Pet safe batteries


#1

Im looking at building a dog collar project and I want to make sure to use a battery that would be safe from fire. Lithium is of course preferable for power, weight and rechargability but I am worried about it being punctured by another dog playing or some other way.
I know many training collars use lithium so I am curious if there are hardened batteries available out there?


#2

I know of no batteries that could be used for you application that are non-toxic unfortunately.

You may want to run this by Www.Batteryspace.com


#3

The best you can do is put the battery in a case that provides some protection from being chewed - that would apply to all the electronics.


#4

My plan is, of course, to use an enclosure for the entire project. I suppose my goal here was to find out if there were any particular batteries that were more fragile than others and which would be best. I see Adafruit has 18650 batteries with JST connectors. I thought maybe that would be a better option than the Lithium polymer foil pack style.


#5

I don’t know if a 3.7V cylindrical cell is (or isn’t) the best choice for this application, but I would agree with you that it is better than a Li-Po, for sure.


#6

All batteries are densely packed energy made from hazardous chemicals.
Primary Lithium-thionyl chloride cells are commonly used in animal tracking due to high energy density, wide temperature range, and relative safely from accidental discharge.


#7

Thanks Jack. A quick google search tells me that LiSOCl2 are not rechargeable. So that would probably be out for my project given the usage. Research on LiFePO4 seems promising as far as safety goes. Thoughts?


#8

Be aware that the Particle device will always think it’s recharging a 3.7 V nominal Li-On type battery.
LiFePO4 is 3.2V.

You would need to make sure the Particle never attempted to re-charge the LiFePO4 when connected to a usb source, for instance. And use a separate charger for anything other than 3.7V Li-On/Li-Po.


#9

Agreed, that was a consideration. I have found this nifty charger for LiFe


#10

X[quote=“docwisdom, post:7, topic:53373”]
LiFePO4 seems promising as far as safety goes.
[/quote]

LiFePo4 cells are the safest lithium battery out there but they are still full of chemicals that would probably kill a dog.

You would need a custom charging + boost converter chip for charging this battery type but it does have a much longer lifespan and higher recharge current capability usually.

The SOM-B boards that have no Battery management on board is a good pick if you want to stick with LiFePo4 cells and use a charger, BMS, and Fuel gauge solution from Texas Instruments which is what I would recommend using.

I’ve cracked open a few LiFePo4 cells in the past and it’s a very strong chemical solvent smell with high acidity so I would not say they are safe.

They call a HazMat team if any of these battery shipments are damaged during transit on larger LiFePo4 battery shipments I have received in the past.

Batteryspace sells some nice 1 amp hour 3.2v LiFePo4 pouch cell batteries if your looking for something in a dog collar sized format.


#11

Maybe electrostatic double-layer supercapacitors will be more safety than electrochemical capacitors/battery, of course they have less capacitance than battery

How to use a “super” capacitor


#12

Much appreciated!
I am a lot lets worried about ingestion than I am fire. The dogs tend not to chew or eat on things especially those things that dont taste good. Rolling around and jumping and playing, however could easily puncture a traditional Lipo and cause fire. I definitely wouldn’t want that with them playing somewhere on our 20 acres.


#13

Yea, you don’t want a Soft pouch cell type battery then. Just go with a round LiFePo4 cell in a steel case, you can get them in smaller sizes.


#14

second this comment. it’s all about that case, enclose it in something robust and pot it with some heavy duty epoxy so even if it gets torn up and swallowed the battery will go right through.


#15

Why use a battery at all? RFID tags are passive, and with a little bit of engineering, I was able to get 3" range. How big is the dog?


#16

Im wanting to track 20+ acres. RFID definitely wont suit


#17

Which particle are you using? You can probably get away with a lithium coin cell for extra small system or a 18350 cell which are in steel cases.

I don’t want to discourage you but dog tracking collars are a dime a dozed. I just found these guys the other day using LTE-M


#18

Im using a boron right now. I may alter my build to something other than a particle due to size though.

One thing that all dog trackers are missing is on-board geofencing with auto-correction. They rely on cellular communication to do the geofence tracking and most dont provide correction.
My build is to have geofences downloaded to the collar via cellular or LoRa then have the collar run autonomously in calculating the geofence. If the dog leaves the fence, they will get a vibration auto-correction. Depending on which uplink is available at the time, notifications of the alert will go over LoRa or cellular.


#19

Ultracap + onboard generator that harvests energy from the dog’s motion (basically a coil and a magnet).
No battery, and if you can get the power requirements low enough it will never need external charging.

I think you will find the fire risk from cylindrical cells is pretty low - its really the prismatic cells in phones that are a problem as they push the construction to the limits to pack in as much energy as possible. Steel encased cylindrical cells are a somewhat different animal.

Tadiran used to make self-protecting cells that had a polymer inside that would melt if the cell got too hot and disconnect everything