Total voltage when charging

[Kingmeow]

You know what, when I was writing "the only thing wrong with it was pilot error", I was thinking to myself, that I seem to remember the same issue happening after I reseated the tx battery connector when flying my Blade 130X (resulting in a crash). But then I started to doubt my memory gave the DX7s the benefit of the doubt, hence why I wrote what I wrote. But reading your post has got me wondering again whether that particular 130X crash truly was after I'd reseated the battery connector. To be fair, I've crashed that 130X countless times trying out new stuff (or sometimes just due to me being a muppet - I went through a lot of spares! ), but the reason why that specific crash sticks in my mind is because I was convinced it wasn't my fault and thought I'd already fixed seating of the battery connector.

Like you, I have never had the slightest issue with my Futaba TX/RX's and I've been really pleased with them. For RC cars I have the Futaba 3PL, but I can't use it with the TRX-4 because it doesn't have enough channels. I did think about changing it for a Futaba with more channels when I have a little more cash to spend, but can't find one with a wheel on it that has more than 4 channels, or at least if I could I expect it would be more than I'd want to spend. Gotta say though, that Flysky GT-5 you have looks perfect and great value for money!

Back on the battery charger front, the voltages aren't aligning as well as I'd like; on the same pack, sometimes, it's better than others (it changes over the cycle), a couple of times I've seen perfect alignment whilst charging, but then the next charge of the same pack, it's out again - I'll note that each time I've charged a pack, I've disconnected it, used it in the TRX-4 and then connected it back to the charger to either storage charge it or charge it for use again. Although the charger has the option, I've not used the charge/discharge cycle option. I might get a new pack and see how closely that aligns, but I'm thinking it's probably more likely the charger than the packs at the moment. I have noticed that turning the charge cable banana plugs in the charger's output connectors affects the displayed voltage by up to 150mV, so maybe there is some connector corrosion in the charger. The cable looks perfect, but I haven't checked the connector on the charger. I'm going to check for breaks in the cable and after that, I might take it apart to take a look. If all else fails, I'll think about getting a new charger (kind of reluctant until I know it's definitely an issue with the charger that can't be easily resolved).

I have a friend who flies a Blade 200(SX or X, don't quite remember) using a DX8 I think but could be the newer DX6. It was a black case. One day he was just hovering about 50 ft out and the heli just dropped out of the sky for no reason. The battery was fully charged and it happened no less than a minute into the flight. I have seen other club members who had planes/helis just not being able to be controlled by a Spektrum Tx.

As for your batteries, do you know anyone near by that may have a lipo charger with a display so you can check the various voltages? Another alternative is what you said, just get a new battery and see how it behaves on your iCharger. Just get a cheapie $15-$20 2S 5000 mAh on Amazon. I still say it's the packs and not your iCharger. Remember the many years sitting in dormancy!

BTW, Nightcrawler48 does make some very good points.

 

[Voodoobrew]

It seems there is a lot of confusion around here as to how chargers actually work.
1) in order to move the electrons there must be a difference in pressure, or voltage. So if you wish to charge a battery you must have a higher voltage then the batteries current voltage.
2) You can't read the batteries voltage while it is charging. In order for your charger to see the batteries voltage it must stop charging take a voltage reading then resume charging again.
3) If you take a reading of the voltage while a battery is charging you are reading the chargers voltage, which is higher then the batteries voltage.
4) The speed of charging is most accurately measured in watts because the voltage and amps can vary.
5) Your charger should limit the voltage or amperage or both while charging a battery.
6) mid charge voltage reading are more like guestimates, because there has been no trickle charge, voltage drop occurs ass soon as the charge stops.
7) it would take a really long time to charge a cell to 4.2v if you only supply 4.2v so chargers will use over 4.2v then trickle charge as the battery reaches equilibrium.

Batteries themselves form dendrites inside them which shrink and grow during different charge discharge phases. So you should always measure the IR at the same charge for comparison.
As the size of the dendrites inside the battery increase, batteries IR increases.
As the batteries IR increases more powered is wasted as heat inside the battery.
At low amp draws the heat is dissipated relatively safely, but at high amp draws the heat can build resulting in thermal runaway and fire.

 

[AC49]

It seems there is a lot of confusion around here as to how chargers actually work.

2) You can't read the batteries voltage while it is charging. In order for your charger to see the batteries voltage it must stop charging take a voltage reading then resume charging again.
3) If you take a reading of the voltage while a battery is charging you are reading the chargers voltage, which is higher then the batteries voltage.

Question for you (not being a smart ass, real question) When chargers are displaying voltage, all the chargers I have seen display some increasing voltage on each cell. If your above points are true then does that mean the charger stops charging every few miliseconds to read the voltage?

I assumed that because Li-po chargers use a CCCV charge cycle they actually display battery voltage, (perhaps from the balance board?) because if they displayed the charger voltage they would simply display 4.2 volts for the entire time the charger is in it's second phase (Constant voltage) and that doesn't seem to be the case with any charger I have ever used.

 

[Voodoobrew]

Yes, most chargers will use a form of PWM for charging. Meaning they stop charging, take a reading and resume with out you knowing.
as far a CCCV charging this is why I say watts are better. But the charger can go above 4.2v in order to keep the amperage up. It all depends on how a charger is programed.
Because the time given to read the batteries voltage is so short, the internal chemistry hasn't has time to equalize so voltage will settle. The entire time the battery reads 4.2v is because the electrons are basically still settling (sorry I dont have a more accurate term for this) But they are not fully saturated.

So the Battery read voltage will be higher then the battery voltage after even a few seconds of being disconnected to a charger. You can see this by randomly disconnecting a battery mid charge and immediately putting a voltage meter on it for 10 seconds and watching the voltage fall.

Programmers could be added to adjust the voltage shown to more accurately represent the percentage of charge for a specific battery but overall it wouldn't be very accurate so you just get this quick and dirty battery reading.

Fully charged is a relative term.
Fully charged 4.2v at 5A is not as good as fully chard at 1A or a trickle charge, because of this saturation and settling of electrons.

 

[Voodoobrew]

What I say is only mostly true, or sometimes true, but not always true. Its complicated. Much more complicated then I could fully comprehend for sure. As they say there are multiple ways to skin a cat. And there are certainly multiple ways to charge a battery.

 

[Voodoobrew]

Taking a voltage reading from the balance board during charging will have a tainted reading from the higher charge voltage on the main plug.