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Author Topic: Battery output..  (Read 2047 times)

tizdaz

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Battery output..
« on: January 14, 2018, 07:09:16 PM »

Hi guys, if i wire my batterys in the config below, will it give me a total output of 24v & 44Ah ?



cheers

T33cno

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Re: Battery output..
« Reply #1 on: January 14, 2018, 07:42:07 PM »

Yes
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tizdaz

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Re: Battery output..
« Reply #2 on: January 14, 2018, 07:54:45 PM »

cool thanks :)

T33cno

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Re: Battery output..
« Reply #3 on: January 14, 2018, 07:58:05 PM »

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tizdaz

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Re: Battery output..
« Reply #4 on: January 14, 2018, 10:25:02 PM »

aye!


well, to be honest when I do my 1st water test at the weekend, i'm hoping she will run just fine on 12 volt, 2 benefits of this is first, I can run the rest of my electrics off of the same circuit & secondly, the battery's will last twice as long as running in Parallel will give me 12v but 88Ah. On the stand when I've ran the motor with the prop attached on 12v there seems to be plenty of RPM even on just half throttle, but once in the water...whole new ball game as they say!


So time will tell!


Just out of curiosity, Is there any drawback when running a 24v motor off 12v instead of 24 (except for the lower RPM) ?

T33cno

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Re: Battery output..
« Reply #5 on: January 15, 2018, 09:21:53 AM »

Same effect as running a 12 volt motor on 6 volts. Without knowing your situation the first thing that comes to mind is fit a 12 volt motor.
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Steve Dean

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Re: Battery output..
« Reply #6 on: January 17, 2018, 06:33:28 PM »

Whoa! ....... 88aH is a huge amount of capacity. Do you really need that much. What type of motor are you running ..... in what type of boat?
I run my 1/12  trawler on a single 12 volt, 7aH battery and it operates for several hours.
Make sure you have some sensible fusing arrangement as that amount of current capacity has the ability to melt everything.
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tizdaz

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Re: Battery output..
« Reply #7 on: January 17, 2018, 06:55:52 PM »

hey, its a 24v motor from MMM, yeh ive got a couple of fuses in place, not sure yet if im going to run 12v 88Ah or 24v 44Ah, hopefully doing 1st water test at the weekend so will see whats what :)


heres diagram if I use 24v..


malcolmfrary

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Re: Battery output..
« Reply #8 on: January 18, 2018, 10:23:23 AM »

In a single motor, single ESC setup, there really isn't much need for a fuse between ESC and motor.  Especially since most ESCs limit the current output anyway.  Far better to have the fuse between battery and ESC.  As shown, the fuse, its wiring and the connection points are just unwanted fault liabilities.
That way, if anything internal happens to the ESC (rare, but not unknown) you don't have the battery dumping its charge into a faulty ESC.  The results are quite dramatic with just two or three AH of battery power.  A different word is needed to describe the possible results of 88AH (a bit over 1KWH) all trying to dissipate itself into a bit of wiring and the ESC in a few seconds.
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tizdaz

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Re: Battery output..
« Reply #9 on: January 18, 2018, 12:52:56 PM »

In a single motor, single ESC setup, there really isn't much need for a fuse between ESC and motor.  Especially since most ESCs limit the current output anyway.  Far better to have the fuse between battery and ESC.  As shown, the fuse, its wiring and the connection points are just unwanted fault liabilities.
That way, if anything internal happens to the ESC (rare, but not unknown) you don't have the battery dumping its charge into a faulty ESC.  The results are quite dramatic with just two or three AH of battery power.  A different word is needed to describe the possible results of 88AH (a bit over 1KWH) all trying to dissipate itself into a bit of wiring and the ESC in a few seconds.


hi there,


There is a fuse between the Battery & ESC (at bottom of diagram labelled FSE) along with a power switch also labelled SW) There's also an fuse in between the motor & ESC should anything go wrong with the motor etc, the fuse for the motor is an Action P95 inline fuse, the fuse in between the battery & ESC is just a simple inline fuse but i may swap this out for another P95 from Action.


The other option' ive been thinking of, is if i do stick with 12v instead of 24v, then have 2 sets of battery setups each consisting of 2x 12v 22Ah in parellel to give total output of 12v 44Ah. I want to keep the 4 batterys in the hull as these are also to help with the ballast. All I would need to do is should one of the setups run low on juice then I just unplug & connect the other, at least this way I'm not going to be pumping out 88Ah, But as I've already mentioned, I wont know for sure about final setup until after I've done my water test at the weekend as I will either be using 12v or 24v depending on the performance in the water.


So basically..
if 12v, then i will have 2 sets each being 12v 44Ah, but only 1 connected at a time,
if 24v then it will be all 4 batterys connected in series/parallel to give total output of 24v 44Ah.

RAAArtyGunner

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Re: Battery output..
« Reply #10 on: January 19, 2018, 12:52:13 AM »

I too missed the fse AKA fuse.

Guess what everyone is saying is,

why are you carrying a full semi trailer fuel tank (88AH) in you little Ford Focus (7AH) when you don't need it.?
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McGherkin

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Re: Battery output..
« Reply #11 on: January 19, 2018, 02:37:42 AM »

I too missed the fse AKA fuse.

Guess what everyone is saying is,

why are you carrying a full semi trailer fuel tank (88AH) in you little Ford Focus (7AH) when you don't need it.?


He needs ballast. If you’re going to carry ballast, it makes sense for it to at least be useful.

If he ever wants to go on a boating holiday he can tie a dinghy onto his model and go boating for a few weeks on a single charge.
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Stavros

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Re: Battery output..
« Reply #12 on: January 19, 2018, 07:24:12 AM »

That set up will see you getting bored at the lakeside....it wont run out of power for weeks....but what do i know......ah ha yes of course i got the same boat




Dave
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tizdaz

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Re: Battery output..
« Reply #13 on: January 19, 2018, 04:35:20 PM »


Hi guys!


Let me clear a couple of things up!


The batterys are also for ballast, NOT just the power, my motor is a 24v 350watt, Even with 4 of these batterys, im still going to need more ballast. With SLA batterys, the more capacity, the heavier they are. Would of been pointless buying low capacity batterys only to be needing alot more ballast!


I was going to use 2x car batterys as this is what others have used in the same build (& most car batterys have much higher capacity than what my 12v 22Ah have!) but I opted for these instead as they are much smaller in size, so when I do smaller builds in future, I can use these same batterys. If I bought car batterys, then chances are they will only be suitable for this build which would have meant I would have had to buy more smaller size batterys for smaller builds which would have been a little daft!


I'm doing water test on sunday so I will then know exactly how much more ballast im going to need, but I've done a few calculations & I still think im going to need around another 6-10kg more ballast.


As I explained in my previous post, If 12v is enough to power her (which hopefully it will) then I wont be hooking up all 4 batterys at once for juice as originally planned, I will split them to have 2 sets, each consisting of 12v 44Ah) but all 4 will still be placed in the hull for ballast! ..I may even just have 1 hooked up at a time if 12v, its no biggy.. but all of them will still be in the hull.. as they say "2 birds with one stone!"


Dave out of curiositry, what batterys are you using for your build?


Cheers :)

tizdaz

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Re: Battery output..
« Reply #14 on: January 19, 2018, 04:37:56 PM »


He needs ballast. If you’re going to carry ballast, it makes sense for it to at least be useful.

If he ever wants to go on a boating holiday he can tie a dinghy onto his model and go boating for a few weeks on a single charge.


:D ...sounds a plan! lol

Stavros

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Re: Battery output..
« Reply #15 on: January 19, 2018, 05:51:43 PM »

12v 063 car batt and a couple of dead gell cells....if memory is right i used 3x12 10amp ones


Dave
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tizdaz

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Re: Battery output..
« Reply #16 on: January 19, 2018, 06:17:28 PM »

12v 063 car batt and a couple of dead gell cells....if memory is right i used 3x12 10amp ones


Dave


she definately needs a lot of ballast then! ..at the mo I have my 4 batterys, each one weighing around 6.5kg so will see how she sits in the water on sunday, i'm hoping its not too far off the waterline!

RAAArtyGunner

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Re: Battery output..
« Reply #17 on: January 20, 2018, 01:23:10 AM »


To satisfy our curiosity how about a pic or drawing of this 'beast'?
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McGherkin

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Re: Battery output..
« Reply #18 on: January 20, 2018, 07:34:33 AM »

To satisfy our curiosity how about a pic or drawing of this 'beast'?


There’s a link attached to every one of his posts  ;)
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tizdaz

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Re: Battery output..
« Reply #19 on: January 20, 2018, 09:32:49 AM »

yup, in my sig there's links to my build, but here they are anyway :)


My Website Build Log: http://www.tizdaz.co.uk/boat/build.html


Forum Build Log: http://www.modelboatmayhem.co.uk/forum/index.php/topic,56353.0.html

RAAArtyGunner

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Re: Battery output..
« Reply #20 on: January 22, 2018, 01:59:55 AM »

Thank you, I tend not to follow links unless in the body of the thread, could lead anywhere??

Mate you should be building it with concrete then ballast wouldn't be a problem, you just wouldn't be able to carry it.

Yes, you don't need to have all the batteries hooked up, in fact you could have two identical parallel circuits and just switch on circuit no.1 or Circuit No.2.
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tizdaz

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Re: Battery output..
« Reply #21 on: January 22, 2018, 03:52:23 PM »

Thank you, I tend not to follow links unless in the body of the thread, could lead anywhere??

Mate you should be building it with concrete then ballast wouldn't be a problem, you just wouldn't be able to carry it.

Yes, you don't need to have all the batteries hooked up, in fact you could have two identical parallel circuits and just switch on circuit no.1 or Circuit No.2.


hehe aye concrete would have been much simpler!


I was hoping for her first water test on sunday (was going to take her to Ellesmere port boat museum as it's only a 5-10 min drive from where I live (& use the canal just by the side of it as its enclosed) but thanks to the damn weather, it was a no go! ..didn't stop raining ALL day, even had a little snow! :( so I'm going to see if I can make some time in the week or if not, then it will be next weekend! ...depending on the bloody weather!!


In the meantime I'm going to start fixing the deck in place :)

Tinny

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Re: Battery output..
« Reply #22 on: January 25, 2018, 07:32:04 AM »

...Is there any drawback when running a 24v motor off 12v instead of 24 (except for the lower RPM) ?
I do not know about boats in water, but motors having to lift/pull a set load weight draws a certain amount of power to do so. This is especially so when the load is not moving and the motor shaft is getting under greater strain, the motor starts using more current (amperes). Stall currents can be very high.


The motor will have a power (watts) reading either with or without a load (prop in water). So if the motor voltage drops by half, the motor will drop down in speed, but it will draw more current, if one may give the motor increased power to go against a water current. So the amps will increase.


But lets say the 24 volt motor draws 10 amps under load. That is 24V  x 10A = 240W.  At 12 volts, to draw the same amount of power, the current will increase  240W / 12V = 20A
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malcolmfrary

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Re: Battery output..
« Reply #23 on: January 25, 2018, 09:39:01 AM »

I do not know about boats in water, but motors having to lift/pull a set load weight draws a certain amount of power to do so. This is especially so when the load is not moving and the motor shaft is getting under greater strain, the motor starts using more current (amperes). Stall currents can be very high.


The motor will have a power (watts) reading either with or without a load (prop in water). So if the motor voltage drops by half, the motor will drop down in speed, but it will draw more current, if one may give the motor increased power to go against a water current. So the amps will increase.


But lets say the 24 volt motor draws 10 amps under load. That is 24V  x 10A = 240W.  At 12 volts, to draw the same amount of power, the current will increase  240W / 12V = 20A
No. 
Provided that the motor can move the load, it will not go into stall mode, and Ohms Law will be followed very closely. 
At reduced voltage, you do not draw the same power with the same motor, you get 12V X 5A = 60W. 
To get the same power from the reduced voltage, you need a different motor, wound to draw the increased current at the lower voltage.
In model boat use, using permanent magnet motors, you never get anywhere near stall loading.  If you do, either the boat needs fixing or the wrong motor was used in the first place.
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