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Lipo help


#1

A little bit of help required guys, but i think i already know the answer :stuck_out_tongue:

I bought last week a lipo battery tester on Ebay

So when i plugged it into the 1st one of my 3s 4400mAh lipo’s

Cell1:4.06v
Cell2:4.09v
Cell3:4.04v
All:12.1v
Which is ok i guess.

Then the 2nd:
Cell1:1.38v
Cell2:5.06
Cell3:4.53
All:10.9

Which is funny because the 2nd doesnt look the same as the 1st. It doesnt look as flat as the other one, a little bulgy. I guess theres a dead cell and its ready to burst the next time i charge it.

I thought the balance charger would have stopped the charging process if there was a faulty cell?

Bin it???!!???

Thoughts…

Adrian
MM0TAI


#2

In reply to MM0TAI:

Hi Adrian

That’s a bit worrying. I’m afraid your second LiPo is definitely dead and needs disposing of safely (find manufacturer’s instructions don’t believe some of the drivel you find on forums) but I’d also consider binning your charger. If it is a proper balanced charger, no cell should be over 4.2V whatever the state of the others in the battery. Also if battery 1 was showing as fully charged, there’s something wrong - should cut off at 12.6V max /4.2V per cell.

Whatever you do (and despite what you may read on some forums etc.) don’t try charging battery 2 again - below 1.8V per cell changes in the cell chemistry occur which greatly increase the risk of the affected cell suffering “catastrophic disruption” on charging. A proper LiPo charger will not charge a cell registering less than about 2.2V.

Hope that helps

73 de Paul G4MD


#3

In reply to G4MD:
Hi Paul, th 1st battery isn’t fully charged it has had some use since the last charge so I expect it to be fine. I can’t remember the exact model of the charger but it’s something like Rc6 or bc6?? What do others use?

There’s a recycling place near to home so it will get popped in there asap.

Cheers
Adrian


#4

In reply to MM0TAI:
Hi Adrian,
Your charger is the same as mine. An excellent device, more or less fool proof, as it needs to be for my use. It may have a fault, of course, but that should be evident in use. First LIPO ‘fatality’ I have heard of in the SOTA community. Bad luck!
73,
Frank


#5

In reply to MM0TAI:

I can’t remember the exact
model of the charger but it’s something like Rc6 or bc6??

There are two very similar chargers which are easily confused - the Bantam BC6 and the iMax B6. The former is more expensive and I think it has a slightly better reputation for accurate voltage measurement, but I haven’t heard anything seriously bad about either of them. I use the Bantam BC6.

I suppose it is possible that a high resistance connection to the balance connector could cause the balancing process to go sour. It seems odd that one cell is very high and the adjacent one low. Perhaps a high resistance in the wire common to those cells could have caused the malfunction.

I have one battery that now seems to be developing a weak cell, but in general the BC6 has been doing a good job for me.


#6

In reply to MM0TAI:
I am using an IMax B6 (probably a Chinese fake) which does a good job in balancing the cells of my 3S pack. But I am not sure whether there is a fast charge mode without balancing in the B6. Did not try this out up to now.
Your battery 2 looks like cell 1 has died and cells 2 and 3 were overcharged. I wonder why cell 2 is stable at such a high voltage. Charging should have been stopped at 4.2 V. Perhaps your charger has a fault. Watch carefully what happens when charging the second LiPo. Can you display the single cell voltages with your charger? Do they match the battery tester?

73 de Michael, DB7MM


#7

In reply to DB7MM:
I am using the Titan B6…I think it is the same board inside. I am very happy, but I just discovered a S6 noise on 14060. It is only present when the charger shows current. So I thought it might be interesting…although a bit off topic.

Tom, DJ5RE


#8

In reply to MM0TAI:

Hi Adrian

I use a very cheap and cheerful little unit from RCMdirect - calls itself “2-3 cell Li-poly balanced charger” and it does just what it says on the tin! Absolutely foolproof, no user adjustments just plug the balance connector of the battery into the socket on the device and bingo. Takes a 12V supply so have used a SLAB to provide the power when camping away from a mains socket, or you could use a 12V 1A DC wallwart when power is available.

Only charges at 800mA so not ideal if you’ve got a high capacity LiPo and you’re in a hurry, but lower charge rates are good for the cells’ longevity!

73 de Paul


#9

In reply to G4MD:
Hi Paul, i have been charging my lipos at 3A, they are rated for 1C charging so i thought that would be ok, maybe should reduced it to 2A perhaps. But it is never on the high current for long at it drops off the closer to fully charged it gets. It seems to sit on 0.1A for long enough before it stops charging.

Adrian
MM0TAI


#10

In reply to MM0TAI:

Then the 2nd:
Cell1:1.38v
Cell2:5.06
Cell3:4.53
All:10.9

The battery has not been connected to any load yet the voltages have changed in the 2nd(FAULTY) battery but not in the 1st(the healthy one)

Cell1:2.06V
Cell2:3.70v
Cell3:3.40v
All:9.75v

Still its going to head to the recyclers!!

Adrian


#11

In reply to MM0TAI:
Thanks for the tip -off about the tester. £3 or so and 3 days later it arrived. My working LiPo showed that after charging with the Mystery balanced charger with flame decals to inspire confidence!!! An MM0FMF ebay recommendation] it had a cell voltages in the 4.04 to 4.14V range. It’s companion which the charger refused to charge from the outset has 0V on cell 1. I regret that I didn’t complain at the time. I’ll be buying some more cells and a better balanced charger in any event as SOTA without LiPo isn’t something I’d contemplate.

73
David M0YDH


#12

In reply to M0YDH:

Go for the PP3 option. Safe and economical!

73

Richard
G3CWI