HiTec HS-5745MG travel ?

awallin · Post by **awallin** » 28 Sep 2005, 13:44

Hi all,

I intend to use a HiTec HS-5745MG servo as the sail control on my next boat. Does anyone know what the maximum programmable travel on this servo is ?
I plan on getting the HFP-10 programmer or borrowing one sometime in the future but in the meantime I would like to design the sheeting system before building the boat...

If there is anyone using the 100mm SailsETC wheel with this winch, please could you post the details of it here: servo travel in degrees, how much is the wheel offset from center, what is the sheet travel achieved ?

thanks,

Anders

Nigel · Post by **Nigel** » 28 Sep 2005, 14:44

Hi Anders,

the 5745MG provides a max. travel of 140Â°

Just to add to your confusion I would also consider the HS 5995TG which is a new generation of robot servos. It comes in a "standard" servo housing and only ways 62g compared to >140g of the 5745MG.

It provides more than 50% more torque and has a max. travel of 180Â° and at about â‚¬ 100 it still doesn't break the bank.

Lester · Post by **Lester** » 28 Sep 2005, 15:05

Nigel wrote:Just to add to your confusion I would also consider the HS 5995TG

Hi Nigel

And just to add to the confusion I would not recommend this servo! I understand that it is very intolerant of a continuous load and overheats. All of the Hitec digital servos burn out very quickly if overloaded -- that is, if the sheeting line gets tied up for some reason, you do not realise this from the pond side, and you continue to have your stick at closehauled wondering why the sails to do not come in... An analogue servo is much more tolerant.

Some of the digital servos, like the 1/4 scale item Anders mentions, have built-in heat sinks, and they take around 30 or 40 seconds to burn out. (For comparison, an analogue servo will take somewhere between 5 and 10 minutes, and sometimes instead of burning out will just burst into flames.) The 5995 does not have a heat sink, and I think will burn out within around 10 seconds if you are not careful.

Of course, you could buy one of Ken Binks' thermal fuses, designed exactly to protect the Hitec digital winches, but I would expect the 5995 to trip such a fuse quite regularly when sailing at the top of No.1 rig.

Nigel · Post by **Nigel** » 28 Sep 2005, 15:29

That doesn't sound very good at all. I had considered using on of these on my next boat but I just might think again

I know that Heinz has installed a sail-servo on his Topiko but am not sure if he opted for the 5995TG or the 5745 as he offers both. I'll ask him and see what his experience is so far.

Another servo to consider is built by Volz problem with those is, that they actually do break the bank at > â‚¬ 250 a shot

Ohh, by the way Anders, which new boat are you considering

Olivier Cohen · Post by **Olivier Cohen** » 28 Sep 2005, 15:30

The Hitec 5998TG has a heat sink, and the same torque as 5745MG, but it's small size doesn't protect it from burning!

ReyNewman · Post by **ReyNewman** » 28 Sep 2005, 17:49

The 5745 is a good servo to use. I have been using its predecessor (5735) for over 3 years on one of my boats and it has performed flawlessly. It takes a lot of abuse...

As for the 5995TG, I have been using them on three other boats since they first came out last year and have not had any problems with them in terms of overheating, burning, etc... I have sailed the boat up to top of B rig conditions without problems and have had plenty of mishaps that caused the servo to stall (ie: stuck sheets) for a while without frying it.

I don't use a thermal or current fuse for the servo, but given its power, I do attach the sheets to a short length of 15lb line so if something goes wrong the servo doesn't rip something off the deck - the 15lb line will break before that happens. I have to say this line fuse has yet to break...

I have heard second/third hand stories of 5995TGs frying but have yet to hear a first hand account (ie: it happenned to me.) I'd like to learn more about the 5995TG failures so I can either take steps to prevent problems or even replace the servos.

Regards,

Rey

Lester · Post by **Lester** » 28 Sep 2005, 19:33

ReyNewman wrote:The 5745 is a good servo to use.

Hi Rey

Yup, this is the one I use.

As for the 5995TG, I have been using them on three other boats since they first came out last year and have not had any problems with them ... I have heard second/third hand stories of 5995TGs frying

Yup, my stories are second hand as well.

One of the issues that might explain different experiences is the quality of the wiring and interconnects. The stall current of the 5995 is around 5 amps (wow!) at 7.2 volts. If you are running relatively thin wires then they effectively "throttle" amperage delivery and help protect the servo. I've converted my wiring to heavy gauge, and promptly personally fried a 5745 (when I hadn't previously!) with a sheet snag that lasted around 20 seconds. I put it down to upgrading my wiring (and battery pack!) which allowed higher current than previously...

awallin · Post by **awallin** » 28 Sep 2005, 22:30

Nigel wrote: Ohh, by the way Anders, which new boat are you considering

Now it looks like I am building a Noux2. The Noux hullshape is a modified TripleCrown for which we got a plug cnc milled in 2002. Two or three prototypes have been sailing but I never got time to put together a boat for myself.

Right now I am thinking of a cockatoo(1)-style deck with a ts3-like mainsheet-bridge using a topiko-like sheetingsystem and an obsession or disco-like deck hatch. (golden rule of yacht design: if you don't know what to do, copy the fast guys...)

I hope to document the building process in detail on my website and also publish the plans once I know everything is working and that the boat is competitive.

AW

ReyNewman · Post by **ReyNewman** » 29 Sep 2005, 17:09

Hi Lester,

Good point on the wiring.

The 5745 and 5995TG have similar stall currents, 4000mA and 4200mA respectively. The 5595TG is more efficient in that it draws 3mA (idle) and 300mA (running) ve the 5745 which draws 3mA (idle) and 700mA (running.)

The one issue that I had with the 5995TG early on was that if the bottom case is too tight (ie: screws fully tightened up) then the servo thinks it is under full load and draws down a battery pack in no time at all (at 4.2A that's quick...) I struggled with that for a while - I just couldn't figure out why the same battery packs I used with the 5735 would last only about 20% as long... The rule of thumb I came up with is to tighten the screws and back them off 1/2 turn. Works like a charm. This seems to be evem more true of the flush bottom case (vs the robot case which has a slug on the bottom) - it appears that the cutouts in the flush case are shallower than in the robot case and seem to press on the circuit board.

Rey

soeren_andresen · Post by **soeren_andresen** » 30 Sep 2005, 10:03

Hi Anders

My 2 cents.

I have being using both the 5745 and the 5995, in my boats (IOM).
As for the 5745 it has worked fin with no problems at all, it is heavy but reliable. If you use the HiTec programmer and a good Tx you can easily get 180 0 of travel.

As for the 5995: I have being using it in my new IOM, but not with great success. Along with my brother I have big problems with gears. Until today we have stript 5 sets of gears, well actually it is only 1 of gear-trains that gets stript. Even that HiTec says it is with Titanium gears there is still 1 gears-train that is of plastic, and it is this gear that keeps stripping. Some of the gears has got striped even when there no load on the servo, and I knew of the problem with the tightning of the screws.
An other problem with the servo that I have experienced is that, even though that is has the force it is slow to deliver it, an example: with winds in the top of any rig and you are and you are fully sheeted out and wants to sheet in (pre-start). I move the stick to full in, the servo starts to pull in, but as soon as the sails start to get filled it stalls. After a second it then starts to sheet full in, it seems like it is slow to turn up the current to take the load.
I am no longer using the 5995, and would not use it again, to many problems.

What I am using now is the HS 5955TG, and with this I have no problems at all. It is rated to be as powerful as the 5995, but the casing is a little different, it has like the 5745 some kind of heatsink. I have sailed with in all kind of wind, I used it at the WC in AUS and anybody who was there knows that we had wind from 0 â€“ 20+ m/s. I did not noticed any hesitation from the servo when sheeting, and it runs so smooth that the elastic for the sheets would turn the servo if the power what turn off when full sheeted in.

All I can say is that if I was to build a new IOM, I would definitely go for the 5955 again.

Here is a link to some info on the HS 5955TG: http://www.hitecrcd.com/Servos/HS5955TG.htm

Marko Majic · Post by **Marko Majic** » 12 May 2006, 05:19

Hi Soeren and others using HS 5955TG... I have a question for you.

On my new boat (soon to hit the water) I decided to try out the digital servo as I was quite intrigued by what I've seen from others so far.

I bought the 5955 because, well it was lighter for the same specs but more importantly, having built the boat with a conventional (drum winch) setup in mind there was no room in my tray for 5745. This lack of space also lead to some interesting arm design and sheeting scheme - but that's a different story altogether...

Anyway, just as I thought it's all coming together and I finally put the servo in and connected it all - I was astounded by the complete lack of power provided by the winch. I mean - I can easily hold the mainsheet in my hand and hold the servo stalled in the mid-stride... Certainly makes me doubt if it would ever be able to pull that mainsheet in in any kind of a breeze. Also, at any point (and even when the winch is all the way at the beginning of the travel) some tug on the line can generate as much as 10mm of "give" in the line. At first I thought this is due to my home-made arm - but when I take the arm off and try tugging the line while holding it or twisting, bending etc. I simply can't induce any sort of appreciable amount of flex in the arm (I moulded this cam-type variable-radius thingamajig in polyurethane plastic compound)...

At present, the servo is "fed" by the DX-6 receiver which itself is powered up by a 6.0 volt pack. The wiring going into the receiver (at the moment) is not ideal (standard servo wire) - but I doubt that's what's causing the lack of power. For one - there is nothing else drawing from the receiver (the rudder servo is disconnected) and for other - with the exact same wiring, my old RMG winch would have happily broken my fingers had I ever tried pulling the same stunt on it.

So... My question is - what gives? Do I have a faulty unit? I hooked it up to (a friend's) servo tester unit - and the servo communicates happily with it.

I'm just about ready to throw it all in a "failed experiments" drawer (which is getting quite full

) and pop the RMG back in - but I thought I'd check with other users first...

I would love to hear experiences of others with the said 5955...

Thanks!

Marko

soeren_andresen · Post by **soeren_andresen** » 15 May 2006, 13:31

Hi Marko

Just my 2 cents.

I have been using the 5955TG for almost a year now, and I am very happy with it. For the next boat I am currently building, I would definitely use it again.

That say I can maybe give an answer to your problem, it is the batteries. When I started using the 5955 the batteries I was using was 2500mAH LiMH size AA, 5 cells giving 6 volts, and with them I had some problems like you descript. When the wind was at the top of each rig range, and trying to sheet in, the servo had some problems. It was worse when it was cold, and it got worse as you drain the batteries when sailing.
My brother, also had the same problem, and I then did a little test of the batteries. What we found was that when putting some load on them, the volts quickly dropped and that they could not give the Amps we needed.

To solve the problem we have shifted to Li-ion batteries. They are capable of giving 20 Amps, with nearly no drop in volts. The ones that I use is 1600 mAH at 7,2 volts, and I have done a little quick test of them. The idle current is 7,9 volts, and when putting a 4 A load on them they drop to 7,6 volts at start. After that I have drained them for about half (app. 800 mAH), the volts have drop to about 7,4 volts.
When sailing with them is where you see the biggest different, is it hard to see any different in servo speed over time, or when it is loaded. Even when the boat starts to nosedive on a run down wind, it is possible to sheet in.
One of the other sailors is using the same batteries but with the 5745 servo, and he has had to put a bigger fuse in.

An other advantages is that they are lighter than the LiMH batteries, they have no memory effect and they will not self-drain over time.

Before go out an buy some Li-ion cells, you should be sure that the DX-6 receiver is capable of running on 7,2 volts, and that it can handle that the servo drains up to 2 Amps.

I hope it can help you a little.

Best regards

Marko Majic · Post by **Marko Majic** » 15 May 2006, 22:25

Hi Soeren,

Thank you very much for your reply!!!

I suspected that the battery might be a problem - but only because it was the last remaining component of the system...

I've re-worked my wiring path so that everything between the battery and the servo is gauge 22 or better (20) so I figured if not better it's at least no worse than anyone else's...

I've measured voltage under load and it very easily (and quickly) falls to around 4.2V (if I apply "manual" load on the sheets) which seemed a cause for concern - but, again, I figured, my battery (2500mAh AA 5 cell NiMh) is at the very least no worse than what others were using.

I also went back to the hobby shop and they were kind enough to let me swap in a brand new 5955 in place of the one I had in there and the pulling power of their unit seemed to be exactly the same (within margin of error of my measuring equipment - which were my thumb & forefinger) as my old unit - which reasonably convinced me that there was nothing faulty about my particular servo unit.

While I have a couple of chargers that are suitable for Li-Po/Li-Ion batteries - I was always uneasy with the idea of using lithium chemistry owing to the warnings I read about how easy it is to burn down the house and everything in it...

And, of course, in addition to boats I have a few other valuables in there which I would hate to put in harms way (chief among them are 3 children under the age of 7)... Something to think about. I think if I DO go with lithium chemistry batteries - I would probably have to look into some kind of a double-insulated metal container that would fit the charger and put the whole thing inside while charging. Do you take any extra precautions while charging your batteries? On the other hand - I'm fairly certain that my cell phone and my laptop both employ lithium batteries and I never think twice about charging those so perhaps the fears are somewhat unfounded (or are relating to older or no-name versions of the product)? Something to research at any rate...

I did check the Spektrum website and on their FAQ they state that the DX-6 receiver will handle as much voltage as the servos will - up to 9 volts - which seems more than plenty for a 2-cell lithium battery.

Hitec's specs, though, say that the 5955's operating voltage range is 4.8V-6.0V - but I take it you had no problems running yours on 7.9?

Then again - there's always the option of going back to the good, old RMG...

Thanks again for your input Soeren...

Cheers,

Marko

soeren_andresen · Post by **soeren_andresen** » 17 May 2006, 16:03

Hi Marko

Thank you very much for your reply!!!

You are very welcome

I suspected that the battery might be a problem - but only because it was the last remaining component of the system...

For me it was the same, the batteries were the last thing to check. I had been using the same for an other boat with a RMG winch, with no trouble at all.

I've re-worked my wiring path so that everything between the battery and the servo is gauge 22 or better (20) so I figured if not better it's at least no worse than anyone else's...

I did think of doing the same, but it works fine now I do not think I will do it.

I've measured voltage under load and it very easily (and quickly) falls to around 4.2V (if I apply "manual" load on the sheets) which seemed a cause for concern - but, again, I figured, my battery (2500mAh AA 5 cells LiMH) is at the very least no worse than what others were using.

My experience too.

I also went back to the hobby shop and they were kind enough to let me swap in a brand new 5955 in place of the one I had in there and the pulling power of their unit seemed to be exactly the same (within margin of error of my measuring equipment - which were my thumb & forefinger) as my old unit - which reasonably convinced me that there was nothing faulty about my particular servo unit.

Great service!

While I have a couple of chargers that are suitable for Li-Po/Li-Ion batteries - I was always uneasy with the idea of using lithium chemistry owing to the warnings I read about how easy it is to burn down the house and everything in it... And, of course, in addition to boats I have a few other valuables in there which I would hate to put in harms way (chief among them are 3 children under the age of 7)... Something to think about. I think if I DO go with lithium chemistry batteries - I would probably have to look into some kind of a double-insulated metal container that would fit the charger and put the whole thing inside while charging. Do you take any extra precautions while charging your batteries? On the other hand - I'm fairly certain that my cell phone and my laptop both employ lithium batteries and I never think twice about charging those so perhaps the fears are somewhat unfounded (or are relating to older or no-name versions of the product)? Something to research at any rate...

The batteries with a charger, they have a deal where you get the charger virtually for free. I do not take any particular extra precautions when charging; I just check the batteries before I start to see if they should be damaged in any way. As long as you use the correct charger and that they are not physical damaged, it should be ok. With correct charger I mean that it should be designed for charging Li-ion cell, that it should be set for the correct number of cells, and finally cut-of when they are fully charged. And as you say you do not think twice when charging your cell phone or laptop, so all stories about them properly is to faulty handling of them.
My charger is rated at 500 mA, and one thing that have striked me is that the batteries do not become warm. Well they do not even become warm when de-charged them with a 4 Amp load.
Just one cautions about them, and that do not de-charge them to under 2,5 volts per cell (= 5 V for 2 cells), that will destroy them and it not possible to get them alive again.

I did check the Spektrum website and on their FAQ they state that the DX-6 receiver will handle as much voltage as the servos will - up to 9 volts - which seems more than plenty for a 2-cell lithium battery.

So no problem here.

Hitec's specs, though, say that the 5955's operating voltage range is 4.8V-6.0V - but I take it you had no problems running yours on 7.9?

Both my brother and me have had no problem at all, it is just a little quicker.

Then again - there's always the option of going back to the good, old RMG...
Thanks again for your input Soeren...

If you ones have tried a armwinch that is working properly, you will never waints to go back to a RMG. Well at least I will not.

Best regards