I added a voltwatch to my Aerostar .25
Last night I flew 5 flights of 10 - 12 min. with my instructor and we notices the voltwatch down into the yellow.
It was getting a little dark to fly so we just kept moving the controls to see how far/fast it would go down on the voltwatch.
Boss said this Panisinic NiMH 4.8V 1200mAh, should last a lot longer, if I had charged it properly...If the voltwatch was accurate.
We Moved the sticks for 10 min. or so then My TX stopped working and showed " BIND ". its a spectrum DX6i.
I never looked at my TX while moving the sticks and pebably ran it down. would that cause a loss of Bind?
We didnt have anything else with us to test the battery.

Today I pulled the battery out of the plane and it doesnt look good.
See Pics.

I use a Hobbico Quick Field charger Mkll powered by a converted PC PS.
I set the charger for 1.0 - 1.4 amps . when quick charge ends it goes to a 50mA - 85mA trickle. I leave this on overnight before I fly.

Whats the most likely cause of the battery going??

When do you think it happened? Could it have been like this while flying or did I do it by driving the battery down to the red?

WHAT WOULD A GOOD REPLACEMENT BE?

I hear the DX6i RX (AR6200) Doesnt like low voltage

Should I go to 6V? It has to be the same shape..

Pics

You overcharged it and overheated the pack it seems.

If this is a New pack, you should have charged at C/10 for first few cycles... and should not have exceeded 1.2A for quick charge after that.

Quick Charge a new pack (1200mah) at 1.4 and then trickle at 85mA is just asking for trouble in my opinion.. .... ... Then again, your pack might just have been faulty.


I charge my 1600 pack at 500mA the night before. You don't need to put it on trickle, you're not gonna loose much capacity over night.

only 2 things cause an over heat like that...
1 a short..but you said everything worked ok
2 over charging...

I'm still trying to get a handle on careing for the batteries...I have to do more studying on the electronic issues..Very confusing :-(

With my quick field charger I usually charges at 1.0 - 1.2 amp setting over night before flying the next evening.
yesterday I didnt have the 16 - 20 hours to charge as indicated on the battery so at lunchtime I went out and hooked it up to my field battery in the trunk of my car. I know, I was worried about how hot it was...I also bumped it up to 1.4 amps instead of 1.0 - 1.2 amps.
It was like this for about 4 hours.

When I got to the field after work everything seemed fine except that we thought the voltwatch drop too low before we thought it should.
I'm guessing my lunchtime charge fried it? Would I then have been able to fly with it in this condition???

I've flown this pack about 20 flights so it wasnt new.

The label says charge before use at 100 - 125 mA for 16 - 20 hours. trickle charge at 25 - 50 mA.

What I need is a fuel guage. how much is in the battery and how much am I putting into it.

Is the field charger sufficiant for what I'm doing?

Any info on this subject would be greatly appreciated.

At least its only a $20 battery I lost and not the plane!!!

Thanks Steve

1.4 amps is too fast of a charge. You shouldn't go past 1.2 amps with that battery (1C). Was it charging for the full four hours? Even if the battery was completely drained it should have finished within an hour. When I get a new pack I charge at C/10 and discharge at C/5 three times to check capacity. Even after that I usually only charge at C/5 to be gentle on the battery and reduce the chances of failure.

As for the "fuel" gauge. Buy yourself a loaded voltmeter to use at the field. When the voltmeter reads 4.7 stop flying (battery is almost empty). Check it before each flight. If I ask a student what voltage the battery is at before a flight and they can't answer I consider that a problem.

OK, I see my mistake...
I now have a Sanyo 4H-1700AA NiMH RX pack.
The only thing I have to charge with is the quick field charger.

{quote} I charge at C/10 and discharge at C/5 three times to check capacity. Even after that I usually only charge at C/5 to be gentle on the battery and reduce the chances of failure.
{quote}

What would C/10? be on my field charger. I see now that if I set the charger to 500mA or higher. It quick charges then cuts to a trickle charge.
Sounds like I want to set it on 0.4 or 0.2 amps? This will avoid any quick charge and be more "gentle" on the battery?

Is 0.2 Amps equal to 2 mA ???

How do you discharge at C/5 to check capacity?

How would you suggest I check the battery between flights.
I could take my wing off (elastics) to get at the battery but theres got to be a better way.

Like I said, I have the voltwatch but I dont know how reliable it is..

Thanks for the help.

Steve

"C" stands for capacity. Your 1700mAh (1.7Ah) battery should be charged at 170mA (1700/10) and discharged at around 340mA (1700/5).

mili means 10^(-3). That means that 1A = 1000mA. 1700mA = 1.7A

Taking the wing off to check the battery is a pain. Take the charge jack coming from your switch harness and mount it to the outside of the airplane. This way you have a port to plug into for checking (and charging) the battery without having to take off the wing.

As Nathan stated, C/10 for a 1700 Mah pack is 170 Mah. This is what you should be charging at. A point to make here is that quick charging isn't good for a battery, and every time you do it you reduce the overall life of that pack. For my packs I try to avoid quick charging (anything above C/10 charge rate) them whenever possible. If the only charger you have is the field quick charger you really should invest in a good charger now, otherwise you are likely to face the same situation as you did with this battery pack. Trust me, a good charger is worth it's weight in gold.

Ken

Just wanted to throw it out there... I'm a noob so maybe I still read the directions too much and worry about things I shouldn't worry about. But I think all battery chargers suggest that it's not good to leave batteries charging unattended. Especially if using a fast charger that's only going to take 15 - 20 minutes, isn't leaving it on for hours without watching a bad idea?

If it's set to the higher current rates- ABSOLUTELY. Just scroll back to the top of the thread and look at the battery in the picture. The longer a battery is connected to a high current charge it builds up heat. Eventually the battery is going to cook off, and if unattended it could easily start a fire.

Ken

a "by product" when charging a battery is heat...charging in the heat of your trunk is not a wise idea...heat squared equals smoke in most cases...with a quick charger it would have been better to wait until you got to the field to charge...oh well live and learn...good luck
Good Flying

You have to watch the NiMh packs, They are eaiser to overcharge than the NiCad are. The last batch of NiMh batteries I got warned about leaving them on a trickle charge as they will continue to take a charge and start overheating. I'm not sure about your charger, but you want one that is peak detecting and as soon as reaches the full charge, take the battery off. Also don't "peak" the battery per the instructions with my charger. They tell you to charge it, and then after it goes to trickle, hit the charge button again to "peak" it. I blew one pack apart trying that, and got a second so hot I couldn't hold it.

I've finally decided that a cheap charger usually turns out not to be so cheap after all when you consider battery damage and in some cases loss of your plane.

Don

PS, your charger is a Peak Detecting charger so the trickle charge is what did you in.

Tell me if I'm correct with my thinking here...


My Quick field Charger:

FAST CHARGE SETTINGS then goes to TRICKLE CHARGE RATES
less than 500mA 0mA (no trickle charge)
500mA - 1.0A 50mA
1.0A - 1.5A 85mA
1.5A - 2.0A 100mA

I think I see my mistake? I missunderstood the label on the original battery AND what the quick charger was doing.
Battery said, "charge before use at 100 - 125mA for 16 - 20 hours"
I always used the 1.0A setting which quick charged it then went to a 50mA trickle. AND I left it on for 16 - 20 hours. Not realizing I had actually fully charged the battery in 20 - 30 minutes then trickled for 18 hours??? I didnt realize I was quick charging every time I used it..


I was wrongly thinking the 100 - 125mA the battery asks for = the 1.0A - 1.2A setting on the charger???

It looks like the LOWEST setting on my charger, which is 0.2amps would still be Double the charge rate of 100mA the battery required for a nice easy charge rate.

If I have this correct ??? I can see that I was frying this battery from day one....


If I use this charger at all I would set it below the 0.2 and maybe get 0.15amps ???? This would be 150mA which is still a little high but the best I could do with this charger?

DOES THIS SOUND CORRECT???
Thanks for pounding this info into me, I'll get it eventually..

Now what charger do i buy that is smarter than me.. :-)
I'll be getting into electric park flyers/gliders in addition to the current glow.
Charging and cycling in the $100 range????

Steve

Steve, you are about on board.

The slow charge of 100 to 125 for the first charge is just that, for the first charge. It is a good idea to cycle them once before putting them in service. I'd have to go back and look at your manual, but I didn't see a cycle function on your charger, so that means you need to just peak them off before flying. Your charger is OK for that and after the first charge, a quick charge is OK.

I charge my NiMh at below the recomended amperage. I've got a 6v 1000mah NiCad in one plane and a 1200mah NiMh in the other. I flew my plane with the 6V yesterday and today. I charged it after the first flight yesterday and I'll be good for a couple flights tomorrow. I carry my charger to the field with me and use my starter battery for power. It seldom takes more than 10 minutes at 1.5amps to top them off. I set up the plane, fuel the tank, fuel the battery and while I'm waiting for the BEEP BEEP, I do my "hi, how are ya's"

When I first started flying, my instructor was good for four 15 minute flights a day. My little 600mah was wheezing by the end of the day and my TX wasn't far behind. I got a 2300MAH NI-Mh for the tx and on the first flight of the day, about three minutes into the filght, the alarm went off on my TX. My hearing is shot, but my instructor is hollering at me "WHAT"S THE FOR" A third guy got to the line and saw that the TX voltage was just over 8V, just about ready to shut down. My instructor made a power on dead stick and as soon as the plane stopped rolling, he started chewing some ass. Being a rookie, I went home with my tail between my legs. After I got home, I pulled the new battery out of my TX and saw a bluge something like yours. I had overcharged it and blew out one cell. I salvaged a 4.8 pack from what was left, but I've never had the nerve to put it to the test in a plane. SO, you are not the first, nor will you be the last to cook a battery.

As to which charger to buy, I would think yours should do OK. Just use the wall wart for the first charge. I started with an AcuCycle and it has it's ups and downs. It will cycle a battery, It will charge both the TX and RX at the same time. It will charge my 6V RX packs. BUT it won't do pead detection, only 15 hour timed charges. For the bench, it 115V only, It's OK. I have another field charger that I picked up at a going out of business sale that does some more, It will self detect 1 to 11 cells. It will quick charge up to 5amps. It will cycle the batteries. BUT it is 12V only, and it will not do Li-PO's

I think that a couple moderatly priced chargers that do certain jobs well, and between them you can get done what you need in different task, then you are OK. Your charger is a good start. I would look into a method to cycle the batteries. THere is some inexpensive home made devices to knock down a pack, but they won't tell you how much charge was left. Right now, you know the limitations and abilities of your charger. Just keep yourself in sync with those limits and it should serve you quite well.

Don

One note about supposedly charging your packs overnight on the hobbico field charger. The charger automatically shuts off after 2 hours if a full charge isn't met, so if you charge it at a lower mah don't expect to leave it overnight and have a fully charged pack by morning, you will have to reset if after 2 hours, it will start beeping.

I dont have a wallwart! The Spektrum only comes with a TX charger.
I was hoping to use the field charger at its lowest setting?
It goes a little below the 0.2 so maybe 0.15 - 0.2 amps. Is this low enough for a first charge?

C/10 of the 1700 pack would be 170 mAh, would that be 0.17 amps? if so I'm in the ballpark..


Also can I cycle the batteries with a couple of light bulbs in series?? Just run it down. for now.

I would do this a couple of times with the new battery.


Would it be correct to say I have to charge a 1700 pack at 170mAh (or 0.17amps) for 10 hours?

Steve

Not just the bulbs. They will suck the battery down to nothing and at that point, at least with a Ni-Cad, you stand a good chance of having one or more cells flip polarity when you start the charge. You want to discharge to about 1.1 V per cell and stop there. One way with the bulb, is to wire some diodes in series with the bulb or resistor. The diodes have a forward bias voltage drop of something like 0.2 V. So if you were to wire the correct number of them in series, with your load, then at the pack would discharge down to 1.1V per cell and stop. That's the theory any way. You would have to select the diodes based on their forwar bias voltage and current capacity.

As they say, "in theroy, theory and practice are the same. In practice, they are not". A proper cycler is in order.

Don

Campgems,
Ni-mhs will go into cell reversal as well. With batteries these days there is no reason at all to cycle the batteries other than to find their capacity. So if you don't have a battery cycler that can measure the capacity of the battery you really are wasting your time draining the batteries and calling it cycling. You are better off just recharging the batteries.

Cycling batteries can be one of the best ways to find a pack that is going bad. When you first get a back you should cycle it to find the capacity of the pack, this is your base capacity. Then as the battery is used you should cycle it periodically, I do mine about once a month or so. When the capacity of the pack as dropped to 80% or less of the base capacity you should not use it any longer for flying your planes. Using it past this point is risking failure in flight.

A good charger for your needs would be the Electrifly Triton 2, [link]http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXMAJ0&P=ML[/link] . This battery can be set to any charge voltage that is needed, including the C/10 setting you need for your pack. It also can discharge and measure the capacity of a pack. And lastly, it can serve as a field charger at the field to recharge batteries at the field.

Hope this helps

Ken

Hmmm. I'm fairly new myself, but i have studied and studied this battery thing.
First, as had already been pointed out you overcharged those batteries.
Second; I too use the Hobbico quick charger, WITH a PC power supply. Properly used AND monitored it will work for you. I e-mailed the RCBattery clinic in my research. They arent fond of the charger you and I use but for the opposite reason, it tends to UNDER charge NiMH batteries. Which leads us to reset and charge again...

That said, I NEVER charge at over 600mA and I'm running a 2700mAh battery. Here is my procedure, it may not be perfect but it has worked well for me:

After flying when I can be home to monitor it I set up the charger for a "quick Charge". I run it at up to 600mA for this charge, (Once in a while if I know the battery is real close to dead I will go as high as 800, but the one time I went a full amp I nearly cooked the battery.) While it is charging I periodically check the pack temperature by touch. Now Red told me a NiMH WILL get warm when it is close to fully charged, but should NEVER EVER be allowed to get hot, as this can ruin it.

If the pack is not warm after the 2 hour cycle shuts off, or if it peaks before that and the pack is still cold I will reset it, drop the current to 400 or less and charge cycle again.
Once I am satisfied I have it nearly fully charged, or if I need to leave for any length of time, I shut it all down and unplug the pack from the charger.

I then leave it all until the night before I am flying. the night before I fly, IF it has been more than 24 hours since I charged up, I will set up the charger at minimum current (200mA) and closely monitor the pack. I shut it off as soon as the pack begins to warm above room temp. I can live with a 90-95% charge versus a full charge.

Meanwhile I use the wall wart that came with the DX6i for the TX batteries, again monitoring them until they are warm, NOT HOT.

This has worked well for me, however the following should be noted:

I fly an H9 Arrow. Its a sport capable trainer, but its electronics don't have a really high draw.

I have NEVER been forced to quit flying early due to battery pack s being low.
I did leave one day when I felt it was too low for more than one more flight, I have since learned I had plenty. But I am superstitious, if I cant get in two or more flights I wont take the last one. I have witnessed too many aircraft getting re-kitted from just one more / one last flight.

I have been at the field for a full day, and gotten 6 or more full 15 minute flights out of my batteries, and still had some left at the end of the day.

Ken, I suspected the Ni-MH would not take kindly to being discharged to 0 volt but I wasn't sure. Thanks for that info.

I've got an older AccuCycle and it's main use is to cycle the battery to get a feel for it's condition. That and charging my 6V battery in one of my planes, although I'm liking my field charger bettter all the time.

The charger you give the link to has one thing that I think is vey improtant and that is the thermal sensor. That would have saved me a couple batteries. What I can't figure though is how you use it for a receiver battery. My batteries are usually burried under the fuel tank or some other inaccessable place. Or do you put a sensor on each and run the leads out?

Don

You are CORRECT!
That is whats happening now...after a couple hours it started beeping. A check of the instructions doesnt indicate what you said above as being one of the causes for beeping???? I couldnt figure out why it was beeping? Your explanation makes sense because wheen I hooked it back upit went for another couple of hours...

I'm beliving that this "quick" charger is not going to work for slow charging the RX battery???

I have older wall warts that are for Nicads... I think I'll go out today and pick up a wall wart for these initial long slow charges.
Hope I havent screwed this 2nd battery already?

any specs I should look for?

steve

My batteries are usually burried under the fuel tank or some other inaccessable place. Or do you put a sensor on each and run the leads out?

Don
[/quote]



I'm wondering the same thing? The only reason I found the battery in this condition is I'm changing my fuel tank and figured I would pull the battery while it was in there. If not I would have tried to charge again?

I'm leaning toward pulling the battery every time until I'm sure I know what I'm doing...

Is it ok to wrap string around the battery, wrap the battery in foam and when I stuff it in place its a tight fit. I need to use the string to pull the battery back out...

At this point I dont trust charging in the plane..

Again, Thanks for all the input...

steve

{{{After flying when I can be home to monitor it I set up the charger for a "quick Charge". I run it at up to 600mA for this charge, }}}

To repeat myself, 600mA would be 0.6 on the charger dial??

{{{Once I am satisfied I have it nearly fully charged. I shut it all down and unplug the pack from the charger.}}}

You are useing the fact that it is warm to the touch to determine if its fully charged??
I have never felt the pack warm up to the touch. Although once I put it in the plane where I couldnt feel it, it obviously got very hot!

{{{Meanwhile I use the wall wart that came with the DX6i for the TX batteries, again monitoring them until they are warm,}}}

Do you charge with the back cover off so you can feel the batteries?

Thanks for the blow by blow description... Your procedure should work for me except for the initial charge.. What do you do for that?
I also like the charger you pointed out. what wont that charger do? 12V field battery? I'll DL the manual and check it out...

steve

Steve, I've got a 2300mah NI-MH in two of my tX. They are Futaba 9C's and they show the battery voltage on the screen. When the voltage drops to about 9.8 V, I am done frlying and I take the TX home and put it on the walll wart over night. THat will usually bring the battery up to 10.8V or close. Quite a ways away from 11.5 that I initally had, but 10.8 is good for at least two days flying for me. I don't worry about the over charge and I always have the battery condition at a glance. I use the wall wart because it is a 100ma charger.

With one exception, I stick with Ni-Cads in the planes and there, they can stand a nominal trikle charge without damage. You can still over charge them, but I've never had a problem with my AccuCycle or the wall wart as neither charge over 125ma rate

Don