Opti-power fully charged at 4.18v per cell

[adamf]

hi all
i noticeed today that my 5000mah 6s pack is fully balanced and charged at 4.18 v per cell, now fair enough if it was old but is is about 2-3 months old with max 20 flights on it, i take real good care of my packs, always stored on storage charge never over discharged broken in gently, ive got some heliguy 5000mah 6s packs that are a year old puff slightly after a flight and still charge to 4.19v per cell. i wanted to order a load of these for my 700e but now im not so sure
Anyone else had any issues with opti packs, could this be a one off

[raptorheli2]

does the charger balance them to 4.20?

what charger?

have you put a volt meter on the pos/neg and measured the total?

cheers

[xygax]

Poti power.....

Sounds like the early morning announcment from the playpen...!!

[LaurenceGough]

Which charger?

Was the charger in cold weather mode? - It's caught me out quite a few times...

[Mslater]

Had a similar problem recently - turned out to be the charger.

Don't suppose its an Imax is it ?

[adamf]

Poti power.....

lol just noticed that,

the charger is a hyperion 0615duo+ and it has always charged the pack to 4.20 per cell and the pack to a full 25.2v but now its fully charged at 25.14v,
i just looked at the reciept for it, it was bought on the 8th of september
cheers adamf

[Rctintin]

Call Andy in the morning and send it back to be tested.

[Guest]

Adam,

That's interesting, we have well in excess of a 1000 charge cycles logged and I am not about to say we have had not issues but almost none in fairness. I personaly have hundreds of cycles on a whole range of cells and never had an issue with under voltage but I have always used CellPro chargers in fairness.

I suspect the issue is one of temperature as noted in previous mails, as it gets colder the cells will shut down earlier if the charger has an ambient sensor to protect the cell, this is actually a good thing and will help protect the cell.

If you have any doubts return one to us and we will check it out for you and report on its condition, any return costs we will reimburse for you.

Andy

[Rctintin]

Thats what you call service!

I would like to see that from HK with a Turnigy pack!

[del19_82]

Nice one Andy! Good customer service at it's best

[cjcj1949]

The final charge voltage is an arbitary figure in engineering terms. I usually end up at 4.17 sometimes only 4.15. You get a slightly longer flight at 4.20V than 4.17 but there's not much in it. Most people time their flights so it doesn't matter much anyway.

You will end up with slightly lower volts at the end of the flight but again not an issue unless you are pushing things.

The lower voltage may be due to the battery or the weather or the charger. End of charge for a lipo is defined as the point when a certain current can maintain 4.20V across the battery. This is the external voltage and not the real voltage of the battery or more accurately the cell. The external voltage is the real voltage + the drop due to the charge current times the internal resistance. Once you take the battery off charge the voltage will allways drop. It is not something that has just happened. It may well be that the drop is larger than it was.

You could also be charging at a higher current which would give a higher end of charge current.

Internal resistance increases as temperature goes down and so cells will charge to a lower voltage as things get colder.

For best performance charge and use at about 30 Centigrade.

You could well be right about the battery getting worse. The only way to know is to measure the internal resistances when you buy the battery and monitor it as the battery ages. You must make the measurements at the same temperature or correct them using the cells internal resistance temperature coefficient or plot the results as a graph.

If there is a manufacturing fault with a battery it usually shows up as a change in one cell. This would have given you lower charge volts on one cell which hasn't happened.

It is not likely either that the volts have changed from 4.20 to 4.18. The real values will be between the two and the change may have been exaggerated by rounding errors. My cheap and easy to use led cell checkers often give differences of 20mv which are not there when you measure with a voltmeter.

[adamf]

Adam,

That's interesting, we have well in excess of a 1000 charge cycles logged and I am not about to say we have had not issues but almost none in fairness. I personaly have hundreds of cycles on a whole range of cells and never had an issue with under voltage but I have always used CellPro chargers in fairness.

I suspect the issue is one of temperature as noted in previous mails, as it gets colder the cells will shut down earlier if the charger has an ambient sensor to protect the cell, this is actually a good thing and will help protect the cell.

If you have any doubts return one to us and we will check it out for you and report on its condition, any return costs we will reimburse for you.

Andy

Hi Andy,
That is what i call customer service, i will return the pack for a check just for piece of mind.
however with customer service like this i would not hesitate in purchasing a dozen packs for the 700
many thanks andy for top service
cheers adamf

[adamf]

The final charge voltage is an arbitary figure in engineering terms. I usually end up at 4.17 sometimes only 4.15. You get a slightly longer flight at 4.20V than 4.17 but there's not much in it. Most people time their flights so it doesn't matter much anyway.

You will end up with slightly lower volts at the end of the flight but again not an issue unless you are pushing things.

The lower voltage may be due to the battery or the weather or the charger. End of charge for a lipo is defined as the point when a certain current can maintain 4.20V across the battery. This is the external voltage and not the real voltage of the battery or more accurately the cell. The external voltage is the real voltage + the drop due to the charge current times the internal resistance. Once you take the battery off charge the voltage will allways drop. It is not something that has just happened. It may well be that the drop is larger than it was.

You could also be charging at a higher current which would give a higher end of charge current.

Internal resistance increases as temperature goes down and so cells will charge to a lower voltage as things get colder.

For best performance charge and use at about 30 Centigrade.

You could well be right about the battery getting worse. The only way to know is to measure the internal resistances when you buy the battery and monitor it as the battery ages. You must make the measurements at the same temperature or correct them using the cells internal resistance temperature coefficient or plot the results as a graph.

If there is a manufacturing fault with a battery it usually shows up as a change in one cell. This would have given you lower charge volts on one cell which hasn't happened.

It is not likely either that the volts have changed from 4.20 to 4.18. The real values will be between the two and the change may have been exaggerated by rounding errors. My cheap and easy to use led cell checkers often give differences of 20mv which are not there when you measure with a voltmeter.

Hi,
I see your point but it is one pack out of three that is doing this the others are fine

[cjcj1949]

Can you compare the internal resitances of all cells on all packs? It is possible that the pack is faulty. No manufacturer can guarantee zero defects, but if they offer a replacement then there is no problem. I wish Giant Cod had a similar Lipo policy.

[kylelnsn]

Thats what you call service!

I would like to see that from HK with a Turnigy pack!

That is great! I am already having issues with hobby king, order was faulty, reported, now 21 days into dispute with them and no sign of a resoltion. and my second order is still waiting to be packed (all in stock) after almost 15 days! Contact them to no avail!

So nice work OPTI! Great service