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-   -   Battery charging (http://www.Wattflyer.com/forums/showthread.php?t=73892)

egrave1 06-14-2014 12:32 AM

Battery charging
 
What is the correct setting for charging lipo battery, some guys are telling me they charge their battery at 5 and 10 amps. I though you had to go by the C rating

kyleservicetech 06-14-2014 01:16 AM

Quote:

Originally Posted by egrave1 (Post 950460)
What is the correct setting for charging lipo battery, some guys are telling me they charge their battery at 5 and 10 amps. I though you had to go by the C rating

Uh Oh
Need to be a little careful here. Some LiPo batteries can be charged at over the 1C rate. And, some folks indicate doing so results in shorter life for a LiPo battery.

For other wattflyer readers, here is a bit of information on that "C" terminology.

"C" and what it is
http://www.wattflyer.com/forums/showthread.php?t=65869

So, if you've got a 3200 Mah LiPo battery, that's 3.2 Ampere Hours, so charging it in one hour requires a charge rate of 3.2 Amperes (for that one hour).

As for me, I use those over weight, oversized, undervoltage A123 battery packs that can be charged at up to 10 Amps, per mfg specs. I've been charging mine at 7.5 Amps for a 2.3 Amp Hour battery and have had complete success. As an example, I'm charging my 12S2P A123 battery pack configured as a 6S4P pack, with a charge rate of 30 Amperes.

solentlife 06-14-2014 07:41 AM

Quote:

Originally Posted by egrave1 (Post 950460)
What is the correct setting for charging lipo battery, some guys are telling me they charge their battery at 5 and 10 amps. I though you had to go by the C rating

You need to take care to note :

a) C rating on label
b) mAh size of pack.

As Denny already said - you charge dependent on what size and rating pack is. Personally I do not charge at higher than 1C unless necessary. I believe it's better to be 'kind' to a pack instead of hammering at it. "Knock gently on the door ... instead of sledge hammer style !"

So the answer as I would suggest ..is take mAh size and divide by 1000 ...
ie 2200mAh pack = 2.2A/hr ... so 1C = 2A charge rate.
800mAh pack = 0.8A/hr ... so 1C = 0.8A charge rate.

etc.

Nigel

xmech2k 06-14-2014 02:19 PM

+1! Why abuse them if not necessary? Haves you observed how long their batteries last? I'm still using some fairly old batteries. I just make sure I own 2 or more for each plane and plan ahead and have them charged in advance. Also, you can get a parallel charging board, learn how to do that correctly, and depending on your charge equipment and size of your batts, could charge 2 or more of them at the same time. Probably a bigger time saver than the high c method. Or maybe these chaps aren't really your friends? :rolleyes: "yeah, yeah! That's the ticket! You can charge that at 10 amps, no problem. Yeah! I do that all the time! Me and the Queen of England! Yeah! " ;)

Henry Sistrunk 06-14-2014 07:04 PM

I tried 3C for a couple of years,never had a problem but I can tell you that they "puffed" way too soon. I now charge at 1C.
Henry

fhhuber 06-14-2014 08:46 PM

Quote:

Originally Posted by xmech2k (Post 950488)
+1! Why abuse them if not necessary? Haves you observed how long their batteries last? I'm still using some fairly old batteries. I just make sure I own 2 or more for each plane and plan ahead and have them charged in advance. Also, you can get a parallel charging board, learn how to do that correctly, and depending on your charge equipment and size of your batts, could charge 2 or more of them at the same time. Probably a bigger time saver than the high c method. Or maybe these chaps aren't really your friends? :rolleyes: "yeah, yeah! That's the ticket! You can charge that at 10 amps, no problem. Yeah! I do that all the time! Me and the Queen of England! Yeah! " ;)

+1

Even the battery makers will tell you charging the packs "rated" for 5C charge above a 1C rate will reduce the pack's life.

Pushing the C rating for discharge also reduces pack life.

solentlife 06-14-2014 08:59 PM

Quote:

Originally Posted by fhhuber (Post 950502)
+1

Even the battery makers will tell you charging the packs "rated" for 5C charge above a 1C rate will reduce the pack's life.

Pushing the C rating for discharge also reduces pack life.

This is heaven to my ears !

I posted : "I believe it's better to be 'kind' to a pack instead of hammering at it. "Knock gently on the door ... instead of sledge hammer style !"

I know many people do not have time like I have for charging ... so they want higher rates ... fine. But when the time is there - why push the rates ?

I charge at 2C .. 3C ... when I'm at field - basically because I need the pack quickly. But at home ? Rarely do I need to push rates ... so I stay down at 1C ...

Maybe I'm old fashioned ........ but I still believe that everything comes at cost.

Take a high performance engine ... knackered after a few races. I used to race Class 1 Go-Karts ... and then before marriage raced saloon cars. Basically if you push limits - don't expect long life. But if you treated that race engine with respect and didn't pull the 100 in 4 sec's ... it would last a darned site longer. (I had to finance my racing ... so try tell me what it costs !)

Nigel

fhhuber 06-14-2014 09:34 PM

I just cart about 25 lbs of batteries to the field and make use of the ability to charge over 24 packs at a time.

1 C charge rate is plenty fast.

solentlife 06-14-2014 11:22 PM

Dare I say that I usually have about 10 models in my car for a meet ... with sufficient packs to fly .... BUT I carry my B6 in case I need to charge a particular pack size............... rarely done I might add.

Nigel

kyleservicetech 06-14-2014 11:52 PM

Quote:

Originally Posted by solentlife (Post 950505)
Dare I say that I usually have about 10 models in my car for a meet ... with sufficient packs to fly .... BUT I carry my B6 in case I need to charge a particular pack size............... rarely done I might add.

Nigel

Just came back from a meet with three models. Put on 11 flights on two models in two hours before it got to windy. (12S2P packs)

Sure is nice to be able to charge those A123's in 12-15 minutes.:cool:

kyleservicetech 06-14-2014 11:55 PM

Duplicated by accident

JetPlaneFlyer 06-15-2014 12:13 PM

There is nothing 'magic' about 1c charging. As battery technology moves on both charge and discharge c rating increases. The 1c charge rate was the rule at the time when batteries only typically had 10c-15 discharge rate. We have moved on from there, batteries now have improved chemistry, less internal resistance and are able to happily accept higher charge and discharge rates without increased damage.

I have a dozen batteries that are about three years old and have around 300 cycles, they have never been charged at much less than 2c, sometimes up to 5c and not one is puffed and they all perform very well for batteries of their age.

Having said that, I agree that there is little point charging faster than you need to, but personally I have a lot of batteries to charge and time is important to me, so I generally charge at 2c as a default (rated as optimal charge rate by the manufacturer for the batteries I have) and if I'm in a hurry I'll increase that to the manufacturers 'fast charge' c rate limit. Most times though 2c is fast enough as you can charge a fully depleted battery in half an hour at 2c, less if the battery has a little remaining charge left in it (as is recommended).

solentlife 06-15-2014 02:06 PM

I don't regard 2C as that fast ... it's still in the 'low stress' figures in my view. The ones I am less convinced on are when some people quote really higher rates ... you read some people doing 4C .. 5C and advising it's normal.

To me 1C is a safe recc'd rate to newcomers and once they read up, learn, get more knowledge - they will develop their own routine.

Nigel

JetPlaneFlyer 06-15-2014 02:44 PM

Quote:

Originally Posted by solentlife (Post 950539)
I don't regard 2C as that fast ...

Neither do I:D 2c charge is pretty much the standard for almost all modern LiPos, which was the whole point of my post. But of course 2c is twice as fast an 1c, which is a big difference in time saved.

As for the damage that's done by genuinely fast (around 5c) charging. My personal view is (assuming 5c is within manufacturers rating) that it's best not to charge that fast all the time, but no significant damage will be done if you charge that fast just occasionally when you are in a hurry. I have many batteries that have numerous charges at 5c rate under their belts that are evidence of this.

Of course unless you are using very small batteries you need a reasonably powerful charger to do 5c charging anyway.

sticks 06-26-2014 02:01 AM

1c
 
I mostly go 1c charge, as I have 5 chargers . two small ones that will do 4 amps and big one that does up to 30 amps for two batterys at a time. the 5th just does the TX. I try and charge the day before flying, but I have all day to do it.
I have no problem in charging 2c if the pack allows for it and I might go a little higher once in awhile.
I get good battery life , some are 5 years old.:)

sticks


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