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Old 10-01-2010, 05:38 PM   #1
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Default Smc 28c sport max

Would there be a reason my batteries are swelling so easy. I'm officially open to every suggestion.lol
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Old 10-01-2010, 05:42 PM   #2
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Would there be a reason my batteries are swelling so easy. I'm officially open to every suggestion.lol
We just had a old 28c smc puff.

Get a Acorn or Thunder Power
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Old 10-01-2010, 05:48 PM   #3
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And it dumped
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Old 10-01-2010, 05:52 PM   #4
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And this time I ballanced for the frist time and it dumped
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Old 10-01-2010, 07:01 PM   #5
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how is it charged,
how is it stored(voltage)
what esc is used and is the lipo cut off on
how old is it
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Old 10-01-2010, 07:14 PM   #6
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Battery is charged full before storage. Speed passion 2.0 with 528 10.5 ballistic. Geared at 7.42 running at mikes in porter, Texas. Come to think of it a few years ago I was running gtb's with no cutoff. I never had a problem until I was able to adjust the cut off. I may have set it 2 high in an oops today when changing settings. I will check an post. What is suggested?
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Old 10-01-2010, 07:22 PM   #7
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smc batteries can not be stored fully charged they will puff,it can take a week or take months they should be stored around 3.3-.5v per cell
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Old 10-01-2010, 07:27 PM   #8
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smc batteries can not be stored fully charged they will puff,it can take a week or take months they should be stored around 3.3-.5v per cell
What can take weeks or months? For them to discharge?? I am not to familiar with amperage and so on. Been racing for 5 years and never really took the time to learn... Lol

Maybe I should consider that...haha

I had my cutoff set at 3.2 volts per cell. I believe I had it at 2.8v per cell before.
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Old 10-01-2010, 07:34 PM   #9
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they can not be stored fully charged,it will damage them (puff,burn catch on fire) this can happen any where from a day,a week,or month there is no way to know if a batteries chemical balance is off to make them puff.basically you left to much voltage in the battery to be sitting on the shelf
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Old 10-01-2010, 07:51 PM   #10
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they can not be stored fully charged,it will damage them (puff,burn catch on fire) this can happen any where from a day,a week,or month there is no way to know if a batteries chemical balance is off to make them puff.basically you left to much voltage in the battery to be sitting on the shelf
So having my cutoff set at 3.2 running a 10.5 could be to high. I had a five minute run about 20 minutes before my second. I decided to balance the pack before the second run and with what I aware of balance charging takes quote a bit longer to charge. I must have set my cutoff to high and went and ran on the pack after not enough mah going back into the pack. Resulting in the flat run after 3 minutes. Could this be possible?
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Old 10-01-2010, 08:36 PM   #11
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NO,if there was no cut off and you ran it until dead that can ruin the battery and leaving to much voltage for storage can ruin it
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Old 10-01-2010, 08:42 PM   #12
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K, so what would the recommended cut off setting. I was at 3.2 per cell and that when I had problems. When set at 2.8 I had no problems at all. I hope all this is not repetitive. I really appreciate the help 20
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Old 10-01-2010, 08:45 PM   #13
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I also don't ever really run packs longer than the race heat time. Like I stated before I never had any problems when runnin no cutoff a few years back. I just don't understand why I am having problems all te sudden. My packs were even swelling with 17.5. Ahhhhhhhhhhhhhhhh!!!
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Old 10-01-2010, 08:55 PM   #14
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Battery is charged full before storage.YOU CANT DO THIS,IT IS BAD
3.2 is no problem,always check the manufactures guide for use and storage of a lipo
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Old 10-02-2010, 04:43 AM   #15
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Setting your ESC LiPo cut off too high won't cause any problems. It will just shorten your run time as your battery won't be fully discharging or going into the danger zone. I tend to do this to add a bit of a buffer to avoid over discharging my packs.

Storing your packs fully charged WILL cause a problem and is probably why your packs have puffed.

Couldn't find SMC's instruction sheet on their web site (maybe I'm blind) but I've scanned and uploaded the instructions I just got with my latest SMC packs and they can be seen here:

SMC Page 1

SMC Page 2

From the instructions:
Quote:
Discharging:

LiPo batteries are sensitive to being over-discharged. The recommended cut-off is 3.0v per cell. The
absolute minimum is 2.7v per cell. lf the battery is discharged below 2.7v permanent damage may
occur. lf your electronic speed controller allows, set the cut-off to 3.0v per cell. lf not, stop driving
when your motor loses power remove the battery from the car and charge it back up.

A pack can be discharged at the claimed C rate but with high C rate packs this will not be possible
due to the limitations of the wire and connectors. A 40C/5200 pack can be discharged at 208 amps
continuous with bursts of 416 amps. This can only be done by using the proper size wire directly
soldered to the cells tabs. ln RC applications there will not be enough cunent draw to get the wires or
connectors to fail.

Li-Po packs are designed for operating temperatures up to 40'C. The pack itself must under no
circumstance become hotter than 140oF (60"C).
Lithium polymer batteries do not have a hard steel case like a NiMH batteries. lnstead a special
aluminum foil encloses them. Therefore they do no-t veni. if the integrity of the baitery is compromised
swelling will occur. lf the battery is damaged and the case begins to expand, discontinue use
immediately and dispose of properly.

Storage:

LiPo packs have a very slow self discharge rate. This means ihey can be stored for long periods of
time. The goal is io keep the cells above 3V to keep them from getting damaged. The standard has
been 50% storage charge. This means a7.4Y (2 cells) pack should be stored at 7.6 volts. ln some
of our testing we have noticed that keeping the packs stored with more than 50% charge wili reduce
some of the packs capacity permanently. Serious car racers want their packs capacity to stay as high
as possible. Our testing has revealed that storing them at 6.6 volts for a 2 cell pack will keep the
capacity as high as possible.

lf the pack is kept in storage for a long term (3 months or more), it is strongly recommended that the
pack be preserved in a dry and low temperature atmosphere. For a pack stored at 6.6 volts lve
recommend you check the packs voltage every 2 months. lf the voltage has dropped charge it back
up to 6.6 volts.

Generally. the cycle life of a battery heavily depends on how it is handled and used. Therefore it is
impossible to specify exactly how long your battery will last. You will get the most from your battery by
using proper equipment with recommended charge/diseharge methods listed in this instruction sheet.
Hope this helps explain things a bit.
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