jrowles91

The last few times I used my charger I noticed that I'm able to put in the max mah into my batteries. Some even go over the rated power and only stop charging when the time cut off hits. What's going on here? The last battery I charged (which is the same age, size and brand) as the others peaked at about 4400mah which is what I expected to put in my 5000mah batteries. The other took all of 5300 and only stopped because of the mah cut off. Any ideas?

d_bodary

My Feedback: (85)

are you using a external balance charger?

TheWoodCrafter

My Feedback: (1)

What charger are you using?

Can you measure the voltage of your packs?

Sounds more like you are over discharging.

Are you timing your flights?

jrowles91

I'm not sure what an external balance charger is bit my charger is separate from the power supply. ?
As far as the charger I got it from hobbyking and it got good reviews on this forum. I guess I didn't think I could over discharge the batteries as the esc had a LVC. I can measure the voltage of the individual cells yes. They also seemed to balance just fine.

TheWoodCrafter

My Feedback: (1)

Well full charge on a LiPo is 4.20V/cell.
Pretty much discharged is 3.70V
A balance charger is when you have to plug in the balance connector to the charger.
Most better ones also require you to plug the 2 power leads from the battery into the charger also.
If you have a balance charge there is no need for an external balancer.
They are just a throw back to the days when charger didn't have built in balancers.

LVC in your ESC could be really low, like 3.0V. nothing left in the pack at that voltage.
You have over discharged if you even get near that.

Time your flights and make sure you don't use more than 80% of the packs rated mAh.

jrowles91

Got it. Yes tjats how my charger is and I do balance the cells every time. I have my LVC set at 3.3v. I have only hit that once though. Normally something is broken on my or my friends rig before that cut off.

TheWoodCrafter

My Feedback: (1)

3.3V is too low to accidentally let your batteries discharge to.

Time your flights and don't use more than 80% of the rated mAh.

Your batteries will last way longer.

jrowles91

Thanks all. I am going to up my lvc to 3.5-3.7v and will see how things go. I've been running my batteries how I've stated for over a year now. Would like to get some more time from them. Thanks again!

BarracudaHockey

My Feedback: (11)

You don't want to put back more than 80 percent of the capacity of the battery when you charge, otherwise you're over discharging them.

Goldenduff

Also when balancing the charger will discharge a cell then charge it. I have a battery that doesn't balance- one cell 0.1v off the others. My charger will charge this battery for ever, discharging and charging in an attempt to balance. As such the mah it puts in is almost infinite!

bgosselin

Before you adjust your LVC point; is this in a car, plane, heli? Not sure what LVC would be recommended in a plane/heli, but in a car, 3.3-3.5 is about the highest you want to go. Cars pull a lot of current in bursts, and when that happens, voltage dips. You don't want to set the LVC so low that it trips falsely during those high-current voltage dips.

But otherwise; yeah, you don't want to discharge more than 80% of the capacity.

If you have a pack that appears to be taking a long time and too much capacity (mAh), then it could be like Goldenduff said. If the pack is out of balance, the charge current will be offset by the bleeding current of the high cells, and would appear to be taking more than it should. And with balance chargers, if they detect imbalances, they may slow down the charge rate to allow the low cells to "catch up". If your charger doesn't have a mode where you can read individual cell voltage, I would measure each cell via the balance tap and see what it going on to be sure.

jrowles91

This is a truck that I'm referring too. guess I won't change it then

guver

My Feedback: (325)

You've asked a very good ans simple question. All the above info is also good. The easy way to answer (answer is no) the question is to simply measure the voltage when charged. It should be as stated above 4.2 volts/cell. One clue is that you've been doing this for a year and has apparently not done any harm.

I can add to the side roads as well. I think your trouble may be an inaccurate current indicated on the charger's screen. The charger uses time and current to come up with capacity and the time I have never seen stray from being accurate. It may also be a combination of a few of these things giving you a false or actual capacity reading. One clue is that it is happening with more than one pack.

jrowles91

If it is an inaccurate reading, is it recommended to just replace the charger?

guver

My Feedback: (325)

If it is then you can simply figure that in and live with it. It should surely be verified before replacement.

tlrascal

My Feedback: (56)

Here's my .02$ worth. Most battery manufacturers rate their batteries optimistically while a few are conservative. I have some multiplex 2200mah batteries that I notice give me significantly longer flight times than my other brands of batteries. These were more expensive than most of the other batteries I have. When I charge I am replacing over the 2200 mah, sometimes as much as 2450. It is my belief that these are better batteries and are more conservatively rated. Keep those batteries, they are probably some of your better ones.

jrowles91

Well you .02 cents have been received. I do believe they are good batteries but I did check my LVC now that I got my program card, and it was set at 3.0v, which I am aware is too low. I haven't hit the cut off since changing it just due to not running the rig for very long.

Goldenduff

Hello, 

 If you don't balance charge the lipo when you charge it how many mahs do you put in? Compare this to the mahs you put in when you balance charge the same lipo (after a v.similar use/discharge).

I suspect you will find the balance charge requires you to "put in" say 125% of the packs capacity whilst the normal non balance charge may give you something more like the acceptable 80%?

I say this because as mentioned before I had a pack that would take infinite mahs because one cell failed to balance within .1v of the others so the charger kept ticking away!

Good luck