Lipo batteries-bat-safe or fireballs!

[Failed Flyer]

After using my 3s lipo batteries I store them ( at storage voltage or lower) in a unmodified Sentry 1200 fire proof chest in my garage along with the cars! This is for long term storage .Would a bat-safe or sussex model centre "extron fireballs soft safe" or fireball granules pack around my batteries be a better option. I also note many cheap soft cases advertised in Amazon uk. What is the recommendation by BMFA or by other flyers on this forum in late 2022. Is the safest place  my shed at -10C to 40C!!  Thank you .

[EvilC57]

I and several people in my club use ammunition boxes with the seal removed for storage. Easily obtained in different sizes from eBay.

[Zflyer]

I too use ammo boxes and leave them closed but unhooked so in the event anything does go wrong the expanding gas can escape. I have seen people recommending drilling one or more holes to achieve the same thing but i am loathe to ruin one as they may get used for other things.

[Trevor]

I’m not aware of any reports of LiPos spontaneously combusting when in storage. I do use a Bat Safe box when charging but, as long as the pack comes off the charger at ambient temperature, I consider it fairly safe - as long as it doesn’t get any sharp tools dropped on it!

[Simon Chaddock]

Just a point but storing several LiPo together even in a 'safe' container not only increases the chance of a failure but also the severity of the failure if it occurs. In such a circumstance one failure is quite likely to set off another. It comes down to the container as to whether the more severe LiPo event increases the risk of collateral damage.

 

If you have a lot of LiPo the chance of a failure is increased in direct proportion. You are stuck with that but sufficient physical separation is the only way of limiting the severity of any LiPo failure event.

 

I do suspect the risk of a LiPo "spontaneous" failure over the 'population' of LiPo in use by the general public is really quite small and less than the perception, however throw in use, charging or mismanagement and the risk of failure is likely whole orders higher.

 

It is pity there are reliable statistics.   

Edited November 1, 2022 by Simon Chaddock

[Zflyer]

I don't have the space or the equipment to store all my lipo's individually. The incidents we are aware of occur during charging or shortly after, and/or when damaged either by misuse or accident.  Given the amount of items in storage and sitting in model shops I would be interested how many fires occur in such establishments. I would suspect data concerning this would be actively sought when you consider that insurance companies have a vested interest in risk. On that note the question is never asked on household policies nor, to date, highlighted as risk element in policies. (This may change if an insurance employee see's this and suggests it to his employers)

As stated mine are stored in ammo boxes, in my garage. The risk there is keeping the flammable material that accumulates in there separate.

[John Lee]

The UK Government produces a detailed analysis of fires, the latest being:

 

https://www.gov.uk/government/statistics/detailed-analysis-of-fires-attended-by-fire-and-rescue-services-england-april-2021-to-march-2022/detailed-analysis-of-fires-attended-by-fire-and-rescue-services-england-april-2021-to-march-2022

 

For me, I think the most pertinent aspect in relation to this discussion is that there is nothing to suggest that there is a significant problem in the storage of batteries. 

 

Here are some extracts:

4. Causes of dwelling fires and fire-related fatalities

The IRS collects information on the source of ignition (e.g. “smokers’ materials”), the cause of fire (e.g. “fault in equipment or appliance”), which item or material was mainly responsible for the spread of the fire (e.g. “clothing or textiles”), and ignition power (e.g. gas)^{[footnote 5]}.

4.1 Key results

In the year ending March 2022:

• cooking appliances were the largest ignition category for accidental dwelling fires, accounting for 45 per cent of these fires and 46 per cent of non-fatal casualties but only 11 per cent of the fire-related fatalities

• smokers’ materials were the source of ignition in seven per cent of accidental dwelling fires and ten per cent of accidental dwelling fire non-fatal casualties, but were the largest ignition category (except “other/unspecified”) for fire-related fatalities in accidental dwelling fires, accounting for 24 per cent

• of the 24,541 accidental dwelling fires^{[footnote 6]}, 31 per cent were caused by “misuse of equipment or appliances”, virtually unchanged from the year ending March 2021

4.3 Main cause of, and material mainly responsible for, dwelling fires

Exactly how a fire originated, and then the material which was mainly responsible for it spreading, are both important determinants in the outcomes of fires. Notably, and similarly to sources of ignition, the most common causes and materials responsible for the spread of fires are not those that lead to the greatest proportion of fire-related fatalities.

Of the 24,541 dwelling fires with accidental causes in the year ending March 2022, 31 per cent were caused by “misuse of equipment or appliance” (Figure 4.2), virtually unchanged compared to the previous year (31%). The second largest cause category was “faulty appliances and leads” which caused 15 per cent of all accidental dwelling fires. (Source: FIRE0601)

The material mainly responsible for the development of the fire in 24 per cent of all dwelling fires and the item first ignited in 27 per cent of all dwelling fires in the year ending March 2022 was “Textiles, upholstery and furnishings”. This material was mainly responsible for 58 per cent of all fire-related fatalities in dwellings. (Source: FIRE0603, FIRE0604)

“Food” was the material mainly responsible for the development of the fire in 17 per cent of all dwelling fires and the item first ignited in 25 per cent of all dwelling fires in the year ending March 2022. However, it was the material mainly responsible for the development of the fire in only four per cent of all fire-related fatalities in dwelling fires.

 

 

 

[MattyB]

The most critical part here is storing your batteries at a low SOC. If you do that a) the rate that dendrites are formed is way, way slower meaning the risk of a catastrophic spontaneous failure is dramatically reduced, and b) if anything does go wrong (I.e container falls off shelf and a pack getting punctured) the impact of that will be a much less because there is far less energy stored in the pack.

It’s true that storing a lot together does increase the risk and potential impact of a failure, but that must be pretty small factor if they are at storage charge (remember they will still be stored together in large numbers in supply warehouses etc, and those don’t seem to be burning down left right and centre!).

[Allan Bennett]

A couple of posts in this thread have mentioned that the risk of failure is increased when storing a lot of packs together.  I understand that the potential impact of failure is increased, but how is the risk of failure increased?

 

My packs are charged in 'fireproof' pouches, but they're stored in a 'pigeon hole' assembly with a hinged front flap, made of plasterboard.

[MattyB]

On 02/11/2022 at 20:20, Allan Bennett said:

A couple of posts in this thread have mentioned that the risk of failure is increased when storing a lot of packs together.  I understand that the potential impact of failure is increased, but how is the risk of failure increased?

 

My packs are charged in 'fireproof' pouches, but they're stored in a 'pigeon hole' assembly with a hinged front flap, made of plasterboard.

 

The risk of any single pack failing within a time period remains the same whether stored individually or in a group. However, if you put 5 packs together in close proximity within a container, the risk there will be a failure of any one pack within that container is 5x higher, and obviously if one does fail it is highly likely that the other four would ignite too.

 

Having said that, I still store my packs (at storage charge) in groups of 5 or 6 in fireproof ammo boxes because a) I don't have space to store them with large separations away from anything else flammable, and b) because 5x diddly squat is still diddly squat! As I suggested above, the key bit is storing them with minimal energy - it is that which decreases the likelihood and impact of any incident dramatically.  

[leccyflyer]

Mine are currently stored in a vented steel cabinet, either in a couple of Sentry firesafes, or in a few Lipo Sacks or Lipo Bags - with multiple batteries stored in each. I have them separated by size - <2000mah pack in separate LipoSacks for charged and discharged packs, 2000-3500mah packs from 3s1p-4s1p which are in regular use in a compartmentalised manufacturers' Lipo Bag holding about 20 batteries in total and a second one of these with packs from 4000mah=5200mah up to6s1p. Some of the larger packs which are less frequently used are stored at storage voltage in the Sentry fire safes. I've made those changes since changing to charging at home, rather than charging entirely at the field.

 

All Lipo battery pack charging is now conducted in a pair of Bat-Safes, using dedicated chargers - I have separate chargers in my flight box if I need to charge at the field and genuine Lipo Sacks to charge in.

[GrumpyGnome]

Maybe I should be losing sleep over this.....

 

Currently in my workshop (ex pigeon coop), I have about a dozen changed LiPo packs in a soft LiPo 'bag' - that's going to slow down an inferno by just a little.  About a dozen newly discharged LiPo packs in another bag.  And about 50 random packs sitting randomly in a plastic tray, in various states of charge/discharge.

 

Maybe I've just been lucky, but I was a relatively early adopter of LiPos and in what must be tens of thousands of cycles, I've only ever had 2 issues:

 

1. Charged a pack (pre balance charger days) as 3S when it was 2S - pooof!

2. Damaged a LiPo in a crash - much smoke, few flames.

 

No, I won't lose sleep. Just carry on being relatively careful.