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AC/DC adapter for a 8pk AA batteries wired in a series

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#1 dr phil

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Posted 22 September 2020 - 10:55 AM

I have a device that uses a 8pk AA Alkaline batteries wired in a series and replacing them four times a year is getting expensive.  I need direction on the amperes needed to power my device. I do understand i will need a 12 volt adapter but i am nor sure how to determine the amperes needed.

Thanks for you direction.

phil

 



#2 Dynan

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Posted 22 September 2020 - 10:59 AM

This'll do ya' fine:

 

https://www.amazon.c...ref_=ast_slp_dp


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#3 John Fitzgerald

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Posted 22 September 2020 - 11:13 AM

One of these 7Ah batteries would work well too, and be portable.  You would need to get a very small charger and squeeze some female spade connectors onto the cord of your device, with polarity marked.

 

https://www.amazon.c...,aps,202&sr=8-3


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#4 JohnBear

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Posted 22 September 2020 - 11:27 AM

 

I have a device that uses a 8pk AA Alkaline batteries wired in a series and replacing them four times a year is getting expensive.

Welcome to CN dr phil! 

 

It might help to describe what the mysterious device is and the type of connector it requires. Assuming it is typical telescope mount powered by 8 AAs, we often generally recommend a Talentcell 12V (2A or more) Li-ion battery pack, or equivalent, from Amazon for about $30.   

 

AAs can't really deliver over 500 ma for very long, so anything with over 1A  output will probably do. 


Edited by JohnBear, 22 September 2020 - 11:27 AM.

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#5 dr phil

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Posted 22 September 2020 - 11:54 AM

Welcome to CN dr phil! 

 

It might help to describe what the mysterious device is and the type of connector it requires. Assuming it is typical telescope mount powered by 8 AAs, we often generally recommend a Talentcell 12V (2A or more) Li-ion battery pack, or equivalent, from Amazon for about $30.   

 

AAs can't really deliver over 500 ma for very long, so anything with over 1A  output will probably do. 

Thanks for the quick reply.  The mysterious device is a game cam that i use for security purposes around our house.  by the by - also an entrepreneur  Appreciate any direction or advice.



#6 dr phil

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Posted 22 September 2020 - 11:56 AM

One of these 7Ah batteries would work well too, and be portable.  You would need to get a very small charger and squeeze some female spade connectors onto the cord of your device, with polarity marked.

 

https://www.amazon.c...,aps,202&sr=8-3

Thanks for the quick reply.  What would be a good charger for the battery? 



#7 John Fitzgerald

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Posted 22 September 2020 - 12:20 PM

Any small one to 1.5 amp trickle charger that can be bought at WalMart, Amazon or similar.  This one should work fine.

 

https://www.amazon.c...00794648&sr=8-8

 

or

 

https://www.walmart....arger/108265818



#8 Steve Haverl

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Posted 23 September 2020 - 07:30 PM

Suggest you look in your stash of power supplies ( I know everyone has one ! ) from past computers, peripherals or cell phones. You could easily have a 12volt, 1 +/- amp hiding in there. I have several in service on my model railroad and they are very stable.


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#9 dr phil

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Posted 24 September 2020 - 10:51 AM

Thanks for the response.  As you suggest - so have several.  Being i don't quite get the technical side of making this adaption, how can one determine if 1 amp is enough?

best



#10 John Fitzgerald

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Posted 24 September 2020 - 11:07 AM

If you are currently using AA batteries, then one amp is enough.



#11 Steve Haverl

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Posted 24 September 2020 - 02:01 PM

since you stated you’re not quite hip to the technical side, one more tip.

 

if your device is polarity sensitive ( that is, there is a + terminal and a - one) the power supply should have a little diagram either on the label or embossed on the housing that represents if the center of the plug is positive or negative. Since you’re going to cut the plug off to attach the power supply to your device, keep track of this so you don’t wire it in reverse polarity. That is not a good thing.

If your device is not polarity sensitive, it doesn’t matter which is which.


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#12 dr phil

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Posted 27 September 2020 - 03:08 PM

Hello Steve  (been out of town helping kiddos move).  Getting back to the thread - i appreciate your concern - nice of you to make the comment.  I do have some experience with polarity from working on my boat - which is all DC and know the importance of which is which.  However, what i have not come to understand is amperes and its implications in running a device.  From your experience, is there a good source that i can access that helps to explain this phenomena.  I don't think i need a grand theoretical explanation but one that addresses issues in a practical and common sense way.

 

Here is a practical Q:  If you have 8 AA batteries in a series  what is amperes of this set up.  I realize, 1.5 volts wired in a series is 8 * 1.5 = 12 volts.  But what is the ampere output or capacity.  (I know the factory suggests each battery is 2.8 amperes - learned from this forum)



#13 John Fitzgerald

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Posted 27 September 2020 - 04:28 PM

Each AA alkaline battery may be 2800 milliamp hours at 1.5 volts. That's 2.8 amp hours.  So eight of them will put out 12 volts, but it will still be a 2.8 amp hour pack. 

 

For practical purposes, the voltage will drop to unusable levels by the time the pack is about half exhausted, so really about 1.4 amp-hours at the relatively high drain of a half ampere load.  They probably should not be loaded to more than a half amp, which is 500 milliamps.  At that load, they will last about three hours. 

 

The way alkaline batteries work, they last longer and will put out more total energy at very low drain.  At high drain rates, they get hot and die quickly.   Some type of rechargeable battery would be much better, sealed lead acid, nickel-metal hydride, lithium-ion, or the more expensive lithium iron phosphate.

 

The game cam probably has only a small fraction of an ampere of drain unless it is actively taking pictures.  A 12 volt regulated power supply of the correct polarity with the proper tip would be your best bet. 

 

https://www.amazon.c...1241952&sr=8-11

This would work great, but you could buy a lot of AA batteries for the cost.



#14 dr phil

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Posted 06 October 2020 - 04:16 PM

Did some more research on the cam.  Here are the specifics:

power consumption: 250mA;(+1300mA when all LEDS fire)

stand by current: .25m7mAh/day)

 

I am grateful for all the comments - but i am still not quite sure what i need for and adapter.  I do not want to blowup/burn out the cam not to be under-powered.




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