Older Futaba T6XA Transmitter fully charged voltage ?

Reading the voltage without having the battery supplying power to the intended load will provide you with no useful information.

It is the battery's voltage while supplying power to the intended load that will provide you with a hint as to the battery's condition.

This is the reason why ESV meters (Expanded Scale Voltmeters) exist and why you, as an active modeler, should own one.

Tower and Horizon sell good ones at very reasonable prices, as do other dealer/distributorships.

Ed Cregger

Don't look now, but he *is* measuring the battery under the load provided by the very transmitter with which that battery is intended to be used. AND using the digital voltage meter built into the transmitter - which I dare say is a lot more accurate than analog ESVs of lore.

No doubt the battery pack is on its way to RC Heaven...

Cheers

/daytripper

You are correct. 11.2 is right, cycle it a few times.( discharge it, recharge it) if it still reads low, change it. mk

First I would charge the pack and then put it on a cycler to check the capacity. While 10.7 is a bit low I have seen a number of transmitters that read this on a new battery pack when fully charged.

Red S. Red's R/C Battery Clinic

us out for "revolting" information.

Thanks for all the tips / confirmation. I'm only a once in a while flyer these days, so its been awhile..

Would this be such a cycler (see below).. I dont have one currently.. seems a little pricey but I guess it charges too.. or would I be just as well off to let the tx stay on and drain manually and then recharge? (Also.. I cant recall what the typical lower limit on voltage on the tx readout should be to keep flying.. 9.5 volts or so?)

Here is the cylcer I did find on a quick search:

Thanks again

Your cycler choice is a good one...I have one and rely on it. I cycle and check my nicad packs each fall and sprinig...any below specs are discarded and replaced. Cheaper than losing a nice plane. Frank

Just let the transmitter discharge the battery while you watch the built-in meter to keep from going too low. I did that when mine was new to check how long I could use the xmtr. Took a little over 3 hours to get to where the curve steepened downward. Now, when mine reaches 9.5 V, I know I've got about half left. Here's my data:

Minutes Volts 0 11.1 10 10.5 20 10.2 30 10.1 40 10 50 9.9 60 9.7 70 9.6 80 9.6 90 9.5 100 9.5 110 9.4 120 9.4 130 9.3 140 9.3 150 9.2 160 9.2 170 9.1 180 9 190 8.9 200 8.7

Note that those measurements were with the transmitter's built-in voltmeter, and yours may differ.

I have the Accucycle and use it every year to check receiver batteries. Transmitter batteries typically have to be removed from the transmitter because of a diode in the transmitter which prevents reverse charging, like with a different manufacturer's charger.

-Dave

snipped-for-privacy@mindspring.com ANTI-SPAM: To email, replace "lastname" with "plumpe"

Thanks everyone for the help.. I think it is indeed time to replace my

8+ year old battery pack.

The model is NT8jY, rated at 9.6volts, 600mah.. it is listed as 4.375" wide and 0.5" thick, 2" wide.. Does anyone know if any of the off brand type batteries could be used in this guy.. like this one:

this one Otherwise, I did find an exact replacement but its abit more money.

I didnt know if the new replacement was slightly bigger (4.4") if this would be that big a deal, or the increase mah rating from 600 to

2000+?

Thanks

or this one

> or this one

>

I am sure ether of those will be fine, they are 8 AA size batteries, The size can't be much different, I suspect just measuring errors. Brian

| The model is NT8jY, rated at 9.6volts, 600mah.. it is listed as 4.375" | wide and 0.5" thick, 2" wide.. Does anyone know if any of the off | brand type batteries could be used in this guy..

Yes. It's just 8 AA cells in a `flat' pack. You can replace it with NiCd or NiMH cells, though if you go for NiMH cells do be aware that it'll take a lot longer to go from fully discharged to fully charged if you're using your stock wal-wart charger. Having a peak charger is a good idea.

You can even make your own pack, if you know how to solder packs. Considering that Harbor Freight Tool often has 4 700 mAh cells for $3, or 4 2000 mAh NiMH cells for $4, you could replace the entire pack (re-use your connector) for $6 or $8. But if you don't feel comfortable doing that, there's lots of places that will sell you packs -- you don't have to get that exact model. You just need the same shape and plug (and can skip the plug, if you are willing to re-use your existing plug.)

gives some appropriate packs. (Not all are the right shape, but some are.)

Thanks for the info..

When you say it will take longer to charge on some of these, is this due to the higher mah rating? IE: I should try to get the same mah rating on the new pack if using the wall charger?

Thanks

| > You can replace it with | > NiCd or NiMH cells, though if you go for NiMH cells do be aware that | > it'll take a lot longer to go from fully discharged to fully charged | > if you're using your stock wal-wart charger. Having a peak charger is | > a good idea. ... | When you say it will take longer to charge on some of these, is this | due to the higher mah rating?

Yes. If you double the mAh rating, you'll double the time going from fully discharged to fully charged. If you quadruple it, you quadruple the time.

But you notice how I keep harping on `fully discharged to fully charged?' It's because it's not what normally happens. What normally happens is that your battery is somewhat charged, and then you charge it for 16 hours, even though you only needed to charge it for four hours (warning: made up figure!) Without a peak charger to charge it and then detect that it's full and shut off, the only way you'll know that it's fully charged is 1) you've charged it for long enough to be fully charged if starting from being fully discharged, or 2) you feel that the batteries are getting warm (and the charge rate is still low, like with the stock charger. If the charge rate is high, then the batteries will get warm even when not fully charged yet.)

| IE: I should try to get the same mah rating on the new pack if using | the wall charger?

You could do this. You could also assume that if 16 hours is enough to charge your old battery 140%, and the old battery (when new) had enough juice to fly all day, then you can just charge the new `4x the capacity' battery for 16 hours before flying and be safe in knowing that it must have at least as much energy in it as the stock battery had.

NiMH batteries do have some downsides. They don't last quite as long (but it's comparable) and they have a faster self-discharge rate. And higher internal resistances, but that doesn't matter for a TX pack. Overall, going to NiMH is well worth it for TX packs -- the added capacity is well worth it.

But if you're serious about the hobby, get a cheap peak charger that can at least do 4-8 cells. If you do glow planes, it's also useful if it can do 1 cell Ni-starter cells, but that's much less important. Sooner or later, you'll want to go fly, but won't have charged your batteries the night before, and you'll be tempted to make do with 4 hours of charging, or just assume that your batteries probably have enough juice left to fly. And most of the time this guess might be right, but if not ...

(If it's the TX pack, your TX will probably start beeping, or the graph will show the battery being almost dead (which is harder to notice.) But if it's the RX, the servos will go sluggish and then stop, often in just a minute or two. If that happens in flight ...)

You don't have to spend a lot for this charger. For example, this one --

should be just fine, and I'll bet there's some cheaper ones out there that can do the same thing.

"Doug McLaren" But if you're serious about the hobby, get a cheap peak charger that

I got a 4 or 8 cell peak charger, and it is the best investment I have ever made, bar none, for RCing.

It will not do a 1 cell glow charger battery, but I did another cheap work-around.

I got a peak detecting charger for loose household rechargeables, (make sure you get one with a LED indicator for each cell, not for pairs of cells) and use that for my glow lighter.

I made a wood dowel rod battery the size of an AA battery, and put a screw in one end for the positive, and a screw and washer in the other end for the negative, and ran a wire from each end.

To hook up the glow plug clamp, I used a earphone type plug, and put a wheel collar around it, away from the tip end. It works well enough for the plug clamp to hold onto. If you want to charge in the field, you would need to get a charger that runs off of a wall wart plugged into the side, and get a

12 volt converter, or else get a small voltage inverter so you can have your 120 volts to plug into.

It charges well, and quickly to a peak. Now, I don't have to plan 12 hours or more in advance, to get everything charged up. I don't fly as often as I would like, and when I get the chance, it is nice to throw everything in the van, and by the time I get to the field, I'm done or almost done charging, and ready to fly.

So keeping this simple.. the higher Mah rating, will result in longer charge times, unless I use the other device to charge it.. but will the higher mah mean longer fly times (transmitter life while flying.. ie: takes longer to go from say 11.2 volts down to 9.6?)...

If using the higher mah means, for example, I can fly a total time of say 45 minutes till the battery is dead vs 15 minutes then to me, I think I'd rather get the higher mah battery and the other charger..

Btw.. I'm doing mainly electrics here.. still flying a Zagi :) Someday I'll probably (go back) to some gas, or get another electric plane. Time is usually short now for me, so getting out 2-3 times an entire year is lucky :(

Thanks

| So keeping this simple.. the higher Mah rating, will result in longer | charge times, unless I use the other device to charge it..

Well, yes and no. Yes if the battery is dead when you start charging. But in real life, not really, no.

But if you do only fly a few times a year, then the battery probably will be dead each time you fly, so it might be a `yes' -- with the stock charger (50 mA) and a 2400 mAh battery, it'll take 2 - 2.5 days for the battery pack to get fully charged -- but once done, it'll probably last for 10 hours.

But it's dangerous to extrapolate that to mean `if 2 days of charging gives me 10 hours of flying, then 10 hours of charging gives me 2 hours of flying' -- while that reasoning is accurate, it tends to mean that once the battery voltage starts dropping, it'll drop very quicky

-- perhaps too quickly to bring your plane down before it goes too low. (And it's worse for a RX pack, because you don't have any real warning before it poops out entirely.)

| If using the higher mah means, for example, I can fly a total time of | say 45 minutes till the battery is dead vs 15 minutes then to me, I | think I'd rather get the higher mah battery and the other charger..

Seems reasonable, but your time figures are off. The stock battery (600 mAh) will probably power your radio for 2-3 hours rather than 15 minutes. And a 2400 mAh battery for 8-12 hours.

If it's an electric Zagi (as opposed to a glider), then a similar computation applies to your battery there, but it gets more complicated, as internal resistance and weight of your pack becomes important.

But I do agree -- a low end peak charger is well worth the investment. Make sure you get one that can do NiMH cells too (the older ones can only do NiCd.)

| Btw.. I'm doing mainly electrics here.. still flying a Zagi :)

Nothing wrong with Zagis ...

Once again thanks for all the great info and assistance..

I ended up (for now) just getting another 600mah battery, using the stock charger..

but i'm now looking at doing the whole conditioner/quick charger type setup.. there only appear to be 2 out there that are both a conditioner and quickcharger:

I see that the $129 unit will put out alot more amps.. anyone know what the max amp. i should charge a 600mah battery (transmitter) battery pack at? I think the max on the less expensive charger maxes out at 120mah.. I think this is 5 hours if my math is right? I didnt know if getting the more expensive charger will allow me to charge up at a quicker than 5 hour pace (on 600mah battery)?

I know that from flying zagi's (cant remember the exact values) but I can charge the double size receiver battery packs in about 15 minutes at something like 2.5 amps (but this is using a field charger and only the receiver battery packs).

I really didnt notice many/any quick chargers out there that were just quick chargers and not conditioners as well.

These models above, I'm assuming I could use an invertor and charge things in a vehicle if desired as well? (though I guess unless travelling 5 hours, at least with the less expensive unit, this isnt practical, for transmitter batteries anyway).

Cheers

| I ended up (for now) just getting another 600mah battery, using the | stock charger.. | | but i'm now looking at doing the whole conditioner/quick charger type | setup.. there only appear to be 2 out there that are both a | conditioner and quickcharger: | |

| or You've been mislead by the nomenclature.

`Conditioner' generally just means that your charger can also discharge. There's a lot more than two chargers out there that can do it.

Having a charger that can discharge too is useful for measuring how much capacity your batteries have, so you can quantify how much `oomph' they still have. But it's not that important.

For example, if you don't need a discharger, this would work --

for only $30. If you do need a dishcarger, this would work nicely --

for $80, and it would also charge whatever batteries you're likely to get in the future. And there are many other possible choices.

| I see that the $129 unit will put out alot more amps.. anyone know | what the max amp. i should charge a 600mah battery (transmitter) | battery pack at?

TX (AA) packs probably shouldn't be charged at over 2C, so that works out to 1200 mA (1.2 amps.)

| I think the max on the less expensive charger maxes | out at 120mah..

That's not very quick. (and it's 120 mA, not 120 mAh.) And it looks like you read it right (except for mAh vs mA.)

| I think this is 5 hours if my math is right?

It is.

| know if getting the more expensive charger will allow me to charge up | at a quicker than 5 hour pace (on 600mah battery)?

It will, but there are a lot more options out there, cheaper ones too.

| I know that from flying zagi's (cant remember the exact values) but I | can charge the double size receiver battery packs in about 15 minutes | at something like 2.5 amps (but this is using a field charger and only | the receiver battery packs).

Double size? If it's AA NiCd, don't charge at over 2C, which means 30 minutes from empty to full. If it's AA NiMH, don't charge at over 1C. If they get hot, you're charging too fast. 15 minutes = 4C, and that's pretty fast for anything that's not sub-C sized.

| I really didnt notice many/any quick chargers out there that were just | quick chargers and not conditioners as well.

There's a few. I pointed out one. | These models above, I'm assuming I could use an invertor and charge | things in a vehicle if desired as well?

Actually, the ICE charger is a 12v charger. You'll need a PS to power it from 110v ...

| (though I guess unless travelling 5 hours, at least with the less | expensive unit, this isnt practical, for transmitter batteries | anyway).

You could charge in your car with the car parked. (If they're LiPos, it's best to do that with the battery outside of the car, but you're not doing LiPos yet.)

You mentioned with Lipos.. they should be charged outside of the car.. did you mean, using a Lipo charger attached to the battery terminals on the car, outside.. due to their volatility?

I've actually started looking at switching my Zagi 400 equipment over to Lipo capable equipment. So this definitely means, that at least for the receiver battery in the plane.. I'd have to have a different charger then? Side note: I was considering switching to Lipo due to their power differences and longevity, I was also assuming would be lighter than the 1700mah nicad 8 cell battery packs I use in the plane right now.. as I want to do an onboard camera setup, but I figured with Lipos, this will make the weight issue less of a problem (or so i think). (Thinking of going with one of the 900mhz or 2.4ghz 100mW camera systems on rangevideo.com as a start, with seperate lipo battery for the camera transmitter)

So if I do go all Lipo, or even just a lipo for the camera setup, the conditioner will only prove useful for the transmitter batter on the radio (I actually already have a nimh/nicad field charger which I think ranges from 0.5 to say 5 amp, which I use to charge those

1700mah batteries). Actually, I thought I read that the Lipos can take up to an hour to charge, but last for 20 minutes, depending on type.. this would be far better than the batteries i have now, which I think take 20 minutes to charge and last 10-12 minutes max.