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Old Sep 15, 2014, 07:59 AM
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Thanks for the concise explanation, helps a lot! :-)

The charger is max 60 watts.
I tried charging in parallel 2x 2s 4000mah lipos at 6A, but my charger only charged at about 4.5A max. Any idea why it can't reach 6A since 7.4V x 6A is only 44.4 watts?
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Old Sep 15, 2014, 11:13 AM
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See post #3360
With a 12V-5A PS, you'll get 60W minus charger/PS/wire losses.. Like abenn said, maybe 50W or less.

If you are in the Constant Voltage charge phase, the current will be reduced gradually till charging current is down to about 2% of set current. So the current from the charger will depend on the charged state once the Constant Current phase is complete.

What was the pack voltage when you noticed 4.5A?
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Old Sep 15, 2014, 05:04 PM
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Quote:
Originally Posted by abenn View Post
However, if you try to charge 3S at 6A, you won't be able to do it because that would be 75 watts out -- beyond the capability of the power supply.
So does that mean it'll charge but at a slower rate (ie. will still charge without problems)..?
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Old Sep 15, 2014, 07:22 PM
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Yes.

mw
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Old Sep 15, 2014, 07:34 PM
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Ratings tend to be optimistic under specific conditions. I would not expect to get the max rated current out of a charger under useful circumstances. Fortunately lower current wont harm anything, it will just take longer.
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Old Sep 15, 2014, 08:46 PM
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It was about 7.8-7.9v i believe.

Quote:
Originally Posted by hoppy View Post
See post #3360
What was the pack voltage when you noticed 4.5A?
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Old Sep 15, 2014, 10:49 PM
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Originally Posted by gabc View Post
It was about 7.8-7.9v i believe.
OK, a little over 1/2 charged maybe. Once the charge voltage reaches 4.2V, the current drops. You had not reached that point so that wouldn't explain the lower charge amps.

I think the PS might be over-rated.
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Old Sep 28, 2014, 04:07 PM
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I too have had a freightenning experience with a LiPo exploding and starting a fire. At the time both my brother and I were in highschool, but it was a weekend. He was out with some friends and had left the battery charging on a smart charger, I'm not sure what brand/make/model exactly but we did discover later that the charger was at fault and not the battery. I heard the fire alarm go off but usually that means we need to change the batteries so I wasn't worried at first. As I was walking upstars I saw flames through the open door to his room and got my mom out of the house while we called the fire department. My dog we got out of the house, but my two housecats were left inside; fortunately they were unharmed as we responded quickly to the fire. I was greatly surprised to see how a relatively small fire could have such a massive impact on our lives. I Harry Potter book collection was just about all that was damaged aside from his carpet, but we had several insurance inspectors in the house and lots of time spent removing the soot from the cielings all over the house, plus we needed to clean ALL of the clothes in the house to remove soot from them too.
My brother got off with a warning from a fire department member about having to always watch charging ithium batteries and to try not to have so many items plugged into one surge protector, althought that was unrelated to the cause of the fire. We were lucky that there were no real lasting effects, although we do keep a local newspaper clipping about the event framed in the office. The misinformed headline reads: "Robot Project Goes Awry, Causing Fire" I also learned that members of the police and fire departments have trouble pronouncing the word "Oscilloscope."
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Old Sep 29, 2014, 06:08 PM
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The misinformed headline reads: "Robot Project Goes Awry, Causing Fire" I also learned that members of the police and fire departments have trouble pronouncing the word "Oscilloscope."
Ha ha, glad it worked out in the end, scary stuff
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