Quick Field Charger Mk II - Doesn't fully charge RX

| I just bought a Quick Field Charger Mk II, and when I charged my Fut 8U | it stop charging it (in goes in trickle mode) when it reach 9.5 volts | while my original charger charge it over 11.5v to 12v. | | is this normal, is it a way to allow my Quick Field Charger Mk II to do | the same thing, (I think I can let it in trickle mode until it reach | 12v)

Well, the voltage does not really tell you what the state of charge is, but for an 8 cell pack, when fully charged the voltage should be at least 8 * 1.4 volts or 11.2 volts. (Now, it can read 11.2 volts and be not fully charged, but it can't really read less than that and be fully charged. Does that make sense?)

And if you're charging through a diode, the reading on the charger will be even higher, about 0.5 volts higher.

Your subject says RX. Did you mean TX?

In any event, this doesn't sound normal. Have you checked the voltages with a multimeter? It may just be that the display is inaccurate, but that it's still properly peak charging. (NiCd/NiMH peak charging is based on changes in voltage, not absolute voltages, so the chances of it still properly peak charging if the voltage display is wildly off are good.)

It's not so important with the TX pack, but if it can't get the RX pack near fully charged, I'd be very reluctant to use it. At least with the TX pack, you have a meter or alarm to tell you that the battery is about to die -- with the RX pack, often the first indication that you have that the battery is dead is a figure 9 maneuver.

You should be able to get a rough estimate of how many mA it put into a pack by taking the time and multiplying by the current rating. But if the display is wrong, who knows what else is wrong if you don't measure it?

Sorry, yes it is the TX pack which is a 8 cells (11.2 volts), and while charging with the original charger (which came with the tx) it charged up to 11.5 volts without any trouble.

It's a NiCd pack charged and tested directly (not throught a diode) and tested with a very good multimeter.

Thanks,

Doug may have made a mistake when calculating the voltage of your pack. All the NiCD cells I have seen were 1.2 volts per cell and not 1.4 volts. 1.2 v X 8 cells = 9.6 volts. The 11.5 volts you see is the no load voltage reading. With a load applied, you will see 9.6 or 9.5 volts. I would not trust the volt gage on the transmitter. I would get an ESV that will read the voltage under a load.

As a courtesy to everyone else, please include a quote of what you are replying to in your posts.

Ni-Cd voltage while still on charge can be a bit over 1.4 volts/cell. Freshly charged with a transmitter load they will read a bit over 1.3 volts/cell.

| Doug may have made a mistake when calculating the voltage of your pack.

No, but there may be some confusion.

| All the NiCD cells I have seen were 1.2 volts per cell and not 1.4 | volts. 1.2 v X 8 cells = 9.6 volts. The 11.5 volts you see is the no | load voltage reading.

I was under the impression that he was looking at the voltage as it was charging. I was thinking that the charger had a voltage display, but it turns out the Mk II doesn't -- I guess I was thinking of the Accucycle instead.

In any event, a fully charged battery with no or minimal load will read around 1.4 volts/cell, and if it's being slowly charged while you're reading the voltage it'll read even a bit higher. If the battery reads 9.6 volts with no or light load, then it's certainly fully charged.

The 1.2 volt figure really is just a nominal reading -- the actual voltage is higher than that for most of the lifetime of the battery.

| With a load applied, you will see 9.6 or 9.5 volts. I would not | trust the volt gage on the transmitter. I would get an ESV that will | read the voltage under a load.

If your TX pack reads 9.6 or 9.5 volts on an ESV, then it's either almost dead or there's a bad cell in there. Or your ESV isn't very accurate.

All of the digital voltage readings I've seen on TXs have been reasonably accurate, and the TX itself adds enough of a load to use that figure instead of pulling out the ESV. (The analog meters usually don't give readings in volts, so ...)

If your TX reads 11.2 volts or so right after the battery is fully charged, even if just for a few minutes, then it's probably quite accurate and your battery was probably fully charged. If the reading is under 10 volts right after the battery is `fully' charged, something is wrong -- the batteries weren't charged, there's a bad cell or the voltage reading is quite inaccurate.

Of course, the only way to really accurately determine the condition of your battery is to discharge it to 1.0 volts/cell or so and measure the total current drawn (usually in mAh) required to do so. You can tell some things by looking at the voltage, but that doesn't tell the entire story.

(Of course, the downside of discharging your battery to determine it's condition is that you've changed it's condition -- it's now almost fully discharged! (That, and it's lost a little bit of it's life.) But the assumption is that after you charge it up again, it'll be in a similar state to what it was before.)

| In any event, a fully charged battery with no or minimal load will | read around 1.4 volts/cell, and if it's being slowly charged while | you're reading the voltage it'll read even a bit higher. If the | battery reads 9.6 volts with no or light load, then it's certainly | fully charged.

Sorry, `not fully charged'. (Or it could have a bad cell.)

Well...

Sorry...

I just see that I was connecting the lead to the voltmeter connector instead of baterry... (it's because they are reversed on each side...)

so now I connected in the right side and I got my 11.5 volts...

But, all the information you provided was/is very interresting,

Then, thanks to all.

Robin

Doug McLaren a =E9crit :

Good job, glad it's all ok. mk (never can have too much help)

Sorry...

I just see that I was connecting the lead to the voltmeter connector instead of baterry... (it's because they are reversed on each side...)

so now I connected in the right side and I got my 11.5 volts...

But, all the information you provided was/is very interresting,

Then, thanks to all.

Robin

Doug McLaren a écrit :