Balance charging question

[Paul Taylor]

I have a very decent HiTec charger that was graciously gifted to me.
I can charge 4 batteries at a time.
I’m balance charging 4s 3000 mah batteries at 3amps.
99.9% of the time the charger will time out at 120 minutes. I know I can extend the time but it gets the batteries to 98-99% charge. I know it just doing the balance of cells but just curious if this is the norm. Batteries are pretty new.
Thanks.

[bill bischoff]

Is this while charging one pack, or multiple packs at a time? If you're charging multiple packs at once, you need to verify that you are not trying to exceed the charger's total maximum output wattage.

[Paul Taylor]

No I have 4 different ports on 1 charger I could charge different sizes on other ports if needed. So it’s like 4 separate chargers in 1.

[Motorman]

I'd say that was normal for a charger with a time out feature. I would extend the time so the battery cells can fully balance.

[Ken Culbertson]

My charger does this a lot. Especially if I am putting a full battery into storage.  Even if the charge appears to be balanced, I put it back on and let it finish.

Ken

[Perry Rose]

I've charged several brands and amp ratings on several brands of chargers and none went over an hour to full charge. One at a time or four at a time.

[dave siegler]

state of charge is a pretty difficult thing to measure.  Overcharging is bad so a small error on the undercharge direction isn't bad.  I'm not sure you can tell 2% in a flight. 

It's likely the charger is a 5% accuracy device.   More accurate components would make the charger expressive.
Your Milwaukee tool battery isn't any more precise. 

It's also temperature-dependent, which your charger is likely not considering. 

A variety of methods measure SOC.  A battery without a BMS would probably only look at the pack voltage.
So the voltage measurement has to be very precise. For best accuracy, the charger has to know the exact cell data ( which it doesn't), wait 10 minutes after finishing the charge (the cells will relax in voltage a little) , and have a temperature correction.

So I would live with it,  and understand is not a gas gauge, it is an indicator. 

[Ken Culbertson]

Are these Li-Po or Li-Ion batteries?  3.0 is more than I would use for a Li-Ion.  My charger is set to 2.5 and I only charge to about 98% of capacity.  I suppose I could push it to 3 or more for my Li-Po's but it is simpler to use the same settings for both. Charge time is not important to me since I do it while doing something else.  I don't recall the charger ever reaching the safety time out during a charging session.  I think your problem lies in the balancing.  It should be an easy exercise to figure out exactly how long it will take to recharge a battery.  I am not the math expert so I will hope someone else will fill in here.  Charge a battery for that exact time then stop it.  Check the cell voltages and confirm that it is changed then resume charging and see how long it runs before the charger signals it is complete.  I have one battery, a 5s TP 2800 LiPo that periodically has either a low voltage or an overvolt after flying and it won't charge.  Running the balancing only option on the charger fixes that and will let me charge as normal.  Doing that the balancing ran to the safety time out several times before I discovered that all it took was a minute or two on the balancer. Wish I could be of more help.

Ken

What brand of battery are we talking about?

[Dennis Adamisin]

Hi Paul
I have several different brands of charges and they all behave - to some degree - as you describe - SOMETIMES!  Pretty sure different chargers have somewhat different criteria for what constitutes "balanced" and how they get there.

I have had brand new packs sometimes meander about getting to peak; the hit the nominal charge peak but just meander about and even time out without balancing.  If I sense this MIGHT be happening I will stop the charge cycle and put it into a STORAGE cycle.  Then back to a balanced charge cycle.  Actually I like to go through 3 cycles on a new pack before the first flight.

I balance charge EVERY time.  I figure this is the surest way to make sure the cells stay as close to each other as possible.

During a charge or discharge cycle, push the "+" key. that will switch you over o a screen that lets you see the status of each cell individually.  Normally these are within a couple hundredths of a volt, but if there is a snafu, you will see a cell that is way off, like .7V or so - this is a problem. Twice I tacked this down to a bent pin that did not allow the balance board to plug in correctly, twice I figured out it was a problem with the balance board itself.


All a windy way of saying I recommend you put them through a few cycles and call the Dr. in the morning!

[Bob Hudak]

You may be able to turn off the timeout feature in the Hitec charger. The ICharger 306b allows you to shut it off in the settings.