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Old 2017.10.28, 11:46 AM   #1
BitChar-G
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Join Date: Apr 2017
Posts: 28
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.

Cheers,

Last edited by BitChar-G; 2017.10.29 at 09:24 AM.
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