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August 16, 2018, 19:07:39 PM

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Author Topic: Strange Overlande r 4s  (Read 802 times)

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Offline Skyleader

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Strange Overlande r 4s
« on: July 19, 2018, 13:08:21 PM »
As above, brand new only been charged about 4 times. Three cells read 4.08, fourth cell says 4.20. And my charger won't charge or balance any further. Is this ok or 😢. Normally use lots of Ovetlander, but twosome worries me.
Any ideas anybody ?.
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Online Chippie

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Re: Strange Overlande r 4s
« Reply #1 on: July 19, 2018, 14:19:47 PM »
If your charger charges other packs fine then,  I would discharge the high reading cell to somewhere near the same readings as the other three, then try charging again...

Do you have access to another charger?
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Offline Skyleader

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Re: Strange Overlande r 4s
« Reply #2 on: July 19, 2018, 15:57:15 PM »
If your charger charges other packs fine then,  I would discharge the high reading cell to somewhere near the same readings as the other three, then try charging again...

Do you have access to another charger?

No sir, just the basic Robotbirds (I think they call them B8 ) type charger. I cannot discharge the high reading cell on its own. J
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Re: Strange Overlande r 4s
« Reply #3 on: July 19, 2018, 15:59:24 PM »
Do you have access to a digital multimeter and know how to use it?
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Offline Skyleader

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Re: Strange Overlande r 4s
« Reply #4 on: July 19, 2018, 16:01:13 PM »
Do you have access to a digital multimeter and know how to use it?
[/quote

Indeed,yes. And thanks for the help
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Re: Strange Overlande r 4s
« Reply #5 on: July 19, 2018, 16:05:07 PM »
Not familiar with the charger, got a foto of it?

Ok, take something like a torch bulb that uses around 2-3 cells ( carbon batteries..) ....connect wires to it and plug it into the high reading lipo cell using the balance connector on the lipo, monitor the voltage with the dvm...
When it gets to 4.1v try charging it again....
« Last Edit: July 19, 2018, 16:07:57 PM by Chippie, Reason: »
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Offline Skyleader

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Re: Strange Overlande r 4s
« Reply #6 on: July 20, 2018, 07:23:17 AM »
Not familiar with the charger, got a foto of it?

Ok, take something like a torch bulb that uses around 2-3 cells ( carbon batteries..) ....connect wires to it and plug it into the high reading lipo cell using the balance connector on the lipo, monitor the voltage with the dvm...
When it gets to 4.1v try charging it again....

Sorry, lost me there. The balance lead has 5 wired coming off of it. Don't understand how I find the high reading cell ?
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Re: Strange Overlande r 4s
« Reply #7 on: July 20, 2018, 12:27:55 PM »
There are 5 leads going to the balance connector.....
At one end, connect your dvm positive lead to it, then with the negative lead go to the next wire, your dvm should read 4.08v or there abouts.....if there is a - sign in the display, swap the meter  leads around......
Now measure between the 2nd pin and the 3rd pin, the reading should be 4.08v ,go between the 3rd and 4th, note the reading....same with 4 & 5... Note the reading....from this you should be able to identify the high cell......then connect your bulb/multimeter and discharge that cell untill it reads the same as the others....then try recharging.....

I cant help any further without detail of your charger....

Post up how you get on.....this reply,  is in lieu of the pm you sent me, for the benefit of others...
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Re: Strange Overlande r 4s
« Reply #8 on: July 31, 2018, 16:17:21 PM »
Chipper
Sorry for the delay. Had no luck with you're suggestion, my fault not yours. But I charge it now by Balance, not charge. And although I always charge with the balance lead connected, for some reason it works better with BALANCE as opposed to CHARGE with this battery pack, all cells now read 4.20. Thanks for your help. ☺
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Offline leckyBB

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Re: Strange Overlande r 4s
« Reply #9 on: August 09, 2018, 19:53:48 PM »
I always charge in the "Balance" mode. Never had a problem with pack balance.
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Re: Strange Overlande r 4s
« Reply #10 on: August 09, 2018, 21:29:59 PM »
Chipper
But I charge it now by Balance, not charge. And although I always charge with the balance lead connected, for some reason it works better with BALANCE as opposed to CHARGE with this battery pack,

That's probably because (as with most B6-derived chargers) it doesn't actually attempt to balance in "charge" mode - it just measures the voltages. That's why they have a "balance" mode, which charges and balances. Note that charging in Balance mode usually takes longer due to the restricted balance currents.

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Re: Strange Overlande r 4s
« Reply #11 on: August 10, 2018, 07:41:03 AM »
PDR - Spot on, I have had several fellow club members make that mistake. On one type of charger chip, CHARGE does NOT balance at all. (It does on the other type of chip/install where balance is handled by if the balance lead is connected or not!)

I ALWAYS balance charge even though you "can" speed up the process intermittently, balancing one in several times not every time.

HOWEVER

The Balance port connections are pretty crude and often very suspect with regards resistance pin to pin. False readings into the charger give false balance.

The other  week I "caught" a 2200mAh 3S under charge which was warming one cell unduly on a 1C charge.

My ISDT BattGo then showed that low cell up and a B606 with impedance checking (not all had this option on menu) showed it appeared badly unbalanced due to very high impedance on that low cell.

Looked for the salt water bath to oblivion. I suspect many would have scrapped it as failed.

I cleaned the balance port contacts with evaporating contact cleaner, and put it on the BattGo's balancing process.That cell was initially showing 4.0x volts when the other two were 4.17. It took around half a day to balance outdoors away from fire risk.

Having balanced to 3.99v per cell with a 17mV range, I charged it, again outdoors, on the same charger that had warmed one cell up.

It charged to a full nominal 4.2v with a final imbalance of only 5mV.

It's been cycled in use since and stayed balanced and gives normal full discharge on a high current quad and a low current plane model.

Not the first time I have caught this happening and not the first time it has been correctable.

Its not a good idea to blindly trust what a lot of chargers tell you!
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Offline PDR

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Re: Strange Overlande r 4s
« Reply #12 on: August 10, 2018, 08:39:01 AM »
I only balance-charge the 1st charge and then if I see a problem, or perhaps after every dozen normal charges (depends on how bored I am). Most of the time I use the normal charge with the cell voltage display on, and I look at them from time to time. If the individual cells are within ~20mV of eachother I regard them as good-to-go.

I remain to be convinced that cell imbalance is a serious problem with lipos - we don't take them down to empty, so there is zero-risk of reverse-charging under load (which would be the only real problem that I can see).

0.0006 supplied, YMMV etc

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