Icom IC-7300 Clock Repair

The Icom IC-7300 has an internal rechargeable battery to retain the running of the Real Time Clock – RTC. The battery charges when connected to your power supply, however drains deeply when left un-powered for a while. The issue seems to be that this Lithium Ion battery has a limited number of deep cycles and will eventually no longer be able to hold enough charge to keep the RTC running.

This is more of a nuisance and doesn’t really hinder the normal operations of the radio, except time-stamps on recordings or screenshots will all be labelled with the wrong date and time, typically starting at 1st January at 00:00.

Icom UK Official notice on mitigating the issue

1st, the “wash my hands” bit – DISCLAIMER

Quite a bit of heating is needed to remove the battery, and you are very close to other components, critical ones even, such as the main CPU. Any mistake can cause serious damage to your radio. So if you are not experienced in SMD soldering or using a soldering iron in a very FRAGILE environment – do not try to perform this fix yourself, buy the parts and a 6 pack of beer and give them to someone who can do it for you ! I will not be held responsible for any damage you cause to your radio based on this article.

My Solution

The best way, in my opinion, to solve this once and for all, is to replace the battery type. A non-rechargeable CR-2032, as used for the RTC on most PC motherboards should do the trick. Using a CR-2032 battery socket would make swapping the battery a 5 minute job a few years down the line.

The normal CR-2032 is NOT rechargeable, you may use a rechargeable type, but not really worth the risk of matching the charge profile and current, so an in-series diode will keep a non-rechargeable type like the CR-2032 from getting charged. The 0.6v voltage drop of the diode doesn’t bother the RTC, but may stop a few months earlier when the battery gets depleted, even though a little juice might still be there. I don’t see this as an issue, A quality branded CR-2032 is around €2 from most shops, even stationaries.

The battery is located just in the corner of the mainboard, next to the CPU
Original schematic of RTC circuit from Icom service manual
The diode shown in series with the non-rechargeable CR-2032A

A common diode such as a 1N4148 or 1N4001 may be used and is simply connected to the battery holder and covered in some heat shrink.

Affix the battery holder with some good double -sided tape to some place it cannot short anything, the top of the FPGA “screen” seems like a good place.


  1. I used a rechargeable one but there is too less current. So indeed the best way is as you did.

      • on 24/11/2021 at 18:57
      • Reply

      yes indeed the charge current is also very low and that 3.3K (R382) slows is further. I feel this is a design flaw to be honest. Icom could have done better.

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