Hi Everyone,
Nothing big here but I've had a couple of inexperienced students ask about this.
I have written up how to, with lots of details...
Regards, Terry King
...In The Woods In Vermont
The one who dies with the most Parts LOSES! WHAT DO YOU NEED??
Hmmm... Nothing wrong with this "how to", but... Too many text to say a few obvious things... ?
Are your students 5 yrs old? 
What is it they need to know? Are they asking how to connect a battery? Is it wise to have students using these dangerous batteries? Much safer to use 3 AA in series.
Make leads that fits the DC socket of an Uno R3 at one end and the battery connector at the other end. Check if the battery packs have over/under voltage and over current protection boards inside.
Leo..
I prefer RC style 2S lipo packs that can easily connect via whatever connector yours come with (EC-3, Traxxas, Deans, whatever) to Arduino (5.5mm OD, 2.1mm ID iirc?) barrel jack.
With an RC hobby charger, it's easy to balance charge these types of batteries and add a low-voltage lipo alarm to the balance lead in your project to avoid over discharging.
An alternative to these is, using the same charger from RC hobby, use NiMh batteries of 7.2 or 8.4V or such and don't worry about all the storage needs and concerns of lipos at all. Chances are one's Arduino project doesn't require the energy density advantage that lipos are great for, such as in drones. NiMh are more affordable, very safe and compact. Look for 1/10 or 1/16 scale stick packs by companies such as Traxxas.
Not a criticism here of your how to, @terryking228 , just a couple of alternatives for anyone who might find it useful.
The picture shows a pack designed for very high discharge currents.
Could be very dangerous in the hands of a beginner.
If the pack that Terry posted has a protection board included, then that is a much safer solution for an Uno.
Leo..
Hi, @terryking228
I would get one of these so that safe charging and low battery cutoff occurs.
2S 3S Lithium Battery Charging Module 94% Efficient Conversion Type-C Interface QC Fast Charging Charging Protection Board
Thanks.. Tom... 
How? It's NiMh. Plugged into an Arduino, the current will be what the Arduino demands. For accessory devices such as servos, pick off a line between the battery and devices and run it into a buck converter dialed in for 5-6V (in a servo example).
I do this all the time and in fact, prefer this to lipo solutions of similar capacity.
I only use lipo when I need that energy density for things like BLDC motors or the small form factor I can get away with lipo shorty packs in brushed motor rock crawlers (7.4V, 3300mAh is a good one on a 1/10 scale crawler such as the Losi Night Crawler - good half hour or so runtime, easy placement on front end over servo allows the stock battery tray to be used for other things. In my case, a multi gas alarm for culvert/under rail car inspections in a prototype and also a Fat Shark FPV camera system all on the one battery).
Most of the time, that's not necessary. NiMh will get the job done in the same way @sonofcy refers with AA alkaline batteries, although having the rechargeable advantage.
For larger projects that can accommodate the space and don't move around, I choose 12V, 5-7 (ish) Ah sealed lead acid batteries such as those in fire alarm system control panel battery backups. Cheap as chips, great runtime, non-spillable, connectors are very common at any hardware store.
That's just me. Lipos are great when the right care is taken and you know their inherent risks. How many among us store our lipos outside our homes and in something like a steel ammunition box when not is use? If you don't, you should...
Hi, THANKS for the added information. OK if I copy your comment to a school website?
One project will be a very light simple robot with a laser-cut cardboard base, The batteries I showed would be light enough. And the fact that they come WITH a balancing charger for $8 total or so makes it affordable for school projects and each kid can take theirs home WITH a charger.
No, but some are 8 to 10. And I assume some have never done anything like this before and have never heard the terminology before. They ain't US
Of course!
A key takeaway for anyone in a school setting is responsible use of lipos. As you can see from post #8 is that lipos are a different animal altogether from any other battery chemistry. As a firefighter this is a big learning curve for us as these batteries become more ubiquitous in everything from toy drones in the $20-30 range right up to Tesla cars.
I charge my lipos in a fire-resistant bag and discharge them using the RC charger to storage mode when I don't anticipate using them for six months or more, then store those in a steel ammo box in my detached garage.
As I said, anything I post here is to the best of my experience and understanding and hope that users err on the side of caution with these batteries and hope that any info I can share might be useful to others.
(Note regarding the fire on the Toronto subway: I suspect that it was brine water intrusion into the battery box that caused the battery to flare and burn. In Toronto, a brine solution is sprayed on roads in winter for traction control and being that it was wet on the night of this fire, it's likely that the owner through normal use of their scooter had this spraying up in the battery box as the wheels turned, leading to the fire)
A lot of Lithium danger can be removed if a Lithium specific charger is used. I use a programmable charger. I will mention the well known manufacturer if it is allowed. Often people charge them to 100% then store them for long periods. That is unwise handling, I have a storage program that I apply if I am storing them then If I need one I drop it in the charger and invoke the full charge program.
I searched the forum for stuff on Lithium Battery Safety. About 150 threads. So let's not do it all again here. I DO agree with what you are saying and doing..
No escaping SOME risk. They're all around us. When I fly from Montreal Canada to Istanbul Turkey next month, I'll be surrounded by laptop computers containing Lithium Batteries. With supposedly very safe battery management systems. For 10+ hours. Out over oceans. Cabin crews take training on extinguishing a burning Laptop.
Still makes me nervous. At home I have some control. All my LiPos not in use are in a metal ammo box on the concrete floor against the metal outdoor door to my shop.
Ahhh.... Us Old Guys Talk Too Much...
A cellphone powerbank could be an easy and relative safe option for kids.
Just connect the USB lead of the Uno to the powerbank.
Most power banks turn off after a while when the current draw drops below a certain value (~75mA?). That can be fixed with extra hardware.
Some powerbanks have an 'always on' mode.
Leo..
Your presentation looks good.
This is a "3S" with a 'barrel plug' (for the dreaded and much maligned 'barrel jack') --
[Amazon.com: KBT 12V 1200mAh Rechargeable Li-ion Battery, 12V DC5521 Male Connector, Replacement Battery Pack with 12V Charger Compatible for 12V Devices RC Car, Boat, Robot, DIY, LED Light Strip, CCTV Camera : Health & Household](Amazon.com: KBT 12V 1200mAh Rechargeable Li-ion Battery, 12V DC5521 Male Connector, Replacement Battery Pack with 12V Charger Compatible for 12V Devices RC Car, Boat, Robot, DIY, LED Light Strip, CCTV Camera : Health & Household
Enjoy your trip!
That looks really good! Thanks for finding that. Especially like 3 choices of MaH and connectors by that supplier. Ordered one.
I have been known to spend TOO much time Browsing Amazon, but I had not seen that one..
T
I'll enjoy it when I take the last leg of that to Cairo, Egypt. I'll get to be with my wife Mary Alice again, and get back to some friends I made there the past 2 years.
I will be teaching Arduino and ESP32 stuff to high school age refugees from South Sudan. Take a look at what we are doing CLICK HERE. Any help appreciated!
T
See the Arduinos on the table! I'm the Old White Guy.
Would not have guessed 
I have bookmarked your wiki and will probably be refering others to it here on the form
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.
