Model Boat Mayhem - Forum

Dry Dock / Shipyard: Builds & Questions => Submarines => Topic started by: sealion on May 23, 2009, 09:21:32 AM

Title: Problem with TT Neptune sub.
Post by: sealion on May 23, 2009, 09:21:32 AM
I posted this in another Forum but no real luck with replies.

I have recently finished building the kit version of the Neptune and have tried out the sub in our local lake.

My problem is that after only about 5 minutes the sub is very slow going forwards and will not dive even with the hydroplanes fully functioning. I have managed to submerge statically a couple of times 3/4 feet and on returning to the surface it refuses to sink anymore.

I lift the sub out of the water and the pump continues to run and water is expelled from the bag until I switch off.

Returning home on both occassions I have checked the battery voltage (at the charge terminals) and each time the voltage was above 12 volts.

I have spoken to Amerang (the UK importers) but the Service guy can offer very little help. He suggested the (new) battery might be faulty or the control board might not be working correctly. Basically he did not know what to suggest.

Can anybody offer any advice please?
Title: Re: Problem with TT Neptune sub.
Post by: das boot on May 23, 2009, 10:32:16 AM
Person to ask about this is Andy(subculture)...drop him a pm or an email, he'll sort you out.

Rich
Title: Re: Problem with TT Neptune sub.
Post by: sealion on May 23, 2009, 11:56:59 AM
Thanks. Tried to send Andy a PM but not sure if it went OK.
Title: Re: Problem with TT Neptune sub.
Post by: boatmadman on May 23, 2009, 12:24:32 PM
My son bought one of these second hand.

It sounds like you have something pulling a lot of current causing the battery to drain - I know you said the voltage is ok when you get home, but batteries recover some voltage when rested, this recovered voltage soon vanishes again when under load.

Is the drive free to rotate with fingers - ours has almost no resistance.

The electronics have a low voltage failsafe sensor that puts the pump to empty the bag when the voltage drops, this continues to run until the power is switched off, again suggesting power drain from the battery.

If you have a similar battery it would be worth swapping over and trying again - Not a 5 min job I know, but you need to eliminate things one by one.

Alternatively, return to your supplier and tell him its not working as it should and request a refund or replacement.

Let us know how you get on

Ian
Title: Re: Problem with TT Neptune sub.
Post by: sealion on May 23, 2009, 12:34:58 PM
Will do, thanks.
Title: Re: Problem with TT Neptune sub.
Post by: boatmadman on May 23, 2009, 02:58:03 PM
Thinking about this somemore while making a mess in the workshop - ours doesnt go particularly fast, nor dive fully on the hydroplanes only. I think this may be normal, as to get a dynamic dive would need the sub to move quite quickly.

Regarding the dynamic dive, the battery is only a 3a/hr battery, so wont last too long if you dive lots and run it at full speed. We tend to dive to just below the surface - any deeper and we lose sight the water is so mucky!

Make the checks I suggested, but it may just be behaving as expected, unless someone else has better experience.

One other check I recommend is to put it in the bath without the yellow plsastic outer shell, run the pump to fill the bag and make sure the overpressure switch operates to stop the pump.

When we got ours I tested it in my tank and the bag split, filling the watertight tube. I tracked this down to the pressure switch failing. If this had happened in open water the sub would have been lost.

Ian
Title: Re: Problem with TT Neptune sub.
Post by: Mankster on May 23, 2009, 03:24:54 PM
I think Colin had a similar problem with his, so it does not seem to be a one off. It should be pretty easy to diagnose the fault but will require a bit of investigative work. Can you reproduce the problem on the bench? if so hook up an ammeter and see what sort of current your pulling. If all is ok, it may be the battery, try swaping it on the bench and see if you get the same problem. Still giving you grief? Then it could be a faulty low voltage saftey cutting in- try swapping to a 12v NiMh pack (voltage shouldnt drop below 12v under load) and see if that sort out your problem.
Title: Re: Problem with TT Neptune sub.
Post by: Subculture on May 23, 2009, 05:17:16 PM
Mike Stothers gave an excellent response to this over on RC Groups where you also posted, and is much better qualified than I one these matters. His answer makes a lot of sense.

http://www.rcgroups.com/forums/showthread.php?s=a1428f5ad0fbc679b9d2ce51c3cbe499&t=1053453

You might want to consider replacing the lead acid battery with some Ni-Mh batteries, which can deliver more current, and also give you more capacity for their size and weight.

Another alternative would be A123 Lithium LiFE batteries. Four of those would give you 13.2 volts, which the Neptune's kit should easily handle, and will give a little bit of voltage in hand if Mike's prognosis is correct.

The electrics in the Neptune seem to be the only fly in the ointment of an otherwise very well engineered kit.

I didn't receive your PM, BTW.
Title: Re: Problem with TT Neptune sub.
Post by: sealion on May 23, 2009, 08:04:57 PM
Gentlemen, thank you all for your help.
Title: Re: Problem with TT Neptune sub.
Post by: 6705russell on May 23, 2009, 09:15:52 PM
I had the same problem with mine, did some tests and found it to be a faulty circuit board, sent to Amerang and they replaced within a week.

Russ
Title: Re: Problem with TT Neptune sub.
Post by: microgyros on May 23, 2009, 09:47:33 PM
  Reading some internet searches on "TT Neptune" battery and charger would suggest it is worth getting the charger function checked out and using a decent charger meantime.You can't go wrong with a proper lead-acid charger with a two step action with a bulk charge rate of 0.5 amp.
 
 
Title: Re: Problem with TT Neptune sub.
Post by: getemuphigh on August 01, 2009, 01:02:08 PM
If the battery has low voltage the internal RD LED should be flashing, see page 24 in the manual.
Title: Re: Problem with TT Neptune sub.
Post by: colin-stevens on August 15, 2009, 09:39:08 AM
just came across this thread. Mankster is right, got the same problem. have the control board changed by Amerang. no difference. using a decent charger, no improvement. the batteries do seem to be ok, ran it forever on the bench, ok i know that is minimum load, but still ran for several hours, with the occasional pumping carried out.
can i ask, have you ever used the tranny with the arial down?
colin
Title: Re: Problem with TT Neptune sub.
Post by: Subculture on August 15, 2009, 11:40:40 AM
It's been a year nearly since the first shenanigans with your Neptune, so you'll have to forgive me if I'm repeating myself. Did you try swapping out the ESC with a known good one?

The control board is only a straightforward microcontroller based relay switcher. I suspect the voltage checker is based on a potential divider routed through the microcontrollers A/D converter, although this is guesstimation as I haven't seen the control board up close.

As this now your second board, and it's unlikely (but not impossible) for lightning to strike twice I'm starting to lean towards the ESC.
Title: Re: Problem with TT Neptune sub.
Post by: colin-stevens on August 15, 2009, 11:52:15 AM
i am starting to suspect the the tranny, took her out the other day, ok close in, but the minute it was down a bit, wollpop. all went wrong. put her in the car and ran me e boat. that was fine close in, but the minute it went out about 20 ft, wollop, lost it. common denomitator, the tranny.
hoping to try her later with a different tranny
colin
Title: Re: Problem with TT Neptune sub.
Post by: Subculture on August 15, 2009, 12:40:11 PM
Do a range test in air. Put it down in a field or something and walk away and see when you lose the signal (easier if you have an assistant).

Title: Re: Problem with TT Neptune sub.
Post by: sheerline on August 16, 2009, 09:36:28 AM
Try putting the tx down and walking off with the boat.... don't need an assistant! :-))
Title: Re: Problem with TT Neptune sub.
Post by: das boot on August 16, 2009, 09:47:43 AM
Try putting the boat down and walking off with the tx...it's lighter!!   %)


Rich


Yea, I know....I'll get me coat.
Title: Re: Problem with TT Neptune sub.
Post by: Subculture on August 16, 2009, 10:08:29 AM
I'd still rather have an assistant, as they can operate the controls as you take the boat or TX away. If you're on your own, all you can do is latch on a function, like the ESC and move away, and hope that the reason the motor keeps spinning is because it's still receiving and not for some other reason.
Title: Re: Problem with TT Neptune sub.
Post by: tigertiger on August 16, 2009, 11:27:58 AM
Do a range test in air. Put it down in a field or something and walk away and see when you lose the signal (easier if you have an assistant).



Or where I live, put it down in a field or something and walk away and see when you loose your kit. I imagine that most of them (thieves) would think 50m would give them enougbh of a head start. If they left it much longer someone else would beat them to it.

I jest not.
Title: Re: Problem with TT Neptune sub.
Post by: sheerline on August 16, 2009, 05:41:35 PM
It's only a Neptune, hardy a back breaker chaps! If the sub is working, all the controls will be static as the sticks aren't being waggled around. Walk away with the sub, as it goes out of range, the rx will struggle to decode the weak signal and the servos will begin to glitch,  the motor may also intermittently cut in and out. This is an indication that you have reached the limit of your useable range. There is no need to waggle the sticks when range testing.
Title: Re: Problem with TT Neptune sub.
Post by: sheerline on August 16, 2009, 05:46:12 PM
Forgot something, if the thing is fitted with a failsafe, it should set to failsafe when the signal is lost so, plenty going on there as the signal goes out.
Title: Re: Problem with TT Neptune sub.
Post by: colin-stevens on August 23, 2009, 08:10:41 PM
really hacked off. chandged the tranny for the one i use in the Layfette. annoyingly there is an improvement. it now dives and runs, for a bit, then packs up. better than before, where a foot or two down she packed up. did a range test. was ok for a bit then i got a bit of twitching, and the motor bliipping.
guess that is implying that the second tranny is also low on range. apperently the "trannsmitting" part can go wrong in degrees, so maybe my second one is not as knackered as the first. guess i will have to bite the bullet and bye a new tranny and receiver.
colin
Title: Re: Problem with TT Neptune sub.
Post by: Subculture on August 23, 2009, 09:12:55 PM
I might have missed this, but you have tried swapping out the receiver with a known goody too, haven't you?
Title: Re: Problem with TT Neptune sub.
Post by: colin-stevens on August 24, 2009, 02:52:10 PM
no, i didnt do that. didnt occur to me. but will try it next. getting very aggravating. trying to avoid changing the thunder tiger ESC, ect, as i am not sure what alll the extra pcb boards do.
Title: Re: Problem with TT Neptune sub.
Post by: Subculture on August 24, 2009, 03:42:55 PM
AFAIK you have a receiver, ESC and ballast tank control board. Anyhting else?

The ESC is a fairly bog standard design, I believe with a built in BEC.

From what I've sen of the control board, it looks like a knock-off of Norbert Bruggens design. A micro controller based relay switcher, that simply enables the peristaltic pump to push each way. I believe it has a low voltage failsafe, missing pulse detection, a pressure senser input to cut the pump before the bag bursts (hopefully), and maybe a water detector(?).

If the receiver is a bit duff, it's entirely possible that you would experience the symptoms you are getting. Add to this the fact that you have tried it with a separate TX, and it is still playing up.

The other thing I would check is to ensure you are getting a good 5 volts to the receiver bus from the BEC. Ideally this wants to be done with a load put on it. You could wire a 5 ohm 10 watt resistor across the leads. This will pull 1 amp across the BEC, which it should be able to manage. Measure the voltage, it should maintain the unloaded reading, if it drops significantly, you might want to consider an external BEC. Depending on the make of receiver, some will happily work down well down to about 3 volts or so (i.e. a lot of futaba kit) whilst others will start to flake out if you drop much below 5 volts.

One other final thing to try. Change the crystals in both TX and RX- sometimes they can get damaged, and I have read that they age, although I'm using crystals that are years old without issues.
Title: Re: Problem with TT Neptune sub.
Post by: getemuphigh on August 25, 2009, 05:42:52 PM
Hope you get it sorted, keeping my eye on this thread, just in case.....
Title: Re: Problem with TT Neptune sub.
Post by: 6705russell on October 09, 2009, 02:09:09 PM
After purchasing Colins Neptune and making some alterations/additions to it including re-soldering some dry joints on the main board and added some ferrite rings to the motor cables, I have added some lighting and carried out several bath tests and also in the lake to a range of 20metres and there were no problems, i shall try a further range test this weekend...

Russ
Title: Re: Problem with TT Neptune sub.
Post by: colin-stevens on October 11, 2009, 06:56:35 PM
have you managed to keep it dived yet?
colin
Title: Re: Problem with TT Neptune sub.
Post by: 6705russell on October 11, 2009, 07:02:12 PM
Hi Colin

I am still tweeking the ballast (adding more) and using some styrafoam to compensate the extra weight, I have had it just under the surface and no problems yet....

It needs quite a lot of extra ballast to compensate for the side tanks which are making it to bouyant and stopping it going deeper.

Russ
Title: Re: Problem with TT Neptune sub.
Post by: Albion on October 12, 2009, 02:01:43 AM
What a great modification, looks like a proper sub not a toy. hope you solve your problems
Title: Re: Problem with TT Neptune sub.
Post by: colin-stevens on October 12, 2009, 08:49:57 PM
MMMMmmm, suprised. i did get it to stay under for a couple of minutes, was down quite a few feet before the signal was lost and she surfaced. i was ready to start to mess with the ballast but didnt think i would have to.
sugestion, reckon performance could be increased with nicads or whatever it is that has replaced them and had considered putting them in the battery tubes on the sides.
keep me updated please
colin
Title: Re: Problem with TT Neptune sub.
Post by: 6705russell on October 12, 2009, 08:54:12 PM
When you were submerging how long did you run the pump for Colin? I f you keep the pump going when the bag is full it reverses and pumps back out unless you kill the pump, perhaps you kept it onto long??

Russ
Title: Re: Problem with TT Neptune sub.
Post by: colin-stevens on October 12, 2009, 09:01:46 PM
please dont say that was all it was.
certain there was an auto cut off to prevent over filling?
colin
Title: Re: Problem with TT Neptune sub.
Post by: 6705russell on October 12, 2009, 09:07:31 PM
That is the auto cut-off, it reverses and pumps the other way before it overfills the bag.
Title: Re: Problem with TT Neptune sub.
Post by: colin-stevens on October 12, 2009, 09:12:26 PM
naw wernt that, everything cut off. turning tranny of then on sorted it
Title: Re: Problem with TT Neptune sub.
Post by: Subculture on October 13, 2009, 07:30:54 PM
Surely the auto cut-off should just prevent your from over-filling e.g. shut the pump down when the pressure switch trips. Then keep the pump off until commanded to surface from the transmitter. Reversing the pump makes no sense to me at all!
Title: Re: Problem with TT Neptune sub.
Post by: colin-stevens on October 13, 2009, 07:49:37 PM
testing in the bath would not alloe the bag to over fill
it did reverse, just for a second to take the pressure off.
not what was happening in the open water
colin