Li-ion / Battery FAQ?

[StoneDog]

Hi all. I've just acquired an old laptop battery pack that contains 9 18650's (3x3 configuration for 10.8 & 3900mah).

One or more of the cells, or possibly the small circuit board attached to it all, is bad but I'd like to salvage the good batteries if possible. But, I don't know the first thing about Li-ion batteries... Is there a FAQ somewhere, or even a site, that I can read up on them?

Jon

 

[shiftd]

dunno about any faq, but you can try measure the V under load.
Just a suggestion /ubbthreads/images/graemlins/icon3.gif

 

[StoneDog]

Well, I have to figure out how to charge them first then. /ubbthreads/images/graemlins/smile.gif I'm a total neophyte, so I'm basically starting from square one.

I guess what I'm looking for is info on charging (I know they need some sort of protection from over draining and over charging) and anything I need to be careful of when I when I dismantle the pack and then try to assemble a new one.

I'm probably asking some very basic stuff here, which is why I asked for a FAQ. /ubbthreads/images/graemlins/smile.gif

Jon

 

[Kevin Tan]

Use the search function and search on li-ion and/or 18650.,

Basically the li-ion cannot be:-
charged more than 4.2V
discharged more than 2.5V

If you are looking at rebuilding the batt pack then get all new cells at www.sabahoceanic.com . Just send them a foto or drawing and they will tag and pack them for you. You will have to solder the circuit board install the batt into the casing yourself unless you send them the pack to rebuild.

If you are looking at using them in flashlights, the safest is to use them in the Surefire KL1,3 and 4 heads. The KL heads have a built in low voltage cutout. But the 18650 are too wide to fit into the E2 series and they are also too thin to be reamed to widen it. If you have the E2 + KL series flashlights the li-ion to use is the 17670.

You can mod a smart universal camcorder charger rated for 3.6v to charge the cell individually. Do not try to charge them by the pairs until more experience have been gleaned from using and charging them. If you feel like experimenting then do let us know the results. Check my thread on my method used to charged 17670.

But most important be very careful not to short circuit it or kabluie!!!

 

[Streak]

Another interesting fact about LiIon cells is that once they have been charged to the correct voltage at the correct current and then topped off at a lower current you can not trickle charge them. The charging process must stop.

I have succesfuly charged a single cell just using a variable voltage power supply set at the correct voltage. The temptation is to set the PS at say 4.2v and just leave it attached the cell indefinitley but one should not do this.

 

[Glow Bug]

This is a quote from another thread about the safety of a Li-Ion D size cell.

"Hi All:

I am in the final stages of the Li-Ion D solution, and testing will begin. It seems I will be getting the final Li-Ion 2 D battery soon from engineering. There is serious concern by the manufacturer since the cells upon short will source 80 AMPS (Yes eighty amps) and could present quite a danger to the consumer. So my test pack will be available soon. I did not realize how long it takes for some of these manufacturers to follow up on their promise.

I DO SUGGEST YOU DO NOT experiment on the D size Li-Ion cells that do not have factory installed circuits on the cells themselves!

I don't want to insult the generally high intelligence of the members of this forum, BUT.

IT WOULD BE EXTREMELY STUPID TO PUT THESE CELLS IN THE ONTARIO HOUSING WITHOUT PROTECTION. HOBBYING WITH THESE CELLS IS VERY DANGEROUS!

The cells are already explosive on their own. When one puts them in a containment / pressure vessel the situation becomes leathal.

The cells being made for me are safe and if they run MR-X for over 4 hours they will be well worth the price.

I will try to keep you posted, sorry for the delay, and PLEASE, take my warning seriously. I have been to the factory and I have seen what happens when these cells internally short from external abuse.

NOT EVEN THE HOTLIPS WILL SURVIVE!"

Smaller sizes need to be handled with care too if not using built in circuit protection.



Here is the link...

http://www.candlepowerforums.com/ubbthreads/showflat.php?Cat=&Board=UBB14&Number=293256&page=&view=&sb=5&o=&fpart=50&vc=1

 

[StoneDog]

Hmmm... This seemed like a good idea at the time, but given the risk (thanks Glow Bug!) and what it will probably take to do this the right way I think I'll pass. /ubbthreads/images/graemlins/frown.gif

Anybody interested in 9 18650's of unknown quality that came out of a '99 Micron laptop power pack?

Jon

 

[Mark_Paulus]

I have ordered a Pila charger (used for their 150s & 168s.) However, based upon the specs of the 150 & 168, it looks like their charger should also be able to charge 18650s (The Pila 168 looks like a 19680). I currently use a Maha C777Plus-II to charge 18650s, which I use successfully in my Elektrolumens Blaster VI, which is a Luxeon Portable V in a 2D cell body. This thing can either consume 6 AA (using (2) 3toD adapters), 3 CR-123, or (2) 18650. If the Pila Charger will work with the 18650s, then I will use them, since I need 2 for the light, and the charger handles 2 at a time.

Just my $0.02

 

[StoneDog]

Mark,

How do you know when the batteries are getting close to their 2.5v minimum?

Jon

 

[JSWrightOC]

Regarding overdischarge/overcharge protection...

When using bare cells in a light (or any other device, for that matter) it would be suitable to provide overdischarge protection in the device itself, right? As long as you don't discharge the cells with a resistor or other "dumb" load, I would think you should be fine. In case of failure, the only loss is the cells...no catastrophic failures here.

As for charging, is the overcharge protection present in the charger not enough? I realize that explosion and/or fire is the result of overcharge, but what is the rate of failure (in a potentially dangerous state) for Li-Ion chargers compared to the internal protection circuits?

 

[Mark_Paulus]

Right now, my AM ride is 40 minutes or so, so I figure I can ride 2 days on a full charge, and then I throw them back in the charger. For my 2 days ride, both batteries seem to take about 750-800 mah charge (as indicated by my charger).

I haven't tried taking them down to the point of my light not working anymore to see what they are at. I suppose I could, but for now I will not be in that situation. I carry spare batteries in my pack in case my light(s) should fail, so it's not an issue with me.

A piece of 1" Schedule 40 PVC is pretty close (within a frog's hair) to the size of a D cell, and I got some 3/4" ID / 1" OD clear vinyl tubing that fits inside that and is about the size of my 18650s. It's not pretty, but it hold the batteries in center and keeps them from rattling around.