Hi All,

A good friend recently gave me some 12V 2.2A lead-acid batteries. It
occurred to me that I can use them to power my VX-5R HT while at home,
using the accessory port power adapter. I went to RS and bought an
accessory port, soldered up some power connectors, and connected the HT to
one of the batteries.

It works fine when receiving, and the HT charges its internal battery when
off. But if I try to transmit at 5W (and sometimes at 2.5W) the VX-5R's
"safety reset" triggers. According to the manual this happens when power
is interrupted. This doesn't happen at the two lowest power settings.

What is happening here? I don't know how this safety reset works "under
the hood", and I don't know a lot about lead-acid batteries. Is my power
really being interrupted and if so how can I remedy this? Or is the HT
just seeing a large voltage drop on transmit and assuming that power is
being interrupted, thus triggering the reset (I assume this can be
remedied by putting two of the batteries in parallel to get more current
capacity).

Some background information, when plugged in and monitoring, the HT's
voltage readout shows 11 volts, coming from an external power source. On
transmit at 5W the voltage drops to less than 9.5 volts, and the VX-5R
says that the power source is from the internal Li-Ion battery, and then
resets. I'm guessing that the voltage drop is caused by the battery's
inability to supply the needed current, and that the HT assumes that
certain voltage levels correspond to certain power sources.

The VX-5R draws about 1.9A at 5W output, but note that the lead-acid
batteries I have are old, and so are probably not able to output the full
2.2A.

Any help is appreciated.

Thanks!

-Josh, AE6IQ

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