10 Gauge

iTrader: (8)

Curious to know if there is a "formula" for figuring max input charge rate for different discharge rate batteries.

I personally only have 40C+ 5000mah batteries that are rated to accept up to a 5C charge by the mfg and I usually charge at ~20a with no problems.

A friend of mine just picked up a MERV and it came with 2 x 2S 20C 2200mah Zippy's.

Can these only be charged at 1C, or would 2C be safe, or is there a calculation that can be made to determine the fastest safe charge rate?

Thanks in advance for the advice and input.

Edumakated

iTrader: (19)

There is no way to know without seeing the mfg's label. The label will tell you acceptable charge rates. As far as I know, there is no mathemetical formula or test you can do with your charger to know if they will accept higher charge rates without damage to the cells or risk of fire.

Most of the newer zippy/turnigy cells allow up to 5c. I have a few that are a year or two old that only allow 2c though.

If the label doesn't tell you, I would assume 1c maximum to play it safe.

Davidka

iTrader: (86)

Any charge rate over 1c will shorten the life of the pack regardless of the rating. If the pack is not rated for a specific charge rate do not exceed 1c, it's not worth the risk.

lowroad

iTrader: (79)

mah x charge rating. So 5c charge x 5000mah is 25, so your 20amps is good (if your battery truly carries a 5c charge rate).

Homie should be chargin at 2 or 2.2 amps since 2200mah x 1c is 2200

most don't receommend ever charging more than 1C though. not sure how current that wisdom is however.

10 Gauge

iTrader: (8)

10-4, thanks for that guys!

Edit: I suppose I should have checked HK's website, lol... It says right in the info section for his batteries that they will accept a 2C charge. Guess that answers that question!!!

racer1812

iTrader: (31)

BS

thecman26

iTrader: (112)

I agree, I don't really worry about this since these AREN'T NiMH packs and the charging rate only shortens the charge time.

I have Hyperion EOS0606i chargers and I let them do the calculations, put in how many cells and how many mah and hit go! Thats it... 1C is plenty for me! But I have several batteries so I don't have to wait for one to charge.. The best way to do things to let them rest for a while. I also have never had a lipo fire!

Rick Hohwart

Always follow the manufacturer's charging recommendation. That said, many know LiPo manufacturers inflate their specs so if you do not trust their capacity or C ratings, I would not trust their max charge rate either. Especially if it is over 1C.

Davidka

iTrader: (86)

Is that an engineering term?

Dave H

Well, going by how often it's used in engineering.... it must be!

fredswain

iTrader: (1)

I've always just followed the rule that slower is better. When I'm charging "fast", I charge at 1/2c of my battery. The battery and charger won't even get warm to the touch that way. I figure that back in the old days I could charge a nicad battery in 15 minutes (and they would get very hot!) but it would only last about 5. If the pack can last me over half hour now, why charge it fast?

racer1812

iTrader: (31)

It is when there is no data showing a relationship between higher charge rates and cycle life loss. For packs rated for higher charge rates of course. Would I charge at a 5C rate, probably not. 2-3C sure, do it all the time.

Lipo media has a limited life span no matter what, charge it a hundred times or ten times in about 2-3 years it's gonna be junk anyways..

racer1812

iTrader: (31)

If you want to charge that way that's fine, you're not hurting anything BUT you're not gaining anything either. Your packs aren't going to last longer or perform any better. It's your time, do what you want, just don't think your gaining anything by turtle charging..

turbowop

iTrader: (33)

For all my packs that allow a higher charge rate according to the manufacturer, I charge at 2c. Packs are all fine, no degradation, no puffing, no heat, no issues. Been doing this for over a year now.

10 Gauge

iTrader: (8)

I only pay $67 a piece for my 6S packs which are claimed to be 5C charge capable and in the field I charge at a full 25a and the batteries don't even get warm. I haven't had one die on me yet either.