Battery types used in detectors.. a FYI for safety

[wvrick]

I been looking for my next detector and notice that LiPo batteries are making their way to detectors now, these are great batteries but I think some of the dangers are not being seen in metal detectors as in there other uses. I have been involved for years using LiPo and other forms of Lithium batteries in hobby that use them 100% for a power source, and seen a few outcomes that everyone should know about. I'm not saying its bad for a Manufacturer to use LiPos because they are not, but there should be more warning about the danger with using them. I own and use all types but I also use great care in their storage and use. I never charge them unattended or in a place I can't get them outside if they catch fire, I charge my battery indoors in a metal box and have used a pan with a handle that I have carried one to the door and chucked it into the yard that swelled and was starting to vent. I have known people that lost their home from a LiPo caused fire.

I would not, not buy a detector that uses LiPos and will but I will keep a eye on them when charging.

The big differences between the two types.

1. LiPos come in soft cases and, if abused, can vent and flame. Abuse includes physical abuse such as dropping, charging or discharging too fast, charging or discharging to too high or too low a voltage, or storage in extreme conditions, such as a hot car.

2. The Li-ion packs we normally use are LiFePo4, most commonly a brand known as A123. They come in hard cases, like regular batteries, and If abused they may vent through a safety valve in the case, but they're unlikely to flame or to create vast amounts of smoke an flame like LiPos do when they flame.

One major thing about LiPos are if you discharge them completely you have lost the pack, they will not charge.

Just remember, never trust your LiPo alone.

[video]http://www.youtube.com/watch?v=yc8NTkUKJ8k[/video]

 

[ironsight]

Was tempted to convert to Lithium Ion but after reasoning the logic behind the cost and potential safety issues, i reverted to my trusty hi capacity Nimh batteries.
I personally don't have the need to have a battery pack that will last for one or more hunts. I like to start a day's hunt with a fresh fully charged battery pack.

With hi cap. Nimh batteries, my eTRAC will easily keep on sqwaking for a day's hunt.
With my smart quick charger, i charge them before breakfast and they're ready to go after breakfast and a quick shower, fully charged.

 

[skookum]

Hi,
There is a lot of hype involved when it comes to Lithium batteries.
Today, almost all cell phones use them and nobody watches their phone as it is charging or even puts it in a fireproof box.
Same goes for cameras and lap tops and all sorts of other gadgets.
A bottle of propane for your gas barbecue could blow you apart - yet people carelessly throw them in the back of the trunk of their car after refilling them, even though they have many times the potential destructive power of a Lithium battery.
There are dozens and dozens of good tutorial videos on youtube concerning Lithium batteries / charging them and their care.
And yes, if you pound a nail through your LiPo pack it will catch fire.
By the way, if you completely discharge your LiPo pack you can save it by charging it up to 9Volts on the NiMh mode and then switching back to the LiPo mode to finish charging it to full capacity - although the life of the pack will be decreased.
hh
skookum

 

[wvrick]

Hi,
There is a lot of hype involved when it comes to Lithium batteries.
Today, almost all cell phones use them and nobody watches their phone as it is charging or even puts it in a fireproof box.
Same goes for cameras and lap tops and all sorts of other gadgets.
A bottle of propane for your gas barbecue could blow you apart - yet people carelessly throw them in the back of the trunk of their car after refilling them, even though they have many times the potential destructive power of a Lithium battery.
There are dozens and dozens of good tutorial videos on youtube concerning Lithium batteries / charging them and their care.
And yes, if you pound a nail through your LiPo pack it will catch fire.
By the way, if you completely discharge your LiPo pack you can save it by charging it up to 9Volts on the NiMh mode and then switching back to the LiPo mode to finish charging it to full capacity - although the life of the pack will be decreased.
hh
skookum

Cell phones use Li-lon pack not lipo that I know of, and yes if you overcharge a LiPo you will burn. PERIOD and no one is suggesting anyone damage their packs. Sure if you have a old type revolver without a safety bar and drop it and it lands on the hammer it will fire, so why stand over it all day and drop it to see if it does go off. So why not use care with a dangerous battery. Sure there are youtube videos of people damaging batteries to cause the failure, but it is a real failure. Only the effect it triggered to show in the video, most of the fires are in R/C planes and Helis that crash to cause the damage. The purpose of this whole post is more to watch when charging what can happen. The plugging your battery in to another battery will work as long as its not 100% discharges, I have 35 years in industrial batteries and there are tricks to bring a battery back to life, but also dangers in doing so. Like the titles says, its a FYI for safety.

 

[skookum]

Hi,
Fair enough.
On the other hand, you did link a video from Youtube that CLAIMS the car caught on fire cause someone was charging a LiPo.
I got no proof of that and neither do you.
If so, I guess the instructions provided by the manufactuer were not printed in Albanian or whatever language they

 

[wvrick]

and have used a pan with a handle that I have carried one to the door and chucked it into the yard that swelled and was starting to vent.

No I can't say what really caused the fire and can only take it for what its worth, my own experience is I have had two batteries vent with one catching fire by a faulty charger. I still use LiPos almost every day because I build flight controllers (SMD hand soldered, and reflow under a microscope) for "Drones" and write some code as a hobby and fly all types. The reason for them is weight, and I wouldn't not use one. Being around the flying field I have seen a few fire from these batteries, most were damaged but some were not and charged at the wrong charge rate. I charge them at 1C and never charge a hot battery so it doesn't cause a "thermal runaway" where the battery would fail. I can only speak of what I've seen and experienced. Last summer while I was at a developers meet in Corfu Greece we had two LiPos catch fire charging, the resort we were staying called "The RC Hotel" does not allow charging in their rooms and has a charging area only.

 

[ironsight]

The lithium ion family of batteries are relatively safe if:
-they are designed properly (stay away from cheap or off brand Li-on batteries)
-not overcharged which can deteriorate and/or cause thermal runaway
-not hyper discharged above design criteria which can cause thermal runaway
-not short circuited which can cause thermal runaway
-the load (device circuitry) is properly fused
-the battery has no manufacturing defect
-not subjected to extreme high temperatures
-not physically abused or punctured allowing the electrolyte to leak out

All batteries have an internal impedance which if short circuited they will all over heat. This is because a high internal wattage develops due to the high short circuit current through the batteries internal impedance, simple Ohms law, Wattage = Current x Current x Resistance.

The problem with Li ion batteries is that they contain a flammable electrolyte unlike lead-acid or other conventional batteries which are water based, the reason we keep hearing about Li-on-on fires. Further, under the right or should i say wrong conditions they could even explode.

For now i'll stick with my trusty Nimh batteries.

 

[skookum]

Hi,
Well, there are two items to be mentioned that with an application of a LiPo pack would not occur in a metal detector as opposed to the flying crowd.
The owner of a metal detector would not need to charge at a rate of even 1C - the flying crowd often charges hot packs taken out of their devices that had just cycled withdrawal rates of 25C to 50C - at 12 Volts in a 5 Amp pack, this makes peak withdrawal rates of 250Amps - we are talking welding currents here that produce large amounts of heat.
You take such a stressed, heated pack and then charge it at a rate of 4C or 5C and you will compound the thermal issue that will cause venting and may cause a fire.
A metal detector has a withdrawal rate in the Milliamp region not producing any heat at all.

To sum it up:
If you take a little time to educate yourself on the use and charging techniques, a LiPo pack is not to be considered a dangerous item.
At least not more dangerous than the propane bottle I mentioned above.
hh
skookum

 

[wvrick]

I agree with both replies, most don't apply to metal detectors all but overcharging or rapid charging. I did see a post that mentioned a charger that wouldn't shut off, this would worry me if the charger was faulty.