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Thread: XPR8400 - Battery backup doesn't work properly

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    Default XPR8400 - Battery backup doesn't work properly

    Has anyone played with the XPR8400 and the battery backup/revert option?

    I ordered the RKN4152A revert cable from Moto. It's basically 10AWG stranded wire with inline fuses on both leads, with a MOLEX 42816 connector on the end.

    I hooked up to a gel cell booster pack which works fine for everything -- I can even start my damn truck off the thing. Batteries are good. It sits around 12.8VDC. Well, as soon as I hook up to the repeater (on DC backup -- NO AC) it starts draining. The repeater locks up and reboots once voltage drops below 12.30VDC. (12.29 is when it reboots). I can't even get 5 seconds of battery backup time off the repeater. Yet I can run my Quantar for 5 hours!

    Upon reboot, the repeater is in a corrupted state and all the lights stay on. If I plug AC back in and power cycle, all lights still come on and it's non-operational.

    If I write my codeplug back to the repeater, this restores normal operation and there are no further problems.

    I thought perhaps the 12.30VDC was too low, however it says in the installation guide I'm good until 7.5VDC. So what the heck's going on?

    Bad firmware? (I'm running latest R02.20.02) or maybe the circuit isn't working properly?

    ---

    For anyone who wants to build their own battery backup cable and not give Motorola $50~ for the damn thing, here's some pics of the connector. As I said, it's the MOLEX 42816.
    Attached Images Attached Images


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    Im not sure about the lockup, but xpr's do not charge the battery, you must provide charger.
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    Quote Originally Posted by Magnus View Post
    Im not sure about the lockup, but xpr's do not charge the battery, you must provide charger.
    Maybe it was just the 8300 that it didn't charge?

    I measure a trickle charge current coming off the 8400's DC revert connection. The cell voltage does rise. The 8400 installation guide says it trickle charges when AC is present.

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    According to the XPR 8300 installation guide:

    "Backup battery supplies backup power to the repeater. The battery is an optional accessory. The repeater will trickle charge battery, but an external charger is recommended to equalize battery after a prolonged use. Auto switching from AC to battery with loss of AC power is a function of the standard repeater power supply. Supply will automatically switch back to AC operation upon the return of AC power. The front panel power LED switches from green to red when on battery power."

    So either the guide is wrong, the 8400 is different (but they cut and pasted the text from the 8300 manual), or the PSU is dead. I will measure mine and post results.
    It is a fine thing to be honest, but it is also very important to be right