, Enterprise
     
  4. ares93

    ares93 Notebook Evangelist

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    I think its rather the battery itself. I have noticed the same issue in my CF-28, and that one doesn't have a heater. And mine also operates at -10 to -20 degrees celsius during the winters.
     
  5. kevin1162

    kevin1162 Notebook Guru

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    Exactly.

    Lithium batteries are still better than NiMh/NiCd in cold weather but once you go below freezing performance will become degraded.
     
  6. mnementh

    mnementh Crusty Ol' TinkerDwagon

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    The heater in these laptops only operates at pre-boot; it is designed to get the bearings of the HDD up to a minimum acceptable operating temp and then let the natural heat generated by the HDD sustain its operation. I've never had it last more than 5 min, even in -10 degree temps. I don't know how much heat an SSD would generate under normal use; but given the TWD, I'd guess maybe half as much as most common HDDs. This should STILL be enough to keep the heater from turning back on during use.

    mnem
    Baybeee, it's CO-O-OLD outside!!!
     
  7. ransu

    ransu Notebook Enthusiast NBR Reviewer

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    Here are some initial test results:

    SETUP1: Model CF-18 Mk1 (CF-18BEL01ME)
    Battery on this individual is original (2003) and holds about 1h charge.

    TEST1: froze the Toughbook overnight with battery. Freezer temp was -28C (-18F). Straight out of the freezer and power on:

    The green power led came on momentarily for a few seconds and then went out. Repeat: same.

    Plugged in the mains adaptor: power led came on and text appear under the still frozen screen (in BIOS font) "Warming up the harddrive. Please wait...". After about 1 minute Windows booted and everything seemed to function normally. Sensors showed motherboard temperature as +8C and harddrive as +10C.

    SETUP2: Soldered parellal wires (Fluke 83 for voltage measurement) on the harddrive heat element's connector (showed 2 ohms resistive load) and also placed a thermocouple probe (Fluke 52) against the harddrive chassis.

    TEST2: froze the Toughbook WITHOUT battery for the rest of the day. Plugged in the room temperature battery and powered on.

    RESULT: The battery indicator led started blinking green and amber with a 1 second period. The voltage on the heat element also swiched between 4.66V and 0V with the same period. Display shows no text. The harddrive thermocouple temperature began to climb rapidly up from -25C at a rate of about 0.1-0.2C/sec.

    After about 5 minutes, when the harddrive surface temperature was +1.2C Windows logo appeared and booted all the way to the desktop, only to give a battery warning and return to suspend state. Forced out of suspend back to desktop. Battery showed 8% charge left. Motherboard temp was +10C and harddrive +12C.

    Plugged back to mains and did dignostic tests (with condensation melt dripping in and out of the chassis...

    CONCLUSIONS:

    The heater functions differently depending on if its mains plugged or battery powered.

    - When mains plugged it supplies the heater element with full voltage (not measured but probably 10-12V, 50-75W) which heats up the harddrive to 0C more rapidly (in the test in one minute). Also the display is powered during the heating and shows the text "Warming up the harddrive. Please wait..."

    - However when powered by a battery, it gives the heater only 5V or 12W of power and took about 5 minutes to warm up the battery to 0C. In this mode the warming up indication is given by blinking the battery led green and amber in a 1 second period.

    - The battery charge required to heat up the harddrive from freezing (-25C) temperatures is less than 10% of its full (new) capacity.

    - Therefore no need to disable the heater in SSD mods to save battery power.

    - ...and Toughbooks RULE!!!

    Sincerely Ransu :D
     
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