IC-7300 Clock Battery Failure

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

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  1. I1WSM

    I1WSM Ham Member QRZ Page

    Even on my IC7300 after two years from the purchase has presented the problem of loss of clock data (RTC), I think that the problem is due to the charging circuit, because the voltage of 3.3 volts passing through the diode D381 L1SS400 suffers a voltage drop of 0.4-0.6 volts and therefore the small battery BT381 is not charged at 100% and in the long run deteriorates by not maintaining the charge anymore. I think that a solution could be to detach the diode D381 and replace the small battery with a normal CR2032 thus ensuring the tightness of the watch for several years.
    73's Silvano I1WSM
  2. NZ4J

    NZ4J Ham Member QRZ Page

    Hello Silvano,
    Your suggestion seems like a good solution to the problem. I have a battery holder and may install the non-rechargeable battery in place of the existing rechargeable battery. As you have remarked, removing the diode will isolate the battery from the 3.3V DC input.
    Thank you for the suggestion.

    73 Cheers
  3. NZ4J

    NZ4J Ham Member QRZ Page

    Hi Neal,
    Sorry for the late response. I used a magnifying lamp and a fluke 287 meter with sharp probes to make the measurement. Yes, the chassis ground and the battery ground are the same. The real problem is just being able to "see" clearly what your are probing.

    73 Cheers
  4. ZL2MF

    ZL2MF Ham Member QRZ Page

    Thanks Jim for your post
    My 7300 lost its clock when we moved house and radio was stored with no DC supply attached. Surprised at ICOM for doing this on the 7300 a real oversight in what otherwise is a great radio. I have an IC7000 annd clock has worked perfectly since purchase at least 5 years ago! 73 Maurice ZL2MF
  5. ZL2MF

    ZL2MF Ham Member QRZ Page

    Thanks Jim for your information - sorry for not replying earlier....I will attempt a replacement. Warranty well passed Hi! 73 Maurice ZL2MF
  6. ZL2MF

    ZL2MF Ham Member QRZ Page

    Jim and anyone else interested here is the datasheet for the ML414HIV01E rechargeable battery https://media.digikey.com/PDF/Data Sheets/Seiko Instruments PDFs/ML414H_E.pdf
    Maurice ZL2MF
  7. ZL2MF

    ZL2MF Ham Member QRZ Page

    I cant export batteries from US into ZL land so went searching for an equivalent and found the Seiko catalogue here and there is an equivalent MS621FE but watch the protection resistor value compared to the ML414HIV01E. 300ohm compared with 3000ohm
    Hope it helps other folk
    Cheers 73 Maurice ZL2MF
  8. OE9CBV

    OE9CBV Ham Member QRZ Page

    hi i have the same problem that the clock is resetet if i remove the power for 3 days. is there space for a supercap so that i can replace the battery with a supercap?
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    I don't see why not.

    I would run small wires to the PCB to avoid stress, And mount the battery as close as possible, Using RTV.

    The original battery life is rated in hours, So it is not intended for long term storage.

    Good Luck.
  10. K0OKS

    K0OKS Premium Subscriber QRZ Page

    I suppose another option is just to a small 12V SLA battery in parallel with the power supply (with diodes). In other words make a backup battery for the whole rig.

    I don't seem to have trouble with my 7300 battery, but I do turn on the power supply for a few hours almost every night.

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