Limn Probs!
 

My limn seem to have gotten bigger. I cant really tell. I tested out the LVC with a foward/brake. Before, my lvc woudl throw my revo into full reverse when the voltage got low. So i put brakes, and now ti didnt work at all. I drove it till the batts at were 2.9v. I tried to bump them back up by hooking up the packs in parrelel. They seem fine, but it seems as if one of the packs gotten bigger. I was having trouble balencing the pack that grew. it wouldnt seeem to work with my balencer. After bringing them up, i had 3.86v for one cell and the total was 7.67. Thats a .06v diff betwen cells. WOuld that explain? My temps are fine on them, not warm or anythign. I was only chargint that at 250mah too. Are these packs gargabe? Theres no way for them to blow up correct, cuz they limn?

Are you saying your Lithium Polymer pack got bigger? If this is the case, than you are in a dangerous situation, when they swell up like that, they are very sensitive to anything, if you pock them, or anything they might explode.

Does Limn mean Li-Po? Or are you talking about Lithium Manganese?

lithim manganese

Any battery will have a limit as to how many amps it can supply on a continual basis without overheating. AFAIK, LiMn was "safe" against explosions from puncturing, but you can still pull more current than the C rating and ruin them. Even though they aren't Lipo, they still have a C rating you have to follow.

You can measure the voltage on each cells in a pack by using the balancer connector. Just measure across each pair of wires. For instance, let's say you have a 2s pack; it will have three balancer wires. Let's call these wires wire1, wire2, and wire3. You can measure one cell by measuring across wire1 and wire2, measure the other cell across wire2 and wire3, and the whole pack by measuring across wire1 and wire3 (or the main power connector).

What do you mean it won't work with the balancer? Does the balancer display some type of error or something? What happens if you try to hook the suspect pack on a charger without the balancer (just as a test)?

I suppose you could measure both packs with a micrometer or precision ruler and compare the dimensions.

BTW: Before you hook up any battery pack in parallel with another, you really should make sure they are the exact same voltage. If they aren't the same, or very very close, you will have a potentially high current flow between the two packs, which could cause problems.

they had same voltage. The balencer is a inline one. it would balence, but it wouldnt say CHARGE on teh apache. The other pack can charge. I think the other pack might have grew, not exactly sure though. It still charges without the balencer.

my micrometer measures 21.08mm, the other pack, which i think grew, but not as much is 20.18mm. these results shoudl be pretty accurate.

That's weird. The pack was at 7.67 and there was only a 0.06v imbalance. The balancer should balance it fine. Some balancers have an automatic cutoff when the cells are too low/high, but that doesn't seem to be the case here.

Does your charger have a discharge mode? If so, discharge the "bad" pack at like 2A and while it is discharging, use a meter to measure the voltages on each cell through the balance connector. From what you've said, you've been measuring open circuit voltages. A bad cell can seem OK with no load at all, but as soon as you either charge or discharge, there can be a large imbalance.

the packs grew 2mm larger. I was able to charge the otehr pack. Not sure why, but i think its the balence tabs. I had to move it aroudn till the red CHARGE light on teh apache showed up. It didnt balence compeltely but i didnt want to risk charging it fully, it was already at 4.17v and not finished balencing. Sorry, not discharge. Should i toss the packs or are they still usable?

Honestly, I would contact wherever you got them and explain the situation. It might be under a warranty. You were using both packs in series and one pack went bad. Could be a defect. If they won't help you, then maybe you can try a few things to make them OK again. No sense in doing something they won't cover under warranty. The fact they are bigger and are staying that way is a little troubling...

well, do limn explode? if theres no fire hazard, ima just run em till they smoke or vent or watever.

Like I said, I think they are safe from puncturing, but not sure if you run with a bad pack...

Like BrianG says, call where you got them from. You did get them new, didn't you?

I never had a problem with mine. Maybe running them under did something. They don't want you to go under 3v per cell.

I think he's running a 9l, so, is it possible he went beyond the 76amp(20c 3800)constant and damaged them

are u serious????? 20c aint enough for a 9l motor?

I agree with both of you; either ran them beyond the continuous C or set the cutoff too low.

The general consensus for cutoff seems to be to set the cutoff so that after the batteries dump, they drift or "rebound" back to about 3.6v-3.7v after 20 minutes or so. If they only get to say 3.5v, increase the per-cell cutoff in 0.1v increments until they do.

this automatically programs to cut off at 3v i believe. It cut off at 3.2v before when i was seeing why it went in reverse.

The C doesn't matter, its the amps that matter. The C tells you how much discharge its capable of, miltiuply C by the ah (3800 is 3.8AH) and you get 76 amps. Thats why I got the 8000 maxamps packs, 20c on 8ah is 160 amps constant.

WOW I said that, guess i'm learning

nbcaz, of course you aren't drawing 76A continuously or runtime would only be 3 minutes. However, I am sure you are drawing above that value in bursts, which is fine. But, the batteries need some time in between these bursts. Unfortunately, the battery makers don't tell you how much time between these bursts is needed for safe operation. For instance; if you are pulling 1 second 120A bursts every 10 seconds, it might not be enough "settling down time" in between.

This is why I tend to look more at the continuous C value.

Lol. Now you are surprising yourself? :)

Just trying to pass on what i learn, but reading that i look like you experts

Lol, I'm not an expert. Just like you, I read and learn and pass on. You gotta start somewhere!

lucky! i miss the middle part of ur procedure.

Just to let others know. These batteries supplied 196 amp thru a bk controller.
They have a 30c burst as well. I have ran them on a 2250 and mgm 24160.
I don't really know what these batteries are good for.
He has run them below 3 volts a few times. They didn't want to charge back up
low. I think that may be a problem.

so its not the amp draw? so they should should not grow anymore as long as i dont drop em below 3v right?

WEll if they have puffed. That means they are tainted goods.
That means you have damaged them and they may be no more than paper weights.
You could take them out and see how much charge it takes ti make it blow.

i thought limn dont blow up.

EVERY battery could blow up if not handled properlly.. id just get a new pack.

well, i mean the blowing up as in flames. Nimh vent and crap, but they wont damage the truck. i heard limn only smoke but no actuay fire.

Well im not sure, but they could possibly burst into flames.. maybe ask Alex at www.boomboombatteries.com what could happen, since he stocks the apogee limn batteries.

Only NiXX "blow up" :010:. Lipo more of bursts into flames (or erupts as I call it). LiMn isn't supposed to go up in flames, but it will put out smoke.

I've had a NIMH blow up in a truck while running, it scared the crap out of everybody there, thought it was deer hunting season already

So if my revo goes up in flame, i cna just sue Apoggee. Ima run em till they crap now!

Why? You would be suing for less money than the lawyer(s) would cost. Just for safety reasons, it is worth it to dispose of the pack.

If its puffed, its not a question of if but when it breaks down and causes damage. If you race it and it blows you could get them banned as well as yourself, for being iresponsible enough to run a bad pack. I'm being a downer here, but only trying to tell you that there could be a high price to pay for running a bad pack. Lets not even talk about if it blows when corner marshaled.

lol, who cares bout them marshels, i jsut dont want my car to get damaged. When lipos blow up, is it randomly or are tehre signs? my limn dont look that much bigger, and it aint growing.

Well, a major sign is if your vehicle turns into a rolling mass of flames!

Kidding aside, if you absolutely insist on running a potentially bad pack, watch for inconsistent power. It might smoke first too.

However, I strongly recommend not running them. Running a bad pack is just asking for trouble. You really ought to see if you can warranty it...

Till somebody sues you for negligence and the track banns you. We're not talking about a cap pistol here, its loaded and could do serious damage. You think you're parents don't like the hobby now? Wait till you set the house on fire.

Not trying to be a downer, but if you continue to run a potentially bad pack, any one or some of thesethings could happen. Whats a week or two to warranty or replace, as opposed to hurting a friend or burning a house down

Heh, I can't believe that anyone is even considering running a puffed pack!

Read this thread, and then decide if you want to keep running it:

http://www.wattflyer.com/forums/showthread.php?t=12371

Be sure to look at the picture attachments in the 1st post. Sure wouldn't want that to be my SUV.

Sleebus

Well, the difference here is that nbcaz is running LiMn, which are supposedly inherently safer, but I personally wouldn't want to test that theory...