Large Scale Central

Dead LiIon Pack

Electronics Power and Sound
#1

I have two 14.8V 2200Ma 4 Cell tenergy LiIon packs that I abused last summer. I foolishly used them to power a device that pulled more than the rated amps from the pack. I figured the PCB would keep me from pulling too much power - not quite so. At the time the packs got hot enough to melt the shrink wrap. They will take a charge on my dumb charger and work for a while, but easily go below the minimum voltage without the PCB shutting it down. My fast charger won’t charge them - says “Low Voltage” unless I start the charge with the dumb charger.

Yesterday I decided to rip one pack open and attempt to set it up for baance charging. When checking each cell I find all of them under .6V which is why the smart charger won’t proceed, even one call at a time.

I think it’s time to just toss these in the recycling bin at Lowes and get new cells, but before I do I thought I’d check here and see if anyone has any sage advice that might ressurect these cells.

#2

No, my sage advice is toss them, you have damaged them chemically and physically.

There is no magic potion to restore this kind of damage… you must be thinking back to the “zapping” of nicads, that actually killed of SOME internal shorts, a much different situation.

Greg

#3

That was what I thought, but figured it was best to ask before tossing them.

What’s worse than the stupid mistake of killing them is not jumping on the $15 deal to replace them at All Electronics before they sold out. The same Tenergy pack is now $37 from All Battery. I can save about $10 each by just buying cells and roll my own re-using the PCBs from the dead packs.

#4

Is there anyone that “fixes” them? I have three that quit. Not from abuse, they just quit. They are all from the same place bought at the same time. 14.8v LiIon brick packs. If getting them working is cheaper than buying new I’d be very interested.

Terry

#5

Your lithium pack was fried when you fast-charged it. You can only fast-charge HRD Lithium cells for cordless drills. The cells in your pack are only rated at 500 milliamps per hour charge rate. A lithium battery-pack always charges cold and should never get warm when charging. When a lithium pack drops below 1 volt per cell, it’s dead! Put your pack in a bucket of water until it stops bubbling, then recycle it.

Question? Does your pack smell sweet?

Rick Isard

Cordless Renovations, LLC

RCS America

#6

So what will make a pack just quit? Mine worked fine, when I charged them they took a charge then they never worked again. I put them on a meter and they are dead. They take a charge but then are dead again.

Terry

#7

Hi Rick -

I usually charge all my Tenergy LiIon packs using a smart charger at .5C per the Tenergy spec sheet. Supposedly they can be fast charged at 1.0C, but I don’t do that. None of them (even the toasted ones) get warm when charging. The overheatuing occurred during use while pulling too much current from them.

I have a dumb charger that relies on the PCB to regulate the charge with only a voltage selection, but I rarely use it. I have used it to try and charge these toasted packs because it doesn’t care waht it’s input voltage is, so long as it can detect something.

None of them smelled sweet, but on disasembly one cell in one of the toasted packs is corroded on the + end indicating some leakage has occurred.

#8

Terry Burr said:

So what will make a pack just quit? Mine worked fine, when I charged them they took a charge then they never worked again. I put them on a meter and they are dead. They take a charge but then are dead again.

Terry

Lots of possabilities Terry. I have had PCB’s go bad while the cells remained good. As Rick points out, incorrect charging can toast them. I don’t have any idea what rate the “dumb” chargers work at. I used one for a while when I first started using LiIon, but came into a great deal on a smart charger (Thanks Bruce) that lets me control everything.

If you feele comfortable messing around with it, cut the pack open and measure individual cells. They should measure above 1V each. If they do your PCB may be toast, or it may have gone into protection mode that shuts down the pack. Packs in protection mode can be jump started, but it takes opening up the pack to short two terminals of the PCB while the pack is under load.

If the voltages of each individual cell varies too much, the pack needs to be balanced which requires a smart charger and a lead to each cell from the charger…

#9

I just use tenergy “dumb chargers” to charge my packs. In all the years I have had zero problems with them. For me though i think there may be more to the problem. The batteries all in question were used in my b-mann shay and with the same electronics. The pack in my climax has been just fine. The loco has always had a “stutter” to it when it runs. the “stutter” is either in the battery or the airwire board. It doesn’t do it on direct DC power. But, i don’t want to hijack your thread with my loco problems i’m just wondering if the packs are fixable. I’m ok with simple soldering and volt meter work but much past that I don’t wanna mess with them.

#10

No problem with Hijack Terry. I have my answer.

Working on LiIon packs isn’t something one should take on without at least a little backgriound info. I had several phone conversations with Rick before I tore into mine. Having a smart, or balancing charger available can help with repairs if pack balance is an issue.

Go ahead and open up the top of your dead pack so you can get access to the solder pads on the PCB. I can tell you where to meter to test each cell which will get us to the next step.

#11

Terry, how do you know your charger charged the pack you said was dead? After you charged the pack, what was the voltage reading?

Here’s how you can test to see which device is making your loco stutter? Take the Airwire board out of the mix and hookup the battery or your DC power supply directly to the motors, only do this for a second or two. Set the DC power supply at 12V @ 1 amp. If the motors run smoothly, then it’s the Airwire board.

John, at .5C charge rating on your 2200mah pack is 600mah over the maximum capacity those cells can be charged at. They are only rated at 500mah per hour rate, I would stay with that setting, or you will burn up your back and possibly balloon the cells and catch them on fire!

Also, there are no PCB’s that regulate the amount of amp hours you can charge a lithium battery. The PCB only regulates two things, (1) voltage limts while charging/discharging, (2) the amount of amps that the pack will discharge at. You and your charger sets the amount of current and voltage limits that your pack is charged at not the PCB. Once the voltage limit of reached after the first charging cycle, the PCB will automatically disconnect current coming into the pack. Then to gain more “runtime” the PCB needs (cycle through 3 - 5 times) to learn the capacity of the pack, that’s way your pack will never be fully charged on the first charging cycle.

The corrosion is due to the cell venting, that is why you see a green and/or white powered film along the end. You pack is dead. A cell vents for two reasons, over-charging and/or over-discharging. My guess, it was over-charging. The Tenergy cells are not manufactured for high drain. Unlike my SC2200, HC3000, and HRD2500mah packs that can be discharge at 10A - 25A bursts. Purchasing a cheap pack (in price) sometimes you don’t get your money’s worth out of the pack? Plus, I think Tenergy only has a 6 month warranty?

Also, because your cells measure below nominal voltage of the cell, (3V per cell) doesn’t mean your PCB is bad? It could be beacuse your not using a DPDT switch in your wiring scheme and the pack is discharging when you switch the Aristocraft “Battery/Track” switch to “Track.” Your still discharging the battery-pack.

A lithium battery-pack can never be “jumped started.” You can reset the PCB if it’s not taking a charge, but this would be done at the manufacturer.

Rick Isard

Cordless Renovations, LLC

RCS America

#12

Rick -

I do not wish to engage in an argument with you. Yes I know the Tenergy batteries are crap compared to other cells. Unfortunately there are many of us that can’t shell out $50 a pop for a great pack, so we settle for less.

Please go back and read my original post. I overheated both of these packs while DIScharging; drawing much more current over time then they were rated for. I knew I was in trouble when I noticed the shrink wrap on the pack was melting. It was a stupid move on my part and I know it. The cost of replacing the pack is what I call “stupid tax”. I pay a lot of that (http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-frown.gif)

The .5C charge rate comes directly from the Tenergy data sheet for the 18650 cells. You can read it here: http://www.all-battery.com/productimages/li-ion/Data%20sheet%2018650%202200mAh.pdf

If my math is correct, C for a 2200Mah Pack is 2.2 Amps. .5C then equals 1.1 Amps which is the charge setting I use and have never had an issue with ANY of my packs caused by charging. These two abused packs are the only ones that I have had cells fail in over 4 years of use. The discharge rate according to the spec shet is 1100Ma, not the 600Ma you mention. I’m sure it’s possible that these Chineese made cells do not live up to thier published specs and that is what you are referring to, but that is a different story.

Regarding the PCB reset; it was YOU who taught me how to do that in a phone conversation a little over a year ago. I am certaily glad that I learned the technique because I have needed it several times. You were very helpful then in private telephone conversations. I realize that liability issues prevent you from documenting or condoning these techniques in a public forum.

P.S. You wuill need to copy and paste that link. The forum software ignores everything beyond the % in the hot link.

#13

John, the cells on Tenergy’s website not All-Battery.com are only rated at .5C which is 500mah discharge rate, and that is 600mah over the discharge rating on All-Battery.com specifications sheet for the same cells? Maybe that’s a misprint, who knows? But, whomever packs you purchase it is extremely important to never let a lithium pack charge warm!

Here’s something I tell everyone in the southwest states while operating in temperatures above 85 degrees, is to put a small fan within the loco to dissipate heat generated while discharging. This will circulate the ambient temperature inside the loco while cooling the battery.

I do remember our phone conversation on resetting the PCB and those steps are not widely known, but as you said; it’s something I don’t promote because of product liability concerns. That is also why “my company” has a very strick policy on opening the pack or cutting the 2-Pin connector, safety comes first when dealing with a lithium battery-pack.

So, I try to teach as well as inform our fellow enthusaists, but at the same time my comments may sound like I’m preaching or parenting…and it’s for a good reason. We can afford for anyone to have a problem causing warm!

Time for the NBA All-Star game!

Rick Isard

Cordless Renovations, LLC

RCS America

#14

Thanks Rick -

So - by searching Tenergy’s site I was able to find a conflicting charge spec. http://www.tenergy.com/31021_2

While this isn’t the exact pack that I own, it is very similar. On this pack the Maximum charge current is 1C, Reccomended charge current for fast charge is .5C and standard is .2C - So now I see where you are comming from. I’m rarely in a hurry to charge a pack, so I’ll see if I can reprogram my charger for 440Ma. More likely my charger will only go in 500Ma steps, so it will end up being 500Ma.

I’ve been using the Tenergy 30023 cells when building packs inside engines and will use them to replace the cells that have gone south. On Tenergy’s site they don’t have specs for the single cell. All Battery shows pretty much the same spec as the data sheet I referenced above.

I undestand now what you’ve been trying to get across and will change my charging habit. Anything I can do to extend the battery lifetime is a good thing.

#15

I know the pack was charged because the pack was at 16.6v or some such there abouts. The loco would run for about 5 minutes then the sound goes out (phoenix needs 12v) then the loco stops. As I stated above it does not do it on DC power. The board has been to A/W for a service check and it came back OK. But, to do it to 3 seperate battery packs although the same kind/style of packs seems odd to me. I even use different chargers. Oh well, if a battery eating shay is my only problem then i guess i’m doing pretty good.

Terry

#16

Terry Burr said:

I know the pack was charged because the pack was at 16.6v or some such there abouts. The loco would run for about 5 minutes then the sound goes out (phoenix needs 12v) then the loco stops. As I stated above it does not do it on DC power.

Does your track/battery switch completely isolate the track pick-ups when in batery mode (dual pole / diual throw switch)? If not, you could be backfeeding power from the battery into the rails which could be sucking down the battery.

You said 3 packs do the same thing. Have you tried these packs in other locos? If so, do they act the same?

If you can’t try them in another loco, can you hook them up to an automotive tail light bulb? Depending on the bulb wattage and the pack capacity, the bulb should stay lit for at least an hour, probably more. If it goes dim in 5-10 minutes there is a problem with the pack.

#17

Terry,

If you want to send me the packs that are dead, I can run them through our analyzer and see what the problem is?

Rick Isard

Cordless Renovations, LLC

RCS America

#18

The loco has been gutted including track pickups. The DPDT switch is on off on, one side being wired to the A/W board and the other the charge jack. I don’t know if there is bleed off or not i ran the loco immediately after it was done charging and the above mentioned happens. I have another of those batteries in my climax and it has been fine for 6 years. The three bad ones will not work anymore. They take a charge and then are DOA even on the bench. What sucks is they are the “brick” or square style pack because that’s all that fits and for whatever reason are almost twice as much as the flat pack of the same MaH and voltage.

Rick, I’ll contact you through PM about the batteries. thanks.

Terry

#19

Hmm… never seen a rechargeable that would not take at least 1/2 C charge rate.

I’ll have to read some of the links to see it… but manufacturers sometimes do mess up on data sheets.

Greg

#20

I’ve been charging at .5C ever since I got the smart charger with no issues. I’ll try the .2C from Tenergy’s specs and see how long it takes. If reasonable there’s no reason for me not to do that if it might extend the pack life a bit.

I’m curious what current the Tenergy dumb chargers put out. Maybe my multi-meter could measure it. I’m willing to bet it’s at least 1 Amp as the batteries charge pretty quick.