Trouble with La Crosse BC-900

I was charging 4 2500mah Energizers on the low setting
at night the following morning the charger and batteries
were cooking. The batts were leaking, labels peeling,
the charger was warping from heat the middel of the
lcd screen had turned black.
I had used this charger for....maybe a year with no
problem and considered it my high end charger.
Now I'm unsure of what to replace it with.
Anyone else have any troubles with this unit?

The first thing I would do is put the whole mess in a ziplock bag and send it to LaCrosse. They should replace your charger and cells.

I was one of the early people on this forum to to own and praise this charger. The capabilities are excellent-if it worked reliably. I too am about to scrap it.

Yesterday, I put 4 new Sanyo 2500's on and ran them through the test cycle. It took about 7½ hours at 700 mA charge current and the resultant readings were as expected. Today I put four more new cells on and just checked it. Over 12 hours have passed and the readings look like end results but it has not finished. When I looked at the elapsed time it reads 3½ hours. Now I am going to pull these apparently fully charged cells off.

I have had it with this thing. Too flaky and quite possibly dangerous. Resets for no reason and constant charging cannot be good for your cells or maybe your house.

Like you, I don't know what to get as a replacement. I have already bought and returned the new Maha 801D. Primary charge current at 2000 mA is too high, IMO and the condition cycle at the lower current takes forever, 24-36 hours.

Looking for a solid recommendation. I just charge AA's and I do not want or need some expensive charger that needs an external power source.

Mark

PKT said:

The batts were leaking, labels peeling,
the charger was warping from heat the middel of the
lcd screen had turned black

Click to expand...

Can you post a photo, i can not believe that....

The BC900 has a temperature sensor, am i right?

Yes, it has a circuit board mounted temp sensor. However, there have been numerous reports in this forum of melted and sunken buttons. If the unit itself is melting I have to question the safety factor provided the sensor.

Even if you have a bad cell short out, run away, whatever, it is supposed to have protection for this too.

I have two of the La Crosse 900's and they haven't failed me yet, but after that experience I will keep a tight look out for trouble.


My others chargers are two Maha 777 plus II, which I use with 9 batteries holders.
I also have two vanson 6988 for slow charging (250 mah) and two quick one hour chargers from RayOVac which overheat the cells too much.

I will recommend NO MATTER WHICH CHARGER YOU USE to have a small fan blowing gentle air.

It will be smart (I will have to look for a couple) to do the charging on top of ceramic tyles. (just as a precaution)



regards
Juan C.

Hello PKT and Mark,

It is interesting that a lot of problems with a variety of chargers have occurred while charging new cells.

The reason for this is that it is difficult to detect the end of charge signal. New cells often are the most difficult to charge properly.

My La Crosse charger has performed quite well, however I do take some precautions...

The first charge on a new cell should be done at a 0.1C rate for 14 hours. This means that if you have a 2000 mAh cell, you should set the charger for 200 mA, and pull the cells at the end of 14 hours. Don't wait for the charger to shut off, just pull the cells at the end of the charge time.

Depending on the cells, you may have to do this more than once...

Once your cells are "broken in," keep in mind that the end of charge signal is quite small (usually in the 3-5 mV range). It is recommended that to get a strong end of charge signal you should charge at a minimum of 0.5C. This means charging at 1000 mA for your 2000 mAh cells.

I am of the opinion that if you want to utilize the La Crosse's (or any other chargers) refresh function, you should first do a timed 0.1C charge. Then you can do some cycling to work the cells and get the capacity up.

I must also add that there are always units that malfunction. As Juan has pointed out, it is best to charge on a fire proof surface and to keep an eye on the charging process.

This is just some food for thought...

Tom

SilverFox said:

Hello PKT and Mark,

...
The first charge on a new cell should be done at a 0.1C rate for 14 hours. This means that if you have a 2000 mAh cell, you should set the charger for 200 mA, and pull the cells at the end of 14 hours. Don't wait for the charger to shut off, just pull the cells at the end of the charge time.

Depending on the cells, you may have to do this more than once...

Once your cells are "broken in," keep in mind that the end of charge signal is quite small (usually in the 3-5 mV range). It is recommended that to get a strong end of charge signal you should charge at a minimum of 0.5C. This means charging at 1000 mA for your 2000 mAh cells.

...

This is just some food for thought...

Tom

Click to expand...

I have a dumb/timer Uniross Sprint Photo that I was about to give away, now I will keep it to "first charge" new batteries.

This forum is a mother-lode of information, thanks for that food for thought.

Hi Tom-

I appreciate the information. I have been charging my Sanyo 2500's at 700 mA. I have now completed the second test cycle on both sets and the results have improved. I see capacities where I expect them to be.

Next time I will step up the charge current to 1000 mA. I was just trying to walk that line between too slow and too hot. At 700 mA I would call them just warm to the touch so 1000 should be fine. That will also speed up the cycle time to a more reasonable length.

I had no idea that the end of charge signal was related to charge current. That would possibly explain the behavior I was seeing. I just got concerned when these cells were charging at 700 mA much much longer than should have been required.

The LaCrosse is a pretty sophisticated and capable charger. It would be nice if they would provide better information in the manual. Most people that buy this charger with these advanced functions could understand your recommended procedures and follow them.

I do think it is a very good idea to put your charging setup on a fireproof surface and babysit it at least a little. I'll be doing this from now on.

Mark

When I read these threads about many "high-end", or at least fairly expensive chargers malfunctioning, it really makes me wonder. How do all the typical electronically unsophisticated consumers that buy NiMH battery/charger packages at Walmart or RatShack for under $20 avoid burning their houses down or ruining all of their equipment?

Despite its complexity, the BC900 is not quite so smart when it comes to a propper charge termination. Apparently it uses a simple -dV algorhytm with quite large voltage drop and an absolute temperature as a backup. The result is overcharging, even at low currents. At 700 mA charging current it heats my cells up more than my Lenmar pro66 does at 2A charge current! The reason is that the Lenmar has dT/dt termination (temperature gradient rather than absolute temperature). Once the cell temperature rise reaches 1 degree per minute the charger switches to trickle mode. This and 0dV (peak voltage detection) are the propper methods for charging NiMH cells. Unfortunately, there are very few chargers on the market that charge properly. If you read the cell manufacturers technical papers you'll see that -dV is not recommended as a primary charge termination method. According to Sanyo it can be used (with 10 mV drop per cell max.) at the expense of 20% reduction of cycle life. I've seen chargers (and suspect the BC900 is also like this) that terminate when a voltage drop of 20-30 mA has been detected. By this time even at lower currents your cells are frying. Using one of this I wouldn't expect more than 100-150 cycles and the capacity will start decreasing even sooner.
What I do is using the BC900 only for cell testing/matching and use a better charger (Lightning pack 4000N, Lenmar Pro66, Lenmar Mach1 gamma) for day to day charging.

Hello Blr,

Welcome to CPF.

I believe you may be misunderstanding the Sanyo information.

The - delta V termination is utilized by most of the high end chargers because it gets more capacity into the cells under a wider variety of ambient temperature conditions. Temperature is used as a back up in the event the - delta V signal is missed, as you have indicated.

The ICE and Triton chargers can terminate on maximum temperature, but I am not aware of any charger that is utilizing dT/dt for termination.

Sanyo indicates that they are rating their cells by first charging them utilizing a -deltaV=10mV for their charge termination. Here is the discharge information on their HR-3U 2500 mAh cells. Since I expect a battery manufacturer to list their cells performance under the best possible conditions, I would conclude that using a - delta V = 10 mV termination is not detrimental to the normal cycle life of the cell.

I believe the confusion comes from this document. In chapter 3 I believe they are saying that while you can use a NiCd charger to charge the Sanyo cells, it will reduce the cycle life by 20%. (NiCd chargers typically utilize a 20-30 mV delta V value.) To keep from damaging the battery, you should utilize a - delta V of 10 mV or less.

It is also interesting to note that Sanyo suggests that in order to get a proper end of charge termination you need to charge at a rate between 0.5C and 1C.

This means that when you compare charging at 700 mA vs charging at 2000 mA, charging at a lower rate should end up with hotter cells and may possibly do damage to them in terms of cycle life.

I would also like to know where you got the idea that the Lenmar Pro66 uses temperature as a end of charge signal... I was unable to find a spec sheet on that charger, so I called them. They told me they use -delta V termination on that charger...

Tom

Thanks guys....I'm learning so much here!!!

SilverFox said:

I believe you may be misunderstanding the Sanyo information.

The - delta V termination is utilized by most of the high end chargers because it gets more capacity into the cells under a wider variety of ambient temperature conditions. Temperature is used as a back up in the event the - delta V signal is missed, as you have indicated.

Click to expand...

100% agree

also worth to read.
http://panasonic.com/industrial/battery/oem/images/pdf/Panasonic_NiMH_ChargeMethods.pdf

lrp said:

Thanks guys....I'm learning so much here!!!

Click to expand...

YEAR - Internet can be a powerfull knowledge-source...

This thread started with PKT's very negative experience and some of my issues with a particular charger.

On the positive side, much good information has been posted as well as links to some excellent reference material.

I expect my battery/charger results to improve. I only wish the manufacturers would provide at least some of this information with their products. If you tell me how to use your gear in the best, most efficient way it's better for both of us. If I can't or won't follow guidelines and instructions, then it is my fault.

Mark

Flash_Gordon said:

there have been numerous reports in this forum of melted and sunken buttons. If the unit itself is melting I have to question the safety factor provided the sensor.

Click to expand...

HUH!!...........What?..........Please point me to ONE reliable mention of buttons melting into the charger. You say there are "Nunerous Reports" one should not be hard to find.

Flash_Gordon said:

On the positive side, much good information has been posted as well as links to some excellent reference material.

Click to expand...

Please define what you call "Good" information. The manual that comes with this charger tells you all you need to know, if you read it.

I have 2 of the real early 900s and both of them sense end of charge without any problems at all charge rates. I might also point out I have not tampered with them and use the stock "Wall Wart"

Thanks SilverFox for posting a link to the Sanyo technical paper, this was the one I was refereing to. Exactly in Chapter 3, as you pointed out, the Sanyo engineers list several methods for charging their NiMH cells and state that the following ones are suitable: 1) 0dV (also known as peak voltage detection or PVD); 2) dT/dt (temperature gradient) and 3) delta T (temperature difference i.e. cell-ambient). It is stated that although -dV can be used it shortens cycle life by 20%. If used, however the dV value should be kept BELOW 10 mV/cell. Clearly -dV is not the first choice. If you look at the graphs you'll se that 100% SOC is reached at the plateau of the overvoltage curve and NOT after the inflection, i.e. when the voltage drop occurrs the cell is already overcharged.

The "idea" about Lenmar Pro66 comes from the manual, which can be found at http://www.lenmar.com/manuals.asp

Besides it is not difficult to see that the Lenmar charger uses some better termination control. At the end of the fast charge(2A current) the cells measure 42-43 degrees C. Run the BC900 at 1.8A and you'll end up with cells 10-15 degrees C hotter than that. Same with, say Vanson V6000, which charges NiMH cells at 2A. Both use -dV at high currents and overcharge badly. You'll be lucky to get 100 cycles out of your cells treating them like this. Sanyo NC-MQR02 charges 2 cells at about 1.2 A with PVD and end of charge temperature again in the range 40-42C. Now compare this to Maha 401FS in fast mode (and they call this cool charger LOL!!!).

I have tested about 30 chargers, and believe me, the ones using -dV run much hotter, many unhealthy hot and some dangerously hot. It is possible to design a kinder -dV charger with 2-5 mV/cell but this means better sensing electronics=higher cost. On the other hand most users don't mind getting reduced cycle life.

The only times I had problems with the BC900 is when I used the "recommended" Cisco 3.3V power supply: BC900 runs too hot. And, yes, I got the two middle buttons melted. N162E, I can report that

Now, I'm using back the stock power supply. So far not any more problems.
Learned lesson: don't mod something working great only because others have troubles...

blr2005, have you used the Lenmar Pro66 with 2500 mAH cells. The 71 minute max time cutoff in the manual looks low based on the 2A charge rate assuming you have to put in about 10% more than the cells capacity for a full charge. Do you need to leave the cells trickle charging to reach full capacity? The Pro66 trickle charge current is a little high for my tastes to leave cells in overnight.

Thanks for posting this info. I've actually found the BC-900 to be pretty good at charge cutoff assuming a reasonably high charge rate but I've been aware the NiMH manufacturers didn't advise- dV cutoff. I just wasn't aware of any chargers that used dT/dt until now. I'm curious how they manage to get the temp probe in good conatct with the cell for both AA and AAA sizes but your statements that it works is enough for me. I'm going to try to track one down even though I've hated Lenmar based on my experience with their NiMH cells.

Mike

Re: Trouble with BC-900

Thanks Flash
Lots of good info, alot of it's over my head though.
Thomas Distributing has a new charger-MAHA MH-C808M.
Expensive but sounds like it may fit a few of the parameters
mentioned here.
More info at Maha's site. Take a look tell me what you think.
Thanks for all the feedback.