Brads Electronic Projects Forum

Alright, so I am going to start working on a portable N64 system. It is going to use 2 3.7V lithium batteries, which is a little bit over the minimum required required 7V to power the N64 and the screen. I do not know a lot about lithium batteries, and I want to make sure they do not explode, so does anyone know how to properly use them?

This is what I bought (off ebay):

Batteries 1
Batteries 2

Charger

Some protection circuit I do not understand how to use, or what it does for that matter


It should be noted that I do NOT have everything yet, but they are already shipped.

Saimaster13 wrote:I do not know a lot about lithium batteries, and I want to make sure they do not explode, so does anyone know how to properly use them?

I looked on Youtube for Lipo Battery Fire and I have observed that they are very flammable and dangers exist.

I would make sure you have protection circuits with the batteries.

(Someone might find the video in this link offensive because of language and my purpose is not to offend anyone:)

There are five main things to watch for when charging and using batteries:

•Do not charge them above their maximum safe voltage (say 4.2V)
•Do not discharge them below their minimum safe voltage (say 3.0V)
•Do not draw more current than the battery can provide (say about 1-2C)
•Do not charge them with more current than the battery can take (say about 1C)
•Do not charge the batteries above or below certain temperatures (usually about 0-50 degrees C)
For specifics on each battery you must look at the datasheet to know what the safe voltages, currents and temperatures are - they can vary from cell to cell.

For the first 3 items, a circuit board attached to the battery can monitor the battery voltage and the current going out. These are often referred to simply as protection circuits. They are very common on standard batteries but you must check the datasheet or product image to verify that a protection circuit is attached

On the batteries we sell, the protection circuit is soldered onto the battery and then taped into the little cavity at the top of the battery. This is very common for lipoly cells.

http://learn.adafruit.com/li-ion-and-li ... -circuitry

Additional safety notes: Do not use a NiMH/NiCad/lead-acid charger! Also, do not abuse these batteries, do not short, bend, crush or puncture. As with all Lithium ion polymer batteries and with any power source – they should be used by experts who are comfortable working with power supplies.

http://www.adafruit.com/blog/category/batteriespower/

Saimaster13 wrote:Alright, so I am going to start working on a portable N64 system. It is going to use 2 3.7V lithium batteries, which is a little bit over the minimum required required 7V to power the N64 and the screen. I do not know a lot about lithium batteries, and I want to make sure they do not explode, so does anyone know how to properly use them?

I use them in my Cree Flashlights. I think the batteries are great but keep them away from water. The .pdf I will quote later says that water can cool the batteries off so I'm scratching my head on this one because I don't know and it is okay for me to say, "I don't know".

I use the two battery 18650 travel charger which carries a warning not to invert the battery:

http://www.ebay.com/sch/i.html?_trksid= ... &_from=R40

I also have rechargeable batteries that I use to use with my Canon Powershot A540 digital camera before I replaced it. They were 2500 mAH Energizer batteries and I had a slow charger and the batteries got really hot in the charger. I contacted Energizer and they sent me a label to return the unit but I didn't because they couldn't prove to me that they wouldn't send me the exact same charger or batteries. I also have 2300 mAH batteries and a fast charger by Energizer which is a little bit better. Someone on the Parallax forum posted pictures of a Radio Shack charger that burned up with rechargeable batteries so it can happen. My rule is that I don't charge batteries unless I am home and preferably where they won't do too much damage if there is a product malfunction.

Most primary lithium cells have a warning printed on the label that cautions against the
following conditions:
- Short-circuit
- Charging
- Forced over-discharge
- Excessive heat or incineration
- Crush, puncture, or disassembly

http://www.electrochemsolutions.com/pdf ... _Guide.pdf

The .pdf says to use sand on a lithium battery fire. The advice varies as to what kind of fire extinguisher to use for a Lithium Ion battery fire and I don't know what the correct advice is. My advice is to also find an MSDS (Material Safety Data Sheet) for the Lithium Ion in your batteries.

Class D fire extinguishers (copper based) have been developed for and proven successful for
extinguishing lithium and lithium alloy fires. The compound acts as a smothering agent and also
acts as a heat sink. Copper-based extinguishing media is able to cling to vertical surfaces. Care
should be taken to ensure that Class D fire extinguishers are of the copper-type, and not
sodium chloride. The sodium chloride extinguishing agent is not intended for the high heat of a
lithium fire, nor will it cling to vertical surfaces.

http://www.electrochemsolutions.com/pdf ... _Guide.pdf

There are also warnings against dropping the batteries.

I don't suggest anyone using lithium rechargeable batteries in smoke detectors because they suddenly give out. I think Duracell is the best, Energizer is a good 2nd best and Rayovac is 3RD. We use to use Rayovac because they are cheap but they won't give you six months in a smoke detector.

Thanks Chuck! You answered all my questions! Good to know that most batteries have protection circuitry in them, I'll have to make sure I buy those.

That would be a great project!

You should be good with those batteries - you just don't want to damage them because then they can explode. You may even want to put a couple more in parallel to give you a greater current capacity for longer battery life.

Also, have you though about incorporating an internal charging circuit so you don't need to take the batteries out to charge them?

I saw putting more batteries in parallel as an option, but when the batteries I have ordered are calculated to give 3-4 hours of play time, I don't see the point (also, I plan on selling the system.) For the internal charging circuit, I wouldn't know where to begin. I would especially be scared to try it on lithium batteries, but if you knew how to do it that would be awesome.

Check out these from microchip:
http://www.microchip.com/wwwproducts/De ... e=en010555

They cost around $1 and will charge two lithium ion batteries.

I use the cheaper version of these which only charge one cell.

Saimaster13 wrote:Thanks Chuck! You answered all my questions! Good to know that most batteries have protection circuitry in them, I'll have to make sure I buy those.

I found a claim I've been buying the wrong 18650 Lithium Ion batteries from Ebay. I heard that the ones marked Ultrafire are cells soldered together from recycled laptop or damaged batteries and aren't rated for what they say they are and the chargers are hacked nicad battery chargers that can scorch the cells. I was told to buy the batteries from Panasonic, Sony, Sanyo or Samsung because they are legitimate.

I was told that I could take them apart and see the welding marks.

I too have been stung by the bad ebay batteries

I took a razor blade to the wrapping on the 18650 battery and the battery is in a casing and one of the ends is crimped so I think I have to get a hack saw to investigate this claim.

I have some beach front property in the Mojave desert if your interested --lol
$36 for two batteries!
look at this site, it might save you a few dollars
http://www.batteryspace.com/howtochoose ... ypack.aspx
I couldn't even find 4000MAH batteries single cell?
Good luck and have a good fire extinguisher near by.

MrDEB wrote:$36 for two batteries!
look at this site, it might save you a few dollars
http://www.batteryspace.com/howtochoose ... ypack.aspx
I couldn't even find 4000MAH batteries single cell?
Good luck and have a good fire extinguisher near by.

I believe a single 18650 battery should cost $5 or $10 dollars.
The Ultrafire batteries I have are rated 2400 MAH and lasted a while but if they are underrated then I don't think people need 4000 MAH.
I've charged these batteries before and they stay cool which is unlike the energizer rechargeable batteries that I bought.
I think that if you are home when you charge it and if it is charged in a safe place, you are better off than not being aware.
Cree flashlights deliver more light than a regular incandescent light bulb and make nighttime look like daytime. I have found things in the dark which I couldn't have easily have done with a regular flashlight.
Cree flashlights are usually alluminum so not only do you have a metal container for the battery but the flashlights are aluminum as well which gives you greater protection.

I'm not from overseas so I didn't know this was a possible scam. If they test the cells and don't give you a totally bad one, it is not that bad.