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using rechargable Alkaline or NiMh batteries on Huzzah Feath
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using rechargable Alkaline or NiMh batteries on Huzzah Feath

by weaVaer on Thu Jan 17, 2019 9:37 pm

Is it OK to use rechargable NiMh batteries on Huzzah Feather ESP8266 ?

My concern is 3 x 1.2V NiMh cells would be too low with 3.6V and 4 x 1.2V cells would be a bit high with 4.8V to be directly connected to the battery connector on the board.
(since fully charged LiPo batteries goes at about 4.2V)

If this way of thinking is right, then is it a better solution to have 3 X standard rechargable AA batteries for 4.5V direct to the battery connector on board ?

Does it make any difference for the battery charger on board if it feeds either type of rechargable cells ?

weaVaer
 
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Re: using rechargable Alkaline or NiMh batteries on Huzzah F

by adafruit_support_bill on Thu Jan 17, 2019 9:48 pm

The Feathers are designed to be powered from a supply voltage between 3.3 and 5v. So either 3.6v or 4.8v will work. But it gets regulated down to 3.3v anyway, so there is no advantage to having a 4th NiMH cell.

If plugging into the battery connector on-board, be aware that if you also are connected via USB, it will try to charge the battery. Since it is a LiPo charge controller, it will not be a good match for the NiMH cells. So it would be best to disconnect your NiMH pack when connecting via USB.

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Re: using rechargable Alkaline or NiMh batteries on Huzzah F

by weaVaer on Sat Jan 19, 2019 7:42 pm

adafruit_support_bill wrote:The Feathers are designed to be powered from a supply voltage between 3.3 and 5v. So either 3.6v or 4.8v will work. But it gets regulated down to 3.3v anyway, so there is no advantage to having a 4th NiMH cell.

If plugging into the battery connector on-board, be aware that if you also are connected via USB, it will try to charge the battery. Since it is a LiPo charge controller, it will not be a good match for the NiMH cells. So it would be best to disconnect your NiMH pack when connecting via USB.


Thanks for the heads up.
And I am aware of the charging issue if connected to the PC via the USB connector.

In this case, I wonder what happens if I simply use 3 x 1.5V AA Alkaline rechargables in series for 4.5V into the battery connector and let the charger try to fill them up ?
Since I dont have information about the difference in charging either type of batteries, should I expect trouble from the LiPoly charger ?
Is it a fatal thing that will destroy something or just an inefficent method to use on standard alkaline rechargables?

weaVaer
 
Posts: 32
Joined: Mon May 01, 2017 1:40 pm

Re: using rechargable Alkaline or NiMh batteries on Huzzah F

by adafruit_support_bill on Sun Jan 20, 2019 8:19 am

The full-charge voltage for a LiPo cell is 4.2v. And that is the maximum voltage output of the charge controller. If your battery voltage is less than 4.2v, some charge current will flow into the cells. How that is current is handled by the cells is another story.

Most chargers are designed to charge cells individually. Unless the cells have been precision matched at the factory for charge & discharge characteristics, trying to charge several cells in series will result in an unbalanced pack. The cell with the highest internal resistance will see the highest charge voltage and current.

Alkaline and NiMH cells are not likely to explode or go up in flames like a Lithium cells. But they may leak or suffer internal damage that shortens their useful lifespan.

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Re: using rechargable Alkaline or NiMh batteries on Huzzah F

by weaVaer on Sun Jan 20, 2019 7:20 pm

Gotcha,
I feel gloriously enlightened about this matter now.

Thank you very much.

weaVaer
 
Posts: 32
Joined: Mon May 01, 2017 1:40 pm

Please be positive and constructive with your questions and comments.