ad: elecraft

IC-7300 Clock Battery Failure

Discussion in 'Radio Circuits, Repair & Performance' started by NZ4J, Jun 25, 2018.

ad: L-HROutlet
ad: l-rl
ad: Subscribe
ad: K5AB-Elect-1
ad: Left-2
ad: Left-3
ad: MessiPaoloni-1
ad: L-MFJ
  1. NZ4J

    NZ4J Premium Subscriber QRZ Page

    Hi George.

    Sorry for the long reply...


    While I agree that many radios simply do not care, the IC-7300 is very different in its behavior.

    If the time is lost due to the battery not being charged sufficiently to hold up the RTC, the radio will display a screen when powering up that shows both the time and date reset to factory defaults. The displayed data covers almost the entire touch screen. At that moment, no matter what you press or touch, the radio is unresponsive.

    The screen and the radio become responsive fairly quickly (10-20 seconds) after the screen is displayed IF THE BATTERY IS CAPABLE of being recharged normally.

    When the battery catastrophically fails in a similar manner as mine did, the delay before you can operate the radio is much longer. I waited over 3 minutes before the touch screen would let me operate the radio normally. In one instance I was frustrated and just left the radio powered for a couple hours and came back to the rig, set the time, and operated the radio.

    But leaving the radio powered for two weeks did not charge the battery to a normal level and the clock would fail after only 4-5 days of being unpowered.


    I think the software behavior regarding the RTC when the battery has failed to keep the RTC running is abominable.

    That frustration is what drove me to investigate the battery condition after being on charge for weeks. After removing the battery from the unit, I was able to determine that the charge voltage was correctly generated by the surrounding circuit.

    I really hope that my experience is unique and that everyone keeps their rig attached to DC power for longer periods of time between uses.
    Contracting cancer (and beating it so far) distracted me from the hobby for a very, very long time.

    Either the individual battery part was marginal from the OEM part supplier (when the radio was built,) or the stress I placed on the battery in discharge mode (battery voltage allowed to go too low) precipitated damage that limited the ability of the lithium cell to be re-charged. I don't have empiric proof that the chemistry of the battery is prone to degraded charge capability.
    Some day I will do the research regarding the battery chemistry.

    Right now, I have a perfectly operating radio that keeps time very well.

    Will I pull it off the power supply for 6-8 months at a time again?

    Not likely!

    I hope you enjoy your radio. I really enjoy the 7300.

    73/Cheers

    Jim
     
  2. N3GWZ

    N3GWZ Ham Member QRZ Page

    Thanks for posting the photos and part number for the battery. One of my IC7300s is losing clock and I want to replace the battery. I am curious what process worked best for you. Is the battery surface mount? Did you remove anything to get to the battery easier? Do you have a source for the battery that you would recommend?

    Thanks and 73,
    Pat N3GWZ
     
  3. NZ4J

    NZ4J Premium Subscriber QRZ Page

    Hi Pat.

    The battery is small enough to create a bit of a challenge in removal and to a limited degree, replacement.

    The battery may have been flow soldered to the board. Not sure. It is not a through-hole part.

    The battery has two points of attachment:

    - The lightest point of attachment is a thin conductor that terminates on a pad adjacent to the battery. It is shown on the battery in the 10:30 position (NW?). Since it is relatively light and flexible, it is easy to remove the attachment and bend the conductor up and away from the board. I removed this attachment first.

    - The largest battery tab is on the bottom of the battery and it extends outside the circumference of the battery. This tab is soldered to a large ground plane. It is shown below on the right side of the battery in the 3 o'clock position. The obvious guidance here would be to be sure that you allow sufficient heating of the tab before trying to remove the tab from the circuit board. It is possible to damage the ground plane at that location if the tab does not release cleanly. Take lots of time here to be sure it comes off cleanly.
    According to the geometry of the battery attachment points, it is possible to damage the ground plane and still successfully replace the battery by expanding the "other attachment" away from the battery which allows the large tab to reach the remaining ground plane. I considered that possibility before I started the repair. I have experience in making problems of this type and have become wary of any repair and the possibility of bad things happening. ;-)



    upload_2018-7-26_8-37-50.png



    I used a magnifying light (on an arm) to be sure I could see what was happening. The area is not too crowded for this repair. Simply remove the cover as described above.
    I employed a METCAL SP-200 using the smallest tip in my inventory. Note that the METCAL tip is at ground potential. While you could consider static discharge to be an potential issue, just use good common sense for avoiding zapping the rig.

    If you have a good tip that is small enough to avoid obscuring the points of contact when working in the rig, you should be fine.

    [​IMG]



    PS - I like your use of the quad to lift messenger lines into the tress for antenna erection! Another great use for the quads.
    They use them for fishing lure placement down here... A bit risky!

    Let me know if you have any other questions... I will share what I have found out.

    I have not installed the high capacity battery assembly that I discussed earlier. I have the parts and I am going to do some tests to see how much time is required to charge the battery from a low charge state. Might take a week or more given the low current supplied by the IC-7300 circuit...

    Cheers/73
    Jim
     
  4. NZ4J

    NZ4J Premium Subscriber QRZ Page

    I bought the battery from here:
    https://www.digikey.com/product-detail/en/seiko-instruments/ML414H-IV01E/728-1052-1-ND/1889213

    Since you have two rigs, buying two might be a good idea since the shipping is steep for such a small part.

    You will be surprised at the packaging they use. It is huge. The packaging rules require a box of sufficient size to post all the required warnings and stickers relevant to shipping Lithium batteries. Not that this tiny cell poses a significant fire risk.

    Cheers/73
    Jim
     
  5. KA9JLM

    KA9JLM Ham Member QRZ Page

    Batteries are normally hand soldered. Flow solder would short them out.

    Those batteries have a very limited usage time before they need recharging.

    The rating is in hours, Very few days.

    Even if they held charge for months, The clock would be way off.

    Have Fun.
     
  6. NZ4J

    NZ4J Premium Subscriber QRZ Page

    Sorry Don...

    At Rockwell Collins, we machine placed and heat flow soldered many batteries like these - but slightly larger. You must be confusing flow soldering with wave soldering?
    The time to bring the battery to a level that is considered too low to support the time chip (~2.2vdc) is in the order of weeks but less than several months.
    Perhaps you didn't read the data sheet for the battery consumption and do the calculations.

    Cheers
     
  7. N3GWZ

    N3GWZ Ham Member QRZ Page

    Awesome, detailed explanation. I have no questions. Your response is very detailed. Greatly appreciate it. I'll take your suggestion and pick up 2, and be careful with the swap out.

    I watched plenty of YouTube Drone Fishing videos to learn about methods and abilities before I bought my drone. Way cool!
     
  8. KA9JLM

    KA9JLM Ham Member QRZ Page

    I did.

    All good soldering is flow soldering, If you want a good fillet.

    Thank you for the correction.
     
  9. N6YFM

    N6YFM XML Subscriber QRZ Page

    NZ4J:

    How did you measure the battery? I ask, because it looks in the photos like that battery
    is in a corner in the case, and two test probes for my meter would likely short. Also, the RTC
    chip looks so small that my test probe would likely short pin 3 (Battery + and Vcc) to each
    pin next to it :)

    Did you simply clip meter ground to the rig case, and then carefully touch the plus probe
    to the edge pad of the battery?

    Cheers,

    Neal N6YFM
     
  10. NQ4T

    NQ4T Ham Member QRZ Page

    Then just add a diode.

    The old Williams MPU boards for pinball machines used a rechargeable Ni-Cad for it's memory backup. While you can replace it with an easily available Ni-Cad. But I have..in a pinch...replaced it with 2 AA batteries in a 3AA holder, placing a diode in an empty slot to prevent the charging circuit from dumping voltage in to them. In fact there's been a LOT of coin-op stuff that takes Ni-Cads I've put lithiums in using that same trick.
     
    W1TRY likes this.

Share This Page