08-12-2023, 01:29 PM
Forgive me "necroing" this thread. I have finally worked out the issue.
As I am sitting at home with "Catastrophic Fire Danger Rating" outside I decided to charge up the HT's and once again came across this issue.
This time I have a solution!
The 3.7V lithium batteries are ever so slightly thicker in diameter than an AA alkaline. Not enough to prevent them fitting into the AA carrier - or so I thought.
In the previous attempt I modified the carrier so only the top two slots (of six) are in play. If I put in the lithiums and measure the OC voltage at the contacts I get 7.2V. All good.
When I put the carrier into the radio, nothing, nada, zero, zilch.
Maybe the contacts on the ebay carrier are dodgy? I duly beefed up the contacts with some foil. Still nothing. I had been through this before...
Then I made a fortuitous mistake. I forgot to turn the radio off as I removed the carrier. The radio briefly came to life, well, until the carrier was removed.
So new experimentation ensued.
It turns out that the extra diameter of the top cell was causing some tension as the carrier was snapped home. This tension pushed the cell back against the spring which inserted an air gap between the positive terminal and the carrier contact. Wedging in a bit of foil closed the gap and Hey! Presto! the radio came to life.
I hope that helps others!
As I am sitting at home with "Catastrophic Fire Danger Rating" outside I decided to charge up the HT's and once again came across this issue.
This time I have a solution!
The 3.7V lithium batteries are ever so slightly thicker in diameter than an AA alkaline. Not enough to prevent them fitting into the AA carrier - or so I thought.
In the previous attempt I modified the carrier so only the top two slots (of six) are in play. If I put in the lithiums and measure the OC voltage at the contacts I get 7.2V. All good.
When I put the carrier into the radio, nothing, nada, zero, zilch.
Maybe the contacts on the ebay carrier are dodgy? I duly beefed up the contacts with some foil. Still nothing. I had been through this before...
Then I made a fortuitous mistake. I forgot to turn the radio off as I removed the carrier. The radio briefly came to life, well, until the carrier was removed.
So new experimentation ensued.
It turns out that the extra diameter of the top cell was causing some tension as the carrier was snapped home. This tension pushed the cell back against the spring which inserted an air gap between the positive terminal and the carrier contact. Wedging in a bit of foil closed the gap and Hey! Presto! the radio came to life.
I hope that helps others!
Colin
Barossa Valley, SAP. PF95ln
(aka VK5CSW)
Barossa Valley, SAP. PF95ln
(aka VK5CSW)