how to charge my 1st lipo?

[novak]

guys, i need help.... just came back from rotor to buy lipo. this would be my 1st
time using lipo battery. hehehe...
i bought (3E) 7.4V 800mah, 12C. should i set my charger to 400mah or 800mah for the first time??? i'm using T15 AC with T6B balancer. how much the voltage of each cell should be? 3.8xx V or 4.2xx V ?

i'm afraid lipo is the same like Ni-Mh, need to slow charge at 100ma for the 1st time use. e.g like hand phone, need to charge 8 hours for the first time.

one more thing, should i charge it together with balancer or without? just balanced the lipo by the time i open it from packaging.
thanks in advance.

[traderghost]

You can safely charge your 800mAh lipo using 800mA charging current, even though it is the first time the battery is being charged.

The nominal voltage of each lipo cell should be 3.7V, and after it's fully charged, should be 4.2V. Try not to let it discharge below 3V. Though some manufacturers say it's safe to go down to 2.75V, but I rather be safe.
Whether to balance first then charge or charge and balance at the same time, it's up to you. If you decide to balance first (then charge), take note that some balancer will not balance (discharge) the cells if the lowest cell voltage in the pack is 3V or lower, so you will have no choice but to do charging and balancing at the same time (or at least charge it a bit first to go above 3V if you insist on doing balancing and charging separately).

[novak]

You can safely charge your 800mAh lipo using 800mA charging current, even though it is the first time the battery is being charged.

The nominal voltage of each lipo cell should be 3.7V, and after it's fully charged, should be 4.2V. Try not to let it discharge below 3V. Though some manufacturers say it's safe to go down to 2.75V, but I rather be safe.
Whether to balance first then charge or charge and balance at the same time, it's up to you. If you decide to balance first (then charge), take note that some balancer will not balance (discharge) the cells if the lowest cell voltage in the pack is 3V or lower, so you will have no choice but to do charging and balancing at the same time (or at least charge it a bit first to go above 3V if you insist on doing balancing and charging separately).

thanks a lot bro. i'm charging it now. but i notice something is strange, i put 600mah, then after 40 minutes of charging, the charging current is drop to 270mah and the lipo capacity is 380mah-still charging. each cell is 4.15v, both are the same. is this normal??

[traderghost]

thanks a lot bro. i'm charging it now. but i notice something is strange, i put 600mah, then after 40 minutes of charging, the charging current is drop to 270mah and the lipo capacity is 380mah-still charging. each cell is 4.15v, both are the same. is this normal??

That's normal. Firstly, your batt already has some charge in it. It must have, because lipo should be stored 30-50% full, not 100% nor should it be empty. All batt manufacturers do that, so that means your batt should already have about 300-400mAh in it when you first bought it.
Charging method for lipo is using Constant Current/Constant Voltage. When the batt is not full, the charger will apply a constant current to charge it. When it's almost full, the batt will resist current going into it (increased resistance), so the charger will switch to constant voltage (4.2V) to charge the batt and let the batt tell it that it's full by forcing the current to decrease until it stop totally (V=IR). That explains why your current is decreasing. That's why I said previously that the last 10-15% of charging is *very* slow because the charger is using constant voltage charging and the charge current is generally very small and decreasing gradually.

[novak]

thank you so much. now i understand how to charge lipo. i still have a question,
i'm charging again for the 2nd time(after finished my flight), but when i connect to the balancer, how come my balancer only detect 1 cell instead of 2 cells.
when i first bought the lipo is not like this, its detect 2 cells immediately.

BUT during the charging state the balancer still detect 1 cell (i'm charging w/ the balancer), after a while the LED detects 2 cells. then not so long it detect 1 cells again until the process of charging completed.
*after the lipo runs out, i check the voltage. both cells are 3.45v equally.

i think i should connect to balancer again after the charging completed. just wanted to see if my balancer can detect as 2 cells.

[traderghost]

thank you so much. now i understand how to charge lipo. i still have a question,
i'm charging again for the 2nd time(after finished my flight), but when i connect to the balancer, how come my balancer only detect 1 cell instead of 2 cells.
when i first bought the lipo is not like this, its detect 2 cells immediately.

BUT during the charging state the balancer still detect 1 cell (i'm charging w/ the balancer), after a while the LED detects 2 cells. then not so long it detect 1 cells again until the process of charging completed.
*after the lipo runs out, i check the voltage. both cells are 3.45v equally.

i think i should connect to balancer again after the charging completed. just wanted to see if my balancer can detect as 2 cells.

Not sure why your balancer is behaving this way. Are you sure you are interpreting your balancer correctly? Could it be that the balancer is showing its balancing activity by blinking or switching some lights on and off?

First, you must connect the battery to the balancer without connecting the balancer to the charger and see if the balancer is detecting the number of cells correctly. If it shows the correct number, then your balancer should be alright. You should read the manual carefully to determine if the behaviour described by you earlier is normal or not, or you can go ask SHS about this.

If your balancer *cannot* detect the number of cells correctly, this is pretty serious and you should NEVER charge a lipo with a faulty balancer connected.

[novak]

OMG.... after finished charging i use the balancer again to detect. still cannot detect. too late i charged it already

bro check your PM.

[novak]

still cannot detect leh..... use the lipo 4th times already. my balancer still detect as a 1 cells. but i check the voltage, both have the same V rating and both cells are detected by my charger. please help....

[traderghost]

Since the balancer can balance your cells correctly, could it be that one of the LED on your balancer is kaput

Ok, seriously, you better go down to Singa Hobby to ask them about the balancer. Anyone else can offer any suggestion or help?

[novak]

no, i don't think is kaput. hahaha.... anyway the issue is solved now. dunno why, suddenly my balancer can detect my lipo again after i used the lipo for a couple of times. wierd leh... dunno why.

i think no more issue . oh btw, "clai" and "jansonfinn" are the one who gave me a lot of info and help about lipo. thanks to both of you. and "traderghost" thanks to you too