Is the BC-900 problem of refusing to charge completely drained battery fixed?

[geepondy]

I am thinking at $35 vs. $60 for the Maha C-9000, this charger is a better value and I think should suit my needs but my biggest concern is the reports it thinks completely discharged cells are no good whereas the Maha doesn't have this problem. Has by any chance this problem been addressed and fixed by LaCrosse?

 

[SilverFox]

Hello Geepondy,

I am not aware of a recent revision of the BC-900, so I would expect that if you let your cells get much below 0.9 volts, they will respond the same.

I might add that in normal use, completely discharged cells will still show over 1.0 volts. When your cells drop below that, there is damage going on, and it may be time to recycle them.

Tom

 

[gOhAsE]

Why not use a second cheap charger.
Every time you have a cell with a too low voltage to be accepted from the BC-900, you just have to put the cell a few minutes in the cheap charger, that doesn't care about the drained battery.
After that the BC-900 should accept the cell.

But remember SilverFox's answer. I used this procedure to be able to load very old cells that have been lying around some time.

 

[geepondy]

So if my digital camera says the battery is dead and no longer will take pictures, it doesn't mean the voltage has dropped so low, the BC-900 won't charge them?

No, I'm not really interested in trying to bring back my old cells, in fact I'm trying to go 100% Eneloop.

 

[SilverFox]

Hello Geepondy,

When your camera says the battery is dead, that means that the battery voltage has dropped below around 1.0 volts per cell under load. This means that the batteries are simply discharged. Any charger will charge those cells back up.

When the open circuit resting voltage of a NiMh cell drops below 0.9 volts, it means that the cell is very dead. This is where you run into problems. A discharged battery often has a voltage above 1.0 volts.

Tom

 

[Mr Happy]

After reading through this thread I just thought I would throw in an example of what others are saying. I discharged an Eneloop down to 0.9 V under load on the C9000 last night, and today it has recovered to a resting voltage of 1.23 V.

 

[geepondy]

What I like about both of these chargers is that you can completely discharge the battery and then charge it back up and they will tell you the capacity. I find that somewhat comforting as typically I'll recharge only partially discharged batteries particularly ones that reside in the digital camera as I don't know their charge level and if I'm going out on a shoot, can't take the chance they are not fully charged.

Do either of these chargers have an edge as far as the treatment and charging of Eneloops?

 

[SilverFox]

Hello Geepondy,

There are two aspects of the C9000 that make it a better choice...

It has a Break-In function, and its default charging rate is 1000 mA.

Tom

 

[geepondy]

I see too from looking at the BC-900 manual that when charging three or four cells at once, the maximum charging current is 1000 ma.

 

[n3eg]

I put a "dead" cell on my BC900. It sat there at "null". I left the room, came back, and it was charging.

Mine is a 33, and here's what it does: It sits there putting out .065 mA while it says "null" - then when the voltage rises above 0.6 volts, it changes to 200 mA.

 

[Handlobraesing]

The BC-900 is easier to use if you will almost always be treating 4 cells at once since you can program all of them at once.

BC-900: easier to program all bays the same, trickly to program each bay.

MH-C9000: You can't program multiple bays at once, you have to program each one every time.

 

[Wicho]

True, but the MH-C9000 is actually really easy to use once you take the time to learn how to use it.

I routinely charge 4 batteries in mine at once, and I can set all of the programming in about 12-15 seconds.

The BC-900 is easier to use if you will almost always be treating 4 cells at once since you can program all of them at once.

BC-900: easier to program all bays the same, trickly to program each bay.

MH-C9000: You can't program multiple bays at once, you have to program each one every time.

 

[Mr Happy]

I'll say again that I really wish the MH-C9000 would automatically default the settings on subsequent bays to the choices you made on the previous bay. Then all you would have to do for four bays the same is to program the first bay, then for the second through fourth bays you could just press Enter, Enter, Enter, Enter...

I do all four the same far more commonly than I do two bays differently.

 

[bob_ninja]

GP,

They are both very close, with Maha being more sophisticated while BC900 clearly being a better value. I am surprised no one mentioned that at higher rates (1000+) C9000 keeps cells much cooler than BC900. BC900 keeps cells very closely packed, so less air flow can remove heat.

P.S.: I just threw away a cell that was 0V at rest. The best way to recover deeply discharged cells is to use an old dumb charger using 100 mA or less for a few hours, then if it bounces back up to 1+V you can put them on a normal charger.

 

[NA8]

Have you done any research on the history of the BC-900 ?
I've done the capacitor mod, but haven't gotten around to the ground wire mods. It was an ambitious design at one point in time, but today the Maha is far and away the better charger.

 

[Handlobraesing]

The switches on my BC-900 failed. It doesn't even use a real tick switch and not very reliable. Then, one of the LCD bays failed, so I dumped it on eBay.

 

[Lightingguy321]

Tom speaking of damage, can you explain how one of my energizer 2500mAh AA batteries some how killed itself (the voltage was 0.03v resting) just by sitting around

 

[HWman]

So if my digital camera says the battery is dead and no longer will take pictures, it doesn't mean the voltage has dropped so low, the BC-900 won't charge them?

If the sensor is testing a single rechargeable cell, the battery can probably be recharged.

However, if the sensor is testing a number of rechargeable cells in series, a "weak" cell may suffer a reverse charge because the other cells still have normal voltage. Of course, that reverse polarity is probably fatal to the cell. This is the primary [secondary cell ;-)] reason for the admonition "Do not mix cells".



.

 

[SilverFox]

Hello Lightingguy,

The first thing that comes to mind is that the cell shorted out internally.

Tom

 

[Bones]

Snip ...

The best way to recover deeply discharged cells is to use an old dumb charger using 100 mA or less for a few hours, then if it bounces back up to 1+V you can put them on a normal charger.

I wonder if an old trick employed to pull a little more use out of a laptop battery will work as well?

There are a number of anecdotes on the web that allege that tossing them into the freezer overnight will result in a revival of sorts, so it may also be enough to get a charge started in the BC-900:

http://lifehacker.com ... revive-a-dead-laptop-battery.php