Charging old cell, reports 1.91V???

hammerjoe

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I put an old energizer cell on my new miboxer c4-12 to charge with a selected current of 500mA.

The charger stopped charging it at 1.31v saying that it is full. The Ir on that cell is over a thousand.

Anyway I pulled the cell out, checked it with a multimeter and it read 1.31v.

Put it back on the Miboxer with the same selected current of 500mA and after a couple minutes the charger shows a voltage of 1.38v.... but checking it with my multimeter it reads 1.91v???
I have never seen this before. Any idea whats going on here???
 

ChrisGarrett

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I put an old energizer cell on my new miboxer c4-12 to charge with a selected current of 500mA.

The charger stopped charging it at 1.31v saying that it is full. The Ir on that cell is over a thousand.

Anyway I pulled the cell out, checked it with a multimeter and it read 1.31v.

Put it back on the Miboxer with the same selected current of 500mA and after a couple minutes the charger shows a voltage of 1.38v.... but checking it with my multimeter it reads 1.91v???
I have never seen this before. Any idea whats going on here???

Joe, you seem to be having a lot of problems and it seems that the MilBoxer isn't cuttig it.

Maybe it's time to start over with an Xtar charger?

Do you have a new battery in your DMM?

Chris
 

kpatz

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Did you measure it while it was on the charger? The charger is going to put a higher voltage in to charge the cell, and since you say the IR is high, the charging voltage will be on the high side as well.

Take it out of the charger and you'll get a correct voltage reading. The charger stops charging momentarily to measure and display its 1.38V.
 

hammerjoe

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Did you measure it while it was on the charger? The charger is going to put a higher voltage in to charge the cell, and since you say the IR is high, the charging voltage will be on the high side as well.

Take it out of the charger and you'll get a correct voltage reading. The charger stops charging momentarily to measure and display its 1.38V.

Thank you for the explanation. It makes sense and I understand a little better whats going on.
Yes I measured it while it was on the charger with a selected current of 500mA.

Playing with the miboxer has been a good learning experience imo.

BTW it has stopped charging and the battery reads 1.34 so this charger with a select current of 500mA does not handle this cell that well and it struggles charging it properly.
 
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hammerjoe

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Joe, you seem to be having a lot of problems and it seems that the MilBoxer isn't cuttig it.

Maybe it's time to start over with an Xtar charger?

Do you have a new battery in your DMM?

Chris

I am done using this charger for my good cells as I dont trust it to charge them fully.
I am using older cells to learn more about charging nimh. This was a good experience.

I have other chargers, the littokala 500, the opus c3100 v1 which I also think is not very accurate and the opus c700 which is my workhorse to charge the cells.

I like the idea of the Miboxer and I might get another one hoping that I got a fluke but this is not my last charger for sure. :)
 

Lynx_Arc

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If the cell is a AA cell and old then 500ma can be too low of a charging current to properly detect charge finish often you need to go to 1/2C to get old cells to charge properly.
 

hammerjoe

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If the cell is a AA cell and old then 500ma can be too low of a charging current to properly detect charge finish often you need to go to 1/2C to get old cells to charge properly.


The energizer is a 2000mah and being an old cell with high IR putting 1A into it wount it overheat and thus prevent detection?
 

ChrisGarrett

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I am done using this charger for my good cells as I dont trust it to charge them fully.
I am using older cells to learn more about charging nimh. This was a good experience.

I have other chargers, the littokala 500, the opus c3100 v1 which I also think is not very accurate and the opus c700 which is my workhorse to charge the cells.

I like the idea of the Miboxer and I might get another one hoping that I got a fluke but this is not my last charger for sure. :)

Older cells/batteries need to be recycled, as they're not worth the drama.

Carry on, regardless.

It's just the nature of the beast.

Chris
 

Lynx_Arc

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The energizer is a 2000mah and being an old cell with high IR putting 1A into it wount it overheat and thus prevent detection?

Actually just the opposite would happen. A higher charge rate would help the charger detect when the cell is full a lot better it may get a little hotter to do so but a lower charge rate could have the cell cooking a lot longer at a slightly lower temperature vs a short time at a higher temperature. BTW I agree with ChrisGarrett in that these old Energizer cells are trash and will do nothing but cause you constant grief in any charger and most likely the high discharge rate and lower performance under load will have you charging them quite often.
I had a dozen high capacity Energizer nimh cells do this to me and tossed them all finally when I could afford to get better cells.
 

hammerjoe

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Actually just the opposite would happen. A higher charge rate would help the charger detect when the cell is full a lot better it may get a little hotter to do so but a lower charge rate could have the cell cooking a lot longer at a slightly lower temperature vs a short time at a higher temperature. BTW I agree with ChrisGarrett in that these old Energizer cells are trash and will do nothing but cause you constant grief in any charger and most likely the high discharge rate and lower performance under load will have you charging them quite often.
I had a dozen high capacity Energizer nimh cells do this to me and tossed them all finally when I could afford to get better cells.

Thanks for the info, learning a little bit more today.
The Energizer cells have been already replaced for quite some time. I use them to test chargers and see how they behave...
In the case of the Miboxer it stopped charging at 1.31v with a 500mA current selected. Its the first time I see a charger struggle with a 500mA current to detect a full nimh battery.
 

WalkIntoTheLight

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The Liitokala Li-500 is great for charging old NiMH cells with very high internal resistance. Most other chargers give up on old cells and they never fully charge them. The Li-500 (at a 300mA charge rate) will chug along until the cell is full. On very old cells it sometimes misses the end-of-charge signal, but that's okay. I'd rather it shove more in (which just gets wasted as heat), than not charge them at all.

Most of my other chargers are only designed to charge NiMH cells that in good condition (i.e., fairly low internal resistance).

Old cells are crap, but they're still useful in low-drain applications like dim LED lights, lawn lights, etc. No good for remotes, since their self-discharge is too fast, unless you want to charge them every couple of weeks.
 
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