Charging/ maintaining question

Discussion in 'General Electronics Chat' started by mbohuntr, Jun 23, 2013.

  1. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
    413
    32
    Hello again,

    My barn alarm project is coming along nicely. Starting to look at power supplies. I'm thinking about a SLA battery and charger/maintainer. I'm not comfortable with building a charger because of the UL label missing and homeowner insurance liabilities. If I purchase this to keep the battery topped off and place a 4001 between the battery and my circuit, will it work as designed? The circuit uses 5mA on standby, and the siren/s not more than 300mA total when in alarm. Right now, the circuit is designed with no time out/reset function, so it will alarm until it is reset manually, or goes dead. Any thoughts?


    Thanks!, Mike
     
  2. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    Ni-MH might be a better battery choice. You can easily buy chargers for most any standard size battery of this chemistry.
     
  3. LDC3

    Active Member

    Apr 27, 2013
    920
    160
    Since the charger (Solar Battery Maintainer) you indicated is not waterproof, you cannot leave it outside without protection. You probably want to get a solar panel that is waterproof like this one. It does provide a lower current, but your demand is not very high.

    BTW, what is the capacity of the SLA battery?
     
  4. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
    1,190
    156
    What about using a standard wall charger???
     
  5. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
    413
    32
    I thought about that, it would be under the eaves of the barn, and I think unless it was a hard wind driven rain, it might not bother it. About the battery... I haven't picked one yet, I was going to research the A/hr vs. charge rate issue before I bought one.
     
  6. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
    413
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    I wasn't sure about the non UL homebuilt(and fused ;)) circuit being connected to mains. Any thoughts would be appreciated! I realize the risk is minimal, but the stuff I'm not proficient at usually bites me in the rear...:p
     
  7. sq-aristo

    New Member

    Jun 1, 2013
    20
    1
    At that rate a wall charger would be fine. Just use a fuse and it'll be sweet. Small gel cell worth about $20 would be awsome backup you would have no dramas
     
  8. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
    1,190
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    In a legal insurance way, the stuff you build will make you liable for the damages in case something happens because it's home built items that are unsafe and not tested and not certified not to burn down your house ...So if you don't mind the insurance company telling you to go pi$$ off because you built something that cause damage then go for it and have fun but I would personal get your local code book for the install in order to cover your butt...
     
  9. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
    413
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    Would that be the 2014 NEC book, or some local manual? We are allowed to do our own wiring here as long as its inspected by an approved inspection company. I use Atlantic inland (I think)
     
  10. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
    413
    32
    I LIKE that charger!!!
     
  11. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
    413
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    I ordered the charger, siren and battery this morning. It ended up being the 2.5 watt charger as I got free shipping along with the 8A/hr 12v battery. If my math is correct, 8A/hr divided by 20 (C/20) equals 400mA. and 2.5W/12 = 208 mA so I'm well below the C/10 charging rate, as well as the C/20 rate for constant charge rate for batteries. The siren is turned on by a DPST relay. Once triggered, it stays on. I was thinking of using the other pole (NC) as a reset input for a 555 delay timer when it goes open, but can't seem to work the details out. If the magnet switch contacts are still open, the circuit will still alarm, and the neighbors will likely become annoyed..... Maybe the circuit needs a one shot non-resettable time out....
     
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