Spektrum Dx5e and battery power (a tale of woe).

[kevinm]

Originally Posted by williamk

Hello,

Have (had) an Eflite Apprentice with the Spektrum Dx5e transmitter. Had the original Alkaline double A batteries in it. Had been to the flying field about 9 times with it and was still showing 3 out of 4 LED lights on the charge indicator (75% power?). Was flying with a fully charged lipo battery in the plane when I noticed the plane was not responding well to my inputs, so I tried to bring it down. All the sudden I lost all control and the plane went to full throttle. Result was a full speed nose dive into the ground. Major bummer. After the crash I looked at the charge indicator and I was down to 2 out of 4 lights.

So my questions are. What did I do wrong and how can I prevent this from happening again? Another question would be could something else have caused the signal loss? Should I take it that the charge indicator lights are not that accurate? I am pretty new to the hobby so your advice is appreciated.

IME, battery meters are not to be trusted-at all - theyll indicate alls welll when one or more of the AA alkalines is below 1.4 volts- nearly dead - i just check each battery individually , it can be done without removing them , and i always put a thin film of oil on the battery ends- -it really helps keep them electrons moving from cell to cell

[kevinm]

Originally Posted by kyleservicetech

williamk
I've not been a fan of any radio that uses alkaline cells. Why? How many times have you had to "shake" your flashlite to make it come on?

I'd much rather have soldered or welded connections to your batteries than pressure contacts to the single use cells.

if you lightly oil all of your battery ends, you wont have to shake it (transmitter included, lol ) unless its badly designed flashlight -oil really keeps them dogies (electrons) movin' movin' movin'-- but yes plug in packs are better , (cheaper in the long run ) taking half dead batterys out of a transmitter gets old - still good for something, but im up to my ears in flashlight usable AAs
rechargables dont get to the voltage nessessary even when theyre charged- 1.2 volts x8 isnt enough for a 12v Tx

[ragazo]

Hi Guys, great to find a forum like this!
I assume this post is not perfectly placed but somehow it fits the topic. I recently bought a Spektrum DX5e receiver and Transmitter - both without batteries. Can you give me specific advices (maybe links for concrete products) what battery I should buy for the receiver and for the transmitter. I will use it in a glider, no throttle necessary. Also re the receiver, you write about a lamp that indicates the amount of charge. I assume I will need to buy that also. Could you please also give me advice? Sorry for posting these questions, I am back in business after 20 years ...

Thank you for any support!

[slipstick]

Best cells for the transmitter are Sanyo Eneloop rechargeables (IMO at least).

Best battery for receiver will be a 4 cell NiMH pack. The size depends on the size of the glider and what servos you're using.

Where to buy will depend on where in the world you live.

Steve

[pmullen503]

+1 on the eneloop batteries. Invest in a good charger/analyzer.

[ragazo]

Thank you very much already. Never heared of eneloop, will consider it! Re. the receiver: I will fly an Amigo III from Graupner (span 2m), I have two TopLine Servos RS-2 (torque 3.2 kg/cm with 4.8V) for the rudders and one mini servo 10G (torque 1.2 kg/cm with
4.8V) to control the unhooking process. What battery package do I need? I live in NY, Internet order appreciated. What is a good charger? And what is an analyzer?!? (ok, very stupid question I assume)
How can I determine the charging state at the receiver - is that the analyzer (which basically would fly with the plane)?

Thanks again!

[pmullen503]

Get a microprocessor controlled charger that not only puts a charge on the battery but tells you how many milliamps it took to charge the battery. Something like this:http://www.valuehobby.com/power-systems/chargers/gt-power-x-charger-c6-6s-lipo-charger-with-power-supply.html

For the eneloops I have a Maha 9000. It will do anything for Nimh batteries that you can think of. It also has an analyse function where it will automatically top off, discharge, and recharge the battery to determine capacity. That allows you to match the cells for use and allows you to identify failing cells.

[kyleservicetech]

Originally Posted by ragazo

Thank you very much already. Never heared of eneloop, will consider it! Re. the receiver: I will fly an Amigo III from Graupner (span 2m), I have two TopLine Servos RS-2 (torque 3.2 kg/cm with 4.8V) for the rudders and one mini servo 10G (torque 1.2 kg/cm with
4.8V) to control the unhooking process. What battery package do I need? I live in NY, Internet order appreciated. What is a good charger? And what is an analyzer?!? (ok, very stupid question I assume)
How can I determine the charging state at the receiver - is that the analyzer (which basically would fly with the plane)?

Thanks again!

Here is where I bought my Eneloop batteries:
http://www.batteriesamerica.com/newpage3.htm

Question, does any supplier provide these packs all ready built up?

[Turner]

Tx pack or Rx pack, or maybe both:

http://www.batteriesamerica.com/newpage8.htm
http://www.radicalrc.com/shop/index.php?cat=20&shop=1&
http://www.cheapbatterypacks.com/Cus...r.aspx?mid=390
http://www.hangtimes.com/txpacks.html
http://www.canuckengineering.com/new...ry-pack-square

[kyleservicetech]

Originally Posted by Turner

Tx pack or Rx pack, or maybe both:

http://www.batteriesamerica.com/newpage8.htm
http://www.radicalrc.com/shop/index.php?cat=20&shop=1&
http://www.cheapbatterypacks.com/Cus...r.aspx?mid=390
http://www.hangtimes.com/txpacks.html
http://www.canuckengineering.com/new...ry-pack-square

Good information, thanks!

Interesting, Radicalrc indicates that these cells should NOT be fast charged for long life. I've always charged mine at a 12 hour rate, and finally had to replace my DX7 transmitter battery last fall after 4 years of service.

That battery still worked, but only had about 75% of original capacity.

[Turner]

I'm still using my oem pack in my DX7 but will probably go with eneloops when I need to replace it. I've gone all in on eneloops and use them in everything we have with AA or AAA cells.

[ragazo]

that's all very valuable information, thanks again. to summarize what I understood/not understood:

- eneloop for receiver AND transmitter is the recommendation, right?
- the receiver needs a pre build-up assembly (plastic around and cable attached) but the battery is technically the same as for the transmitter, which has single batteries?

- you recommend two chargers, one microprozessor controlled for the receive package with cable connection and the Maha for loose batteries like the ones in the transmitter (and for the general household). is that correct? question: if I would have a box, where I could put let's say four batteries in and where a cable is connected to that box, couldn't I just use the microprocessor controlled charger? so far I understand the the connect ability of the microprocessor controlled charger is limited and therefor I would need a second one, or are there other technical reasons to have two chargers?
- the battery package on the first website states: "NEW - SANYO eneloop battery packs for SPEKTRUM DX7s, DX8". Actually the reason why I initially posted was, if it is written like that, is the battery then also good for the DX5e? What size is best for my purpose (I descibed above my equipment)? If the weight is the same, why shouldn't I go for the strongest (2500mAh instead of 2000mAh)? And asked a little bit more specific - using a glider where weight counts most - what is the best battery type delivering the power I need (three servos) and that is also very light! Is NiMh (eneloop) also the best answer to that question? I assume you could say I am seeking for the highest power/weight density.
- Last remaining question: If I want to build in LEDs to check the charging status in the plane, does that exist, is it sensible to build that in, and what and where can I get for that purpose?

Thanks!

[kyleservicetech]

Originally Posted by ragazo

If I want to build in LEDs to check the charging status in the plane, does that exist, is it sensible to build that in, and what and where can I get for that purpose?

Thanks!

If you're looking for some sort of an on board indicator to show state of charge of a typical Nih "AA" receiver battery, IMHO, I will not use one.

Several years ago I ran tests with a $350 Fluke 87V digital multimeter that showed the voltage of a Nih cell has little relation of its state of charge.

(One of those tests involved completely discharging the four cell AA Nih battery down to one volt per cell. Then with a charger, exactly 10% of its milliampere capacity was put back into the battery. A check on that receiver pack showed that the battery voltage with a 10% charge was within one percent of the voltage of the fully charged battery pack. I've done this more than a few times.)

[slipstick]

As a matter of interest, did you run your tests with a load on the battery ? I've long known that unloaded NiXX voltage meant nothing but I thought the voltage under a more or less representative load was a bit more meaningful.

Steve

[Rodneh]

If you measure the voltage of any Nixx type battery under load, the voltage can be quite a good indicator of the state of charge. You really need to run a graph of the voltage versus time at a constant load to have a reference to compare the reading to. The discharge curve is quite flat but it does have a slope that will allow (with a meter with decent accuracy) to get a reasonably accurate measure of "state of charge".

[kyleservicetech]

Originally Posted by slipstick

As a matter of interest, did you run your tests with a load on the battery ? I've long known that unloaded NiXX voltage meant nothing but I thought the voltage under a more or less representative load was a bit more meaningful.

Steve

Yes, that test in posting #38 was at a 400 milliampere load.

Again, after many years of playing with these type batteries, IMHO it is not safe to depend on a simple voltage test either with, or without a load to determine if it's safe to fly.

Take a look at the attached file on a one year old Hickel Hydride transmitter battery. This test was completed yesterday. First, the battery was given a standard 150 Milliampere charge for exactly 12 hours. Imediately after the charge cycle, the first load discharge curve test was conducted. Take a look at the attached load test graphs.

The black curve shows the results at a 0.5 Ampere load discharge cycle using my Western Mountain CBA battery analyzer.

The battery was again charged at 150 Ma for 12 hours. The battery was then put aside for three days. The discharge test was then repeated.

The Red curve shows the results at the same 0.5 Ampere load discharge cycle using the same CBA analyzer. Note how flat the discharge curve is on the second discharge cycle. Also note how fast that battery voltage fell off near the end of the discharge cycle.

Seeing just how flat that discharge curve is for test #2, you have no idea if your quick load test is at 90% capacity, or 10% capacity.

This is one reason my club members that fly giant scale models with gasoline engines up front are going to the LiFe, or A123 batteries for receiver/servo power. Some of the big twin cylinder models have primary/secondary A123 cells. With these type cells, if you measure 3.60 Volts per cell under no load, you can be certain the battery is fully charged.

(At work, before retiring some of our older high voltage circuit breaker controls used Nicad batteries for battery backup power. Don't know how many times I had to tell customers that the battery voltage under load test was not reliable enough to determine if the battery could trip and automatically reclose the high voltage circuit breaker. When you're dealing with high voltage fault currents of up to 12,000 Amps at 38,000 volts three phase, that information is important.)

[ragazo]

Kyle, your answer is very enlightening and interesting - thank you! We came to that through my last question, re measure the charge in the plane, but I still would need some answers to really order some stuff and get started.

1 - Disregarding the voltage measure topic, eneloops are recommended for both, transmitter and receiver?
2 - Would a LiFe or A123 work for a glider? Honestly I would not mind to just always be sure to load the batteries before flying and ensure by loadtime that they are loaded at least enough, so they do their job while flying, so this voltage measuring argument does not really count for me. But if the A123 or LiFe are significantly lighter, then it becomes interesting! Are they?
3 - The difference between the receiver battery (package) and the transmitter battery (singles) is just wrapping and the cables attached to the receiver battery?
4 - For a glider, what is the lightest battery type (NiMh, NiCd, LiPo, LiIon,... ) providing a nescessary capacity over a certain time? Let's forget about the price for a moment. Is it still eneloop?
5 - Specific for my plane: for an Amigo with a Spektrum DX5a with two bigger servos and one mini, what battery type do I need?
6- If the weight is the same, why should I not just take the battery with the highest electrical capacity?
7 - If the manufacturer wrote for "Spektrum DX7, DX8" is there a problem to use it with the DX5e? http://www.batteriesamerica.com/newpage8.htm
8 - Why do I need two chargers (microprocessor AND Maha)?

Sorry for asking all these questions, I really appreciate the effort someone would make to answer briefly!

Thank you

[Rodneh]

Ragazo, Eneloops are most always a very good choice for a transmitter but not always for a receiver. It depends on the current demands of your airborne system. If it is quite high, you will get in trouble with any power source that has a high internal impedance. Now NiMh's have a higher internal impedance than NiCads and the smaller capacity batteries usually a higher impedance than larger capacity batteries. There is also a difference between battery brands. Now, Eneloops do have a high enough internal impedance to cause some concern if you are using servos with a high peak current demand (digital servos are bad in this respect). You can get around this by using a higher capacity battery, by paralleling batteries (two in parallel will have half as much internal impedance driving the same load) or using a different type of battery. The form factor also seems to have some effect, the short fat cells are usually the ones with the lower internal impedance.

[kyleservicetech]

Originally Posted by Rodneh

Ragazo, Eneloops are most always a very good choice for a transmitter but not always for a receiver. It depends on the current demands of your airborne system. If it is quite high, you will get in trouble with any power source that has a high internal impedance. Now NiMh's have a higher internal impedance than NiCads and the smaller capacity batteries usually a higher impedance than larger capacity batteries. There is also a difference between battery brands. Now, Eneloops do have a high enough internal impedance to cause some concern if you are using servos with a high peak current demand (digital servos are bad in this respect). You can get around this by using a higher capacity battery, by paralleling batteries (two in parallel will have half as much internal impedance driving the same load) or using a different type of battery. The form factor also seems to have some effect, the short fat cells are usually the ones with the lower internal impedance.

These are very good points.

IMHO, you need to be very careful in using those "AA" sized Nih receiver batteries in any model with more than perhaps four standard (non-digital) servos. I've got two models with seven Hitec 645MG servos. Peak current required by just moving the transmitter sticks round and round was measured at 14 AMPS! That 14 Amps was measured with a $350 Fluke 87V digital multimeter.

An option, and a good option is those LiFe batteries, available in a few different sizes. The A123's are also excellent, but they are fairly large in size. The 2300 Mah A123's weigh in at 2.6 ounces per cell.

Nice thing about the A123 and LiFe batteries, if your receiver/servos can handle a 5 cell Nih battery pack, it can also handle a two cell LiFe pack. They have the same voltage.

Take a look:
http://www.wattflyer.com/forums/showthread.php?t=62916

[CNY_Dave]

It's an old thread (the OP part anyway) but still relevant- the OPs problem may have been the DX5 power switch problem where the LEDs may stay lit but the TX portion stops transmitting. This happened to me, and has been seen more than a few times. There's a youtube vid of someone demonstrating the problem. In the vid the TX comers back to life, in my case sometimes it didn't until I power cycled.

Faulty Spektrum DX5e Radio

Opened up my troublesome DX5e yesterday, as some have I also also found the slider did not seem to be allowing the switch to travel all the way to either the 'on' or 'off' positions, the 'off' position might not seem to be a problem but the 'off' contacts seem to be involved in the trainer port, so some of the circuit is different when using it as a buddy box.

Something interesting I saw on the 'off' contacts, I was ohming the critter out and saw a dozen ohms across one pair of the 'off' contacts and 200 on the other pair, after working the switch directly a few times with the slider off this dropped to 1-2 ohms.

I think this shows an important component of the failure, that being full travel of the switch is critical to fully wiping off the oxide buildup on the contacts, probably when you set the switch to off or on the contacts actually travel a bit past their rest position, but when restrained by the slider slot the contacts just bulldoze crud up to bu not past their rest position.

Another aspect I also found is that if the switch was not fully in the 'on' position, the long switch arm restrained from the last bit of travel, the entire switch arm is 'rocked' back a tiny bit (tilted towards the 'off' position), so not only are the contacts not fully in position, but the spring pressure on them is actually reduced because if the arm is cocked, so is the actual slider in the switch. In this condition the degree of contact was very susceptible to very small motions of the switch arm.

So it seems like the problem is a perfect storm of crud buildup and reduced pressure on the contacts and the arm being able to transmit tiny motions right through to the contacts, all due to the slider not letting the switch achieve full travel.

What's funny is the hole in the plastic looks adequate, but the thick plastic decal actually has a slightly smaller hole.

Dave

[HobbyJumper]

A worthy thread. Much as I loved my DX5e when I first got back into RC, it was eventually prone to cutting out, unbinding, etc, as above, and caused a few crashes. I wouldn't recommend it to anyone other than a micro flyer on a tight budget.

Once I made the move to the DX6i my life got a lot better.

[Rodneh]

My DX5 started to lose bind and sometimes not rebind. Battery voltage was okay and the indictator LEDs on the panel light up. Checking with a field strength meter showed that the unit would stop any RF output. Playing with the switch (tapping on it and putting a little pressure on it) would cause the unit to start working intermittently. Further testing proved that the switch was not always making good contact, the LED's still lit but the RF section stopped any output. After repeated cycling of the switch and checking the solder joints on the PC board (I opened the unit up to see the switch contacts where they are soldered to the board) the intermittent failures stopped but I am not trusting it on anything but the cheap foamies now. Just a warning, just because the LED lights when you turn on the switch does not guarantee that the RF section is putting out any power.

[zoltron55]

so what I am thinking if you put a better switch on this tx this problem will be solved. has anyone tried that

[CNY_Dave]

Yes, you can use a DPDT switch, remove the slider switch and wire it up with wire, mount it somewhere through the case, someone else just soldered the holes of the switch to the 'on' position and used a SPST switch in the + battery wire. If you do that it won't work as a buddy box, I think.

Haven't used mine yet, too early to tell if the fix I applied will be permanent.