Response from Ansmann re: Energy 16

[JohnnyB]

I posted this thread a few days ago http://www.candlepowerforums.com/vb/showthread.php?t=191642 and Silver Fox formulated my question for me (thanks again SF!)

Here is the text of the question:

Hello Ansmann Technical Support,

I noticed that you offer 2700 mAh NiMh AA batteries. I have an Energy
16
charger and am wondering when you will be coming out with a charger
that
will charge these 2700 mAh batteries?

I have observed that battery manufacturers, such as Sanyo, Panasonic,
and GP
Batteries, recommend charging in the 0.5 - 1.0C range when utilizing
-dV
charge termination. I believe the "Handbook of Batteries" also refers
to the
strong -dV signal obtained at those charging rates.

With 2700 mAh cells, that would mean charging in the 1350 - 2700 mA
range.
Since the Energy 16 charger is only capable of 700 mA and utilizes -dV
charge termination, it does not seem adequate for these cells.

Could you provide me with the Ansmann battery data sheet that shows its
performance under different discharge rates, its capacity under
standard
testing, its tested cycle life, and its recommended charging rates,
times,
and termination methods? I am also looking for information that states
that
charging a 2700 mAh cell at 700 mA provides a strong and reliable -dV
termination signal.

I assume that you will be informing me that the Energy 16 will work
fine
with these cells, so could you provide the back up termination methods
utilized by this charger?

Does it utilize a maximum voltage cut off, and if so, what is the cut
off
value?

Does it utilize a safety timer, and if so, what is the time limit or
mAh
limit used?

Does it utilize a cell temperature cut off, and if so, what is it set
to?

I have enjoyed using the Energy 16 for some years now, but I am feeling
that
it is dated and I need to move up to a more powerful charger, or one
with
adjustable charge rates. Overcharging NiMh batteries destroys them, and
I am
concerned with the effectiveness various termination methods.

Thank you for your help.



I recieved this response today. It has mostly to do with their 2700 battery but has some info re the Energy 16 charger

Dear Mr. B

Thank you for sending your e-mail.

You can see in the Datasheet that you can charge our 2700mAh batteries
with a current of 250 - 2700mA.

The -dU of the cells is about 5...10 mV.

The -dU of the Energy 16 is about 3...8mV.

So you can charge the 2700mAh batteries with the Energy 16 without any
problems and capacity losses.

The Energy Series don't have a maximum voltage and temperature cut off.
The charging timer will cut off the current after 17 hours.

I hope this information answers your questions.

If you have any more question please let me know.

Best regards,

Patrick Leuser

--------------------------------------------------------------------------
ANSMANN AG Technical Support/Service
Industriestr. 10 Phone: +49 6294 4204 34
97959 Assamstadt Fax: +49 6294 4204 47
Germany Email: [email protected]



I think I may just keep my Energy 16 for the day to day charging jobs and get an analyzer/conditioner to work with it.

 

[SilverFox]

Hello John,

The end of termination signal for a NiMh cell actually depends on the rate of charge, and the condition of the cell.

They may be able to get a strong signal at 700 mA with new cells, but I don't believe it would be reliable with older, well used, cells.

However, there are ways to "amplify" the signal, and perhaps that is what they are doing.

Ansmann has utilized a charging algorithm that incorporates a negative discharge pulse periodically throughout the charge. This is their reasoning behind not needing a discharge function on their chargers. It could also be that they measure voltage while the current is being applied. Since they don't worry about maximum cell voltage, they could easily do that. This type of measurement tends to amplify the -dV signal and you could end up with proper termination at a charge rate less than 0.5C.

I would still suggest that you play it safe and set a kitchen timer for somewhere around 5 hours when you charge your high capacity AA cells. If the cells terminate on their own, great, however, if the timer goes off, you find the cells are warm and still charging, feel free to manually terminate the charge.

Tom