Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Working Vessels => Topic started by: jpdenver on July 07, 2020, 04:35:59 am

Title: Chimaera - The story continues
Post by: jpdenver on July 07, 2020, 04:35:59 am
Hello to this group.  I have been hanging out in the steam forum for the past couple of years
but now I find myself playing with batteries and such.I recently completed a build:
https://www.modelboatmayhem.co.uk/forum/index.php/topic,60286.0.html
However, when it came to the steam plant I ran out of funds. 
The boiler I had planned to use was just too big,
and I was informed by my wife that I was not going to get an advanceon my allowance this year. 

TO THE MODERATOR - Its OK with me if you move my thread over from the Steam Forum,I believe in "Truth in advertising".
I had thought to leave the story finished, but since I changed it to electric power,
I wanted to pick the thread up and add to the story.
Here is a picture of the craft so far - - -













Title: Re: Chimaera - The story continues
Post by: Footski on July 07, 2020, 06:36:30 am
That is a beautiful model, superbly built...
Title: Re: Chimaera - The story continues
Post by: Big Ada on July 07, 2020, 05:12:40 pm
Very nice, you could put a steam sound unit in it also a Smoke generator.

Len.
Title: Re: Chimaera - The story continues
Post by: Baldrick on July 07, 2020, 08:00:32 pm
Hi Jim.


   I am interested because I only started my Chimaera build when lockdown started and I have a long way to go. I too was going steam but have now decided to go electric . I had a steam plant lined up but decided it was too heavy.  One thing I have found is that even with a motor with a step down gearbox I am having to cut the frames heavily to get the motor low enough to line up with the prop shaft , have now built in some reinforcements to the framing to bridge the cut away area.


   Am impressed with your build, hope I can do something as good.


Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 02:29:37 am
Thank you for all of your kind reviews.
As I said, the main part of the actual build is in the steam forum.but here are some more pics of the final result.
Then I will get "under the hood" to show you how I converted to electric.

Thanks for reading,Jim PopeDenver, USA


Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 02:33:13 am
And here are some pictures of the lights.



Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 03:11:11 am
So - now to take a look under the hood.
Here is a look under the deck.
You can see the smoke generator
and the 500 series motor with 3:1 gear head.

Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 03:17:46 am
And here is the hull with the batteries added.
I am using 2 voltages,   
7.2 v NIMH for propulsion   
14.4 V LIPO (2-2S in series) for the sound generator.   

More to come on the voltage regulation and controls.


 
Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 03:21:06 am
And the control panel,

Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 03:25:34 am
Here is a view "under the deck"

Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 03:37:21 am
The deck portion that lifts off has lights and also holds servos that
move the wheel and also the spotlight.
In order to be removable, 
I needed to come up with a plug and harness method to connect them.


Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 04:16:35 am
So here is the final result on the electronics:
Power source -
Dual 5000MAh NiMh  (in parallel) - Provides 7.2 V to ESC 
and via multiple regulators - 3V, 5V, and 6V to power LEDs
Grain of Wheat bulbs, and Fan for Smoke Generator.
Dual 1200MAh (2S) Lipo in series to provide 14.4 Volts to regulator - resulting in 12 V for Sound Generator System.

Sound System - From Harbor Models (California, USA) Provides Steam Sound and Whistles. 
Regulated by ESC.
Smoke Generator - From Harbor Models. 
regulated by Motor Voltage.
Servo Morph from ActionElectronics to scale the
Rudder signal for Wheel and Spotlight movement.

Motor - 540 25T Brushed, with 3:1 gear head. 
Brushed ESC from Mtronics.

TX/RX from Spektrum.6 chan RX, 

RC Controlled relay (Polulu - LasVegas,USA)
for Spotlight Power control.

More to come, 
Thanks for reading, 

Jim Pope 
Denver,CO USA

Title: Re: Chimaera - The story continues
Post by: Baldrick on July 08, 2020, 09:34:39 am



  Now, theres a lot to get my head around .  My initial intention was for something less sophisticated , wow.


   for interests sake here is an original image of Chimaera as she started life, a steam yacht. 
https://www.gettyimages.co.uk/detail/news-photo/the-steam-yacht-chimaera-1914-artist-kirk-sons-of-cowes-news-photo/1055102034
Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 11:24:59 pm
Baldrick,
Thanks for the link to the picture.  I have been looking for one! 
Getty Images will not license a copy for personal use (go figure)
So I will just clean their logo off of the sample I downloaded. 


In the meantime -  Three weeks ago I prepared her for her first trip on the water.
I charged the batteries, tested everything, and got it all ready for a early morning run.

At the lakeside, I put the batteries in the hull, and closed her all up - 
waiting for a couple of others to come and join in the fun.   

Plus - just in case she crapped out on the pond, I wanted to have a tug ready to retrieve her. 
I was sitting in my chair, about 5 feet away, when I heard a HISSING sound. 

And then BANG - the removable deck portion of craft, removed itself about two feet in the air, and
smoke spewed out of the hull.  Bang, Bang - I got up and went over to look and the 4th bang made my ears ring (even worse) - I reached in and grabbed the mess - searing my fingers, and threw it on the ground.  Bang for the 5th time. 

Bloody Hell..... and numerous other phrases from around the globe came out of my mouth. 

Here is a pic of the mess.

Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 11:28:36 pm
Battery saga continues -

Then I looked in the hull.

Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 11:30:26 pm
Then I looked again at the side -


Title: Re: Chimaera - The story continues
Post by: jpdenver on July 08, 2020, 11:51:11 pm
I guess no running on the water today!! 


I packed her back up in my car and got out my Club500 for some quick fun and games.
Then we went back to dry-dock.

I called the manufacturer - they are in Utah USA, and discussed the problem with one of their engineers.   
We came to the conclusion that 1 of two things happened: 
Given:  I connected the two batteries in parallel.
1. Either I had forgotten to charge one of the packs and when connected together Pack one charged Pack two.   
    Real fast.  I was pretty sure I had done a "Discharge/Charge" with my Tenurgy Charger. 
2. A cell in one of the packs shorted out and sucked everything out of the packs.
Either way,  the HISSING I heard was the cells overheating and venting hydrogen.
The manufacturer replaced the pack at no charge even though it was 11 1/2 months into the 1 year warranty.

And I sat down to try and figure out how to keep something like this from happening again. 
The obvious thing is to protect the "back-flow" from one to another by using hefty diodes.
SO - What does the forum think?

Thanks for reading -
Jim Pope 
Denver, CO USA
Here are some more pics of the damage, and the start of the repair.




 
Title: Re: Chimaera - The story continues
Post by: derekwarner on July 09, 2020, 01:05:00 am
Jim.......without any real practical or professional experience in electrical or electronics I am unable to offer comment..having said this, it is clear there was an availability of a huge amount of potential energy released [very quickly]


There have been cases reported of hybrid motor vehicles suffering smoking then exploding batteries.....and didn't Boeing put a small battery in a steel box as an aircraft safety precaution?  O0


Oberon Class submarines on the electrical propulsion cycle were powered by banks of 2.2 Volt batteries lead acid batteries ............but 100's of them and connected so to provide 580 Volts for the two propulsion motors


https://maritime.org/doc/oberon/electrical/index.htm

Hydrogen and Chlorine gas from the battery banks during charging were always issues for both the British and German submarines from WW1 onwards


Will certainly be interesting as the thread progresses


Derek
Title: Re: Chimaera - The story continues
Post by: BrianB6 on July 09, 2020, 02:06:26 am
 <:( <:( <:(
Title: Re: Chimaera - The story continues
Post by: Martin [Admin] on July 09, 2020, 04:28:17 am
 
Wow!    :o

Firstly:    At least you were lucky in the hack you hadn't got up in time to put you face over the model at the critical time!

Second:  Not surprised the manufacturer ( Venom power? ) replaced the batteries pretty sharpish, this report makes them look pretty bad!
              ( ... not to mention where the hull blow out might have hit you!   <:(  )

Thirdly:  Your charger, does it have auto battery detect? Any possibility that it was trying charging the NiMH as Lipo's?   {:-{
 
 
Title: Re: Chimaera - The story continues
Post by: NickelBelter on July 10, 2020, 12:46:15 am
Diodes would be good, but if you can't find them, simply using one battery at a time might work.  5AH will give you quite a bit of run-time before you bring it in and swap the connection to the second pack. 

EDIT:  Since it looks like your gearbox and mount are set up for 500-size motors, you could switch to a 555 and a series battery arrangement.  A 555 on 14v is about the same RPM as a 540 on 7.2
Title: Re: Chimaera - The story continues
Post by: jpdenver on July 10, 2020, 03:17:06 am
Thanks for all the sympathy -  at least you guys understand the feeling of watching your hard work smoke.

The Tenurgy charger I have is intelligent, and I always do a Discharge/Charge cycle on NiMH packs. 
That is what is so confusing about the explosion.  I swear I did both packs, but it is possible I did the same one twice.

When I put the remaining pack on the charger after the explosion, it only had 256MAh left on the discharge cycle,
and then gave a reading of 4958MAh on the charge cycle.   That tells me where all the juice came from.     

I am looking into Heavy Duty Diodes, need to do some calculations. 

QUESTION -

With an ESC set for NiMH - what is the cutoff voltage?  Or does it have one?I have seen a lot about LiPOs and brushless ESC's but do not seem to find something definitiveabout NiMH. 
How does it know how many cells are in the pack?  Fully charged when starting would be easy, but
supposed you have a partially charged pack? 

Someone please enlighten me.

Thanks,Jim




Title: Re: Chimaera - The story continues
Post by: tsenecal on July 10, 2020, 06:24:22 am
Jim,

one question...  why do you "need" two batteries?  the Chimaera is not a high performance boat, i would think that a single 5000mah battery would be more than enough to run the boat until YOU are ready for a recharge...
Title: Re: Chimaera - The story continues
Post by: jpdenver on July 10, 2020, 01:20:17 pm
Tim,
To be honest, I am not sure I do need two batteries. 
This is my first boat where I designed the electrical plant.

With steam I can judge the rate of water use, I know the capacity of my boilers and fuel tanks. 
I am kinda feeling my way along when it comes to battery life. 

So since I thought it a good idea to balance the weight, I put in two. 
I suppose it is in the same category as having two testicles.
 
Anyway, since most of my crafts turn into test beds for different technologies, 
The Chimaera was to play with added sound and smoke effects. 

Hopefully the electronics survived the explosion, I have not cleaned them up yet. 

Say - do you want to go out on a lake some time soon? 
I am busy with the day job next week,  but opening up after that.

Stay safe,
Jim


Title: Re: Chimaera - The story continues
Post by: Mark T on July 10, 2020, 09:04:50 pm
Hi Jim


I've wanted to reply to your thread all week but for some reason I can't on my phone so I've had to wait to get home on my laptop.


I've loved this build and I'm really sorry for what happened to you boat as the installation looks good but ~ I don't know much about batteries and their associated problems.


I just think its great that you are dealing with the damage and I am certain that you will sort it out and best of luck with the repairs  :-))
Title: Re: Chimaera - The story continues
Post by: jpdenver on July 11, 2020, 09:33:42 pm
Mark,Thank you for your kind words. 
 I appreciate that my attempts at craftsmanship are recognized by others with so much more experience than I. 

Everyone -

I have a decision to make. 

1. Do I cover the damage up and do a full refinish to hide it and pretend it never happened?
OR
2. Do I repair the damage as if it was a full size ship, and end up with a riveted Painted copper sheathing/patch.   
and a story to tell about a boiler explosion? 

I know that a lot of you go to great lengths to age your models and give realism to the "history"
What do you think I should do with the Chimaera? 

Thanks for reading, 
Jim
Title: Re: Chimaera - The story continues
Post by: Capt Podge on July 11, 2020, 09:48:45 pm
I would go for option #2. If it doesn't work out, then you can always return to option #1.  O0


Regards,
Ray.
Title: Re: Chimaera - The story continues
Post by: boulderboater on July 11, 2020, 11:34:26 pm
Jim,
I looked up "ideal diodes", which are in fact MOSFETs, that would keep your batteries isolated in future. The one I found, 2 diodes rather than a bridge, have forward voltage drop at 15A of 0.075V.  Not a very high current rating, but here is an example: Traditional diode at 15A drops 0.6v and cooks at (15)x(0.6) = 9Watts, whereas the ideal type consume (15)x(0.075) =1.125Watts - meaningfully lower power and voltage loss, and less chance that they themselves will initiate a heat problem.
The ideal diodes are at MPJA.com  (or Marlin P Jones as was) and are $5 including heat sink!! Stock No: 35486 DI. I will keep serching for a higher rated set.Cheers, Paul
Title: Re: Chimaera - The story continues
Post by: jpdenver on July 16, 2020, 11:10:17 pm
Hello again,
I had to take some time to satisfy my day job, 
they still keep me around and want to pay me so I need to actually work once in a while. 

I started to repair the hull.

First was to re-enforce the interior.
Here in the US we have a product that is a FiberGlass infused body putty.I use it to "encase and seal" 
- usually things like prop tubes or motor mounts.

It works really well. 

So I lined the inside of the hull behind the patch and ribs. 

Then I coated the outside of the hull patch with Epoxy Resin. 

When this sets up, I will work on a final "Skin" of copper.




Title: Re: Chimaera - The story continues
Post by: derekwarner on July 16, 2020, 11:21:19 pm
Interesting Jim  :o ...even after abrading the surface of the copper sheet, how do you adhere anything the sheet surface ?...... Derek
Title: Re: Chimaera - The story continues
Post by: jpdenver on July 17, 2020, 02:56:42 am
Derek,
Not a clue.

I am making this up as I go along.Seriously, I will have to think about this.

I may end up laminating another layer of birch ply (1/16") and then add the "rivets"which are actually known as Gimp Nails. 
Little nails with a rounded head. 

Or maybe building up with epoxy and sanding the whole thing smooth.
Still playing with ideas.

Thanks for reading. 
Jim
Title: Re: Chimaera - The story continues
Post by: Mark T on July 17, 2020, 06:57:06 am
Hi Jim it looks like you have stabilised the hole with a strong repair. You could always now place planks using epoxy on the plywood to bring the hull level and the fill and sand it smooth. If you then repainted it would be invisible
Title: Re: Chimaera - The story continues
Post by: jpdenver on July 19, 2020, 10:20:37 pm
So ----
I decided to just repair and repaint it the best I can,   
without trying to emulate a repair. 

Filled it in,  sanded,  primed,   sanded,   painted,   scuffed  -  and finally added back the waterline.
Result, 

The hull lines are pretty close to original. 
There is a slight sheen difference, but the first time she scrapes the hull against a dock that will not matter. 

Now to rebuild the interior and the deck. 

I might get her on the water in a month if I get the time.