Help with a solar flashing beacon schedule

Projects General Guidance
1

Hello to all, NOOB alert....

So I am familiar with electronics but it has been 30 years since I last played with any small scale electronics; my job lead me to being a traffic signal electrician for a large city in California.

We have a solar powered flashing beacon for a pedestrian crosswalk (a master/slave pair which when one is activated it is supposed to tell the other one to flash as well).

Well the beacon stopped working YEARS ago, and finally people want it fixed...boss sends me out to look at it and change the batteries in it, and get it working. Lo and behold this system is so old that the vendor no longer supports it and wants us to purchase a new solar package and beacon system at a DISCOUNTED rate of $8500.00.

The solar 'brain' board has inputs from the solar panel and outputs to the batteries (and beacon lights), as well as communications to/from the master/slave unit....

BUT it also has manual activation pins, as if we had pushbuttons that would turn the beacon on.

This location has no buttons, it used to run on a schedule that was programmed into the 'brain' of the charger system...which is no longer supported. So we have a beacon that will never flash on its own.

After changing batteries, I jumper the pins on the external pushbutton and the beacon flashes as it should for 60 seconds then turns off....so I know the beacon works.

What's strange here is the system voltage...4VDC. yes, four volts! It actually has three sets of 4V batteries wired in parallel. Actually they are three sets consisting of 2-2v batteries in series....so a total number of 6 batteries...with a ample supply of amp-hours run time.

My objective is to use a step up transformer to get me from 4v to 8v and power up an arduino which will control a relay to close from 7am-6pm every day which would simulate someone constantly pressing the activation button.

Simple enough???

Relay Im thinking will work:

Now I have a few questions here....when/if I do ever figure out the coding part and it gets loaded into the arduino I assume the arduino will get current time/date from my PC. How long will that stay accurate???

There should not be any power loss ever, as its a self contained solar system, but should it happen anyway I plan to add a DS3031 clock module...Do I really need to add this?

Or should I add a GPS and have it grab time/date monthly??

I'm TRYING to keep it as SIMPLE as can be, all I need this thing to do it close a set of contacts from 7am-6pm every day for eternity...and keep the time SOMEWHAT accurate.

thanks for any and all help here!

2

Arduinos can work from 1.8V to 5.5V. A 3.3V 8MHz Pro Mini should fit your needs, powered directly by 4V or using the on-board 3.3V voltage regulator.

3

angryandy:
My objective is to use a step up transformer to get me from 4v to 8v and power up an arduino which will control a relay to close from 7am-6pm every day which would simulate someone constantly pressing the activation button.

Simple enough???

I would probably use a small 3.3volt Arduino (ProMini?), and power it directly from the batteries (Raw pin).
And power a DS3231 from it's 3.3volt pin.
The timing of common Arduinos drifts too much over time.

How much current does this button need (use a DMM set to current to 'press the button')
An opto coupler could be an easier way to 'press a button'.
Or a mosfet if button current is more than a few mA.
Leo..

4

thanks much for the replies....

I read that the relay unit I planned to use needs to see more the 5vdc, so that is why I figured I needed a higher operating voltage.

as far as current for the button, as far as I know its basically a dry NO/NC contact, so I would think little to nothing. But that is internal to the solar package 'brain' unit.

Only current I can think of is the amount needed to activate the coil for the external relay to close the contacts.

5

You asked for 'simple'.
8Mhz 3.3volt Arduinos work reliably from ~2.7volt.
No boost converter needed.
Just connect the 4volt battery to the RAW pin.

Just measure the button current with a DMM set to current.
You will activate the light that way, and see the required activation current.
A relay could be overkill, and less reliable.
Leo..

6

angryandy:
We have a solar powered flashing beacon for a pedestrian crosswalk (a master/slave pair which when one is activated it is supposed to tell the other one to flash as well).

This tidbit from the datasheet might interest you:

SAFETY-CRITICAL, MILITARY, AND AUTOMOTIVE APPLICATIONS DISCLAIMER: Atmel products are not designed for and will not be used in connection with any
applications where the failure of such products would reasonably be expected to result in significant personal injury or death (“Safety-Critical Applications”) without
an Atmel officer's specific written consent.

Just sayin'.

7

Probably add a Real Time Clock for keeping time - but I don't know how or if they do daylight savings time - maybe one of the others will chime in - one of the regulars mentioned DS3231 for a clock a few weeks ago

8

Wawa:
Just connect the 4volt battery to the RAW pin.

Why on earth would you do that?

9

Paul__B:
Why on earth would you do that?

Safety.
Who knows what the battery chemistry is. It could be more than 5volt charged.
A tiny 3.3volt regulator of a ProMini should normally only drop 0.1volt max,
so not a problem if it runs through the regulator.
Leo..

10

angryandy:
for a large city in California.

[...]

at a DISCOUNTED rate of $8500.00.

For a large city $8500 is just accounting noise.

...R

11

Hi,

What's strange here is the system voltage...4VDC. yes, four volts! It actually has three sets of 4V batteries wired in parallel. Actually they are three sets consisting of 2-2v batteries in series....so a total number of 6 batteries...with a ample supply of amp-hours run time.

What information do the batteries have printed on them?
Are they still useable?

Can you post a picture of them please?

control a relay to close from 7am-6pm every day

Do you need to compensate for daylight saving?

Do you still have the PV charge control unit for the batteries?

Thanks.. Tom.... :slight_smile:

12

Wawa:
Who knows what the battery chemistry is. It could be more than 5volt charged.

I think that was explained perfectly well.

13

So I got a minute to visit the beacon today, and I could not get a current reading with my voltmeter set to amps, not sure why.

In fact I had to mess with the 'brain' switches to get it to even flash. (TomGeorge is correct in this being the charge controller, but also it handles the output dynamics as well)

There is one rotary knob that adjusts the 'flash pattern', and finally only one setting got it to wig-wag as it should.

Another rotary knob was labeled 'frequency' and it had no effect on any setting, I think that has to to with the channel that the master/slave works on in case there are multiple units near each other.

Third rotary knob was 'time' which varied from 1 second to 60 seconds....strangely the 60 second setting didn't work.

So setting the time to 50 seconds and adding a jumper between the input wires activates the beacon.

BUT only for 50 seconds, it does not recycle like I assumed it would.

It only works with a momentary contact, not a latched contact.

And to top it all off, the master/slave function will not work, as it appears that the auxiliary unit that USED to make these beacons turn on and off was the wireless communication for the two beacons...not a big deal because that just means I need to build a separate Arduino for each beacon in place.

@wawa thanks a ton, I got my board today and its powered up (on my work desk) as you suggested with the battery to RAW in. I didn't realize that it worked OK as low as 3.3v, and I measured a decent 4.8v in the field today so I don't think voltage will be an issue for me...also measured 6v from the solar panel.

@TomGeorge, the batteries are all brand new replacements, I will try to add a picture but its a 2v sealed lead rechargeable battery 25 AH BC cell...and again there are 6 in total, 3 pairs (of 2-2v each in series) wired in parallel, so I assume that adds up to 4v @75AH for power usage.

@TomGeorge yes daylight savings would be best to have in use. And yes the PV charger is what I called the 'brain' as it handles all functions of the system.

I need to now figure out how to program the unit to momentary contact only from 8am-5pm every 51 seconds....

Again THANKS to all here for every bit of help and discussion, much appreciated.

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14

Hi,
Thanks for the info and the battery pic.

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I have come across these batteries, a very old but good design.

Tom.... :slight_smile: