Need an electrical wiz

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TJay

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Maurice IA
Ok I ordered a Quartz clock for my build and I am trying to decide weather or not to hard wire it so it runs 24/7 or wire it into the master buss, Pros with running 24/7 I don't need to set it every flight cons may drain the battery if I don't fly for 6 months, So I need a electrical wiz to help me figure out how long it will take to drain the battery to 50%

My setup is a EarthX lithium battery EXT-680 AH (1 hr 1c rate)=12.4
The quartz clock has no internal battery and draws 10-11 Milliamps.

Hope I provided enough info thanks TJay
 

Dan Thomas

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Sep 17, 2008
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Ok I ordered a Quartz clock for my build and I am trying to decide weather or not to hard wire it so it runs 24/7 or wire it into the master buss, Pros with running 24/7 I don't need to set it every flight cons may drain the battery if I don't fly for 6 months, So I need a electrical wiz to help me figure out how long it will take to drain the battery to 50%

My setup is a EarthX lithium battery EXT-680 AH (1 hr 1c rate)=12.4
The quartz clock has no internal battery and draws 10-11 Milliamps.

Hope I provided enough info thanks TJay
Does this clock have a digital or mechanical display? 10 or 11 mA sounds way too high. 10 mA for an hour is 1/100 of of an amp-hour, and your battery is good for 12.4 Ah, so 1200 hours would drag it down a long way. 1200 hours is almost two months. The clock should take a lot longer than that to run the battery down.
 

lr27

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If the plane lives outside, a small solar cell can keep the battery charged. Inside, for that matter, if you're willing to run wires outside. I'm not sure what kind of charging your lithium battery requires, though.
 

Derswede

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Jan 6, 2016
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Tho not mechanical, some of the LCD type clocks will run for ages without running down a battery. The natural discharge of a cell will drain most batteries before the LCD clock will. On my Triumph, the clock is always on and over the winter, the battery loses a bit of a charge, but not much...of course, it is best if you are not flying, but leave the battery in the airplane, a battery tender or maintenance charger is always a good idea. My bike batteries last more than a year. Most of the battery tenders I've bought are under $30, will help the life of the battery and will easily provide enough current to keep something like a clock going.

A small solar panel can help as well. When the bike sits out, I have a small 5W panel which is mounted on the back rack and it does a fine job of keeping the battery charged up.
I will do something similar on the Kolb I'm getting, as I will have a couple of radios mounted (ham and air band).

Derswede
 

lr27

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We have a clock with mechanical hands. I think it goes a couple of years on one AA battery.
 

TJay

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Jan 18, 2014
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Maurice IA
We have a clock with mechanical hands. I think it goes a couple of years on one AA battery.[/QUOTE

Now that is a good point, Never thought about that, we also have a clock hanging in our kitchen that runs for years on a AA Batery, Maybe Aircraft spruce tech deparment has the 10-11 Milliamps. wrong, I guess I will contact the actuall clock maker monday and ask them, I could always hard wire it in with its own switch, Flip it on and set it at the beginning of the day and shut it off at the end or just fly more often, Thanks for all the help, till next time,
 

Dan Thomas

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We have a clock with mechanical hands. I think it goes a couple of years on one AA battery.[/QUOTE

Now that is a good point, Never thought about that, we also have a clock hanging in our kitchen that runs for years on a AA Batery, Maybe Aircraft spruce tech deparment has the 10-11 Milliamps. wrong, I guess I will contact the actuall clock maker monday and ask them, I could always hard wire it in with its own switch, Flip it on and set it at the beginning of the day and shut it off at the end or just fly more often, Thanks for all the help, till next time,
They might have meant to print microamps instead of milliamps.
 

TJay

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Jan 18, 2014
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Maurice IA
Well got the scoop today from ISI Services they claim that this clock does in fact draw 11-13 milliamps. They also there original clocks drew up to 3 amps to run, Not sure if Ill use this clock or not, Thanks guys
 

lr27

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Nov 3, 2007
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It may be more resistant to vibration than ones meant for home use?
 

Dan Thomas

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Well got the scoop today from ISI Services they claim that this clock does in fact draw 11-13 milliamps. They also there original clocks drew up to 3 amps to run, Not sure if Ill use this clock or not, Thanks guys
Now, the other question: Is that a steady 11-13 mA? Or an occasional pulse? Some of those old clocks, probably the 3-amp versions, had a solenoid in them that pulled a spring that drove the clock mechanism. When the spring relaxed it triggered a switch to get the solenoid to pull it tight again. You'd hear the clock go "clunk" every few minutes, but that 3-amp draw was extremely brief and the battery would last a long time. I'm wondering if your new clock is based on the same principle.
 

gtae07

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If you're letting the airplane sit for six months I'd be worried about a lot more than keeping the clock running.

One thing you could do would be to get the EarthX charger and hook it up when parked for extended periods.
 

TJay

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Maurice IA
I'm gonna wire it so its hot all the time, I have a float charger hookup directly to the battery so I can plug it in all the time, When I know I'm not gonna fly for a wile and don't feel like having the plane on the float charger Ill just pop the fuse out, Pretty easy Since it will be on its own circuit,
 

gtae07

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I'm gonna wire it so its hot all the time, I have a float charger hookup directly to the battery so I can plug it in all the time, When I know I'm not gonna fly for a wile and don't feel like having the plane on the float charger Ill just pop the fuse out, Pretty easy Since it will be on its own circuit,
If you're using an EarthX battery be very careful which charger you use--they are lithium-based batteries and they work differently than "traditional" lead-acid types. You can't just use any old charger as some may not output the right voltage, and those with "desulfating" may damage your battery.

http://earthxbatteries.com/our-batteries/battery-charging
 

TJay

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Jan 18, 2014
Messages
201
Location
Maurice IA
If you're using an EarthX battery be very careful which charger you use--they are lithium-based batteries and they work differently than "traditional" lead-acid types. You can't just use any old charger as some may not output the right voltage, and those with "desulfating" may damage your battery.

http://earthxbatteries.com/our-batteries/battery-charging
Thanks, The Jr. seems to get the job done.
 

cluttonfred

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Why not simply add a separate battery for the clock if you are worried about draining the aircraft battery? 8 AA batteries in a commercial holder would do it, here's one for three bucks.

https://www.adafruit.com/product/449

Or you might go for two battery clips and a 12v voltage regulator chip, a pair of 9v batteries, some wire and an Altoids tin.

Either solution would cost about $10 or less total including the batteries.
 

Dan Thomas

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Why not simply add a separate battery for the clock if you are worried about draining the aircraft battery? 8 AA batteries in a commercial holder would do it, here's one for three bucks.

https://www.adafruit.com/product/449

Or you might go for two battery clips and a 12v voltage regulator chip, a pair of 9v batteries, some wire and an Altoids tin.

Either solution would cost about $10 or less total including the batteries.
At an 11-13 mA draw, those batteries will be dead in short order. http://www.techlib.com/reference/batteries.html
 

cluttonfred

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Hmm, I must be missing something. 2400 mAh per AA battery x 8 batteries = 19,200 mAh ÷ 13 mAh max draw = ~1477 hours ÷ 24 = ~62 days. Changing batteries once every two months doesn't seem unreasonable to me.
 

Dan Thomas

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Hmm, I must be missing something. 2400 mAh per AA battery x 8 batteries = 19,200 mAh ÷ 13 mAh max draw = ~1477 hours ÷ 24 = ~62 days. Changing batteries once every two months doesn't seem unreasonable to me.
Yes, you are missing something. Your adding up the mAh would apply if the batteries were all connected in parallel, but they're not: they're connected in series to get the 12 volts you need. A parallel system would give you a useless 1.5 volts and your 19,200 mAh; series gives you a workable 12 volts and a short-lived 2400 mAh. 185 hours, less than eight days.
 

akwrencher

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Gustavus, AK
Man, that's one thirsty clock. My wall clock in my shop takes one AA bat and lasts a year or more.
 
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