RC102 - A class on Lithium Polymer Battery Safety

In 2 weeks I will be teaching a class on Lithium Polymer Battery Safety. This class will cover the “best practices” for how to keep your LiPo batteries from exploding and burning the DMS building to the ground.

@StanSimmons , @Nick

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Hate it when that happens!

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Make sure you have a friend named Michael around. Just in case…

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We won’t mention what happens when some one member leaves a tiny lipo on the charging octapus and another member plugs in a much larger lipo.

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Not bad… I think you could use that as a primer to ignite a thermite charge…

If I ever get stuck in a locked room, I believe I now have another MacGyver way to take the doorknob out.

JAG “Not On Any Government Lists” MAN

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Thermite can be made from lithium, instead of aluminum.

This supposedly is an example:

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One lipo question I had, what is the timeframe that you can keep a lipo at full charge vs discharging/charging it to storage voltage? Within 24 hours?

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A good rule of thumb is to never store a LiPo with a full charge (i.e. 4.2 V on each cell) for more than 10 hours. You should always discharge a LiPo battery down to at least 4.0 V per cell before storing the battery. If you plan to keep it stored for 2 or more days, then it is best to bring the voltage down to storage levels, 3.80 V per cell.

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rc lipo battery FAQ

Yes, as Nick pointed out, be very cautious when plugging in your LiPo battery to a Charging Octopus because it’s hard to see when somebody leaves a tiny 1-cell LiPo battery plugged into the octopus.

Brandon, most people will put their LiPo batteries into storage mode at the end of the session. It won’t hurt much to leave them charged or completely drained overnight but the risk is forgetting about them or having something come up and they end up sitting for weeks/months. If they are put into storage mode at the end of each session that scenario will never happen.

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Where do you get that information?

I got that info from Team Novak Electronics senior engineer, Charlie Suangka.

The coughing and asking for Febreze is what made this precious… awesome.

JAG “Alkali Metal Porn” MAN

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I just want to remind everybody about this class on LiPo Battery Safety happening on Saturday, July 4, from 5:00 PM to 5:30 PM.

Click here --> http://www.meetup.com/dallasmakerspace/events/223430792/
to RSVP for the event.

Thanks!

I won’t be able to make it to the class, but thought of another question, what are the impacts of chargining at something other than 1c? Some batteries claim they can charge at more, does that shorten life? Does charging at less than 1c have any impact on battery life?

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The latest reports I have read from the RC industry say that it is more important to charge the batteries in balance (i.e. all cell’s voltages climb at the same rate) than it is to charge at a slower rate like 1C or less. I found that when you have a constant balancing monitor on the battery while it’s charging, the current from the charger will self-regulate and keep all cells at the same voltage as they charge up.

I’ve heard this myth before (charging below x value is bad for the batteries) and I have yet to find any substance to it. Now, charging faster than 1C can damage the cells, so check the manufacturer’s datasheet for maximum allowable charge rate.

Additionally, the balance operation is important solely for the reason that lithium ion batteries are extremely sensitive to voltage conditions outside their operating range. You get fire and death above ~4.3 and permanent coma below ~2.0. It doesn’t really matter whether the cells are at the same voltage or not, just that none of them ever leave the 2.5 - 4.2V range.

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Because of the lack of attendance last Saturday (July 4) I am re-scheduling this class for Saturday, July 18, from 5:00 PM to 6:00 PM.

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