How much charge is too much? - RC-Monster Forums

orangecrush · **How much charge is too much? -** 02.15.2008, 12:27 AM

I know when you charge a lipo, by the time it's done, it's usually a volt or so higher than it's listed voltage.

I'm curious because I'm charging a 6000mah 5S battery (18.5) and it's at 20.104 volts and is still charging.

It's on a 606i charger with balancer and in a lipo sack so I'm gonna let it keep going. Perhaps it will shut down shortly.

Was just curious how much "overage" is allowed in general without causing problems. Surely it must be okay, I'm assuming if everything is in working order, it should shut itself off.

Thanks,

Mark

lincpimp · 02.15.2008, 12:31 AM

Lipos charge to 4.2 v per cell. 3.7 is considered a nominal voltage, average if you will. Charger should switch to cv mode at 21v and the amp amount will fall to 0 as the battery fully charges.

MTBikerTim · 02.15.2008, 12:37 AM

My stupid charger took 2 hours to charge a 2000mah battery at 1c last night and it only put <1000mah back in. I don't know what was at fault the battery or the charger but I wanted to drive. but yes 4.2v per cell so you are/were safe.

orangecrush · 02.15.2008, 12:40 AM

Quote:

Originally Posted by lincpimp

Lipos charge to 4.2 v per cell. 3.7 is considered a nominal voltage, average if you will. Charger should switch to cv mode at 21v and the amp amount will fall to 0 as the battery fully charges.

CV? What's CV?

The amp fell to .80 at 21.07'ish volts. I'd say she's about full, wouldn't you?

Thanks for your help.

Mark

lincpimp · 02.15.2008, 12:47 AM

The lipo charge profile is called constant charge / constant voltage (cc/cv)

The intial charge is whatever amp rate you set until voltage reaches 4.2v per cell. The the voltage is held at 4.2v per cell and the amp rate falls until it hits 0. The battery is then fully charged. Usually about 10% of the capacity is put in during the CV mode. The other 90% goes in during the CC mode.

jnev · 02.15.2008, 04:49 AM

Not to hijack the thread or anything, but my TrueRC 4s2p 8000mAH battery does this exact same thing. However my Max Amps 5500mAH 2s5p saddle pack goes straight to 0 amps right after the CC mode finishes... would anyone happen to know why my Max Amps pack doesn't go through the CV stage like my TrueRC pack does?

othello · 02.15.2008, 08:09 AM

Guess it depends on the cells you use and at how much you charge it in CC phase. My A123 cells have a very short CV phase compared to my Sony 18650VT cells even when charged at the same amperage. What i also noticed is the better the balance of the cells, the shorter the cv phase. Perhaps someone could explain it from a more technical perspective.

crazyjr · 02.20.2008, 02:59 PM

Quote:

Originally Posted by MTBikerTim

My stupid charger took 2 hours to charge a 2000mah battery at 1c last night and it only put <1000mah back in. I don't know what was at fault the battery or the charger but I wanted to drive. but yes 4.2v per cell so you are/were safe.

the CV portion may take a while, I know about 30-40% of the charge time in mine is usually in the CV

crazyjr · 02.20.2008, 03:02 PM

Quote:

Originally Posted by jnev

Not to hijack the thread or anything, but my TrueRC 4s2p 8000mAH battery does this exact same thing. However my Max Amps 5500mAH 2s5p saddle pack goes straight to 0 amps right after the CC mode finishes... would anyone happen to know why my Max Amps pack doesn't go through the CV stage like my TrueRC pack does?

Not sure, Mine will go into cv and finish. I guess they are full