Lipo Safety

[tourerjim]

Just beed browsing facebook and seen a mention of someones 1st anniversary of there home burnt down due to lipo fire.

What's the latest ideas for charging and storing our lipo's.

I have smoke detector but obviously not going to be enough to safeguard against a fire.

[myxiplx]

Use a good quality charger, keep an eye on your battery health, and always stay nearby while charging lipos.

I'm a big fan of the CellLog 8S, it always shows individual cell voltages, and the difference between the highest and lowest cells. So every time you check your battery you can see if the cells are healthy. Good, well balanced packs are far less likely to experience a problem, and if you know a pack is a ageing you can keep a closer eye on it.

If you're parallel charging, best practice is to use your cell checker before and after the charge. That ensures the packs are at similar voltages and well balanced when you start, and afterwards. When parallel charging the charger can't monitor the packs individually so it's worth taking that extra second as you disconnect each pack to check it charged properly and you don't have a poor connection or broken wire in your parallel setup.

I store my packs in metal boxes from Ikea, and charge in the conservatory, it's convenient for me and has a stone floor, so the risk is basically non existent. Simple things like charging on a baking tray are also easy precautions to take if you're worried.

[RichardV]

I store them in an ammo case in the car, and charge at the field. I guess I'm prepared to loose the car if anything did happen.

If I need them ready and warm for a quick session, I charge them on the hearth in the morning and I don't leave the lounge until until they are back in the ammo can. I also have a towel nearby in case I need to grab one and get it out the door.

[trillian]

The most likely time for a fire will be during charging. With Lipos that are not connected to anything and are sitting idle, spontaneous fires are very rare. In addition to storing them somewhere 'fire safe' if possible, for longevity you also want to store them somewhere dry and with the most consistent temperature, and store them at or near 3.83 volts per cell. Also it's important to charge them in a warm place (ideally 18-20C) and keep them warm before using them. If charging where the ambient temperature is less than 8 celcius they should only be charged to 90% capacity / 4.1 volts per cell. What you don't want to do is charge them in a cold place to full charge because they'll go to unsafe voltages when they warm up.

[JamieD]

I charge in my garden shed. It's a pain in the cold winter but the safest way for me.

In my opinion the danger is complaicency. I often hear people say "I always stand by my batteries whilst they charge" - Yeah right...you've got to be realistic. We're not going to babysit a stack of lipos for 4 hours whilst they charge in parallel.

[JamieD]

https://www.youtube.com/watch?v=0nrsoMsEMNU

[JamieD]

just had a brain wave for my charging shed set-up.
Radio-linked smoker alarms. When the shed smoke alarm goes off, it sets-off the house smoke alarms as well.

[tourerjim]

just had a brain wave for my charging shed set-up.
Radio-linked smoker alarms. When the shed smoke alarm goes off, it sets-off the house smoke alarms as well.

We live in our conservatory year round and my heli room is adjacent with smoke alarm, the big but is" my lipo's are charged and kept in same room, good or bad its a big risk, there's so few replies here suggest we're all risking our homes.
I do have a shed but be pain in rear to have to use it.

[myxiplx]

The danger with charging in a shed this time of year is that if you charge to full voltage of 4.2V per cell in a cold shed, when you bring the packs indoors or into a warm car the extra heat will raise their internal voltage, and that can create a fire risk.

If you charge in cold temperatures you should limit the max voltage. Revolectrix PowerLab chargers do this automatically as a safety feature.

[Grumpy]

The danger with charging in a shed this time of year is that if you charge to full voltage of 4.2V per cell in a cold shed, when you bring the packs indoors or into a warm car the extra heat will raise their internal voltage, and that can create a fire risk.

If you charge in cold temperatures you should limit the max voltage. Revolectrix PowerLab chargers do this automatically as a safety feature.

Voltage raising when the battery warms is an urban myth, at least in the temp ranges we are talking about there is no significant change.

The reason why the Powerlab chargers reduce target voltage in the cold is because the critical voltage (i.e. the voltage that the battery should not exceed) is (according to Revolectrix's theory) reduced when the battery approaches freezing temperatures. For this reason the charger reduces terminal violtage in cold conditions to avoid damaging the cells due to overcharging, it's more a 'battery longevity thing' rather than a 'safety thing'.

Personally over many batteries and many thousands of charge cycles (not using Powerlab) and many of those charging in cold conditions I've noticed no adverse effect whatsoever, so i think it's over-caution on the part of Revolectrix, no other brand of charge does this. The Powerlab charger does at least give you the option of adjusting or disabling that feature.

here's what the FMA boss says:

Hi:

From our chief engineer who ran a lot of testing on charging Li in cold temperatures:

Lithium is a poor performing battery in cold weather. If the pack is cold, the cell damage voltage reduces from 4.35V down to 4.20V. That means charging a lithium pack to 100% when it is below 50 deg F will reduce cycle life.

Tim Marks

https://www.rcgroups.com/forums/show...9&postcount=11

[JamieD]

Would house insurance cover you if you suffered damage from a Lipo fire in your house?
If my cooker caught fire I would be pretty sure I would be covered. If it was a Lipo fire,I wouldn't be so confident.
I guess it comes down to whether, in their opinion, you had left them unattended. That's a difficult one to prove.

[Grumpy]

There are similar batteries in your phone, your laptop, Ipad etc, so i dont see why they should single out hobby LiPos for special treatment?

[chrisleematt21]

I charge my in a storage container at the field, In the summer it gets pretty hot in there 40c ish, and the winter pretty cold -5ish. They are charged in various temperatures so far no issues and I have been charging them there for a while now and they do get used alot.

Most of the time they are stored at home in a maplin case at about 20% ish (although I try to store them in the container as much as possible), I won't charge them at home anymore after seeing a few videos of fires, in fact the charger lives at the field now, so couldn't charge them at home.

When my older packs have gone puffy I normally chuck them or leave them in the container, I may be a little too cautious.

Has anyone here ever tried to make a lipo explode / go up in flames? I've had a few crashes and only ever seen one go up in smoke from an impact, I've seen 1 smoke due to being shot and I've seen a few on a bonfire none of which went up like they do on the youtube videos.

Is it just over voltage of a cell that does it when charging? and what causes one to go up when flying?

[Grumpy]

Has anyone here ever tried to make a lipo explode / go up in flames? I've had a few crashes and only ever seen one go up in smoke from an impact, I've seen 1 smoke due to being shot and I've seen a few on a bonfire none of which went up like they do on the youtube videos.

The Youtube videos of LiPos exploding are often deliberate and caused by extreme overcharging until the point that the battery bursts into flames. The only time I've personally seen a LiPo burn in a reasonably spectacular way was in a plane which crashed on take off. The fully charged battery was punctured, it smoked initially for long enough to get the battery out then started burning. It wasn't an 'explosion' by any stretch of imagination but it was well ablaze. I've seen other batteries burn after crashes but generally that's been mainly clouds of white smoke and quite modest actual 'flame'.

I've often tried to provoke my old batteries that are ready to retire by knocking a nail through them, or chopping with and axe. The results have always been very disappointing. Typically I get some white smoke and maybe a small flame about the size that from a match. I think that to make them blaze you need to have them close to fully charged and to make them explode they have to be severely over-charged.

[trillian]

Has anyone here ever tried to make a lipo explode / go up in flames? I've had a few crashes and only ever seen one go up in smoke from an impact, I've seen 1 smoke due to being shot and I've seen a few on a bonfire none of which went up like they do on the youtube videos.

Is it just over voltage of a cell that does it when charging? and what causes one to go up when flying?

The only times I've seen them burn in person were in crashes or when violently stabbed with a shovel or something.