Upnet

My Feedback: (8)

So...I am programing my DX7...got the UCD next to me on the cradle. Brand new 1100mah Spektrum Battery is in the fuselage. A week ago this battery was tested(4hrs. after charging on my Triton) on a load for 15 sec showed 5.45v. As I navigate through the myriad of programing options available...I loose track of time. I think about 15-20 minutes pass...as I program and reprogram...cause I make some mistakes. Taking a break for a hot cup of joe....the Spektrum quietly nestled in my lap....suddenly a mechanical noise comes from my left. The rudder snaps hard right!. ***??? I think to myself. I wiggle the sticks on the TX....nothing. Rudder still locked...and no other movement of servos is observed. Turn off the Rx....then TX. Wait about a minute...power up....nothing...rudder still locked. Hmmmm...Must be the battery. Plug in the ESV in the charge jack....4.5v. What!! So...I pull the battery...and test the battery directly on my meter...bypassing the switch. Same deal...4.5v. Pull out a used battery from on the bench...check it....4.95v on a load. Plug it in... rudder goes back to neutral and I finish my programming. I thought 3.5v was when the rx would hit lockout...assuming that what happened,was in fact lockout. Any thoughts?

alan0899

G'day Mate,
SLOW charge the 1100Mah battery for at least 16 hours, now it is flat, use the wall charger that came with you Spektrum system, then discharge it, at half it capacity, about 550ma, & note down either how long it took, or the capacity in Ma, then charge it again, for at least 16 hours, discharge again, & make sure it increases it's capacity, if you do this procedure with every NEW battery you get, you can check what the capacity is over time, & if it starts to dwindle, buy a new pack & start again.
You will be amazed at how little capacity a NEW pack has, & how much it increases after a couple of cycles.

Teachu2

My Feedback: (133)

Aye - but the point isn't the capacity, it's that the radio failed at 4.5 volts!

alan0899

G'day Mate,
How can you be sure that was the voltage that the RX was seeing, when it failed, with servos moving, the voltage could have been much lower at the RX, than when you tested it with your ESV.
You can't be sure how much actual current load was used by the servos, it could have been 2 or 3 times what your ESV was placing on the battery.
I still stand by what I typed earlier, cycle your battery, & find out how much CAPACITY it has, that will tell you if it will last or not, you could have a faulty cell, & cycling it, will expose any faults there may be, or it may just need to be Balance charged, to get it up to full capacity, & that may just save your plane, check this out.
http://members.aol.com/davthacker/balancecharging.htm

blkbird68

My Feedback: (19)

if you read his post....it sounds like no servos were moving at the time it locked out

alan0899

G'day Mate,
I did read the post, but my point is, that it was a NEW battery, it had not been slow charged, had been fast charged a week before & had never been cycled, but had been used to move servos & could have been under load for 1/2 to 1 hour, before it dumped, & he had no idea what it's capacity was, & hence had no idea how much charge it had in it, when he started setting up his plane.
So he just blamed the receiver for locking out, he had no idea what the voltage was, at the time it stopped working.
This is the sort of thing that worries people that have no experience with Spektrum, or any other radio for that matter, they think that if they turn their radio's on, the batteries will go flat in minutes, the RX will lock out, & if the plane is in the air, it will crash.
But if they do a few basic things, like balance charging, & cycling their batteries, to check their capacity, the chances of battery failure are greatly reduced, if not eliminated.

blkbird68

My Feedback: (19)

there was no load on the batt. at the time it locked out. So yes, he does know pretty much what the voltage was when it locked out.
Do you think it magically recharged itself before he put the meter on it?????

airbusdrvr

alan0899 is right. His advice is generally right on. So why not try what he advises. As for saying there was no load since the servos were not moving, how do you know? Without an amp meter between the battery and receiver you wouldn't know.

Upnet

My Feedback: (8)

Actually I did a slow charge on my Triton...and cycled it twice. It had laid dormant on the table for about five days before I put it in the plane. The servos were at rest when the Rudder only kicked hard right. I may have written down the info after the two cycles. I will see if I can find it. But again...the last reading I took on the Battery was 5.45v on a load for 15 sec. Which was 4 hours after cycling...and five days before I put it in the plane.

tomlee

My Feedback: (1)

I had a battery that did the same thing, the airplane locked up. I used a H-0 .5a to 2a loaded volt meter to test the battery. One could watch the voltage depress rapidily. I recharged the battery, but had the same results. Needless to say, the battery was disposed of, with a new battery, all is well.

blkbird68

My Feedback: (19)

..if Upnet tested 4.5 on loaded meter after and it held (he didn't mention it falling off), then I am sorry but alan is not necessarily right. I have had amp meters on planes much larger than a UCD and with a proper setup it pulls less total current at idle than any loaded ESV I have used. I don't think on the UCD he would have multi servos on a surface, so he wouldn't have to worry about them fighting each other so unless he had something binding (like maybe a throttle servo binding at it endpoint), it is unlikely that he had a load approaching what his ESV was putting on the batt.

now if that 4.5V reading was without load, than I would agree. But I am assuming that all voltages were loaded. Because he mentioned that a couple times.

MR G

Hi Guys,

I don't know what the problem is, but I get the impression from reading the posts that people are reading voltage as a measure of current. This is not correct, an example is that a dead car battery will read 12 volts, but has no current to turn the car over.

The batteries had 4.5 volts, but not enough current to drive the servos, hence the lockout.

This might be a reciever thing, because the servos obviously had enough current to hard over (rudder), it was the reciever that lost it.
Check the transmitter, did it have enough power, if so then get another battery and receiver and test when the reciever loses it.

MR G

Terry Spalding

spektrum warned us about fast charging a new battery....spektrum will replace it...I think it was lower then 4.5 for a moment and went into fail safe....need to rebind after you get the battery right....I charge mine about 20 hours w/wall charger....spektrum knows they put to small of charger on the DX-7

DadsToysBG

My Feedback: (35)

I don't have a answer to the first post, but what i find interesting is that before 2.4 there wasn't much talk about batteries. Now that we have 2.4 everybody is paying attention to their systems and many are learning for the first time what it takes to maintain their batteries. This in it's self makes for a safer time at the field. You can't help but wonder how many "hits" were really battery issues before 2.4. I have seen it several times in the past where someone would check their battery and say "it's 4.8 I can get one more flight". Dennis

Airbike

My Feedback: (6)

Well, I'd say you were very lucky to have that happen on the bench.

I slow charged my Spektrum 1100 batt for 2 days before using it. It seemed ok initially, I was getting around 950mah +/- when I cycled it on my Accucycle Elite.

This battery decided to take a dump on my second flight of the day on my Raptor heli (during a downline too!!) and I got a fail-safe (right into the ground)

and No, I was not using My DX7. I used the Spektrum batt in my heli, but the heli was on my JR9303 PCM.

I later cycled this battery and it only cycled to 550 or so mah avg for three cycles. I promptly got rid of it.

I don't think the Spektrum battery is a good quality battery. Perhaps some are ok, but I've seen several that were just junk and caused a lot of grief.

For a UCD, I'd say get yourself a good 1650 mah 5 cell battery (Hydrimax is pretty decent, there are many others)

Upnet

My Feedback: (8)

At the time this happened....the TX was reading 10.6v. Both RX and TX were on...but I was NOT moving the sticks. Also the wing was NOT attached(2 Ailerons) so the only servos that were connected to the RX were Throttle,Rudder,and (2Elevator servos. The ONLY servo that went goofy was the RUDDER (HiTec 605)

The Spektrum wall wart that came is rated at 110ma...most of my other wall warts for 72Mhz are rated at 50-55ma.

When I put the battery on the ESV and put the load on it for 15sec. it stayed at 4.5...did not drop.

I will discharge the Spektrum battery and recharge it at the rate alan0899 recommended.

Ever since I lost my FIRST plane with a new battery that I had not cycled(newbie)...I have been very dedicated in checking my planes BEFORE and AFTER I fly every time. I have a Triton charger and feel competent in using it. I am NO expert on batteries. But I have never lost a plane in 5 years due to battery failure. Mostly I just snap a wing off or something...or dumb thumb it into the ground. I have been lurking and reading all the posts on 2.4Ghz since they started. As it turned out I had outgrown my HiTec Flash Five TX. I needed an upgrade. I made my decision and went Spektrum. I was aware of the potential for lockout at low voltage. When this thing happened I figured it was a Battery problem. I only have one AR7000 Rx right now. So at this point I believe that for whatever reason the battery is the issue. I just received a NEW 1500ma NiMh battery from Hangtime Hobbies, HD switch, a CH-96 high output wall wart rated: Rx 4 cell:180ma.....Rx5 cell:150ma.That battery is going in the UCD after properly charging it.

Dennis is right. Many people that I fly with...NEVER (or RARELY) check their batteries. I have yet fly my UCD having made the switch to 2.4...still in the set up mode with it. I am also working on my first Gas project....I'm thinking A123 for that one. It will be a little while until completion, maybe springtime.

blkbird68

My Feedback: (19)

on a side note upnet. If you want a battery tester that is really nice and can give you a better idea of the state of the batt. I would suggest one of Gordon Anderson's programmable MAESTRO testers.

aviti

My Feedback: (54)

I may have missed this but what load does your voltmeter produce? Most of the units from hobby shops etc give a .25 amp load which is not significant. If the battery is reading anywhere near 4.5 with a small load, it is in a pretty low state of charge. It's not going to take much to drop a full volt at this point.

I'm not doubting the story but this is a rather unscientific way to try and say the receiver cut off at 4.5 volts. If you really want to test this out, there is better equipment available to find out where it really cuts off.

All this being said, I would hope that after everything we've learned, no one would be running a battery that could be at 4.5 volts even with a significant load. I think using a 4 cell pack is playing with fire to begin with on Spektrum. If you are going to run one, you would definitely need to monitor it closely and stop flying sooner than maybe we used to.

Ed

When I converted my Giant Scalers over to Spektrum, I never planned to use that 1100 mah, 4 cell battery that came with the set. I just used my on-board batteries already installed in the aircraft. Typically, these are Two 5 cell packs of 1400 mah NiCd's in parallel. ( For those in Rio Linda, that 2.8 amps. )

But ............... I did process the Spektrum 1100 pack to store on the shelf. C-10 form charged it for 16 hours, and then cycled it 3 times on two different Chargers. All 3 times on two different chargers, it produced less then 550 mah.

I sh.. canned the Spektrum 1100 mah pack ! [>:]

> Jim

Upnet

My Feedback: (8)

Aviti, It's a Hobbico digital. I have no idea what the load is.

I guess the next step would be to buy a much better ESV...........

blkbird68

My Feedback: (19)

not a bad idea, but the 250ma load of the Hobbico meter is still significantly more than the system should have seen at idle with only the servos you had connected. Unless something was seriously wrong like the throttle servo bottomed out.

Flying Geezer

My Feedback: (14)

You can only speculate what the battery voltage was at the time of the lockout. If you had a logging meter attached during your setup you could see low voltage spikes, short of that, all is pure speculation.

When a 4 cell battery drops below 4.8 volts it is depleted. Many people think that battery voltage sinks away as a linear process, but this is not true. After the pack drops below 4.8 volts, and especially down to 4.5 volts, there is very little current left in the pack. Very small changes in load will bounce that pack up and down significantly.

After the lock-out there is a reduction in the load. The battery has a chance to "bounce" a little. You put a relatively small and consistant load from a hobbico voltmeter for 15 sec. and you may see a steady 4.5 volts for that period of time. If you had held it for a minute or so, I can assure you it would haver dropped way down.

Then you pull it out of the circuit, another chance for a little "bounce", then you make a quick test again and it looks like 4.5 volts.

Then simple fact is that you were trying to test a "dead" battery. Once you drop down to less than 4.8 volts with a 4 cell pack the battery is dead. Voltage readings mean nothing a 4.5 volts except the battery is dead.

If you lay that pack aside for half an hour, nothing connected, you will get a no load reading of about 4.8 volts. And a loaded reading well above the 4.5 you were reading, but only for a short time.

Try it some time.

rlmcnii

My Feedback: (3)

FG,
You sure are correct about the variable rate at which the voltage drops during discharge. Cheap Battery Packs, and probably many others including some mfgs., have discharge curves for their cells on-line. One can study those curves and see a graphic representation of the rapidity with which the voltage drops once a cell has gone a couple of tenths below nominal. It is eye-opening. (This would apply to those of us who do not have access to a scope to generate our own curves!)
AA cells tend to have high internal resistance and because of that would be more subject to voltage drops under load than would a similar capacity (MAh) cell of different configuration. There are better cells of similar weight available. AAs are good in a Tx and not much in the air.
A .25 amp load in a loaded meter sounds pretty low. I normally check batteries with a 1 amp load.
OEM batteries may be of questionable quality and of questionable origin. This is not a criticism of Spektrum or the poster..just an observation.
Most Sanyo cells are made in China now. Are they up to their former quality????? One wonders.
There is probably no substitute for a good charger/cycler. Again, this is not a criticism of Tritons or the poster. I do not use a Trition and have no first-hand knowledge thereof.
5-cell packs sound like a worthwhile expenditure.
4.5 in a 4-cell pack is a DEAD pack.
Glad it all happened on the bench.
pax vobiscum

DadsToysBG

My Feedback: (35)

Just a side note on batteries. This time of year I pull all my batteries out and cycle them. Most are Expert brand from Horizon. They are all 2700ma 6v NiM. All eight, a few over 4 years old cycled 120% of rating. I keed a log in the shop of dates and times. Just thought I add this. I use a Hughs RC Spectra 4. It does four batteries at a time. Dennis

aviti

My Feedback: (54)

We have no idea what the load was on the plane but it is rather clear the battery was darn low if it read 4.5 volts with a 250 mah load. Put a 1 amp load on the same battery and I bet it drops at least a full volt. Just to be on the safe side with Spektrum, I'd say treat the low voltage cutoff at 4.5 volts and plan your battery power accordingly.