LaCrosse BC-900 charge calculation method

I'm doing a refresh cycle on some new Eneloops to see how much charge remains since they were charged at the factory. At this point 4:47 has elapsed and 487 mAh has been discharged. I've been watching the discharge rate and it has been at 109 mA. Shouldn't the discharge show as 522 mAh?

Re: LaCrosse BC-900 charhe calculation method

Is there a complete test thread on this charger somewhere? I am thinking of getting it.

Re: LaCrosse BC-900 charhe calculation method

curtis22 said:

I'm doing a refresh cycle on some new Eneloops to see how much charge remains since they were charged at the factory. At this point 4:47 has elapsed and 487 mAh has been discharged. I've been watching the discharge rate and it has been at 109 mA. Shouldn't the discharge show as 522 mAh?

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Not really. The default charge rate for the BC-900 is 200 ma and the discharge is half the charge rate. For a discharge rate of 500 ma you will need to set a charge rate of 1000 ma. If you want to avoid the 1000ma charge rate, charge them at your selected rate remove and re-insert them, choose discharge mode and set the discharge rate at 500ma.

NOTE, when you change the mode on the BC-900 you have to hold down the button for a few seconds to activate selection.

Re: LaCrosse BC-900 charhe calculation method

N162E said:

Not really. The default charge rate for the BC-900 is 200 ma and the discharge is half the charge rate.

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I know all that. The question is which is incorrect, the discharge rate shown or the energy discharged reading or am I missing something?

Re: LaCrosse BC-900 charhe calculation method

FredM said:

Is there a complete test thread on this charger somewhere? I am thinking of getting it.

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Use Google search at the top of this page Fred. Everything you want to know (And don"t Too) is here somewhere. Last I looked you could download the manual from LaCrosse or Thomas Distributing. Althought there was a few problems with the earlier ones they seem to have been resolved with later issues. This is a tried and proven charger used and liked by a lot of us. Well, me anyhow!!:thumbsup:

Re: LaCrosse BC-900 charhe calculation method

curtis22 said:

I know all that. The question is which is incorrect, the discharge rate shown or the energy discharged reading or am I missing something?

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OK, I see your' question now. This has also come up before. The short answer is you are right. The slightly longer answer is that most of us are willing to live with the few percent "Unexplained" to have small, convenient, easy to use and inexpensive equipment like this unit that will add to the reliability, predictability and usefullness of our portable lights and other battery operated equipment.

Re: LaCrosse BC-900 charhe calculation method

The discharge rate probably hasn't been 109mA the whole time. It varies a bit. the mAh would be 478 if it had been discharging at the target rate of 100mA the whole time.

Re: LaCrosse BC-900 charhe calculation method

shadowjk said:

The discharge rate probably hasn't been 109mA the whole time. It varies a bit. the mAh would be 478 if it had been discharging at the target rate of 100mA the whole time.

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I put a couple 2500s on about an hour ago to verify my my responses. One is discharging at 496 and the other 508ma and they both read 433mah discharged. Same time same voltage. Once again close enough for me.

Now if I were the Phoenix Lander..........I MIGHT be concerned.

Happy Memorial Day all!!

Re: LaCrosse BC-900 charhe calculation method

The discharge has completed. They were AAAs with a 12-07 date code.

Displayed mAhs: 607 616 590 580
using the 108-109 mA discharge rate displayed it works out to 646 661 635 625.

You might try this mod and see if it has any affect on the results. A longshot but it would be interesting.

https://www.candlepowerforums.com/threads/130963

NA8 said:

You might try this mod and see if it has any affect on the results. A longshot but it would be interesting.

https://www.candlepowerforums.com/threads/130963

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The mod described above seems to steady out the readings. The problem described in this thread is probably caused by poor power supply bypassing. The charger will attempt to hold the discharge current at the set value but noise entering the circuit will cause the readings to be off and/or fluctuate. BTW, the charger doesn't integrate current readings over time like the MH-C9000. Rather, if you set it for 100 mA after 5 hours the accumulated mAH will be 500 regardless of whether or not the actual discharge rate stayed at 100 mA the whole time. Adding the bypass caps and other mods described causes the instantaneous discharge rate to more closely match the set rate. It will still fluctuate, but the average will be around the set reading.

I'll also add that long term the mods worked out well. Both chargers are still working, there were no meltdowns. The backlights are also still working, although they may have gotten a little dimmer/bluer over time (to be expected with the LEDs I used).