NCR18650B battery pack help

Hello,
I know that this is not flashlight related, but all of you seems to have a lot of knowledge in this

I am looking at making a 3cell pack using the NCR18650B ( panasonic) i was looking at a battery holder for them so i can just charge them with a nitecore charger

This is the battery holder: http://www.batteryspace.com/Battery-holder-Li-Ion-18650-Battery-Holder-3S1P-With-2.6-long-20AWG.aspx


My questions are:

where can i get a better PCB: this one cuts it off at 2.5 volts and that seems way to low, so where would i get a 3.0v per cell or even 3.3?


it is going to be used in a milwaukee heated jacket and it runs off the milwaukee m12 battery, but they don't make packs big enough, so i figure i can make a 10,000 mah battery for under 50 dollers

the jacket runs about 1 hour on a 1.5ah battery on high and 6 hours on low

so what would be the best pcb to use and have the battery last (cycle life) as long as they can

also how long do you think they will last being used 5 days a week (i work in a freezer, so they will get a good workout)

thanks in advance

Dave

Anyone have any idea at all?

You do realize that's the low voltage limit, so it doesn't over discharge?

I want to know this info as well. I just bought a new jacket and it is really nice but there is a ton of plastic around the M12 battery and the M12 connector. It is bulky and doesn't need all of this protection if it is just powering a jacket and not being attached to a worksite tool.

The OP's concern with the 2.5v cutoff was he didn't want to discharge the batteries that low because it will damage them.

Anybody know a slick way to make a 5,000-10,000 pack that can connect to this coat?

well NCA chemistry cells like NCR18650B are rated by the manufacturer to give the a certain number of cycles when discharged down to 2.5v

now if you want to exceed "datasheet specs" for cycle life then you need to have a high-voltage limit that's lower than 4.2v. and a low-voltage limit that's higher than 2.5v.

but you could just hook up a voltmeter. you need to have a fuel gauge for a large pack anyway.

dave2500 said:

Hello,
I know that this is not flashlight related, but all of you seems to have a lot of knowledge in this

also how long do you think they will last being used 5 days a week (i work in a freezer, so they will get a good workout)

thanks in advance Dave

Click to expand...

Dave, do you have any of the 18 volt lithium tools? If so, Milwaukee sells an adapter that works with the jacket and also acts as a power bank providing a 5 volts usb port.

Part number 49-24-2371

I use the three adapters I've got both as a cell phone charger and for the jacket and hand warmer.

I just don't like how huge the battery packs and power sources are. If you have ever seen the one Gerbing or Columbia use, they are smaller than a pack of cards. Sure, they are 7.4v, but adding another battery will make them the same voltage as the M12 and WAY smaller with a lot more capacity.

Again, I get why they have to keep the same form factor for all the tools, it is just kind of clunky in a jacket pocket hanging off my lower left side of my back.

dssguy1 said:

I just don't like how huge the battery packs and power sources are. If you have ever seen the one Gerbing or Columbia use, they are smaller than a pack of cards. Sure, they are 7.4v, but adding another battery will make them the same voltage as the M12 and WAY smaller with a lot more capacity.

Again, I get why they have to keep the same form factor for all the tools, it is just kind of clunky in a jacket pocket hanging off my lower left side of my back.

Click to expand...

You could also purchase a 3s configuration lipo pack and juryrig a plug to attach to the coat and use the charging plug with a Accucel 6 charger. A lot smaller overall. Then you have that pesky problem of how do you charge the batteries.

A few other tool manufacturers also joined inn the heated garment game. They all use the readily available tool battery and charger.

The dedicated pocket for the battery isn't a problem once you get used to it being there. I think this will be my fourth winter with a Milwaukee jacket/coat. The supplied 12 volt power source did run down rather quick. The 18 volt, 4mAH battery more than doubles the run time. It is bulkier than the 12 volt battery, but there ain't no such a thing as a free lunch.

I probably need to also make sure that the output is 12v (or 11.1) from the adapter that is supplied. Who know if they are changing voltage in there or just passing the initial voltage through. I know with the 18volt power pack you have an adapter to install as well, might be dropping it to 12v I would guess.

Looks like somebody already has my idea. But at $44, I think I could do this much cheaper!

http://www.ebay.com/itm/151548792574?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Am I just asking to burst into a ball of flames by using one of these things?

http://www.ebay.com/itm/Long-life-1...ad85f4c&pid=100005&rk=5&rkt=6&sd=151624009378

Is there a safer way to do this? What is the safest type of cell to use? I see some Lithium Polymer and some Li-ion. I guess I could even build a battery pack out of Eneloop XX cells in series to get me to 12 volts right?

I got bored at work and decided to open up the battery pack (M12 compact Red Lithium 2.0) for my Milwaukee coat, here is what I found:



Can I do better than this by making my own?

I looked these cells up and they appear to be made for HIGH drain, which makes sense if you are running a power tool. But for a coat, that clearly is not drawing that many amps (since it claims 2 hours on high setting), couldn't I replace these with high Capacity 3500 maH batteries to get a lot more run time?

If I were going to do something, I think I would make a pack of 3 protected series cells and another set in parallel. If you got 3400 mAH cells it would give you 6800 mAH. From the way the existing cells are configured, this would be essentially the same thickness of the original but wider. It may not be practical to replace the cells on that fixture. I have no idea how they are attached. If you can replace them, that is the simplest solution. Same case, charger, and connection to coat. If you do a series/parallel set you have to consider charging issues. And you need a box, battery holders, and an external charger to charge individual cells.

I am not an expert, and I strongly suspect one of those will critique what I have said. But I believe the existing cells are probably unprotected and charged in series. Check out the circuit wiring. If there is wiring to balance the cells when charging, that would be a good thing. There seem to be a lot of pins on that board, so there might be. With protected cells you should also be able to charge the series string with less chance of a problem.

I am not sure the best way to parallel the batteries. You should start with matched cells for any configuration. If the existing system has balancing circuits, you may be able to just connect the individual cells in parallel. If the charging is just done with a simple voltage source, then parallel two strings.

If you are willing to do external charging in a new case, that is by far the simplest charging scenario. Each battery gets charged separately. Many chargers do 4 at a time.

I am prepared to stand corrected.

I'm ok with chArging the batteries separate. I have a few nice chargers I can tops them in. Can you recommend a good case I can put them in?

I'm ok with just running 3 at a time to keep it small and carrying a spare with me.

I also don't see anything on the stock battery pack that is limiting the minimum voltage so that is probably contained in the portion that the battery plugs into.

I wonder if I get the PCB the OP listed, if it will cover me for low voltage. Or would 3 protected batteries running in series already cover me for low voltage cutoff?

dssguy1 said:

Looks like somebody already has my idea. But at $44, I think I could do this much cheaper!

http://www.ebay.com/itm/151548792574?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Click to expand...

When it comes to something one carries in ones pocket, within reasons, would it not make sense to focus on safety than cost?

Three 18650 can make a very nice fire-work show when trouble occurs. Choice of the day: third degree burn or frostbite.

For that reason, I personally would not wear one. If I am to make one however, it would have a four-position slider switch: Battery 1, Battery 2, Battery 3, Combined.

So, I use one battery at a time. On the fourth position which is "combined" means runs all three in parallel. The circuit prevents it from engaging unless all three batteries are below 3V-ish. That way, they run independent and only run together when the batteries are low enough not to be able to do as big as firework show.

I'm not sure you understand what the requirements are for this coat.

Running three in parallel is not going to get me 12v like the jacket needs. It also seems like you are talking about running them in parallel only if they are below 3v? That would be time to recharge them, not run them more!

dssguy1 said:

I'm not sure you understand what the requirements are for this coat.

Running three in parallel is not going to get me 12v like the jacket needs. It also seems like you are talking about running them in parallel only if they are below 3v? That would be time to recharge them, not run them more!

Click to expand...

I understood that alright. I am merely expressing my personal view that I wont do that to myself. Serial is probably the least safe way to run multi-batteries. Even 2xAA Eneloops can cook rather nicely - I have an Eneloop with melted top shorted during a simple drop of the battery holder. I sure would hate to have that happen inside my coat with 3x18650s after a simple slip on ice.

I know the level of risk one is willing to take is highly individual. I would not risk my life for a good view and the satisfaction of standing on the top of K2; But every year, tens or even hundreds do. Of those, one in four never came back alive. That I wont do it doesn't mean there is anything wrong with them.

Ok..... Well what you are suggesting will not work at all. So that is why I am dismissing it.

Trying to run a 12v coat at 3.6v is not possible so all your suggestions and warnings are kind of moot for this application because anything you would have me do in the name of safety simply won't work at all.....

Do you tell people running 2 double AAs in a Maglite they are being unsafe?

There are plenty of safe ways to run batteries in series. The original coat runs 3 in series and so does every heated coat. I guess the entire heated clothing market is rolling the dice every time they sell an article of clothing?

Like I've posted before. This is my fourth winter with the Milwaukee heated jacket. I've got three of the jackets and one of the hand warmers. Now I just need the heated seat and I'll be set for watching youth football. I hate being cold.

The M12 batteries, be they the 2 amp or higher don't have the capacity to run the coat on high for more that a couple of hours, tops. The M18 has 10 batteries inside verses the 6 at best you 'd get from doubling up the M12 pack.

Since I have close to two dozen M18 either 3 or 4 mAH batteries the purchase of the M18 adapter was a no brainer.

You don't need to reinvent the wheel.

I can understand the desire to find a solution to doubling the present pack, the simplest solution is to use the M18 batteries and the adapter.

I agree that is simple. Unfortunately that pack is FREAKING huge! And I would be willing to bet, 35% of the bulk is just clunky plastic that is needed to protect a battery in a work environment when attached to a heavy duty power tool.