Farmer Ted

My Feedback: (5)

I don't know af anyone else has noticed this or perhaps I'm just nuts...

I have been flying for a few years and have charged many hundred (or thousand) a LiPo pack.

some things I've noticed that have never quite been explained:

LiPo packs are sensitive to vibration when charging...if you watch the charge voltage and handle the pack while charging, the voltage will jump all over the place. Even walking by the charger can cause enough voltage fluctuation to trick the charger into thinking the pack is done.

As my LiPos get more charges on them the charging voltage gets more and more unstable and tends to jump all over the place. My charger will graph charging voltage and I can see this really wild voltage fluctuation, at times the charger will just stop charging, saying the pack is full even though it's not. If I 'massage' the pack a bit or even slap it lightly on the ground and put it back on the charger the charging voltage will stabilize and it will be fine...perhaps something with the electrolyte/ chemical reaction in the pack?

aged LiPos typically need to be charged twice to get them 'full' (reading 12.6v)

I'm usually only getting 35-40 cycles out of my cheap Zippy LiPos before they puff or lose enough capacity that they're no longer practical to use.

For the record: I'm using a Duratrax ICE charger (essentially the same as the Electrifly Triton?) an Electrifly Equinox balancer, I charge at just under 1C for all my packs, never discharge over 20C (which is what the packs are rated at) and all of my ESCs have voltage cutoff set at 3 or 3.1v per cell...I don't feel I'm abusing the batteries at all.

This is just my experience. I'm surprised that I don't seem to get more cycles out of a battery before it's dead or has lost most of it's capacity.

I discard my LiPos when they puff significantly under discharge or no longer fly the plane with authority.

Granted I've been using the cheap Hobby City Zippy Lipos but my experience with other brands has been similar.

Is this consistent with other peoples experiences?

Vuela

I agree with all of the above and I am using a different brand of charger than you are and I balance chrge every time. Lipos seem to be consistenty inconsistent.

Vuela

I agree with all of the above and I am using a different brand of charger than you are and I balance chrge every time. Lipos seem to be consistenty inconsistent.

Vuela

I agree with all of the above and I am using a different brand of charger than you are and I balance chrge every time. Lipos seem to be consistenty inconsistent.

guver

My Feedback: (325)

I'm on the other side and disagree. The problem is in the connections on the banana outputs, or the other end of the lead at the battery connection. The voltage graph should be rock steady even when playing with the leads,pack,connections.

Jezmo

Mine are steady too. I don't think it's the battery, maybe the charge connectors are not up to standard. Hope you get it figured out.

speedy72vega

Also, if you're only getting 30-40 cycles out of your packs, and with different brands as you stated, then I'm going to suggest that maybe you're either running the packs too hard, or charging at too high a rate, or both.
You should recheck the draw of your power system and make sure the batteries are of a high enough capacity and discharge rate for your needs. The fastest ways to kill a pack are to either overdraw them, or to run them too far down. Make sure you're not running them below 3.3v/Cell.
Charging should be done at 1-2C, although I know a few people that charge at a higher rate. I always charge mine at a 1.5-2C charge rate, and I have over 100 cycles on all of my packs (yes, Zippy) with no problems. I will say, I have started to see a small difference in cell readings after charging on some of the packs, but it's .2v or less, so i'm not too concerned.

I'll give a quick example of the overdrawing situation.
I fly with a guy that recently bought one of those Sukhoi thrust vectored EDF jets. It came as a plug and play, with the motors, ESC's, servos, etc. already installed. It also came with a battery and charger. The battery that came with it was a 3000ma 4S 20C pack. His first pack only lasted a couple of weeks, then lost all capacity, and would only fly the plane for barely 2 minutes.
he sent the battery back for a warranty exchange, no problem, however, that battery lasted the same amount of time as the first one. He asked me if I would take a look at it, and maybe give him some suggestions, as I only fly electric.
The firsrt thing i did was to get my Rhino 3700ma 4S 20C pack and my Wattmeter. It turns out, his stock power setup was drawing 68 amps at full throttle, 988 watts. The stock 3000ma 20C packs are only capable of delivering a max of 60 amps constant, 75 amps burst. Since we're up in the thin air here in Colorado, the plane must be flown at or near full throttle all the time just to keep it in the air, so it turns out he was constantly overdrawing the packs until they fried.
I let him use my 3700ma pack, that's capable of delivering a constant 74 amps, and after a 4 minute full throttle flight, the pack was barely even warm.
You would think that the factory would have checked the draw of the plane and supplied a pack of the proper capacity, but they didn't.

You might want to double check your draw, and make sure not to run the packs too low, and I bet they will last longer.

Just a suggestion........Rob.



Edit: I just reread your post, and saw that you're making sure not to overdraw amperage, as you stated you never run above 20C, but your cutoff is WAY too low. You should never run the packs to 3v/Cell. The lowest you should run them is 3.3v/Cell, preferrably not below 3.4-3.6v/Cell. I would reset your cutoff and see if your packs last a bit longer. Sorry for the long post.