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Author Topic: Which battery type is best?  (Read 1350 times)

rmaddock

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Which battery type is best?
« on: April 24, 2012, 06:02:38 PM »

First off, please excuse me if this question has already been answered elsewhere. I have looked but couldn't find quite the answer I was looking for so....

In case you don't know, I'm currently building a 44", scale, traditional sailing trawler with auxiliary motor.  I'm wondering what type of battery would be best employed.

I've got Action Man's electrickery to drive it all but require a 12v source.  Due to the design/layout of the boat, two separate batteries/packs would be required - a la saddle tank.  I would like to get a reasonable running time out of it as I might want to motor around some days and I've also got three Hitec sail winches (drum type) to power.  The motor is a geared 500 (again from Action).

So, do I go lead acid or NIMH (or other)?

Am I best with two 12v batteries in parallel or two 6v batteries in series?

I half expect the answer to be "whatever takes your fancy mate" but just thought there might be differences. Reliability etc.

Cheers!
Robert.
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boatmadman

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Re: Which battery type is best?
« Reply #1 on: April 24, 2012, 06:26:37 PM »

Rob,

For your particular requirements, I think a Nimh saddle type battery would probably be best.

If you go to http://www.component-shop.co.uk/html/medium_power_packs.html you will see an example of what can be done.

Component shop will make up a pack to your requirements. You may wish to consider 1 x 12v battery pack in 2 halves., connected to provide the 12v. You can also specify how long you want the wiring connecting the two halves, to allow you to fit them where you want them.

Ian
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rmaddock

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Re: Which battery type is best?
« Reply #2 on: April 24, 2012, 06:42:54 PM »

Ah, custom packs!? I didn't know that was an option.
It'd certainly be better to charge them as a single pack.
Thanks Ian, I shall look into that.
I guess in the meantime, I need to get the meter into the motor and see what current it's drawing (presumably best measured whilst in the test tank?) and so figure how much amperage I might need.
Cheers!
R.
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malcolmfrary

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Re: Which battery type is best?
« Reply #3 on: April 25, 2012, 10:06:53 AM »

Can't just remember what the winches run on, but I feel that the sail setup would be best on its own battery, with the motor and its associated electronicery on its own 12 volt supply.  Supplying the winch off 12 volts via a regulator might be asking a bit too much of the regulator, or at least, any regulator smaller and lighter than the battery it is intended to replace.
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rmaddock

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Re: Which battery type is best?
« Reply #4 on: April 25, 2012, 10:27:09 AM »

Thanks Malcolm, I hadn't thought of that. It had slipped my mind that I'd need to step the voltage down for the winches.  :embarrassed:  That could have been a lot of winch up in smoke.  :o

So, I could get two packs....equal in mass but at different voltages.  The 12v pack could drive the Action P92 and thus the Tx (via BEC) and the motor. A seperate 6v pack could be used to power the winches.

Yep, I'm feeling happier about this now.

Thanks again.
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rmaddock

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Re: Which battery type is best?
« Reply #5 on: April 25, 2012, 10:29:03 AM »

So, I could get two packs....equal in mass but at different voltages.

Duh! One'll be twice the size of the other.  <*<
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pettyofficernick

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Re: Which battery type is best?
« Reply #6 on: April 25, 2012, 03:12:23 PM »

Will not the BEC in your Rx drop the voltage to the winches? they are connected to the reciever after all, or is a different set up used for sail winches? Just get a high capacity 12 battery that will cope with everything and let the BEC sort the voltage out. :-))
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rmaddock

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Re: Which battery type is best?
« Reply #7 on: April 25, 2012, 05:40:24 PM »

That could also be true Nick. I'd have to work out if the current capacity of the BEC was enough.....and I've already leaped in and ordered in a fashion that would frighten the proverbial angels.

Thank though  :-))
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ACTion

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Re: Which battery type is best?
« Reply #8 on: April 25, 2012, 05:47:09 PM »

Will not the BEC in your Rx drop the voltage to the winches? they are connected to the receiver after all, or is a different set up used for sail winches? Just get a high capacity 12 battery that will cope with everything and let the BEC sort the voltage out. :-))

Afraid not, m'duck. The winches are connected to either switches or speed controllers but, while these are in turn connected to the receiver, those connections are for their logic circuitry which runs @ 5v and low current. Their power circuits can be anything to suit the motors (and subject to the spec of the switches or ESCs). That's why speed controllers have three thin wires and four socking great fat beggars - the former for the receiver and the latter for the motor and main battery. If you really want to suffer there's more here http://www.action-electronics.co.uk/pdfs/ESCs.pdf and here http://www.action-electronics.co.uk/pdfs/Relay%20Switches.pdf and even here http://www.action-electronics.co.uk/pdfs/BEC.pdf

Two battery packs is the order of the day here. If using similar size/capacity NiMH cells then the 12v pack will be double the size and mass of the 6v one, but as you aren't using the winches all the time you might opt for smaller and lighter cells in the 6v pack.

Dave M
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rmaddock

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Re: Which battery type is best?
« Reply #9 on: April 25, 2012, 05:50:54 PM »

Thanks for that Dave.
As said, I've ordered to NIMH packs, 6v and 12v. The extra mass on one side should balance out the steering servo, Rx, ESC, P92 etc etc on t'other side.
I should be able to sail for weeks without recharging!
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Netleyned

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Re: Which battery type is best?
« Reply #10 on: April 25, 2012, 06:38:13 PM »

I think that once the nobby is sailing well
The motor will just be a get you home
option as sailing will get into your soul

Ned
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rmaddock

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Re: Which battery type is best?
« Reply #11 on: April 25, 2012, 06:49:48 PM »

It's already there Ned. I chose a sailing model this time as I get so much pleasure sailing my marblehead. Motoring up and down pales quickly by comparison...but the option will be nice.
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