DIY Audio Projects Forum
http://diyaudioprojects.com/Forum/

Power requirements for power adaptor
http://diyaudioprojects.com/Forum/viewtopic.php?f=10&t=5696
Page 1 of 1

Author:  Leonard Slye [ 27 Sep 2016, 16:11 ]
Post subject:  Power requirements for power adaptor

Hi,
I would like to know the current requirements to charge my 14.4V Chicago Electric Power Tools Cordless Electric Drill. Model 34793

The unit is out of production. I have had no luck getting this information from the mfr. and the manual does not address my question.

Thanks,
Leonard

Author:  Peter W. [ 29 Sep 2016, 06:42 ]
Post subject:  Re: Power requirements for power adaptor

The typical 14.4V Li ion battery ranges between 1.5AH and 3AH. Given that Chicago Electric is a Chinese source sold through Harbor Freight, it will be at the lowest end of that range.

Given that a charge on such a tool will last no more than say.... 10 minutes at full draw (if that), you will need a 10 amp at 14.4 V power-supply to run that drill. That is only 144 watts, and why most battery drills are geared very low. The average mains-powered drill runs somewhere between 5 and 8 amps, or 600 to 960 watts.

Now, work backwards. 14.4 V = 4 cells at 3.55 V per cell. Float voltage (voltage over fully charged state) wants to be between 15% and 20%, or about 4.2V per cell. Nor do you want to force a discharged cell with full voltage, and why most chargers are 'smart', gradually increasing voltage as the individual cells charge. In any case, there is much information that is good out there, this being one:

http://batteryuniversity.com/learn/arti ... _batteries

All of this based on a lithium-ion cell. NiCa cells are different.

Author:  Leonard Slye [ 29 Sep 2016, 11:31 ]
Post subject:  Re: Power requirements for power adaptor

Thank you, Peter W. I know this is not an audio issue, so I appreciate you taking the time to respond. Great information. This is a great bulletin board. Will let you know when I get this thing up and running. Len.

Author:  Leonard Slye [ 29 Sep 2016, 11:36 ]
Post subject:  Re: Power requirements for power adaptor

The power adapter (wall wart) is bad, so I must find a way to charge the battery with the proper current and voltage. Any suggestions on how to go about that are welcome. I do have some adjustable regulated power supplies that I can use. Len

Author:  Peter W. [ 29 Sep 2016, 14:00 ]
Post subject:  Re: Power requirements for power adaptor

Leonard Slye wrote:
The power adapter (wall wart) is bad, so I must find a way to charge the battery with the proper current and voltage. Any suggestions on how to go about that are welcome. I do have some adjustable regulated power supplies that I can use. Len


The wall-wart is a minimal item. If you can find _any_ other wallwart with the minimum current rating and same voltage, it will be fine.

So if it is a 500MA WW @ 12VDC, any 12VDC WW at 500MA or better will do. That should be marked directly on the old wart.

Author:  Leonard Slye [ 29 Sep 2016, 20:48 ]
Post subject:  Re: Power requirements for power adaptor

OK, and I should have also asked, what does 1.5AH mean?
So I need to locate a 14.4V wall wart with what current rating? Thanks in advance.

Author:  Peter W. [ 30 Sep 2016, 06:34 ]
Post subject:  Re: Power requirements for power adaptor

Leonard Slye wrote:
OK, and I should have also asked, what does 1.5AH mean?
So I need to locate a 14.4V wall wart with what current rating? Thanks in advance.


AH = Ampere Hours. The basic rating of the battery meaning that it is capable of putting out 1.5 amps for one hour. Or, 6 amps for 15 minutes, 12 amps for 7.5 minutes - you get the picture.

What is written on the bad wall-wart? Match or exceed that rating (probably in MA (Milliamps)) and matching the voltage.

I would start at 500MA, anyway. That will take about six (6) hours to charge the battery +/- 1 hour. As long as you do not greatly exceed the voltage, you cannot go too high on the MA rating as the system will not demand more than it can accept anyway.

Page 1 of 1 All times are UTC - 6 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/