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Old 2017.10.28, 11:46 AM   #1
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Halp! La Crosse BC700 & BC1000 Overheating AAA Cells :S

In the past I usually charged my AAA racing cells (Peak 900) at 1 amp without issue.

I'm downsizing and simplifying my Mini-Z setup and pit box, so the La Crosse BC1000 looked very appealing.

Ordered the BC1000, attempted to charge the crappy included AAAs at 1 amp, overheats and cuts the charge prematurely. Tried 700mA charge rate, same thing, though charged longer before the overheating.

Figured it was the crappy AAAs with really high internal resistance (don't have tools to measure), ordered a set of made in Japan eneloop AAAs (750 mAh 2100x), charged at 1A. Same Thing, though did last longer before overheating. Tried the eneloops at 750mA in it, they still overheat (though once again, happens later).

I noticed that most the heat was being produced by something in the charger, and that heat was transferring to the cells.

Anyway, thought okay, maybe the BC700 will be different. Interestingly it shipped with a 12V 750mA PSU whereas the BC1000 shipped with a 3V 4A PSU. I hypothesise that a lot of the heat the BC1000 was producing was due to this.

Tried the BC700 on the eneloops at 700mA, but noticed as additional cells are inserted each bay no longer sustained 700mA charge rate. The charge rate averaged around 630mA. The cells finished a full charge without overheating. In fairness though the cells didn't get a full 700mA charge rate as they did in the BC1000. I also noticed the underside of the BC700 got nowhere near as hot as the BC1000 did at 700mA charge rate. Figured this may be due to the use of a 12V PSU vs the 3V one as used in the BC1000.

I figured maybe my BC1000 was defective. Got a replacement, no difference.

I figured maybe my BC700 was defective (not being able to sustain 700mA charge with multiple cells). Got a replacement, no difference.

I suspect the BC700's 12V 750mA PSU may be the culprit in the reduced charge rate when charging multiple cells. I have yet to test with another higher amperage 12V PSU.

I also suspect that the cause of the high temperatures when charging eneloops is due to their high internal resistance design to facilitate their LSD characteristics? I'm completely guessing here, not sure if they even have a higher resistance compared to a regular or HSD racing cell.

I don't have any regular or HSD AAAs to test this theory. My Peak 900s are long dead.

I then went back to one of the BC1000s, put a fan blowing directly on the cells, and charged the eneloops at 1A. They stayed cool (cold actually) till they reached capacity and the charger was waiting for negative delta drop, at this point they got slightly warm.

I'm torn as to what to do. I just wanted a simple small charger that can do 1A. The Maha C9000 is too big for my pit box. I'm considering buying an R246 C-05 charger. It supposedly charges at 800mA, is nice and small and USB powered (2A). I haven't found any English instructions for it and don't know what kind of technology it uses to charge or detect a full cell. Will still have access to another charger at home outside the pit box to gather data regarding cell health as necessary.

The SkyRC NC2600 looks real nice, but it's too big for my box.

I know many of you are using the La Crosse series of chargers, your input would be greatly appreciated. Maybe recommend another small charger?

Is my problem simply the fact that I'm using a set of LSD cells?

I may just permanently wire a small 50mm fan into a BC1000, but is it okay for the cells to be that cold during the charge?

Long post I know.


Last edited by BitChar-G; 2017.10.29 at 09:24 AM.
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Old 2017.10.29, 12:21 AM   #2
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I don't have any Lacrosse info to share with you but I can share that I have had (occasionally) similar instances of false peak due to heat with a Hi-Tec multi chemistry charger and I used a fan to cool the cells while charging and that remedied the situation.

I would lean towards it being a charger issue. I use a couple different styles of chargers with LSD cells of various quality and as mentioned above it was an infrequent occurance
I wonder what rocket scientists say to their coworkers when one of them doesn't get it?

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Old 2017.10.29, 09:36 AM   #3
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Which Hi-Tec Charger were you using, one of the SkyRC equivalents? The thing is, when I used the fan on the BC1000 the cells were rather cold during the charge process, not sure if this is optimal for cell health.

My chargers aren't false peaking, they have a thermal protection feature. When they detect a certain temperature, they cut charge rate to 0mA. The manuals state they cut the charge till the charger cools (ie sensors detect low enough temps), but each time it has happened the chargers restart suspiciously around the 15 minute mark. I have a feeling it's simply a timed restart. It's normal for cells to get hot when their at their capacity, as it takes time for the chargers to detect they're full. In this case, each charger takes about 5 minutes to detect a full cell, which is pretty good.

Funny though my GP Power Bank 1 Hour Charger (GBPB01) circa 2002 detects a full cell in 3 minutes and they don't get anywhere near as hot. Not sure what its charge type, rate, or peak detection is though, tried to find some documentation and was unsuccessful.

Another possible variable is that my brand new set of genuine Japanese made eneloops are bad, but I find that unlikely.

Last edited by BitChar-G; 2017.10.29 at 09:39 AM.
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Old 2017.10.29, 10:28 AM   #4
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I have never used anything except the Lacrosse chargers for ten plus years. They will shut down thermally when a temperature of 128* F is reached. To stop this from happening I run a 6" 110V case fan blowing across the charger bank throughout the charging process. They still build plenty of heat but not enough to reach thermal shutdown. I also found that the included AAA batteries were pretty adequate for racing. I also used to use the AA's for my transmitter.

With any new batteries you might want to run them through a complete charge/refresh cycle at the lowest(200mah) setting on the charger. Once done, discharge them at the highest(500mah) setting and let them charge at the full 1000mah until they read full. This should give you a fairly accurate rating of the batteries.
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Old 2017.10.30, 07:58 AM   #5
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i always run a small desk fan, about 8" diameter, with my chargers, all plugged into the same power strip so turning all on/off at the same time. I don't have a lot of time fuss with cells or chargers so it's just a piece of mind that keeps them from melting in a charger. I have a couple chargers running, the SkyRC and a cheap bulk cell charger.

Last edited by arch2b; 2017.10.30 at 01:32 PM.
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Old 2017.10.30, 12:23 PM   #6
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So the consensus seems to run a fan with the La Crosse chargers, and even other chargers. Now that I remember correctly I did eventually start using an XBOX 360 case fan and heat sinks on my AAA cells due to heat. My old charger just didn't have thermal protection and therefore never cut charge to my cells when I ran without the cooling setup.

In that case I'll keep the BC1000 and run a small high CFM case fan on top of the cells. If I get the right size it should be able to sit flush in the charger's bay without taking up extra volume in my pit box.

Thanks for all the input!

Last edited by BitChar-G; 2017.10.30 at 01:07 PM.
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Old 2017.10.30, 02:00 PM   #7
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It isn't necessary to have the fan blow down onto the batteries. Just set the fan beside the charger so it blows air across the cells during charging thereby carrying the heat away. I use one fan to blow across a bank of four chargers.
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