LiPo replacement for Spektrum Tx Li-Ion - care and maintenance?

[Keith Miles 2]

A sincere apology!

I recently attributed a comment to the wrong contributor when I said, in a response to Richard “Maybe at least one contributor is considerably younger than you or I.....”

It was, in fact, Richard who prompted the comment!

OOOPS!

[Keith Miles 2]

Posted by Bob Cotsford on 01/08/2020 10:01:40:

Once upon a time I ran models with glow and petrol motors, most of which were fitted with 2S LiFe packs to power the electronics. What I found was that for most medium size (90-120 4 stroke) models after 4 or so flights I was putting 150-200 mAh charge back in, and that was with a few digital servos in use, but no 3D antics!

For most club sports models I found 1100mAh packs plenty, the exceptions being where more current hungry servos needed something more robust to maintain voltage levels. For those I found the cheap Zippy LiFe packs needed replacing with metal can A123 packs. Total energy consumption on these models was little more than for models running standard servos, the difference was in the peak current demanded.

Useful info there, Bob. I was wondering about digital servos, should I ever decide to buy any! Thus far, I’ve not felt the need to do so for the type of flying that I do.

I can see why different cell chemistry or larger capacity can reduce actual or potential voltage drop issues and in case anyone has misunderstood, my earlier comments about this were entirely related to higher capacity cells of the same chemistry whilst also maintaining the same physical size as in the case of AA, AAA etc.

There does seem to be a fairly common misconception, for example, that a 4-cell 2000mah AA Rx pack will perform equally as well as a 4-cell 1000mah AA Rx pack when, in fact, there is a trade off, although this might not be an issue, in practice, dependant on the load.

Again we seem to have strayed off topic but it’s all good stuff which hopefully, helps to divert our attention away from the negative effects of Covid19!

[Richard Clark 2]

Posted by Keith Miles 2 on 01/08/2020 10:55:37:

Posted by Bob Cotsford on 01/08/2020 10:01:40:

Once upon a time I ran models with glow and petrol motors, most of which were fitted with 2S LiFe packs to power the electronics. What I found was that for most medium size (90-120 4 stroke) models after 4 or so flights I was putting 150-200 mAh charge back in, and that was with a few digital servos in use, but no 3D antics!

For most club sports models I found 1100mAh packs plenty, the exceptions being where more current hungry servos needed something more robust to maintain voltage levels. For those I found the cheap Zippy LiFe packs needed replacing with metal can A123 packs. Total energy consumption on these models was little more than for models running standard servos, the difference was in the peak current demanded.

Useful info there, Bob. I was wondering about digital servos, should I ever decide to buy any! Thus far, I’ve not felt the need to do so for the type of flying that I do.

I can see why different cell chemistry or larger capacity can reduce actual or potential voltage drop issues and in case anyone has misunderstood, my earlier comments about this were entirely related to higher capacity cells of the same chemistry whilst also maintaining the same physical size as in the case of AA, AAA etc.

There does seem to be a fairly common misconception, for example, that a 4-cell 2000mah AA Rx pack will perform equally as well as a 4-cell 1000mah AA Rx pack when, in fact, there is a trade off, although this might not be an issue, in practice, dependant on the load.

Again we seem to have strayed off topic but it’s all good stuff which hopefully, helps to divert our attention away from the negative effects of Covid19!

The only time I've noticed any difference is on a big heli. I replaced the £12 JR analog servos with £55 Multiplex 'Profi' digital servos and it made a big difference.

Our radios are not truly 'digital' anyway. Because the stick potentiometers (or hall effect sensors) are analog, the pots in the servos are analog, and the transmission is a chain of variable length pulses.

The stuff in between these items may be digital but the overall system isn't. There are several analog to digital or digital to analog conversions going on.

[Keith Miles 2]

Thanks to all for your contributions, including the usual thread drift!

One item of interest was Pete Christy’s comment about the 2.4 GHz current demand compared to 35 MHz (and perhaps 27 MHz?). I didn’t know that.

I will assume, however, that this was referring to power consumed to perform the function of producing the radio signal because it immediately seemed to me, on moving to 2.4 GHz, that modern sets did, and do, seem far more power hungry. This, however, is presumably due to the additional features and computerisation!

As for my DX9, I can certainly see why a non-Spektrum, externally chargeable Lithium type battery is a preferred conversion as the Spektrum ones with the latter’s single lead, 2-pin PCB plug and internal balancing electronics are clearly optimised for onboard (and relatively slow) charging at 0.5A, Spektrum batteries ain’t cheap, either, compared to at least one less “dedicated” and more flexible, option of double the capacity, available from 4-Max!

And I would suspect that few RC hobbyists these days have no use for a modern multi-charger, if only a low priced one!

”Dedicated” batteries seem to be, all too often, one of the downsides of much modern technology and sometimes prematurely rendering otherwise functional equipment obsolete! Grrrr!

Edited By Keith Miles 2 on 02/08/2020 13:10:26

[Richard Clark 2]

Posted by Keith Miles 2 on 02/08/2020 13:09:21:

Thanks to all for your contributions, including the usual thread drift!

One item of interest was Pete Christy’s comment about the 2.4 GHz current demand compared to 35 MHz (and perhaps 27 MHz?). I didn’t know that.

I will assume, however, that this was referring to power consumed to perform the function of producing the radio signal because it immediately seemed to me, on moving to 2.4 GHz, that modern sets did, and do, seem far more power hungry. This, however, is presumably due to the additional features and computerisation!

As for my DX9, I can certainly see why a non-Spektrum, externally chargeable Lithium type battery is a preferred conversion as the Spektrum ones with the latter’s single lead, 2-pin PCB plug and internal balancing electronics are clearly optimised for onboard (and relatively slow) charging at 0.5A, Spektrum batteries ain’t cheap, either, compared to at least one less “dedicated” and more flexible, option of double the capacity, available from 4-Max!

And I would suspect that few RC hobbyists these days have no use for a modern multi-charger, if only a low priced one!

”Dedicated” batteries seem to be, all too often, one of the downsides of much modern technology and sometimes prematurely rendering otherwise functional equipment obsolete! Grrrr!

Edited By Keith Miles 2 on 02/08/2020 13:10:26

The Spektrum batteries (and Futaba ones too) are grotesquely overpriced.

EG: RS Components (once called Radiospares) is very old established and is the largest electronic component supplier in the UK. It is the automatic 'go to' place for much of the UK electronics industry, including foreign owned UK divisions such as IBM, but deals with the public as well.

The most common Lithium rechargeable battery is the '18650' 2.6 Ah and is used by everyone from Bosch garden tools to Tesla cars. The Ah capacity varies somewhat from make to make.  I don't know who makes the RS supplied ones.

£6.92 plus VAT each from RS. If they are the right physical size you would need two. You could take the original battery casing case apart and install these keeping any original Spektrum; protection/charging circuit.

Edited By Richard Clark 2 on 02/08/2020 13:51:08

[Keith Miles 2]

Posted by Richard Clark 2 on 02/08/2020 13:42:11

The Spektrum batteries (and Futaba ones too) are grotesquely overpriced.

EG: RS Components (once called Radiospares) is very old established and is the largest electronic component supplier in the UK. It is the automatic 'go to' place for much of the UK electronics industry, included foreign owned UK divisions such as IBM, but deals with the public as well.

The most common Lithium rechargeable battery is thr '18650' 2.6 Ah and iis used by everyone from Bosch garden tools to Tesla cars.

£6.92 plus VAT each from RS. If they are the right physical size you would need two. You could take the original battery casing case apart and install these keeping any original Spektrum s; protection/charging circuit.

Edited By Richard Clark 2 on 02/08/2020 13:43:18

All “original equipment” tends to be overpriced!

Yes, I am very aware of RS. My former employers had an account with them and I have occasionally used them myself for less widely available components. They, too can very expensive compared to other suppliers but they have always offered massive stocks and good service. In fact, they now have a very large warehouse about five minutes from my house!

As for your suggestion, too much “faff” for my tastes when one can buy a “drop-in” alternative for not much more money. Also, the idea of keeping the protection/charging circuit suggests continuing with onboard slow charging as opposed to external fast charging which defeats the whole object.

The 4-Max 4000 2S one can be balance charged at 4A, externally, in exactly the same way as other Li-POs.

Any onboard charging of a battery within the DX9 transmitter is limited to 0.5A and is not adjustable. Only the battery type can be selected i.e. Li-Po/Li-Ion OR NiMh.

[Keith Miles 2]

Further to my last post I decided, out of pure curiosity to check out those 18650 cells mentioned and my question is this, in the context of “faff”.

Even if it could be made to fit the transmitter, why would anyone want to go to all the trouble of having to solder two cheap cells together, dismantle an otherwise good and relatively expensive one, merely to use the latter’s internal electronics with the former (more soldering) to create a “home brew” pack that would take even longer to charge in the transmitter than the now destroyed, and previously neat and serviceable original and all to save about 12 quid?

Please accept my sincere apologies if this was a wind-up and it went over my head!

 

 

Edited By Keith Miles 2 on 02/08/2020 22:26:38

[Keith Miles 2]

ERRATA!

I stated that the maximum charge rate of the Tx internal charging circuit was 0.5A. It is 0.2A, which I knew, but somehow forgot!

Duh!

It did occur to me that it used to take a great deal longer than three or fours to charge the original 2000mah battery!

[leccyflyer]

I have a DX7 and an Futaba FF9,l both fitted with the aftermarket Hobbyking 3s1p 1500mah LiFe packs which I now charge at 0.8c and takes about an hour an a half. I balance charge in the transmitter, through the non-used lead, with the balancer also connected. It's relatively quick and hassle free, but, even with LiFe I want to be in attendance whilst charging. My DX9, with it's dedicated low current charger is even less hassle - just plug in occasionally , happy to leave it unattended and a few hours later the little charging light on the front goes off and it;s done.

In comparison to the weekly, or even daily, 12 =14 hour overnight charging of yesteryear's 35mhz transmitters it much quicker and the lower current requirements of 2.4ghz makes charging an occasional rather than daily occurrence. For the cost I wouldn'y personally consider making up bespoke packs for transmitter use, neither would I use normal LiPo packs requiring rather more care in use than the less volatile LiFes. The only downside I can see is the described feature where the voltage falls off a cliff with LiFe, reading as fine right up until there isn't enough grunt to carry on flying,. AFAIK I've never got close to that. I did puff one LiFE pack through leaving the TX on, which killed that battery-since then I have also gone to 0.8c charging instead of 1.0C.

[Richard Clark 2]

Posted by Keith Miles 2 on 03/08/2020 04:37:14:

ERRATA!

I stated that the maximum charge rate of the Tx internal charging circuit was 0.5A. It is 0.2A, which I knew, but somehow forgot!

Duh!

It did occur to me that it used to take a great deal longer than three or fours to charge the original 2000mah battery!

 

Looking at your post and also bearing in mind leccyflyer's post above, 0.2 Amps is crazy low.

Even the Futaba M6 that I owned in the mid 1970s came with a charger that provided 0.5 Amps for the transmitter and 0.2 Amps for the receiver pack. (Which is sometimes of a lower capacity than the transmitter battery, but  if they are the same capacity you can use the transmitter outlet but if you do  you can't charge the transmitter at 0.5 Amps simultaneously)

My early 1990s JR was the same.

And my modern Multiplex radio doesn't come with a charger but says 'up to 1.5 Amps'. So I use the same 'multi purpose' American 'Thunder Power' charger that charges all commonly available battery chemistries at any charge currents up to 30 Amps and any battery voltages up to 50 volts (14S Lipo for example) you choose to set.

It is 'normal' that the charger sets the charge current. Maybe the Spektrum is  unusual in this respect.

Edited By Richard Clark 2 on 03/08/2020 09:20:48

[Former Member]

[This posting has been removed]

[Keith Miles 2]

Posted by Steve J on 03/08/2020 09:49:48:

Posted by Richard Clark 2 on 03/08/2020 09:15:13:

0.2 Amps is crazy low.

200mA is the slow charge rate for a 2000mAh NiMH.

 

True on both counts but slow charging never bothered us in the old days nor was there any debate about differing cell types!

Any internal charger, though, will only be capable of low current because, due to the laws of physics, size matters, as does heat dissipation, in addition to any fire risk considerations!

The DX9, at least, has an internal charger which, according to the manual, is for use with the supplied Spektrum 2000mah Li-Ion and external adaptor and the internal charger is designed to work with a Li-Ion battery that has inbuilt electronics for balancing and cut-off. The manual does not make this clear which probably explains much apparent confusion especially amongst the uninitiated.

Until recently, it seems, only Spektrum offered a battery with the necessary internal electronics for onboard charging in their transmitters so maybe they’ll come up with something else to restore the initial monopoly? That said, unlike some, I have no complaint with Spektrum. It has served me well so far as has their customer service on a couple of occasions.

As for the debate surrounding the merits of varying chemistries I, too, take the view that in-depth comparisons of operational performance is of minimal relevance where transmitters are concerned, given the very low power demand. What turns you on, I suppose (pardon the pun) but I believe in K.I.S.S.

P.S. I have since noted that some have fitted batteries that have a JST connector which, apparently, has the same pin spacing as the Spektrum PCB plug. Not sure that I would totally trust that myself, though, without further investigation.

Edited By Keith Miles 2 on 03/08/2020 13:18:58

[Keith Miles 2]

I decided to check out that rival “intelligent” battery that I was told about.

Bearing in mind that the “intelligence” would seem to be of little benefit to anyone with a modern “intelligent” multi-charger (the vast majority of us, I would think), and is possibly optimised for use with the relatively very limited capabilities of an internal Tx charging circuit, I note that the “rival” is, seemingly, a Turnigy 2S “intelligent” battery of 4000mah.

So, yes, for a relatively low cost of 17 quid, you actually get more than a rival for the original and twice the capacity BUT with a directly consequential doubling of the time it would take to fully charge it (about 20 hours!) using the Tx and adaptor!

So, again, for me at least, I have yet to see a quicker, simpler or better “upgrade” than the “unintelligent” and immediately more flexible option than that offered by 4-Max which has main power lead with JST connector, balance lead and separate lead with plug for the PCB.

And no, I’m not receiving a “bung”.

And purely to satisfy my curiousity, I have fired off an e-mail to Spektrum regarding compatibility of, at least, their “intelligent” battery with external chargers as the manual is not clear on this, merely advising in non-specific terms.

[leccyflyer]

Posted by Keith Miles 2 on 03/08/2020 16:21:11:

I decided to check out that rival “intelligent” battery that I was told about.

Bearing in mind that the “intelligence” would seem to be of little benefit to anyone with a modern “intelligent” multi-charger (the vast majority of us, I would think), and is possibly optimised for use with the relatively very limited capabilities of an internal Tx charging circuit, I note that the “rival” is, seemingly, a Turnigy 2S “intelligent” battery of 4000mah.

So, yes, for a relatively low cost of 17 quid, you actually get more than a rival for the original and twice the capacity BUT with a directly consequential doubling of the time it would take to fully charge it (about 20 hours!) using the Tx and adaptor!

So, again, for me at least, I have yet to see a quicker, simpler or better “upgrade” than the “unintelligent” and immediately more flexible option than that offered by 4-Max which has main power lead with JST connector, balance lead and separate lead with plug for the PCB.

And no, I’m not receiving a “bung”.

And purely to satisfy my curiousity, I have fired off an e-mail to Spektrum regarding compatibility of, at least, their “intelligent” battery with external chargers as the manual is not clear on this, merely advising in non-specific terms.

It;s still a lipo though Keith, so presumably not to be left charging unattended?

The Hobbyking LiFe TX packs have a Futaba lead, A Spektrum lead and a JXT balancing lead so that avoids the undesireable requirement to break and make the main connection to the transmitter whilst charging. IMO it isn;t good practice to regularly disconnect the battery on that transmitter connection to make every charge.

[Richard Clark 2]

Posted by Steve J on 03/08/2020 09:49:48:

Posted by Richard Clark 2 on 03/08/2020 09:15:13:

0.2 Amps is crazy low.

200mA is the slow charge rate for a 2000mAh NiMH.

The MacGregor wall wart charger that I use for my JR PCM9XII and DSX9 (which is effectively a PCM9XII with a Spektrum RF unit) puts out 110mA which is below 0.1C for the NiMHs that these transmitters were supplied with.

My DX9 (2000mAh Li-Ion) goes on charge for a few hours between flying sessions. No problem. I hate to think how many devices with lithium batteries are plugged into chargers in my house at any give time.

 

Quite.

On the top of our microwave oven there are about 10 'lithium' chargers, not including the model plane ones which are somewhere else. Some are 'wall wart' type, some have a mains cable. They range from a Philips shaver one, through a usb Apple charger to a Bosch 18 cell hedge trimmer charger. All the cables are tangled up and there are only two adjacent mains sockets. If you want to charge any one item it's a right pain. You have to find the appropriate charging cable and then match it to the appropriate mains plug. Pulling the charge plug to see which mains plug moves doesn't work as the  tangle is too tight . Sorting ir all out once a week is hopeless as they get tangled up again far quicker than that

Edited By Richard Clark 2 on 03/08/2020 19:35:49

[Richard Clark 2]

Posted by Keith Miles 2 on 31/07/2020 21:47:07:

.........My I-Charger 208B, in the base settings menu, has separate provisions for Li-Po, Li-Ion and Li-Fe and the manual for it also quotes significantly different parameters for each cell type in terms of nominal voltage, maximum charge voltage, storage voltage, allowable fast charge and minimum discharge voltage cut-off level.........

 

 

 

Keith,

I have been re-reading this thread in an attempt to see where everyone now is as you certainly opened a can of worms

Even the I-Charger manufacturer is using the erratic and illogical terminology of "Li-Po, Li-Ion, and Li-Fe" though it's vaguely understandable to the more 'expert' modellers (modellers, 'expert' or no are of course his target) but probably not to other battery users, even 'professional' and 'industrial' ones.

He defines the first type by a casing method, the second is generic as it covers ALL lithium types including the other two, and the third uses the common 'convention' (it's not a 'standard' unfortunately) of defining a battery type by its two main chemicals, which at least makes some sort of sense.

 

A short history and I hope 'clarification'   for anyone interested.

The very first 'production' lithium batteries were developed by Israel in the  1970s  for military  use.  Due to my then employment I had access to these and used a few  successfully in rc model planes. They used lithium in 'pure metal' form and were  too volatile for 'civilian' use, even industrially. They are still sometimes used in military and space work. They have the   highest power density of all

Then came  lithium oxide batteries which are less volatile. In part of their construction they use  either cobalt (expensive but gives  high output voltage  and thus high power density), iron, or phosphates. The power density is not as high as ones containing  cobalt.

All varieties are available in all case formats and all are lithium ion.

 

Edited By Richard Clark 2 on 03/08/2020 21:14:41

[Keith Miles 2]

Sorry to open a “can of worms”! Indeed life was much simpler pre-lithium!

As for lithium types, they do, clearly, require different charging regimes and that is certainly an important issue to bear in mind quite apart from other considerations!

It also seems that the greatest cautionary advice and horror stories seem to be focused on Li-Po more than the other two, external charging inside a fire resistant bag being just one piece of advice which is not applied to mobile phones!

I also agree that constantly unplugging and reconnecting a Li-Po is probably not ideal but it’s another trade off for the benefit of being able to fast charge without the risk of damaging the Tx! The same argument could, of course, be made for power packs in electric models which suffer far more constant connection and disconnection and it so happens, one of our members recently experienced apparent uneven running of a motor which appears to have been caused by a weakened connection and overheating of the XT60s sufficient to prevent him from pulling the two halves apart without the eventual careful intervention of a narrow blade screwdriver! It took a good five minutes to separate them!

I am also not sure, aside from the general advice not to charge Li-Pos in-situ, if a battery should be left connected to the PCB internal charging circuit at all whilst it is being externally charged, especially at a much higher current rate but am happy to be advised accordingly.

[Keith Miles 2]

Just got a reply back from Horizon Hobby to my question as to whether or not the supplied Spektrum 2000mah Li-Ion battery that came with my DX9 can be charged with an external charger, bearing in mind the built in electronics of the battery and, presumably certain others of similar design.

As I suspected, their reply was as follows, quoting verbatim:

“It’s not possible to charge the batterie with an external charger. We recommend charging about the charge plug in the TX.

Mit freundlichen Grussen/Kind regards,

Matthias Trier

Horizon Hobby Europe

Technischer Service”

So, it’s either slow charge at 0.2 A for up to 10 hours (as per the Tx manual) or so or swap the supplied battery for something less “intelligent” and more convenient!

Or, perhaps, put an external independent charger in “Li-Ion/Charge” NOT “Balance Charge”, turn up the charge current to a desired level and see if the battery goes up in smoke?

I shall NOT be doing the latter (I fitted a 4-Max Li-Po some time ago) and I am NOT advocating that anyone else should do so unless they know better than either I (perfectly possible!) or the man who sent me the above e-mail (less likely?).

This is just some info for anyone who may have been wondering the same thing and/or may be frustrated by slow Tx charge times for the supplied battery using the supplied power adaptor plugged into the Tx (as per the manual).

 

 

 

Edited By Keith Miles 2 on 06/08/2020 21:42:22