ANOTHER BATTERY ?

wolf

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I have just wired my ms20 with the reed 5v relay.I have read alot of the post concerning batteries and I think I have it figured out . I plan on powering the pir with 4 aa batteries.Will this work and give me decent battery life.
 

Dbworld

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Yes it will work...a six volt lantern battery will be cheaper in the long run though.
 

wolf

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I HAVE TO DRIVE 100 MILES ONE WAY TO MY LEASE AND I AM MORE WORRIED ABOUY HOW LONG THEY WILL LAST THAN THE PRICE. WITH THIS IN MIND WHICH WAY WOULD YOU GO.
 

Curtiss

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Hello Wolf,
   The six volt lantern battery will last much longer than the 4 AA's. If you are wanting a long last battery in the six volt, I suggest that you use this battery over the AA's
 

BlackWater

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They won't last long in cold temp.  I never got more than about 12-16 pics with 4 standard AA.  Better if you beef up your battery power, especialy since your not cLose to check every few days
 

Tinhorn

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Blackwater, I assume you mean NON Alkaline AA's, your'e not getting very many pix's, r u sure something's not wrong?

I get about  2 to 4 weeks worth using 4 AA's (alkaline) with the MS20 and a 2 stage timer built with TLC555's

a 6v Lantern (Alkaline) will get 5 to 6 months of continuos use, so would 4-D size batters'

Tinhorn
 

spectr17

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hey knobby,

the statement that it's bad practice to parallel batteries isn't really correct. You wire batteries in parallel to double your amp capacity. As long as your batteries are good they will float at the lowest voltage of the batteries, usually just a little difference in the voltages. Since we should check our batteries often a dead or weak battery shouldn't be  a problem.

Diesel engines and our rescue squads use 12 vdc batteries wired in parallel because of the heavy current needs to start a diesel. They are many applications that require parallel batteries for more current capacity. I wired my truck winch up to two 12 vdc batteries in parallel to help with more juice on heavy yanks.

Wiring consumer batteries in parallel for our game cameras would double your battery life if they have the same amp capacity.
 

Tinhorn

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Spectrl17,

Those are not Knobby's words, he was quoting me

The battery's you mentioned are mostly rechargable and paralleling then is not a problem because the alternator will charge them all to the same level anyway.

but in Non-rechargable batt's, the weakest will run the strongest down to it's level of voltage, and "Float" at that weakest level, as you mentioned.  If the weakest is not run down much then not much of a problem,

BUT, you'll have to replace "ALL" of the battery's at the same time with new, fresh ones.  Don't try to conserve and replace 2 out of the 3, etc (which would be the bad practice) because it'll run down the fresh battery's to match the weakest's voltage, even if the unit is not turned on.

Tinhorn
 

deerdad

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You can get 5-6 months off of an alkaline lantern bat.?
I've stayed with the gel cell cause of the thought of
losing power with reg. batteries was there.
Tinhorn, I don't know a thing about electricity but I think
I understand the value chart you have. In otherwords by
using 4 of any 1.5 volt alkaline with the MS20 those are
the rough number of hours you could expect from bat. life?
(that is if a 5v relay is used)

Greg
 

Tinhorn

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Deer Dad,

You pretty much got it

except the chart is valid for any amount of 1.5 volt cells in series, the voltage they add up to don't matter.  So if you used 8 AA's to get 12 volts, they'd still last 1250 hours as the chart says.

That formula is theory, how long they last depends on temperature, etc but it's a good indicator of battery sizes.  Also, the number of times the relays are kicked in matters too, the chart if for Idle times, and don't take into account energizing the relay when a pix is taken. (those relays pull some juice)

Actually, your Gel-Cel is not very big compared to the "Ampacity" of the C, D, or 6v lantern batteries I don't think

"Ampacity" is the amount of juice the battery contains, BTW (by the way)

Tinhorn
 

spectr17

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Ooooops, okay, hey Tinhorn. *L*

Having wired all kinds of batteries in parallel I don't see a problem unless you have a bad battery in the bunch. I usually find out the life a battery and change it before the life is up no matter what it tests just to make sure.
 

deerdad

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I just checked my spare gel cell and it says
4ah. Any idea what the 4 AA or 4 C bateries would be?
I think there may be hope for me yet in Battery 101.
Thank you.

Greg
 

Tinhorn

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Hi Spectr17,

Yeh, I agree, as long as the batt's are about the same "Freshness" I doubt there'd be much of a problem, if any.  I was mostly afraid somebody'd think he could replace one of the batt's (in a parallel pack of 2 or 3) with a new one and be back in business.  I should have been more clear.

DeerDad,

Here is some Mathamatics 101,  ha ha

4ah = 4 amp hours = 4000 milliamp hours (4000 ma's for short)

Looking at the table Knobby posted above, a "C" battery is 6000 ma or 6 amp hours

That table contains the amp hour ratings of batteries but it's in Milliamps instead of amps like your battery has

1 amp = 1000 ma's   (1000 ma's = .001)

I expected your battery to be 1.2 amp hours (1200ma's) and not as big as 4 amphours.

Boy, now I'm lost - what I just say ! ! ! !

Tinhorn
 

Tinhorn

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Hi Knob

It's the voltage requirements of the Unit we're powering that makes the difference.  

To Increase battery volts, we have to connect more single cells in "Series" with each other, the Positive of one, goes to the Negative of the next, etc.

AAAs, AAs, C's and D's all are 1.5 volt batteries, so if we want a total volts of 9 volts, then we need 6 batteries in series and the chart you posted will tell us how long each size of battery will last.

IF we need 12 volts and use 8 batteries, the life expectancy of the battery is still the same, "AS LONG AS THE CURRENT OF THE UNIT BEING POWERED IS THE SAME"

Usually, current of the unit being powered changes, depending on the voltage.  If the resistance of the device remains the same, no matter the voltage, then the current goes up with more volts>

Forumula for Current:
current = volts / resistance

5 volts / 10 ohms = .5 amps
10 volts / 10 ohms = 1 amp

I checked the MS20 with 6v, 9v, and 12v and here are the current measurements:

6v = 1.61 ma's
9v = 1.68 ma's
12v = 1.72 ma's

I was surprised the MS20 running off 12v's didn't use more current than that because the MS20 actually runs off 5 volts, it has to reduce 12v down to 5 and waste 7 volts doing it.  "12 - 7 = 5v" (usually circuits do this voltage reduction by turning the excess volts to heat, it takes current to make heat)

Tinhorn
 

Archilochus

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Hi Tinhorn, knobby,
Tinhorn.... The MS-20 using relatively constant current at changing voltages sounds normal - consider that power (watts or 'P') = V x A
So the higher voltage supplies are using more total power (burned up through the reg).
>>>>
knobby...on this question....<<"so on these units that regulate the power down to 5v its actually more efficient if the voltage of your batts more closely matches the voltage needs of the device? ">>  That's right - with some restrictions.  To operate properly, a regulator needs an input voltage that is slightly higher than the output voltage.  If your input is at or below the needed operating voltage, the reg can sometimes do odd things.... consume excessive power, oscillate, or other nasty things (particularly at temp extremes).
So if a 6 volt supply is regulated to 5 volts, the batts will run down below the operating voltage of the reg pretty fast (still run quite a while with the RS sensor)  If you use a 9 volt supply, you can run the batts down completely (usually to 0.9volts per cell)  So it's a trade-off  - 6 volts uses less batts, but you can't run them down all the way - 9 volts can be run down all the way, but you're using more batts.  I've never done any tests to see which is more efficient in terms of cost.

Archilochus
 


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