royfellows
7 years ago
Just a heads up with the weather
Its dangerous to charge Li Ion batteries in sub zero temperatures.

Laptops, mobiles etc are usually kept in the house. Caving gear often in garden sheds. If that is where you keep your lamps dont charge them there, its dangerous.
I would not recommend keeping them there, or leaving them in the car.
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Mr.C
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7 years ago
Cheer for that. Just bougbt the ebike battery in from the garage - flamin perishing.
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Pinzgauer
7 years ago
Useful information ! Many thanks Roy.
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royfellows
7 years ago
I have just been looking at the data sheet for the Panasonic NCR18650B cells used in my most popular lamps.

Charging, as I said should never be done below 0C, and according to manufacturers I would recommend above 10C.
It also appears that the discharge characteristics are temperature affected. The graph below is from the data sheet.

🔗113682[linkphoto]113682[/linkphoto][/link]

I have no reason to suppose that this differs between different cells and the advice should include also Sanyo and Tesla.
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AndyJ23Uk
7 years ago
hey - i can confirm that extreme low temps is very bad for discharge profiles too

annecdote - using 28v dewalt li-ion battery tools in sub-zero temperature all fully charged the night before [ in house ] on site [ they had been outside in a peli case for > 3 hours ] - they " died " instantly - in use - but beeing " incubated " inside our smocks for 15 minuite - restored normal preformance

so - in cold weather operations - pre warm batteries - to get best preformance :)

Cuban Bloodhound
7 years ago
When sleeping outdoors in the cold, it's worth keeping your batteries with you in your sleeping bag to maintain their performance.
royfellows
7 years ago
"AndyJ23Uk" wrote:

hey - i can confirm that extreme low temps is very bad for discharge profiles too



NiCad or Li Ion batteries please?

I think that this thread is important. Batteries as we all know are a means of containing an electrical charge and as such are potentially dangerous if used improperly. Li Ions, by their internal chemistry, possibly more so than others.
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John Lawson
7 years ago
Roy,
Everybody who has done a little bit of Chemistry, knows that Lithium is a highly reactive metal, being in the same group of the periodic Table as that well known, Chemistry teachers, pet demonstration, element sodium!
I am sure you will have seen what this does when popped into water!
Personally I think these Lithium ion batteries are fantastic, but their operating parameters are still to be established.
As you may be aware, the larger ones are banned from some aircraft, however well done for posting this up this one!
I for one did not know about these charging problems.
Morlock
7 years ago
Looks like my eldest Son has just bought 480 brand new Chinese incendiary devices!:lol:

🔗113684[linkphoto]113684[/linkphoto][/link]

🔗113685[linkphoto]113685[/linkphoto][/link]

royfellows
7 years ago
You can travel with them but you need to state the watt hour rating, I give this on the web site for my power banks. There is also a max you can take on board an aircraft.

With respect I disagree with your comment about the operating parameters as a lot of money has been spent by Panasonic which also owns Sanyo, and also Tesla with whom Panasonic acts in partnership, in establishing just that. We are talking huge amounts of money, as well as the possible solution to the worlds energy problems. Tesla has just installed the worlds biggest Li Ion power bank in Australia. I predict many more to come until they become a feature of every neighbourhood. Its megabucks territory.
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Morlock
7 years ago
Roy, how many full charge/discharge cycles can one get out of a reputable make 18650, ball park sort of figure?
John Lawson
7 years ago
Whilst I agree with you that a lot of effort and thought has gone into these batteries, the point I am making is that not every operating process has been looked at yet!
Presumably if it had then the aircraft which came down due to a fire in its cargo hold of lithium ion batteries would never have happened.
Whilst I also,agree that these back up batteries will be installed around this country, never mind those set up in South Australia, I actually think that the metals required in their manufacture, namely Lithium & Cobalt may be the limiting factor in how many can be produced.
royfellows
7 years ago
The plane that came down was due to a pallet of Li Ion batteries igniting, but I am unable to determine any more information.

As most are aware on here, the Chinese produce a vast amount of these under various brands the name of which seems to always end in "fire", which could be very appropriate.
Some have been confirmed as being recycled laptop batteries which still bear signs of the metal connection tags. Basically most are junk, and possibly unsafe junk at that.

I think that if an operating process needs looking at its rubbish like these. I do have a lot of respect for companies like Panasonic and Tesla.

The rest of what you say I completely agree, it could well be the raw materials that are the limiting factor here.
Interesting times though.
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lozz
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7 years ago
Vanadium.

Lozz.
AndyJ23Uk
7 years ago
royfellows
7 years ago
Genuine though?
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Graigfawr
7 years ago
Reverting briefly to the effects of low temperatures on discharge characteristics, it was well known among winter climbers that old fashioned dry cells (non-rechargeable) last for far shorter periods in sub-zero temperatures. When the old Petzl Zoom was the only viable head torch for climbing, you could get it supplied with a long lead to enable you to keep the battery case inside your clothing to maintain near-normal output capacity in cold climates.

Rechargeable AA batteries were just as badly affected by low temperatures and possibly more so.

Sounds like all batteries have problems at low temperatures.
Morlock
7 years ago
"Graigfawr" wrote:

Sounds like all batteries have problems at low temperatures.



With a few exceptions I suspect nearly all chemical reactions proceed more slowly as temperature decreases?
pwhole
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7 years ago
My digital SLR shut down a couple of times photographing snowscenes at something like -5°, and it took me by surprise until I realised what was wrong, and put the battery in my pocket for a few minutes. I suspect the camera has a threshold value where it just shuts down if the power drops below a certain rate of delivery?
royfellows
7 years ago
"Morlock" wrote:

Roy, how many full charge/discharge cycles can one get out of a reputable make 18650, ball park sort of figure?



It isn't a 'sudden', its a 'gradual' and its usually referred to as "cycle life"
I would reasonably expect 200 - 300 cycles before performance noticeably deteriorates.
This is the most noticeable difference between quality cells and 'zipfire' brands. That and the fire brands exaggerated capacity and inability to maintain current specs on discharge.
With volume production the price of quality cells has plunged, so junk isn't even worth looking at.
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