Safely charging lipos in an apartment?

[Paul Faria]

I've been doing some research online regarding how to safely store/charge the lipo I bought. I have a fire retardant bag, and have not charged the 3S 2200mAh batteries I received (voltage check shows the cells are all around 3.8V). I do have a balcony, but it's got a wooden railing.

Should I ever attempt to charge these where I am, or should I only charge them when out somewhere safe? There's varying recommendations from "never charge in an apartment" to "just charge in your bathtub" (the latter of which I will never feel comfortable doing). There are also some recommending charging in a surplus ammo container, but that seems like a bad way to make an explosive device given the off-gassing lipos can do.

I can power the device from a bench-top power supply along with the XT-60 to banana plug adapters. Is it safe to attach a few banana plugs together to get more range in that case?

[Richard Chycoski]

Do be careful how you recharge LiPO batteries. See this article from Digikey:

https://www.digikey.com/en/maker/blogs/2021/charging-lithium-ion-and-lipo-batteries-the-right-way

See also this about outgassing:

https://www.frontiersin.org/articles/10.3389/fenrg.2014.00059/full

If I were charging them from my own home-built charger, I would put them on a large ceramic tile. I have my 3D printer on such a tile for similar reasons.

For more safety, you could put the charger on the tile in your kitchen or bathroom and run your exhaust fan. Another option might be to put the tile on a metal table on your balcony?

12-18 inch square plain ceramic tiles are cheap and available from most home-improvement stores.

You can extend banana cords in series, as long as the gauge of the wire is sufficient. Do tape up the connections to prevent shorts.

Another safety tip - You may also be able to find a 'wall wart' of the right rating, so that you don't accidentally set the bench top supply to the wrong voltage, and you can make the connection permanent without banana plugs in the mix.

- Richard, VE7CVS

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[Scott Monaghan]

I’ll be covering this on Wed night’s talk but after struggling with power needs I found this amazing consumer laptop charger that can output 3A separately from 2 USB-A and 1 USB-c outlet. With power-delivery the USB-c can be set to 5,12, or 25v up to 65W, and it’s 20,000mAh capacity keeps RoBud rolling all day.

It handles safe charging all on its own.

Love this thing.

Baseus Power Bank, 65W 20000mAh Laptop Portable Charger, Fast Charging USB C 4-Port PD3.0 Battery Pack for MacBook Dell XPS IPad iPhone 13/12 Pro Mini Samsung Switch https://a.co/d/hiWTgcs

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[Sergei Grichine]

Paul, your best bet is a metal ammo case, not sealed - to avoid accumulating pressure, put it on the balcony. 

You MUST use a good microprocessor controlled charger, not just a power supply. Lithium batteries don't like sudden onset of current, a lab supply in CC/CV mode doesn't do that. 

LiPos are worse than LiIons in terms of fire hazard, but when undamaged and not bloated - they are pretty safe. I never had a fire (knocking on wood) in my R/C airplane or robot years.

Here's what I've been using for the last 20 years. Your local thrift store offers an abundance of cooking containers. You need some way of letting the flames out in controlled fashion, and keeping the lid on.

Best Regards, 
-- Sergei Grichine
   

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[Chris Albertson]

I'd say as long as you have the battery on a fireproof surface like maybe a large frying pan and you are nearby to supervise you are OK.

I actually had a LiPo battery fire.  I tried to salvage some 18650 batteries from a power tool and one of them was bad and caught fire.   It is not that big of a deal.  All you do is carry the fireproof surface (frying pan) outdoors and let it burn out.     A burning battery is not a big deal if you are home to take car of it.   Old cookware is good because you can place a lid over the fire and take the whole thing by the handle outdoors.

A burning battery is not a big emergency.  You don't need to run.  But you do want the smell out of the house.

The fireproof bag would work as well but you need some way to scoop it up while it is hot.  same with a 1 foot square tile, you have to carry the burning mess outdoors.   

But all this is rare and only happens if you have a damaged battery.

I do store my larger batteries inside a flameproof bag ad place the bags inside a metal ammo can.

One more thing, banana jacks are good because they are easy to disconnect

You DO want to use a purpose-built lipo charger the is programmed to watch the state of charge and ramp the current down as needed so it will never over charge the battery even if you forget to turn it off.  All real chargers do this. 

Just remember, the plan for a burning battery is to pick it up and walk it outdoors and let it burn.

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Redondo Beach, California

[Paul Faria]

Thank you all for the suggestions!

I should have clarified that I do have a charger on order (gens ace imars dual channel https://www.genstattu.com/gensace-imars-dual-channel-ac200w-dc300w-x2-balance-charger-black/), I did get an Imax B6, but the build quality was so terrible (buttons literally falling out, reeked of cigarette smoke or some burned component, missing fuses on the inside, etc.) I decided to return it.

Regarding the bench top power supply, I was actually referring to bypassing the battery. I was more worried about possible safety issues with using banana plugs over a few feet..

I'll look into getting the items recommended above. Thanks again!

Best,

Paul

[Marco Walther]

On 8/30/22 21:01, Paul Faria wrote:
> Thank you all for the suggestions!
>
> I should have clarified that I do have a charger on order (gens ace
> imars dual channel
> https://www.genstattu.com/gensace-imars-dual-channel-ac200w-dc300w-x2-balance-charger-black/

> <https://www.genstattu.com/gensace-imars-dual-channel-ac200w-dc300w-x2-balance-charger-black/>),

Not sure, if the breakout-boards are included?! Something like
2 * https://www.genstattu.com/2s-6s-balance-board/

They don't show up in the pictures or in the list of accessories?!

I think, you will need them for the LiPO balancing plugs in the
different sizes.

-- Marco

> <https://groups.google.com/d/msgid/hbrobotics/c40e4e19-3bbf-4fe6-91d7-409c79007d0bn%40googlegroups.com?utm_medium=email&utm_source=footer>.

>
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
>

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[Paul Faria]

Marco, the standard balance cable fits into the plug in the charger with no issues. The link you provided has a different plug which ensures proper indexing, but I'm careful enough to not mix up ground and voltage wires. I always make sure to connect ground first. This is especially after seeing the fireworks generated when my brother hooked up his cables backwards while helping a friend recharge a dead car battery.