Another Lipo charging question

[Terry Caron]

I'm new to Lipos and have an IMax B6 charger, with less-than-crystal-clear-to-me instructions.
For my ignition engine I'm using 1100mah 1S cells, I think 20C.
When charging @ C/1 and 1100mah max Charge Capacity setting, it times out @ 120mins (not settable, best I can tell) without reaching full charge.
I'd assumed that the Waste Time setting (default @ 5 mins) would auto-restart charging until full charge was reached, but Noooo - it just sets there blinking at me.
If I manually restart, the Charge Capacity reading usually resets to 0 and when it reaches full charge may read only 800-ish or whatever.
After a 2-step charge (3rd for the cell), it read 4.05v immediately after, 3.95v after ~20 mins rest.
Another 2-step charge on a different cell (it's 4th) shut down after reaching Charge Capacity and read 3.9v.
Any thoughts on what I'm doing (or thinking) wrong?

Thanks.

Terry

[Target]

I'm not sure what you're saying is happening.
If you're charging at "1C", you should be full well before 120 minutes timeout.
You'd be charging at 1.1 amps.
Most Lipo chargers raise the amperage to the set amperage, and then when 4.2v per cell is reached, taper off the amperage needed to retain that 4.2v.
When the amperage gets to zero and the cell is 4.2v, the charge is complete.
I'm guessing your missing some settings on your machine.
If you can, instead of reading the instructions, try a search on line if how to set up that charger.
One good video could save you a lot of time.
Good luck.
R,
Chris

[Motorman]

Check the termination voltage on the settings menu.


MM

 

[Fredvon4]

Highlighting  IMax B6 charger and using right mouse key I can search google for the highlighted words and it seems many of these chargers, even the REAL not cloned ones, have issues inside

I would suspect the charger and find a friend with a good charger and test the batteries on the known good unit to see if it is just a faulty charger

[Terry Caron]

Chris, MM and Fred:
My main concern is cell end voltage being so low. At least it's not overcharging and ruining them.
Termination v is non-variable, charger says it's 4.2v.
I found a tutorial video that I'll check out.
The Google search (wish I'd thought before I bought) is an eye-opener: a cheap B6 isn't a real B6!
Also, the cells I have are cheap generics, so they may be problematic too.
At least they'll do for engine bench testing and should last through a couple flights of the OTS pattern, so will do for now.
Looks like it's one o' them "ya gets whatcha pays fer" deals. 

Thanks guys!

Terry

[Terry Caron]

Google search was informative - among other things, 'though it says SkyRC on start-up, pressing Dec+Start then plugging in power doesn't bring up the calibration menu, pretty much proof that it's a knock-off.
I found one link for changing to 1% resistors (for which I'm not qualified) to increase accuracy but I'm just stuck with the fact that it simply sees 3.9v is 4.2v.
Again, at least it doesn't overcharge and it was cheap.

Terry

[Target]

I'd get a known good battery from someone, see what your charger does. And, take you're cell to a known good charger and see what it can do with your battery...
Best of luck and should any of this happen, please report your findings.

[Terry Caron]

Actually, Chris, there has been a breakthrough, reported in a separate thread as a mea culpa.
I had a 3rd new cell (one I hadn't mistreated) that I decided to charge and it came out at the correct 4.2v on my DVM, while a check a couple hours later showed it was holding that charge.
And I will take one of the other batteries to try on a buddy's charger, 'though I may've already damaged them to some extent.
As I suspected, my problems were basically due to my inexperience rather than the cheapness of a B6 knock-off (it's too unlike a true B6 to call it a clone, in my opinion).
Always a good idea to buy quality, but since it won't get R/C or drone level use I think it'll do what I need just fine.

Terry

[Motorman]

When a cell starts to go bad it won't come up to full charge and eventually it won't hardly charge at all. Doubt it will work but, you can put it on the Nimh mode at .1 amp charge rate for 10 minutes and see if that brings it up but don't leave the room when you do it and be prepared.  

MM

[Target]

I don't think that is his problem, since it sounds like a single cell LiPo is getting to 3.9v?
Maybe I misunderstood, and its a 2S pack, in which case I would probably try what you suggested.
Although, at 3.9V, you should be able to (non balance charge) a 2S pack up to at least 4.2V.
I often will charge out of balance packs through the balance plug, using two ports only and using the 1S setting to get them all up to @ 4.2V, then go ahead and balance charge them.

[Terry Caron]

Right, Chris - 2ea. 3.7 1S cells.

Terry

[Target]

Thanks for the clarification, Terry.
I hope you get it sorted out and I also hope to maybe learn something from your experience with this problem.

Vr,
Chris

[Terry Caron]

Chris, I'm confident I was the problem, not the cells or charger.
I don't know what I did specifically to damage them, but I did drop both onto the wood shop floor from hip high a couple times, may have drained at least one below 3v, or possibly did incorrectly something I wasn't even aware of.
The charger doesn't even verify one of them as a cell but still charges it to 3.9ish V.
I've tried discharging them to 3.0v (takes 'em down only to 3.2ish v) and recharging, also draining under load to 3.0v and recharging, but they still stop at 3.9v 'though the charger reads them at 4.2v.
They both still supply power, enough for a few minutes bench running at any rate, so they aren't a total loss.

Terry