Lipos not fully charging ??

[SamS]

Trying to charge 6s 3000mah Opti's on my Cell Pro 10s charging, but it's only charging the lipos to around 89%. Each cell is only reading around 4.05 when usually they're around 4.15.

I noticed when I flick through the different modes (while the lipos charging) one of them says CH1 LIPO COLD W.

Are they just not fully charging due to the cold ??


Thanks

[Mark_T]

Yes, your charger is doing its job correctly and reducing the charge due to temperature.

[johnsandywhite]

You can change the setting to ignore this if you wish. I do, and have had no problems.

[SamS]

You can change the setting to ignore this if you wish. I do, and have had no problems.

I know it's lazy of me to ask, but can you tell me how (if its simple) cheers

[challis349]

Lipos not fully charging ??

Surely it's best to keep it how it is Sam, and lose the 30secs flying instead of POSSIBLY damaging your lipo's

[SamS]

True, or perhaps I could just put the charger in a warmer place

[Mark_T]

True, or perhaps I could just put the charger in a warmer place

If you are charging inside and plan to just go straight outside and fly a pack then return to the warm that sounds like a good plan.

If you are charging several packs and then intend to go outside and fly them one after the other I'd stay with the cold charging limit.

[ghost2212]

If you are charging inside and plan to just go straight outside and fly a pack then return to the warm that sounds like a good plan.

If you are charging several packs and then intend to go outside and fly them one after the other I'd stay with the cold charging limit.

Surely LiPo's voltage doesn't rise between cold and warm, The only thing that changes is their internal resistance which causes a lower voltage in the cold when under load.

[cjcj1949]

Only Cellpro limit the charge voltage. I would have thought if anything that charge current should be reduced. Nothing has been published about the effects of charging in the cold. Lipo information is very vague and often contradictory. It is well known that charging to a lower voltage will extend lipo life considerably. Something like a factor of 3 by reducing from 4.20 to 4.10. There are a lot of factors to consider. One of them being do want to extend the life when new lipos are better than old ones, and cheaper. Lipos have also changed in performance by a factor of three or four since they introduced that limit. Using lipos in the cold is a very bad idea and heating them to 30 degrees is a very good idea.

[miniman]

The challenge with charging LiPo cells is not charging in the hot then moving out to the cold, but it is when charging in the cold and then moving them into the warm. Going from cold to hot will increase the cell voltage, and going from warm to cold will lower the cell voltage.

If you are charging at the field then take them home and store them in a warm place the voltage will rise. This could take the cells above their safe limits. The good chargers will have a safe setting that only charges to 95% in the cold allowing the cells to safely rise when taken home into the warm.

If you intend to use the cells in the cold there is no problem charging them to 100%, but use the packs before you take them home.

Peter

[ghost2212]

The challeng with changing LiPo cells is not charging in the hot then moving out to the cold, but it is charging in the cold then moving them into the warm.

If you are charging at the field then take them home and store them in a warm place the voltage will rise. This could take the cells above their safe limits. The good chargers will use a safe setting that only charges to 95% in the cold allowing the cells to rise when taken home.

If you intend to use the cells in the cold there is no problem charging them to 100%.

Peter

I have yet to see any conclusive evidence to suggest the voltage rises under no load when going from cold to hot, Could you tell me where your getting this from?

[cjcj1949]

We had this discussion last year. Mark_T and I both tested lipos and there is little or no change in voltage from 5C to 20C. I think the argument is that the capacity is reduced at lower temperature and so if you fully charge at a high temperature and then cool them, they will be overcharged. This is nonsense, as it is well known that fully charged lipos suffer less degradation at low temperatures than high temperatures. Keeping lipos at 4.20V in the fridge is about the same as lipos at storage volts at room temperature, according to the battery university. Nothing about lipos would surprise me though, as they seem to have their own set of rules. Don't use common sense though, as lipos certainly don't.

[ghost2212]

I don't believe that a lipos energy density changes significantly depending on temperature, It may give the impression that there is less in the cold but this is because more energy is being lost as heat due to the internal resistance in the cells as this is higher when cold. Personally on my iCharger 306B i always charge to 4.18v a cell anyway no matter the temperature. This should help improve the life of them ever so slightly.

[Mark_T]

I gave up trying to figure out the 'right' answer to this a while ago

I just stick to charging them in the way I'm going to use them and wherever possible just keep them warm at all times as the IR does change considerably in response to temperature variations.

Your 25C pack can rapidly become a 12-15C pack if you let it get too cold.

[panosg]

Sam I had the same problem the other night mate. I was charging in the garage and my 2 s packs will charge up to 90%
Moved my charger in the house, got the packs warm and bingo.....100%
PL8 charger has the option to turn the cold weather option off, but I was worried if I damage the packs if I was to do that!