In article ,
Joshua G Senecal wrote:

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?

The batteries aren't able to provide the full (1.9-or-so) amperage, at
the voltage required by the VX-5. The voltage drops when you key up,
and the VX-5's safety disconnect shuts down the radio.

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.

A fully-charged gel cell in good condition ought to be delivering no
less than 12 volts. If you're only getting 11 volts when drawing only
the receive-monitor current, then the battery is either badly run
down, or old and dying. If they don't charge up well and hold 12
volts, then you may not be able to use them for transmitting... just
for receiving, or as a way of providing portable power for recharging
the VX-5's built-in battery pack. [The latter is how I use some old
gel cells I have - I charge 'em on my solar panels, then use them to
charge up the VX-5.]

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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