Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: 12 volts down to 6 volts  (Read 2007 times)

catengineman

  • Guest
12 volts down to 6 volts
« on: January 20, 2012, 11:19:07 PM »

Hi all in the know.
I have put all the various bits and bob's into the hull of a VS tug and I have run out of room and buoyancy!
So I will be running the motors on 12v from one 12 volt 14 amp SLA, I have a 6 volt water pump 6 volt winches (2) and then there are the lighting and radar to get down to 3volt and 1.5 volt respectively
then the biggy I am thinking of using an Action switch but I read that they do not like the SLA supply and will require a separate one (not fully sure yet)
On top of that there is the REC to supply power to all from the 12 volt (REC may be able to have its own supply) there is enough power for all I am just after ideas as to the best way to power the pump, the winches and all the other bits from the one battery.

I don't think a voltage regulator will handle the pump or winches.
I also don't want to go through the changing of battery to smaller ones of various voltages (unless there is no other way)
Give me something clanky and I can make it do what ever but give me this electric stuff and I fine myself going round in circles
3300 KVa is not problem, I know what I need to get down to 330v, 220v, 110v, etc but all those units are BIG (bigger then my model)

Is there a small light transformer to bring 12 down to 6  I can then use a little power board form PMK to get the rest from the 6 volt supply.
Logged

ACTion

  • Guest
Re: 12 volts down to 6 volts
« Reply #1 on: January 20, 2012, 11:30:20 PM »

then the biggy I am thinking of using an Action switch but I read that they do not like the SLA supply and will require a separate one (not fully sure yet)
They don't like being connected to a receiver which is powered directly by a 6v SLA. If you use a BEC then they are fine. Ref the other problem, I'd forget trying to find a way of dropping the voltage down and use a separate 6v supply - much less hassle in the end. Two 3v bulbs in series is 6v and a 1.5v cell weighs nowt and will run a radar motor forever (or near enough).
DM
Logged

dreadnought72

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,855
  • Wood butcher with ten thumbs
  • Location: Airdrie, Scotland
Re: 12 volts down to 6 volts
« Reply #2 on: January 20, 2012, 11:40:00 PM »

I don't think a voltage regulator will handle the pump or winches.

I've just ordered one of these. It's a 6V from 12V regulator, able to handle 5A. Less than 10.

It should be arriving tomorrow - I'll report on it later this weekend. Is 5A enough for the requirements you posted?

Andy
Logged
Enjoying every minute sailing W9465 Mertensia

catengineman

  • Guest
Re: 12 volts down to 6 volts
« Reply #3 on: January 20, 2012, 11:46:57 PM »

Would have been but input voltage is only 6 - 7.2 volts and I am really trying to keep to the 12 volt SLA (as the battery carrier and surrounding area made), plus the boat is right for the trim.

looking like another rethink  <:( :((

Hi Dave,
PMK made me a little board which will give me three outputs from one input I can have variations from the input (6v) adjusted down to 0v via pots which I find is a fantastic little devise which I would like to install.
I just need to get from 12 v down to the 6 volt which would be able to handle the pump and winch's on short term use.
I did think of using a dedicated reciever supply thing from the SLA
http://www.ebay.co.uk/itm/Direct-Power-supply-Connector-BEC-X-1-/380397167292?pt=LH_DefaultDomain_0&hash=item58917022bc
again if needed then a rec battery pack could be put into the build (I'll just have to dig out some lead and resin)
Logged

dreadnought72

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,855
  • Wood butcher with ten thumbs
  • Location: Airdrie, Scotland
Re: 12 volts down to 6 volts
« Reply #4 on: January 21, 2012, 12:18:17 AM »

The input is 12V, catengineman. It must use something like a LM338T to do the electronic work. I'll open it when I get it and confirm this.

Alternatively, a cloud of smoke over Airdrie this weekend will confirm it's not suitable.  %)

Andy

Logged
Enjoying every minute sailing W9465 Mertensia

Umi_Ryuzuki

  • Guest
Re: 12 volts down to 6 volts
« Reply #5 on: January 21, 2012, 01:42:54 AM »

There are alot of voltage regulators that can be purchased, or built that can reduce the 12v source down
to 6volts for the pump. However, you need to make sure they will provide, or are rated for enough amperage
to supply your pump motor. Otherwise you risk burning out the regulator. Most BEC are only rated to 1 amp.
Stand alone BEC, and voltage regulators are often rated higher, but the amperage can be supplied needs to
matched to your pumps amp draw.

 :-)
Logged

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,529
  • Location: Blackpool, Lancs, UK
Re: 12 volts down to 6 volts
« Reply #6 on: January 21, 2012, 01:03:32 PM »

Two different types of regulator mentioned.
Dreadnoughts' ( http://www.cmldistribution.co.uk/cml_product.php?productId=0000005987  ? ) is supposed to be good for up to 25 volts, and will consist of an oscillator to convert the input to AC at a high frequency, a transformer (the higher the frequency, the smaller it can be for a given power level) to reduce the voltage and increase current, and a feedback regulator to look at the output and change the input characteristics to give the right answer.  This sort of thing used to be hideously expensive, but is now becoming more mainstream.
Anything based on an LM338 is liable to run hot with a large voltage drop involved.  Simple, cheap, cheerful, wasteful of power when dropping more than a couple of volts.
Separate batteries seems a bit messy, but, once remembering to charge them has been absorbed, is likely to be the best long term answer, especially for low volt, low current use.
Logged
"With the right tool, you can break anything" - Garfield

ACTion

  • Guest
Re: 12 volts down to 6 volts
« Reply #7 on: January 21, 2012, 01:06:55 PM »

I have heard that these switch-mode regulators can produce a lot of RF interference, so best to range check the radio with everyting running and ensure there are no glitches before you commit your model to the oggin. I still reckon separate batteries would be best.
DM
Logged

dreadnought72

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,855
  • Wood butcher with ten thumbs
  • Location: Airdrie, Scotland
Re: 12 volts down to 6 volts
« Reply #8 on: January 21, 2012, 11:31:20 PM »

Just wired up capacitors to the motor - will do a regulator/range check sometime tomorrow/Monday. Then we'll see any rf problems from the regulator. Thing is, the device says up to 5 amps at 6V. ACTiion's suggesting (is this right?) 30 watts through the heatsink. We'll see - not a problem for a now-and-again sail winch maximum. Might be more warmerer for a high-amperage, longer-running bow thruster, etc.

Andy

Logged
Enjoying every minute sailing W9465 Mertensia

dreadnought72

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,855
  • Wood butcher with ten thumbs
  • Location: Airdrie, Scotland
Re: 12 volts down to 6 volts
« Reply #9 on: January 23, 2012, 09:08:30 PM »

Malcolm is quite correct:

Quote
...It will consist of an oscillator to convert the input to AC at a high frequency, a transformer (the higher the frequency, the smaller it can be for a given power level) to reduce the voltage and increase current, and a feedback regulator to look at the output and change the input characteristics to give the right answer.

It arrived today, and so it does.

Before I plug it merrily in, however, I have a question. The container is not helpfully marked "in" and "out". The only thing I have to go on is that the two pairs of wires running into and out of it have a male and female JST connector. The female end is near the chip, the male end next to the transformer.

Is the female connector the source side?

Answers on a postcard...  >:-o

Thanks,

Andy
Logged
Enjoying every minute sailing W9465 Mertensia

More Coffee

  • Guest
Re: 12 volts down to 6 volts
« Reply #10 on: January 24, 2012, 05:30:17 AM »

Just read this article here:
http://www.reuk.co.uk/High-Current-Voltage-Regulation.htm

Its possiable to chain regulators ,, ..out side the 78xx series unit's, a simple LM317 can be used to regulate a high power transistor. Always wise to use a heat sink ,not only does it disapte heat, getting rid of that heat keeps the system stable..
Logged

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,529
  • Location: Blackpool, Lancs, UK
Re: 12 volts down to 6 volts
« Reply #11 on: January 24, 2012, 09:43:18 AM »

e-postcard for Andy, I would assume that the connector that looks like the one on a battery stick will be the out put, t'other will plug into a battery.  If the maker couldn't be bothered to mark them, I would have my fingers crossed behind my back.
The advantage of a switch mode chopper is that very little power is lost and thus practically no heat generated.
The disadvantage is the chopping of the supply to an inductive circuit, which can put large back EMF voltage spikes back into either or both of the supply and output power lines, causing local interference.  Suppression as on a motor, and/or feeding the wires through ferrite rings or beads might help contain the interfering signal as well, but this is firmly into black art territory.
There is no way I could recommend using a linear resistor to drop more than half the supply voltage at any more than a few dozen milliamps in a closed environment like a boat.  Apart from having to cart around the extra battery capacity which is going to be wasted, there is the need for heatsink(s) and fan(s), which between them will probably take up more space and payload than the extra battery.
One of those cases where you makes your choice and you pays your money.
Logged
"With the right tool, you can break anything" - Garfield

catengineman

  • Guest
Re: 12 volts down to 6 volts
« Reply #12 on: January 24, 2012, 09:52:49 AM »

Bit the bullet and have removed the battery frame I had put in so now will get 6 volt battery and a smaller version of the 12 volt battery and dig out some lead from the hull.

Getting a bit fed up with this low voltage stuff ! why is it sooooooo much easier to sort out 3300 KVa or 415 than it is to the low end power?
OK yes I know the size of units and the fact that with the big stuff there is lots of room in ships to have cooling units  <:(

Oh well back to the work shop and the dremel  :-))
Logged
Pages: [1]   Go Up