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>> Home > Forum > Electrical Related > lipo storage charge
lipo storage charge
(280 views)
Author Message
octman
(Captain)





Forum Posts: 99
26th Oct 2017 14:02  
>> Permalink
mdlbt.com/35024

I am new to this lipo stuff and have a query about the storage charge. I have a SkyRC Imax B6 charger (a genuine one) and 2 x 2S 2200mAh batteries. On the display screen of the charger, before charging has been started, in the storage mode, it says 7.4V. When I press enter it charges the battery up to 7.6 volts. Is this correct?

Electricary confuses me enough without this sort of thing!

Chris

Dave M
(Fleet Admiral!)





Forum Posts: 1402
26th Oct 2017 16:14  
>> Permalink
mdlbt.com/35027

Hi Chris
The storage voltage for a LiPo is 3.7v per cell. You have two cells so 7.4v in total.
A fully charged LiPo is 4.2v per cell but you get longer life if you only charge to 4.15v. Your two cells should therefore be charged to 8.3v but no more than 8.4v.
If your charger is only charging to 7.6v there is something wrong.
Have you checked the battery voltage with a meter before and after charging?
Its possible you charger has a storage charge setting and that may explain the low final voltage.
There is a Utube video which you may find helpful as it shows how to set up and use the Imax B6.
https://www.youtube.com/watch?v=RPzJOKoHhhQ


Live long and prosper

Dave
RNinMunich
(Fleet Admiral!)





Forum Posts: 1087
27th Oct 2017 11:19  
>> Permalink
mdlbt.com/35061

Hi Chris, DON'T PANIC! There's nothing wrong with your charger / controller 😊 3.7V is the 'nominal' voltage per LiPo cell. The 'Storage' voltage used by your charger is quoted in the manual as 3.85V per cell. See pic. Therefore, give or take 50mV or so your charger is operating quite correctly in Storage Charge mode. Before starting the device indicates the nominal voltage of the battery you have specified, i.e. 2S which is why it shows 7.4V before starting the charge. At the end of the cycle the battery voltage should be around 7.6 - 7.7V which it apparently was. 👍 The controller will discharge a battery with a higher starting voltage than 7.6V and charge one with a lower starting voltage.
Dave was talking of Full Charge voltages, which is not recommended for storing LiPos!!
Cheers Doug 😎


Attached Files - Click To View Large


"The brain is not intended to store facts. It is for thinking, and for knowing where to find the facts !" Albert Einstein. 😉 cheers Doug
Dave M
(Fleet Admiral!)





Forum Posts: 1402
27th Oct 2017 11:31  
>> Permalink
mdlbt.com/35063

Sorry Doug
I did not recommend anything of the sort and clearly stated storage charge was 7.4v for two cells.

I did then give further details about charging but suggested a U-tube video that explained in detail how to use the charger.


Live long and prosper

Dave
RNinMunich
(Fleet Admiral!)





Forum Posts: 1087
27th Oct 2017 13:01  
>> Permalink
mdlbt.com/35067

Hi Dave, I'm sorry too cos I didn't say you recommended anything!
But you did state that 'something is wrong', which it clearly wasn't operating the unit in Storage Charge mode.
Also 3.7V is only the nominal cell voltage. The recommended Storage voltage is 3.85V, as stated in the charger manual, and which is what the charger did. The objective is to limit the amount of stored energy which can cause havoc if anything unforeseen happens in storage, as well as to prolong the life of the battery. See also attached LiPo storage tips.
http://uterc.org/files/LipoStorageTips.pdf
http://www.bigrcmodels.com/RC-Helicopter-LiPo-Battery-Storage.asp
https://www.propwashed.com/lipo-storage-voltage/
Just three samples of several which all state the storage voltage (SV) as 3.8 or 3.85V.
The safety leaflets which came with my LiPos also said the same.
Cheers Doug 😎


Attached Files - Click To View Large


"The brain is not intended to store facts. It is for thinking, and for knowing where to find the facts !" Albert Einstein. 😉 cheers Doug
Dave M
(Fleet Admiral!)





Forum Posts: 1402
27th Oct 2017 15:59  
>> Permalink
mdlbt.com/35070

As I explained I was talking about charging at the end of my first post.
For a novice I do believe video explanations are far easier to follow which is why I made my initial suggestion.
I did not look at your first suggestion as it required me to download a pdf file from a source I do not know.
The other two sites both suggest it is safe to discharge down to 2.5v per cell - may have been when written but modern cells should be kept above 3v and I try to keep mine nearer 3.5 v. I also see they recommend charging at 2C from storage!
If you buy a 3 cell LiPo mine are delivered with an 11.1v storage charge which equates to 3.7v per cell.
I did once watch a very long and detailed video made by a developer and manufacturer of LiPo batteries and learn't that at 3.7v the cell was in its most stable state (chemically wise) consistent with long life and storage.
If the battery has any charge I do believe the amount of damage will be the same, but perhaps more spectacular if fully charged.
Most modern chargers from reputable suppliers will provide a safe charging and storage charge. Providing your charger is setting the right voltages no harm should occur.
As they say a video says a thousand words and the one I suggested covered the Imax B6 very comprehensibly.


Live long and prosper

Dave
RNinMunich
(Fleet Admiral!)





Forum Posts: 1087
27th Oct 2017 16:46  
>> Permalink
mdlbt.com/35074

Hi Dave, all well and good, but you told Chris that there is something wrong with his unit. Which there isn't he was simply in Storage Charge mode (as his thread title and query stated) and the unit reacted correctly for that mode.
Battery tech is progressing almost as fast as processors so I guess we can expect frequent updates and differences. 🤔 Have a nice day, the rain has reached us at last after a week or two of Indian Summer.
Cheers Doug 😎
Hope Chris doesn't get confused by info overload from the vid!
I simply checked the operating manual of the unit Chris is using.


"The brain is not intended to store facts. It is for thinking, and for knowing where to find the facts !" Albert Einstein. 😉 cheers Doug
octman
(Captain)





Forum Posts: 99
28th Oct 2017 18:21  
>> Permalink
mdlbt.com/35101

Thanks for the input. Sorry to have started a bit off a heated discussion.
My charger was behaving somewhat differently to what I expected, having already watched many You Tube videos, But at the end of the day all is well now, mainly due the fact that my original power supply was a bit too wimpy and has been replaced by one with the required output. My batteries have now been storage charged and ready for action and a full charge at a future date.
All I need now is a boat to put them in.

Chris

RNinMunich
(Fleet Admiral!)





Forum Posts: 1087
28th Oct 2017 21:58  
>> Permalink
mdlbt.com/35102

All's well that ends well👍
Happy boat hunting, cheers Doug 😎


"The brain is not intended to store facts. It is for thinking, and for knowing where to find the facts !" Albert Einstein. 😉 cheers Doug