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Thread: Low Battery Alert on CDM line

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    Default Low Battery Alert on CDM line

    I've done a bit of searching and didn't find an answer. I know the CDM mobile doesn't have Low Battery Alert option accessable in the software like the HT portable does, I was wondering if anybody has done any mods to the software package to possibly enable it. I have an application where I have put a CDM in a Pelican case for use by our Fire Brigade in the tunnels under NYC. It would be nice if the radio chirped when the battery was getting low. I have a few other ideas, but this would solve the problem with minimal effort.


  2. #2
    iamjason No Longer Registered

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    Someone correct me if I'm wrong, but I would think the low battery alert (and the associated low battery voltage parameter) is part of the HT portables firmware - CPS would only serve to enable or disable it. If this is the case, the same function would have to already be present in the CDM's firmware before CPS can be modified to access it.

    Another option is adding some sort of isolated (so it does not interfere with operation of the radio in any way) external battery alarm and/or volt meter. May not be as "seamless" but it might be a simpler addition.

    Either way, interesting idea. I too can think of a few uses for this if it is indeed possible.
    Last edited by iamjason; Oct 31, 2013 at 10:15 PM.

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    My CDM chirped one time when I was transmitting with a poor battery connection. Sounded just like a portable low battery alert. Surprised the hell out of me. So I think it is in there just not configurable.

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    Quote Originally Posted by radioman2013 View Post
    I've done a bit of searching and didn't find an answer. I know the CDM mobile doesn't have Low Battery Alert option accessable in the software like the HT portable does, I was wondering if anybody has done any mods to the software package to possibly enable it. I have an application where I have put a CDM in a Pelican case for use by our Fire Brigade in the tunnels under NYC. It would be nice if the radio chirped when the battery was getting low. I have a few other ideas, but this would solve the problem with minimal effort.
    I did a google search and found these two threads over on RR. (I know, I know. But every once in a while, there's a useful tidbit to be found over there.) If I understand them correctly, the CDM will beep and cancel transmit when the voltage drops to a certain point.

    http://forums.radioreference.com/mot...4-cdm1250.html

    http://forums.radioreference.com/mot...dm-1250-a.html

  5. #5
    iamjason No Longer Registered

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    Learn something new every day. Kind of a bummer the "low battery" alert coincides with cancelled transmissions though. Kind of goes against the whole idea of having a low battery alert - and probably not super conducive to mission critical use. I'm guessing (if the transmissions were meant to be cut off) its more of a safety feature than anything else (i.e. John Doe is parked on the side of the road talking to dispatch. Battery goes low. Cut radio TX so he doesn't get stranded with a dead battery. If he needs to TX, then start the vehicle.)

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    Thanks for the info, I too generally don't use RR as any kind of reference since it's more like Wikipedia and not very accurate with the exception of certain posters. Yea it is kinda useless to let the Firefighter know that his battery is already dead. You may be right that the low bat beep is in the firmware, I was just wondering if anybody had played with it, if it could be located in the "S" records that would be way cool.
    I have an aftermarket LCD volt meter to put on the case, but it too is not Fire operations friendly. It's not lit and you can't see it in the dark never mind if there is smoke. I'll try and come up with some sort of LED that comes on when battery is getting low using zener diodes.

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    The radio cutoff is to prevent the current from exceeding the design parameters of the final IC in the PA of the radio. It is actually a radio reset. The bus goes below the reset voltage on PTT causing the radio to reset.

    Not only do you lose PTT buy you would also lose receive for the boot time of the radio. Bad juju.
    "God as my witness" - Jeremy Dewitte - Felon