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Lipo diminishing performance?

Lipo diminishing performance?

Old 09-16-2010, 07:54 AM
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Default Lipo diminishing performance?

I have a lipo that has decreased performance the last two times I've used it. It still accelerates fine to a point, but has no top end. I have 4 identical batteries and this is the only one that behaves this way. There is no detectable swelling and it balances and charges up to 8.4 volts. It now comes off warm after use, not hot but warmer than ambient temperature. All my batteries are balance charged everytime. This battery is about one year old.

The battery uses bullet connectors and has now behaved like this in both my Slash and B4 so I know it is not the wire leads to the esc as they both run fine with the other batteries.

Any thoughts on what might be going on?
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Old 09-16-2010, 09:16 AM
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Originally Posted by JMYBFFT
I have a lipo that has decreased performance the last two times I've used it. It still accelerates fine to a point, but has no top end. I have 4 identical batteries and this is the only one that behaves this way. There is no detectable swelling and it balances and charges up to 8.4 volts. It now comes off warm after use, not hot but warmer than ambient temperature. All my batteries are balance charged everytime. This battery is about one year old.

The battery uses bullet connectors and has now behaved like this in both my Slash and B4 so I know it is not the wire leads to the esc as they both run fine with the other batteries.

Any thoughts on what might be going on?
kill it and dont ballance it.
imo ballancing packs just makes them soft
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Old 09-16-2010, 09:45 AM
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don't store them fully charged. it kills the capacity and discharge voltage. store them around 7.4V
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Old 09-16-2010, 09:54 AM
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Lipo performance degredation should happen very slowly, not fast. If it's dropped off significantly there is probably something wrong in one of the cells. Do they balance ok or are they pretty far off when you start?
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Old 09-16-2010, 10:18 AM
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It was in good balance after I ran it last night and charged to 8.4V with each cell within .01 according to my charger. Last night the charger never turned off and said lipo full like it normally does even though it showed the cells within .01 or equal to one another.

The only time I noticed a difference was on the long straight away where you could get on the throttle long enough to get it up to speed. On the more technical tight areas of the track where you only need short bursts I could not tell the difference.

Should I quit using this battery? Is this a warning that a failure might be coming?
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Old 09-16-2010, 11:15 AM
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Do you have multiple vehicles? That sounds more like a speed control adjustment. Usually when a battery is losing performance, it's the "punch" that goes first because the internal resistance goes up.
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Old 09-16-2010, 12:21 PM
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It behaved the same way in my Slash and my B4 and it is possible it doesn't have as mush punch as my other batteries, but it has enough for the technical part of our current track layout that there is no discernible difference.
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Old 09-16-2010, 10:09 PM
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Originally Posted by porkchop
kill it and dont ballance it.
imo ballancing packs just makes them soft
WTF you gotta be out of your mind
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Old 09-17-2010, 07:59 AM
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Is there anything I can try to bring back the performance of this battery or is it time for it to be retired? Thanks.
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Old 09-17-2010, 11:37 AM
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Originally Posted by JMYBFFT
Is there anything I can try to bring back the performance of this battery or is it time for it to be retired? Thanks.
I always hit the store mode after each race to bring down volts and I cycle my lipos every month.
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Old 09-17-2010, 11:40 AM
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Originally Posted by JMYBFFT
Is there anything I can try to bring back the performance of this battery or is it time for it to be retired? Thanks.
Not much. There are no tricks with lipo really. If you've cycled them and balanced them then the performance pretty much is what it is.
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Old 09-17-2010, 05:10 PM
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Originally Posted by RA99GT
don't store them fully charged. it kills the capacity and discharge voltage. store them around 7.4V
Question: when you say don't "store" them fully charged, how long is "store"?

Do you mean storing them for a long time, say several weeks to a month or more, or do you mean just storing them from one race day to the next, say 2-7 day?

I am new to Lipos and not sure what all the terms mean,
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Old 09-17-2010, 05:16 PM
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Originally Posted by bencason
Question: when you say don't "store" them fully charged, how long is "store"?

Do you mean storing them for a long time, say several weeks to a month or more, or do you mean just storing them from one race day to the next, say 2-7 day?

I am new to Lipos and not sure what all the terms mean,
NEVER leave a lipo fully charged for more then a few hours.

keep them around 3.5v per cell to 3.8v per cell.
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Old 09-17-2010, 05:16 PM
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Originally Posted by Davidka
Not much. There are no tricks with lipo really. If you've cycled them and balanced them then the performance pretty much is what it is.
I balance my lipos with every charge. I wasn't aware they needed to be cycled.

How much do you discharge a Lipo battery when you cycle it?

How often do you cycle a Lipo?

What does cycling a lipo accomplish? I used to run Nicds back in the day and understand the reasons for discharging them and cycling them. I am new to Lipos and want to learn more about how to handle them.
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Old 09-17-2010, 05:41 PM
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I just suggested it because it's a way to monitor charge/discharge capacity (assuming your charger has a digital screen that counts that). There's no benefit I'm aware of to cycling lipos, it's just a way to check their health.
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