Charging more than 1C

[davethepitch]

What are the downsides to charging a lipo at more than 1C which is what I mostly do and I am going to purchase some more lipo';s because at the moment I have a Zippy 1800 25C so should Ilook for a better C rating.

Being as i am now at a stage where I am flying side to side instead of mostly hovering which lipo would give me a decent flight time because just hovering i only get minutes if that.

Thanks all

Dave

[ched]

Charging at over 1C can cause the battery to be damaged or shorten it useful life. Some manufacturers will specify the max C charge rate others don';t.

As for flight times I haven';t any experience in that yet  ::)

[davethepitch]

I am sure I read somewhere that they recommended 2-3C unless I read it wrong.

[Revs]

That particular battery has a max charge rate of 5c or 9A. Personally I';d stick to 2c unless you';re in a rush.

[pheasant_plucker]

Charge at 1c and you will not go wrong. It may be possible to charge some batteries at higher rates but it will shorten the number of charge cycles that battery can do before dying.

Gerry

[davethepitch]

That particular battery has a max charge rate of 5c or 9A. Personally I';d stick to 2c unless you';re in a rush.

So the lipo I read about would have the ability to be charged at higher rates and I think they did say if you were in a rush you could use 5C. 

[Revs]

I';ve charged at 8c before on a lipo rated at 10c charge rate. Not something I do on a regular basis but it worked fine. When charging at such a high rate I do find that after a few minutes after charging the voltage drops to ~4.16v/cell whereas with a 1-2c charge it holds 4.2v for days.

As Gerry says, you can';t really go wrong with 1c

HobbyKing do specify charge rate for all their batteries on the site. That';s where I looked to find the 5c rating for yours..

Capacity(mAh)    1800
Config (s)    3
Discharge (c)    25
Weight (g)    134
Max Charge Rate (C) 5
Length-A(mm)    106
Height-B(mm)    17
Width-C(mm)    34

[davethepitch]

Hi Revs

I was of the understanding that we should only charge at 1C and when i read about 2-3C or even 5C i was surprised.

Dave

[kilby]

Oh you can charge @ more than 1c and I have done so.

Some of the issues stem of older LiPo behaviour, however discretion is often the greater part of valour

I tend to go for 1c as I';m seldom in a rush

[Ynot6]

i charge at 1C, as said above, it';s the better way to go.

[guest325]

Charge at 0.5 - 1C and have batteries that have been left fully charged for up to a month that are 3 years old and are still ok - ';nuff said!

[powerlord]

Yeh I charge at maximum amps (6 or 10 depending on what charger I';m using) for pretty much any pack over 2000. Under that it go to 3amps or so. I';ve got packs that are 2 years old and still going strong. So on the 4000s, that';ll be over 2c, on the 2000s that';ll be 5c.

I means how many times are you actually gonna charge the things ?

[Soler]

My Nano Tech 6000mah 6S can be charged at 15S so 90Amps charge,   normally i charge at around 20A each with a dual charger,  15 minutes each to full charge.  Providing I have a 240V power supply I can keep in the air all day.

[jamesb72]

A good charger will only charge at 2C for the first part of charge (till something like 80% capacity), the final section then slows down the charge rate as the lipo gets close to full, and final balancing is slower still for the last few percent, so say a typical 2200mah3S pack will only actually be charging at 4.4Amps initially, and will drop right down as lipo gets full.

2C balance charges take about 40mins on my cellpro chargers, 1C take just over an hour (final balancing stage is pretty much the same time regardless of charge rate), but higher C doesn';t reduce proportionally - I never charge over 2C, but I understand a 5C balance charge still take about 25 minutes (due to balancing time), so for most people 2C is the best compromise.

More details here:
http://www.fpvforme.com/charging-lipo-batteries/

[powerlord]

A charger has no knowledge whatsoever of the ';c'; of the attached battery. It relies on the operator to tell it the max charge current.

[jamesb72]

A charger has no knowledge whatsoever of the ';c'; of the attached battery.

I have cellpro set to auto 2C and can plug in a 1s300mah pack and hit start then plug in a 6s5000mah and hit start again, both get charged at correct voltage and current automatically based on cell count and capacity, so whilst it doesn';t know the C rating of the pack, it knows what I want it to charge at and can work the rest out itself.

[rotorx]

Perhaps someone can put some scientific evidence up to say why charging cant be done at the same rate as discharging as the Chemical process is in reverse.

Considerations;

Fast discharge/charge = heat

Heat is related to internal resistance.

High C rated batteries have lower IR and higher charge capability.

Lower charge/discharge rates produce less heat and prolong cycle life.

Avoiding heat during discharge/charge is equally beneficial to cycle life.

[guest325]

Couldn';t have put it better myself, if batteries are kept cool (not cold) they are happy  - excessive heat upsets the chemistry. Lower charge rates are considerably less likely to cause heating so safer. If you need to store over the winter putting them in the fridge will improve their shelf life!