Timer for a "vibrator"

Discussion in 'The Projects Forum' started by FCHW, Jan 20, 2009.

  1. FCHW

    Thread Starter Member

    Nov 21, 2008
    12
    0
    Good day to all.

    I would like some assistance on building a timer for the vibrator in my solar battery cabinet. A problem we have in Zambia with lead/acid batteries is that they tend to make a lot of bubbles between the plates and this causes the batteries to leak out the electrolite. To overcome this the batteries need to be shaken at about 10h00 and 16h00. I used an automotive starter motor with an offset weight on the shaft and twice a day switch it on for 30 seconds to give the batteries a good shake. (something like a cellphone vibrator) When I am not home for a couple of days, there is no one to switch the vibrator on, resulting in the batteries standing in a puddle of electrolite. NOT GOOD! We have mostly 12V automotive electric parts that can be used or is available, and sometimes other second hand electronic spares, salvaged from TV's or computers, becomes available.

    Any assistance would be appreciated, bearing in mind that you would be explaining it to a facinated stranger to electronic's!

    Thanks
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    This doesn't sound like precision, so there are lots of ways to do this. One is a watch, where you connect to the pizeo speaker, to trigger a monostable (30 seconds) that turns the motor on/off.

    The other is a low accuracy long term timer connect to a similar monostable (30 second timer).

    When I get a chance I'll try to sketch something up, but with this crew someone will likely come up with better first.
     
  3. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Buy a cheap wall wart timer which will drive a 240V or 120V relay and the relay will close the circuit for the motor.
     
  4. FCHW

    Thread Starter Member

    Nov 21, 2008
    12
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    I propably should have mentioned that I only have 12V DC power supply. Mik, thanks for the most obvious solution but, imagine driving to your supermarket to buy bread and there is nothing. Where I am from, this actually happens. Now imagine me trying to find something that is not so common!! Needle in haystack, genuine!
     
  5. Andrew Leigh

    Active Member

    Sep 8, 2008
    85
    0
    Hi,

    I understand that you need a shaker but is there a possibility that shaking the batteries is treating the symptom and not the cause?

    I am trying to figure out why the batteries would boil over? Overcharging, standing in direct sunlight? not too sure. What are the ratings of the battery, the charging current and is the charger regulated, where are the batteries located, is the correct electrolyte being used and what is the ambient temperature?

    Batteries must never be in direct sunlight and kept cool, are yours in the direct sun?



    Perhaps we can explore both paths simultaneously.

    Cheers
    Andrew
     
    Last edited: Jan 20, 2009
  6. FCHW

    Thread Starter Member

    Nov 21, 2008
    12
    0
    Thanks Andrew,

    This is actually a common problem with lead/acid batteries in Zambia, even in vehicles! I am using 2 x 600Ah deep cycle lead/acid batteries, housed in a coolled wooden box. I am using a commercial charge controller for my 2 x 80W crystaline solar panels, which can charge between 4 and 9 Amps. When fully charged (13.9V) the supply is diverted to the cooling unit and extractor fans to keep the temperature in the enclosure between 20 and 25 degrees Celcuis.
     
  7. AlexR

    Well-Known Member

    Jan 16, 2008
    735
    54
    It seems to me highly likely that your batteries are being overcharged. Properly charged batteries should not need to be shaken, in fact shaking lead/acid batteries is going to drastically reduce their life.

    Rather than shaking the batteries to cure the symptoms I would have a look at your charging control circuits and cure the cause of the excess bubbling (boiling?).
     
  8. FCHW

    Thread Starter Member

    Nov 21, 2008
    12
    0
    The charge controllers are Australian as I believe that they are way ahead of the rest of us regarding alternative energy and also the environment is more or less the same. At one stage I removed the one 80W panel. This did not solve the problem, even used a 12W panel. Still boiling.
     
  9. Franco_oz

    Active Member

    Jan 12, 2009
    60
    0
    Make sure you are not overcharging the battery bank, I am in australia and run on solar too, have 1kw solar panels and 2 banks of batteries. I had same problem and the reason was the charging. What solar regulator are you using? We have Plasmatronic 60A and had to twick it a fair bit to optimize it. But whatever you do, stop shaking the batteries. Do you monitor the battery temperature? If you use a good regulator/charger you should be able to change the charging ratio depending on cell temperature.
     
  10. FCHW

    Thread Starter Member

    Nov 21, 2008
    12
    0
    The charge controllers came with temp sensors that attach to to the batteries. Cooling the enclosure did help somewhat. I will "tweak" the controllers a bit more and see what happens. Only strange that even with the smaller panel, (12W) it was still boiling. My whole setup is based on info I received from something to do with Rainbow Company in Australia

    Thanks so far for all the input
     
  11. Franco_oz

    Active Member

    Jan 12, 2009
    60
    0
    ok, what voltage do u have for Absorption? and are you using Equalization?
    Rainbow Company is a reseller for Plasmatronic, Solarex and other companies, what brand is your regulator?
     
  12. Josh Young

    New Member

    Jan 16, 2009
    6
    0
    FCHW,

    Just to throw something out there for you, and I do realize things might be hard to come by there, but what about ultrasonic? There are videos on youtube that show the bubble dispersion ability of ultrasonic transducers in HHO generators. Neat little trick really.
     
  13. FCHW

    Thread Starter Member

    Nov 21, 2008
    12
    0
    Franco oz, you are using words that is not properly described in my "Collins Dictionary"! So, I really have no clue what you are meaning by absorption and equalization. I think it is a Solarex/BP charge controllar. The name was on a clear film sticker that used to be on the aluminuim shell of the controllar. can not remember when it came off. Adjustments are made by changing "bridges" and multi switches inside the controller. No screwdriver needed. The system is in its 5th year now and this problem started about 3 months after installation. Josh, thanks for the info, really neat, but for me to dream about! I would hate to walk into a shop that have all these gadgets available. Would be broke by the time I leave!!
     
  14. Søren

    Senior Member

    Sep 2, 2006
    472
    28
    Boiling comes from a too high voltage (even at fairly low currents).

    http://www.batteryuniversity.com/partone-13.htm

    A quote from another page at that site:
    "To improve charge performance of lead-acid batteries at colder temperatures and avoid thermal runaway during heat spells, controlling the voltage limits, to which the battery is charged, is important. Implementing such a measure can prolong battery life by up to 15%. General guidelines suggest a compensation of approximately 3mV per cell per degree Celsius. The voltage adjustment has a negative coefficient, meaning that the voltage threshold drops as the temperature increases.

    Heat kills batteries. The warmer the cells, the shorter the life is. Elevated temperatures cannot always be prevented, especially during fast charging, but efforts must be made to keep this time brief. While 45°C (113°F) is acceptable if kept short, at 50°C (122°F) and above, the battery starts to suffer. Note that the cells inside the pack are always a few degrees warmer than the temperature of the housing."


    A bit of shade and a PC-fan might help in keeping the temperature of the battery down a bit (and every degree counts).
     
  15. FCHW

    Thread Starter Member

    Nov 21, 2008
    12
    0
    Morning Soeren, thanks for the info. because our temp normally averages between 32 and 45 centigrade, i build a mini airconditioner using a danfos solar compressor with pc fans to cool the unit down (between 20 and 25 degrees centigrade). the whole unit is housed inside a wooden box with a pc fan to extract gas that is formed. my "dump" on the controller go through another regulator (national luna) to charge an ordinary "camper" deep cycle battery for the aircon unit, which is using very little current. even this battery is boiling, but not to the same extent as the other big batteries, propably because it is being used most of the time?
     
  16. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    Still want a timer circuit?
     
  17. FCHW

    Thread Starter Member

    Nov 21, 2008
    12
    0
    Yes please Mr Marsden!!
     
  18. Søren

    Senior Member

    Sep 2, 2006
    472
    28
    Hi,

    at 45°C the termination voltage should be 13.7V max, but I understand that your batteries are kept at a lower temp.
    Is your charge controller temperature compensated?


    Hehe, nice to know that Danish products gets around :D


    Yes, that sounds quite likely, since the boiling only occurs when the battery cannot take the charge at the rate it's allowed to (or is fully charged) - Any battery gets suicidal if given the power (we all know that power corrupts ;))

    If you still want to use a timer, I assume you want to shake the batteries (I would think that might cause some spillage as well though?) at certain intervals after the charging starts, so a light sensor could synchronize even a simple (= not very precise) counter each day (could also be triggered when the charging current gets to a certain level).

    A cheap alarm clock (or even a wrist watch) with a piezo sounder could be used as well, some have more than one daily alarm.

    Most components to interface an alarm clock can be found in dead electronic equipment; a few resistors, capacitors, diodes and a transistor to drive an automotive relay (which drives the starter relay in turn).
    A 4011, a 4093 or a 555 to time the 30s period might be found in dumped equipment as well.
     
  19. triggernum5

    Active Member

    May 4, 2008
    216
    0
    Yea, if your goal is the same each and every day I'd try to interface the circuitry from a basic digital clock/timer.. I have a thread a few pages back that has a timer that would be suitable for your task, and its designed like a basic digital clock, so it would give you insight about how to interface an existing clock into your own circuit if you don't know how already..
    Using a pre-made clock/timer will just save you alot of chip output arrangement.. Long period timer circuits are pretty simple, but get bulky with all the IC connections on the counters etc.. Having that part done would make life alot easier..
     
  20. Søren

    Senior Member

    Sep 2, 2006
    472
    28
    Hi,

    This Alarm Clock Timer should be connected to the piezo disc (not on the disc itself, but on the PCB) of an alarm clock, a 12V supply and a relay and will provide ~30s energizing of the relay with each alarm.
    (If the alarm goes on for more than 30s, it will need some sort of a lock out for the extended time, to keep the output to 30s)
     
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