| lincpimp |
06.09.2009 10:31 AM |
Quote:
Originally Posted by himalaya
(Post 294149)
Some tests done by EveryDayFlyer from rcgroup showed up something that's really interesting, the Hyperion new Chinese packs have their IR keep getting lower and lower when being cycled, making used packs more powerfully than new ones, aren't that ridiculous?
Enerland cell user posts show their batts have reverse behavior, higher and higher IR as time goes, which sounds more normal and reasonable. (Enerland datasheet specs only 50 cycle life typical when discharge at full C rating)
I bought myself a G3 4200mAh 35C 6S pack for my boat(you know fast boats are battery eating beasts ), looks good for the first runs, IR is 2.3mΩ/cell new, I'll watch how it's going.
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That IR is pretty damn good. I will be very interested to see how these new cells perform. 80% DOD seems to be about the correct discharge amount to retain the most useable life out of a lipo. Your boat should be a good test bed to pull the pack hard. Boats are just amp hungry!
Quote:
Originally Posted by jocktheglide
(Post 294154)
I guess being a newbie into this lipo stuff I should of asked the question: how can you tell if they are out of balance? I have a hyperion charger the AC/DC version and I always balance and charge at the same time...so would they still be out of balance?
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A decent cell meter that plugs into the balance port is a good investment to check the individual cells before a charge and after you have stored the pack. Not sure if your hyperion has a balancer readout screen, but I am pretty sure it does. During the charge I think you press the mode button to get to the balancer screen and then you can use the up and down keys to get to the individual cell readings.
Quote:
Originally Posted by glassdoctor
(Post 294178)
When you balance charge, they won't be out of balance unless something is really wrong with one of the cells. If one cell has less capacity than the others, it's possible to over discharge that cell (or just have it at a lower voltage than the rest) when you run the pack to LVC. It would be out of balance at that point... but will be "fixed" on the next charge. No damage would occur as long as no cells go below 3v.
If you are curious, you can check the cells voltage when the pack is first hooked up to charge. If the charger doesn't display the individual cell voltage, you can use dvm.
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Just for info purposes, not all balancing chargers will be able to fully balance a pack during the charge. The hyperion chargers with built in balancers will drop the current way down near the end of the charge to balance the pack, but it may take hours if the pack is way out of balance. If you are using an external balancer it is likely that it will not get the job done during the charge. I went thru this with the various MA packs I had with bad cells, one pack took 48hrs to balance out, then puffed one cell (the low cell).
General rule of thumb is that if your pack is getting out of balance during the run you either have some very cheap unmatched cells, or your setup is drawing too much current. Either way it is time for a better lipo.
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