Model Boat Mayhem - Forum

Technical, Techniques, Hints, and Tips => The "Black Arts!" ( Electrics & Electronics ) => Topic started by: Martin [Admin] on November 14, 2007, 12:07:46 AM

Title: What voltage is your boat?
Post by: Martin [Admin] on November 14, 2007, 12:07:46 AM

For "scale" type boats, why did you choose the voltage that you did?
Title: Re: What voltage is your boat?
Post by: portside II on November 14, 2007, 12:14:25 AM
cos thats what batterys i had  12v 12ah and they make great ballast in me tug.
daz
Title: Re: What voltage is your boat?
Post by: Colin Bishop on November 14, 2007, 12:15:56 AM
8 volts - 'cos I was mad!
Title: Re: What voltage is your boat?
Post by: Bunkerbarge on November 14, 2007, 12:20:40 AM
For big hulls when you need the ballast and the power a 12v battery is perfect.

For smaller stuff such as my Deans HMS Cossack I use two 7.2 packs, one for each motor, because they were easy to place in the bottom of the hull and convenient for removal and charging and small enough to go through the openings.  Also the 7.2 packs now come in 3000 mah so can give you a lot of time on the water.

For my Revel sub a six pack of "C" cells also gives 7.2 but in a smaller battery with just the correct ballast requirements.

But there again for my "Scale" coaster I've used steam anyway!! O0
Title: Re: What voltage is your boat?
Post by: RipSlider on November 14, 2007, 01:04:50 AM
I'm running 2x 4300mAh 8.4v tornado packs driving 2x 540 Sport BB motors, with a 4.8 Ni-Mh for servo's, mixer etc. Driving 2x 35mm props.

Should give the endurance of a gel cell, but slightly more scale speed. Rx pack at 4.8 volts will be used if I want to sdd lightd, rotating radar dome etc, but will probably upp the capacity to a 200mAh pack to make sure I don't run out of juice.


Boat is a 880mm Patrol boat.

Steve
Title: Re: What voltage is your boat?
Post by: Welsh_Druid on November 14, 2007, 09:02:29 AM
Auxiliary motor power on my sailing ketch - 8.4volt nicads  - I had them spare.

Graupner Pegasus - 6volt 10 ahr Sealed Lead Acid (light, easily driven hull)

Northsider tug. 18volts  - 12v 7ahr + 6v 7 ahr  SLA (tried 12v and 24v - not enough push on 12 , too much on 24)

Loyal Tender     18volts    12v + 6v  7 amh SLA.    ( 12 volts -not enough push. two 12volts in series - too heavy)               

Mersey Lifeboat  12volts  7ahr  SLA one for each motor

Type 23 frigate  6volts 7 ahr  SLA (easily driven hull shape but restricted to scale speed and quiet conditions !)

If these seem over the top - we have some rough conditions on our big lake to contend with sometimes and need the extra push  O0

Don B

Title: Re: What voltage is your boat?
Post by: boatmadman on November 14, 2007, 10:23:12 AM
Drifter - 24v 7a.

Why? -  Because not enough power on 12v and it was cheaper to buy anither battery to get 24 v than replace the motor, also, was just the right weight to give the ballast it needed.

All the electronics were rated to 24v as well, so, no further cost there.

Result?  Boat goes faster than scale, but so what, thats what speed controllers are for, duration? 3hrs test so far and no sign of running down!

Ian
Title: Re: What voltage is your boat?
Post by: John W E on November 14, 2007, 10:30:03 AM
hi all

I tend to try and start off with the lowest voltage possible i.e. 6 volts - the reason being, if the model is underpowered, sometimes it is a lot easier to upgrade the battery, rather than ripping out the motor and the electrics.  On several models - e.g. HMS Leeds Castle and ML Fairmile B, I run these now on 12 volt.  

The Leeds Castle was originally built to take part in an endurance 24 hour run, with a minimum of battery change.  She could quite comfortably hold six 6 volt 10 amp batteries.   It did take her a little bit low on the water and you required a mobile crane to lift it in and out of the lake.  Since I changed the motors to a low drain 12 volt, now to bring it to the correct ballast line, you only require two 12 volt 14 amp per hour batteries.  (The big batteries that you see in the mobility scooters.)

The ML Fairmile B just requires one 12 volt battery of the 14 amp per hour this gives her ample endurance on the water but when I had scale size propellers on her, she was rather slow.  So, rather than going up to 18 volts or altering/changing the motors I just increased the size of the propellers.

I always work round the assumption, as I have said, it is far easier to increase battery voltage than to start ripping out electrics.   As a standard speed controller normally handles between 6 and 24 volts and some even handle higher voltages and higher amps.

aye
john e
bluebird
Title: Re: What voltage is your boat?
Post by: cos918 on November 14, 2007, 04:59:13 PM
i go for 12v as i get the battery's from work for free O0 . 6v i have to pay for. john
Title: Re: What voltage is your boat?
Post by: Ghost in the shell on November 14, 2007, 05:35:12 PM
Gemini, a graupner neptun, 7,2v nicad, simple answer, I had some lying around for use on espirit d'atlantique, so of there there why not use them.

celestia, Graupner Sydney Star - 6v 12ah, thats cos the boat needed a BIG A$$ battery! (actually it had to have 2 but one was enough), and the 12v batts were too big for the hull, this left the 12ah as the biggest possible battery that would fit!

Yamato & Nord Icelandia - 6v 4.5AH - thats is what fits in the hull just nicely

Espirit D'Atlanitique - tamiya plugged batteries, 8.4 or 9.6 - 8,4 for cruising 9.6 if i want to be manic!!

Southampton 7.2v (AA) - cos thats what fits!
Title: Re: What voltage is your boat?
Post by: malcolmfrary on November 14, 2007, 09:47:52 PM
A tendency to go for a higher voltage because I can pick a motor with appropriate power and reduced current consumption.
As a last desperate measure, what the instruction book said.
Some, whatever it wound up as because it semed a good idea at the time.
Title: Re: What voltage is your boat?
Post by: Colin Bishop on November 14, 2007, 09:56:37 PM
Going back to my earlier post, I chose 8 volts because it was convenient for both the motors I am using and the shape of the model - a 48" very round bilge fishery cruiser which doesn't lend itself to rectangular gel cells. Power is from four 2v lead acid 4.5ah cylindrical Cyclon batteries. At the moment I am using a Flair Varivolt charger which is supposed to sense the battery voltage and charge accordingly. It uses pulse charging at 500ma. Does anybody know of alternative chargers out there which might be suitable for an 8 volt lead acid setup?
Title: Re: What voltage is your boat?
Post by: John W E on November 14, 2007, 10:02:29 PM
Colin, are you finding the same problem as I have with the Flair Varivolt charger?  Very good charger but you have to keep an eye on the battery when you are charging, as I have had one 6 volt gel cell bubbling and when I checked the voltage across it, it was trying to pump 12 volts into it and the battery had been on for at least an hour.

I still use the charger - but, only when I am in attendance and I can keep an eye on the battery.

I must admit, I have never attempted to charge NiCads with it, although they say you can - for fear the NiCads explode.

aye
john e
bluebird
Title: Re: What voltage is your boat?
Post by: Shipmate60 on November 14, 2007, 10:30:58 PM
I just stick to boring old 6 or 12 volts in All my boats.
6 volts for smaller ones, 12 volt for larger.

Bob
Title: Re: What voltage is your boat?
Post by: Colin Bishop on November 14, 2007, 10:55:08 PM
John,

My Varivolt was bought some years ago and seems to be a different spec from the ones currently advertised. You are right that you do have to watch it. it can be left on indefinitely with a 12v 6ah gel cell but smaller cells do get warm and you need to watch them. In general I follow the instructions. Hope they are readable.

Colin
Title: Re: What voltage is your boat?
Post by: wingertaz on November 15, 2007, 09:27:07 AM
I use either 6 volt 10 ah or 12 volt 7ah sealed lead acid batteries with the exception of my little Garnock Tug, in this I used a 4.8 volt 1700mah Ni cad pack. I can get nearly 3 hours running time.
In my Leeds Castle I will be using 2 x 12 volt 7ah batteries wired in parallel. I hope to get reasonable running time. ?

Gary
Title: Re: What voltage is your boat?
Post by: sheerline on November 15, 2007, 09:53:28 AM
I use 12 volt NiMh packs in the subs. The ballast pumps require 12 volts to give the correct rpm for the pressure required. Also, the motors are running at their optimum voltage and coupled with the correct props and gearboxes consume the minimum current for max thrust at full throttle.

The advantage of NiMh is :
compact size,
high current capacity for size,
ability to be stored beneath dive unit in most boats,
no memory problems such as found in nicads,
no black wire corrosion as found in nicads,
long life.

Dissadvantage:
initally expensive to buy.
Require dedicated charger (delta peak)

Although these cells can be bought cheaper. I source my cells from a supplier who guarantees top quality cells. A lot of cheap cells find their way onto the market such as those found in cheap drills and the like and they don't last. I pay extra for peace of mind and reliability as subs require top quality components and have to be ultra reliable.
If these boats break down, they require recovery as they won't blow ashore in a breeze to the same degree as a surface boat.

As an example, the Type 2D u-boat has a 12Volt 9Ahr waterproof NiMh pack containing 10 'D' size cells and I have them spot welded in series to form a stick. The boat can stay out on the lake for hours (5hours on one outing). On another trip, the boat ran submerged for about three hours.
You've got to have faith in your gear so it's NiMh for the subs. 

 
Title: Re: What voltage is your boat?
Post by: Colin Bishop on November 15, 2007, 10:11:39 AM
Quote
no black wire corrosion as found in nicads

I don't think it's to do with the type of battery. I've got it in my 1:1 scale boat which uses car/deep cycle lead acid types.
Title: Re: What voltage is your boat?
Post by: sheerline on November 15, 2007, 11:07:26 AM
Hi Colin, yes, I have also seen it in that type of battery but not so in the case of the NiMh. I was informed by the battery suppliers that it was one aspect of these batteries which made them more reliable and maintenance free. As yet, I have seen no evidence of this form of corrosion, however there is a possibility of electrolysis causing corrosion should water penetrate the waterproofing but this would happen on any battery where a potential difference exists.
Chris
Title: Re: What voltage is your boat?
Post by: Colin Bishop on November 15, 2007, 11:18:48 AM
Quote
however there is a possibility of electrolysis causing corrosion should water penetrate the waterproofing but this would happen on any battery where a potential difference exists.

Which is almost certainly what has happened to my 1:1 boat - damp salt atmosphere. Gets everywhere!
Title: Re: What voltage is your boat?
Post by: djrobbo on November 15, 2007, 12:53:39 PM
Hi guys......well here goes.............

  SUN XX! tug........m f a torpedo motor  on 2 - 1 gearbox
                           electronize.....45..........esc
                           6 volt...4ah.....sla

 AMSTERDAM  TUG.......850 motor..............direct drive
                                 e.s c from china ??  (50a  works well )
                                 12 volt.....7ah.........sla

 SMALL PUFFER (29in).......portescap rg7 motor ( from o gauge model train )
                                  same chinese esc
                                  12 volt............sla..........................mostly  sla  gell cells...but also use 9.6 and 7.2 buggy packs in some of the others
Title: Re: What voltage is your boat?
Post by: tolnedra on November 15, 2007, 05:12:13 PM
All of mine are on SLA, 6v for the smaller ones, 12v the two larger, from 4ah to 7.5ah; almost all of my scale boats are tugs.

Danny
Title: Re: What voltage is your boat?
Post by: Ghost in the shell on January 10, 2009, 10:51:31 PM
added to the list of mine:

Graupner Elmshorn - 7.2v sub c

Nord Icelandia 6v 4.5ah (cos thats all that will fit)
Title: Re: What voltage is your boat?
Post by: cbr900 on January 11, 2009, 12:11:11 PM
Most of the yachts run on Minh batery packs,
Tugs, one on three 6v 7ah sla
second on two 12v 7ah
Bulk Cargo Ship 12v 20ah plus 20kg lead
Corvette 6v 4ah
the rest on either 6v7ah or 12v 7ah


Roy
Title: Re: What voltage is your boat?
Post by: gingyer on January 11, 2009, 12:17:23 PM
I always try to keep about 6v for my models
it means I can use the same batteries for most of them
Title: Re: What voltage is your boat?
Post by: catengineman on January 11, 2009, 12:30:24 PM
Tito Neri  12 volt SLA X 2 for main motors and fire monitors
              6 volt SLA for winch's cooling and lights
              6 volt SAL for reciever and servos

Dutch ?   to be 12 volt SLA for main motors
                      6 volt SLA for rec, servos and ??????? TBA

R,