02GF74
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| posted on 6/11/09 at 11:11 AM |
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LiPo battery question
what is the connector used for?
(not the thick red/black wires but the white conector)
is it for monitoring the charge status?
assuming LiPo charger is used, can this be left unnconnected?
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ashg
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| posted on 6/11/09 at 11:13 AM |
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its for balancing the voltage between each battery cell.
you can charge them through the normal connector or the balance connector.
the better chargers chargers connect to both connectors. they charge through the big wire and discharge through the little wires to balance the
cells
you can charge it without balancing it but the battery wont last as long.
you can get a good lipo charger off the bay of e for arounf £25-£30.
[Edited on 6/11/09 by ashg]
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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vorn
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| posted on 6/11/09 at 11:16 AM |
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The with plug is for balancing the cells ( make them the same voltage ) .
I use Li-po's in my R/C cars .
I usually ballance charge them every time but other people only balace charge them every 10 charges ,
If you balance charge , it will take longer to charge .
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ashg
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| posted on 6/11/09 at 11:18 AM |
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what is the battery for 35c is quite a high spec.
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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02GF74
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| posted on 6/11/09 at 11:18 AM |
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hmmmm..... but they will just as well if charged via the fat leads?
35 C . nah won't need antying like that, for LED bike lamps.
[Edited on 6/11/09 by 02GF74]
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vorn
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| posted on 6/11/09 at 11:20 AM |
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over time they will become un-balanced and you will not get the same performance .
But yes you can charge through the red and black wire with a Li-Po charger
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vorn
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| posted on 6/11/09 at 11:31 AM |
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Just use a single cell 3.7 volt Li-Po . That would be the right voltage for led's ???
40C 5000mah 3.7 volt
 
lipo
[Edited on 6/11/09 by vorn]
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02GF74
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| posted on 6/11/09 at 11:35 AM |
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quote:
Originally posted by vorn
Just use a single cell 3.7 volt Li-Po . That would be the right voltage for led's ???
not quite LEDs but LED emitters - Vf is 3.5 V but the driver needs 6 V or more to operate.
I have some 7.2 V NiMH that aren't lasting as long as they should - the voltage drops below the headroom of the driver so LED does not light
hence looking at higher voltage battery.
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MikeRJ
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| posted on 6/11/09 at 11:15 PM |
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Cell balancing is really quite important for li-po's, you won't find any (non-Chinese) commercial devices that use a battery of lipo cells
with no balancing, or at the very least cell monitoring.
The problem is that the cells are very sensitive to being overcharged, they like a maximum of about 4.2v (and less then this for the best life).
Charge termination is done by a combination of current and voltage; if you can only measure the end points of the battery the charger has to assume
all cells are at the same voltage levels, e.g. it will pump current into a 3 cell pack until it reaches 12.6v. If one of the cells is faulty with
e.g. a partial short there is a strong risk of overcharging the other cells. I'm sure you have seen videos of the results...
Laptops use cell voltage monitoring, they have no way of actually balancing the cells. When the battery life of a laptop starts reducing
significantly, it's most always a single set of cells (in parallel) that are out of balance, so the charge cycle ends early. I just recovered
the pack in my Dell by charging all the cells to 4.1v individually and after recalibration it's gone from 1/2 hour battery life to about 4
hours.
[Edited on 6/11/09 by MikeRJ]
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