[ARC5] adventures in battery ops

[Dennis Monticelli]

Bill,

Learning to use the Arduino is a worthwhile exercise even if the
application is overkill...and it is.  If that project is your motivation,
then go for it.

You can also put a diode shunting each of your 12V batteries.  When one
battery tries to go reverse on you, the diode will prevent it.  Of course
it is much better to have a 10V detector, but in the meantime the diode
would help.

I wholeheartedly endorse batteries for the receivers.  I use them the same
way as you do and have had the same positive experience.

Dennis AE6C

On Mon, Apr 6, 2015 at 6:06 AM, Bill Cromwell <wrcromwell at gmail.com> wrote:

> Hi Neil,
>
> The Arduino, or any computer at all really *is* overkill for this
> particular job. That is the first thing that occurred to me. Next thing
> that occurred to me about a half second later is having to deal with the
> digital noise it might add. Have you listened to LF and low MF lately.
> What's a little more noise <evil grin>. It might not be too difficult to
> suppress.
>
> The real reason to use the Arduino is to gain more experience using it.
> The next step will be using the computers to monitor and help control
> battery charges - with data logging. The data logging part will help track
> battery health. I'm still doing that with paper and as I get more batteries
> it consumes more time. I also want to use the data logging in other, non
> radio investigations. It's time to trade in the clipboard. So this is
> really a stepping stone to bigger projects. And..I get to point at the cool
> Arduino and the pretty blinking LEDs.
>
> I am NOT going to drag all that to the park with me for field operations!!
> An op-amp comparator with an LED will do nicely. That is even smaller than
> a dedicated voltmeter. Umm...how much are they getting for those Harbor
> Freight DMMs?
>
> 73,
>
> Bill  KU8H
>
>
> On 04/06/2015 02:54 AM, AKLDGUY . wrote:
>
>> Arduino seems a bit overkill for battery level warning.
>> Why not configure a $2 op-amp in a window comparator circuit?
>>
>> I set one up years ago to monitor the falling voltage of my cellphone's
>> NiCad battery, when discharging in my homebrew discharger
>> (remember how we had to ensure NiCads were fully discharged before
>> charging?). The window comparator's output operated a high-pitched
>> buzzer via a cheap transistor of the BC108 class.
>>
>> For those who don't know, a window comparator makes use of the
>> way the op-amp's output rapidly switches from ground to + rail (or vice
>> versa) when one of its input voltages crosses the threshhold voltage on
>> the other input.
>>
>> With a voltage divider or pot, you set the desired battery minimum
>> voltage (eg. 11.5 volts) on the appropriate input of the op-amp and
>> connect the battery to the other input. Nothing happens 'till the battery
>> discharges to the preset voltage, when the op-amp abruptly turns on
>> (or off), triggering the buzzer.
>>
>> 73 de Neil ZL1ANM
>>
>>
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