BC-900 mode question

[ramarco]

Howdy! I've been lurking long enough. It's question askin' time: Santa brought me a La Crosse BC-900U. I've used refresh mode to put more life into some old NiCd's and NiMH's. Cool!

I've been using test mode to establish a mAh baseline on my "old" NiMH's. I put ID labels on each cell and made a chart to record the mAh reading after running them on test mode.

While waiting for my new eneloops to arrive I continued to read many threads (sometimes numerous times). I came to the conclusion that using discharge mode instead of test mode would give me a mAh reading for my baseline chart. When they arrived I decided to put half my eneloops into service without doing anything to them (except label). I ran the other half on discharge mode to establish a mAh baseline for each cell.

Now that I've done this I began to wonder what the difference is between the mAh reading in these modes (test vs. discharge). Are they the same? If not, how might that effect comparing my old NiMH's to my eneloops or other new NiMH's? Also, is one mode better than the other?

OK, I think that's plenty of questions for now. Thanks! -R

 

[ramarco]

Edited. . . My Bad!

 

[SilverFox]

Hello Ramarco,

Welcome to CPF.

I would suggest simply standardizing on using the test mode. The BC-900 begins the discharge immediately after charging, so your results will be a little bit on the high side, but for your own use, there should be no problems.

When you go to compare your results with those from other chargers, you may need to make an adjustment.

Tom

 

[ramarco]

SilverFox - Thanks for the reply. I'm just curious, why do you recommend test mode?

Anyone - What is the difference in the mAh reading you get after running test mode vs. after running discharge mode?

-R
:thanks:

 

[SilverFox]

Hello Ramarco,

I believe you will get more constant results using the test mode. Plus, you don't have to remember to check for your capacity before it starts charging again.

Tom

 

[shadowjk]

Discharge: discharge cell, charge cell. Display power put into cell.
Test: charge cell, discharge cell, charge cell. Display power extracted from cell during discharge.

 

[drmaxx]

Just to complement shadowjks statement and to answer your question: You only can establish a 'baseline' with the testmode.

Comparing the two numbers from 'testmode' and 'discharge mode' is not simple. You could try to get an estimation by comparing the two numbers by running the testmode until the batteries are empty, reading the discharged energy and then put it in discharge mode to recharge the batteries and get the energy put into the batteries. This way you have an approximated idea about the losses during charging, assuming you are always using the same charge and discharge current.

 

[ramarco]

Ahhh, I think I get it. The power extracted from a cell during discharge (after a full charge) is a more accurate representation of a cells capacity. Test mode it is then.

Thank you all!
-R