Getting 4.94 on Minty Boost with eneloop
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Getting 4.94 on Minty Boost with eneloop

by tonyg1 on Mon Oct 22, 2012 9:55 pm

I am using freshly charged new eneloop NIMH. I have tried several pairs. I always get 4.94 Volts with 1.90 or 1.91 on the data pins. I see 2.66V on the input side which is about consistent with 2 times 1.3v for the NIMH. I have checked all the solder joints and component placements. Now what?
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Re: Getting 4.94 on Minty Boost with eneloop

by adafruit_support_bill on Tue Oct 23, 2012 5:50 am

Check the batteries in your meter, and check the meter against a known source voltage. If those eneloops are freshnly charged, they would be closer to 1.4v.
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Re: Getting 4.94 on Minty Boost with eneloop

by tonyg1 on Tue Oct 23, 2012 10:44 am

Replaced the battery in the DVM. Checked vs new C alkaline and 9V alkaline and got 1.55 and 9.2. Recharged the eleloop and have two with 1.39. Invput shows 2.77. Output is still 4.94. Data pins are 1.91. I will get some Alkaline AA and try again.
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Re: Getting 4.94 on Minty Boost with eneloop

by adafruit_support_bill on Tue Oct 23, 2012 11:45 am

You might want to check your meter against another. I get 1.6v from a fresh Duracel. Eneloops coming out of my charger are usually between 1.41v and 1.43v.

If you plug your phone into the MintyBoost, does it charge?
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Re: Getting 4.94 on Minty Boost with eneloop

by tonyg1 on Tue Oct 23, 2012 12:41 pm

OK...I will finish installing the USB and give it a try tonight. It won't hurt my phone will it? BTW. Thanks for responding to my noobie posts so quickly and patiently. Troubleshooting this stuff is really part of the fun. Takes me back to my physics labs forty-something years ago.
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Re: Getting 4.94 on Minty Boost with eneloop

by adafruit_support_bill on Tue Oct 23, 2012 12:47 pm

It won't hurt your phone if the voltage is a little low. At worst, it will just not go into charge mode.
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Re: Getting 4.94 on Minty Boost with eneloop

by tonyg1 on Wed Oct 24, 2012 9:10 am

Finsished installing the USB connector and installed the batteries. It looks like it is charging the phone OK. Now I need to order a new digital multimeter. I also need to do a better job on cutting the hole in the tin on the next one. I used a nibbling tool but still wound up making the hole too big and ugly.
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Re: Getting 4.94 on Minty Boost with eneloop

by adafruit_support_bill on Wed Oct 24, 2012 9:31 am

Congratulations on a successful build. :)
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Re: Getting 4.94 on Minty Boost with eneloop

by RoaminGnome47 on Mon Nov 12, 2012 7:34 pm

I am getting the same voltage output on the USB with a brand new set of standard alkaline energizers. I replaced the 9v in my multi meter with a new lithium and I got the same results.

I turned my phone off when I charged it and it only went from 30% to 40%, I stopped charging with the AAs at 1.2v each

Im not trying to hijack the thread but I have the same issue :)
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Re: Getting 4.94 on Minty Boost with eneloop

by adafruit_support_rick on Mon Nov 12, 2012 9:11 pm

You'll also want to check your meter agains a known source voltage.

Depending on your phone, you might not get a full charge from a pair of AA'a.

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Re: Getting 4.94 on Minty Boost with eneloop

by RoaminGnome47 on Mon Nov 12, 2012 9:19 pm

My phone is a Motorola Droid X and I cant imagine that it would only get around 10% from a set of AAs. I imagine that a set of lithiums would be better but still...

What should a set of dead batteries read for voltage?

What can I use as a known source? I have measured a 9v wall wart and got 9v on the nose.

Thanks for the help, one of the kits is for a friend and I do not want to give him it if its not at 100%
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Re: Getting 4.94 on Minty Boost with eneloop

by adafruit_support_rick on Mon Nov 12, 2012 9:39 pm

Have a look at our multimeter tutorial. Scroll down to Example 1 (batteries) and Example 2 (wall-warts).

With a couple of alkaline AA's , the MintyBoost will give you about 1000mAh of charge at 5V. I don't know what the battery capacity of the Droid X is, but you should be able to divide 1000mAh by whatever the capacity is to get the expected percentage of Droid charge you can expect from the AA's. There's a really good discussion of MintyBoost batteries here.

Finally, if you post some clear, detailed pictures of both sides of the circuit board, we'll have a look for any assembly problems.

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Re: Getting 4.94 on Minty Boost with eneloop

by RoaminGnome47 on Tue Nov 20, 2012 3:13 pm

http://farm9.staticflickr.com/8201/8202 ... ab7a_k.jpg
http://farm9.staticflickr.com/8343/8204 ... 40c4_k.jpg
http://farm9.staticflickr.com/8064/8202 ... 13b4_k.jpg

With a new 9v Lithium in the multimeter I am getting 5.0v and 1.93v with a reading of 1.35v on the batteries in the minty boost
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Re: Getting 4.94 on Minty Boost with eneloop

by adafruit_support_rick on Tue Nov 20, 2012 3:53 pm

The build looks OK, but I'm concerned that you appear to be operating the board inside the mint tin without any insulation between the board and the tin. If so, I'm surprised that it works at all, since the tin will be creating shorts all across the solder side of the board.

The kit should have come with a couple of pieces of double-stick foam tape. These serve to hold the battery case and board in place, and also to electrically insulate them from the metal tin.

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Re: Getting 4.94 on Minty Boost with eneloop

by RoaminGnome47 on Tue Nov 20, 2012 4:03 pm

I am not operating it with no tape, the tape on mine was not holding so I pulled it. I have not used it since so I do not short it out.

So do I not need to worry about the build? If all seems well then I will be giving my friend his and starting to mod mine :D
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