# Battery Sizing for 100Tone Autonomos vechicle conceptual design



## Jordanie (Aug 28, 2012)

Hi all!

I'm working on a conceptual project as summer student(at http://fusionforenergy.europa.eu/) and my task is to estimate how the required battery for a 100 tone electrical transporter(for nuclear components within ITER fusion reactor: (http://www.sciencedirect.com/science/article/pii/S0920379610005624)

As an input information I know the the x,y cordinates of the vechicle and possible velocity profiles for (dV between the x,y cordinates of the trajectory - all in exell table format)

I have done simple exell calulator but not sure if the results I get are relaistic. Do you know if I can use any of the upper mentioned tools for calibrating my estimation. My spread sheet is applied to the tread, please have a look. Here at fusion for energy the IT policy is tite so it is a bit of a pain to instal any software such as open office!


Please let me know, what you think, at the moment I get for:


130meters; 
100tone vechicle,
Crr = 0.01, Vmean=0.1659 m/s 
Total time = 1160seconds, 

and you can see the axeleration profile within the sheet, I get I would require about

--> 1839 W of Power(rms) and 30kg of (lead acid batteries).


If I ignore friction forces, I get that the energy required just for the change of momentum for this velocity profile and 100Tone vechicle is only 2.35kg


Do you have any sugestions of how I can calibrate my battery estimator?

Thank you allot!


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## Jordanie (Aug 28, 2012)

missed to apply the spreadsheet!



Jordanie said:


> Hi all!
> 
> I'm working on a conceptual project as summer student(at http://fusionforenergy.europa.eu/) and my task is to estimate how the required battery for a 100 tone electrical transporter(for nuclear components within ITER fusion reactor: (http://www.sciencedirect.com/science/article/pii/S0920379610005624)
> 
> ...


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## Duncan (Dec 8, 2008)

Jordanie said:


> Hi all!
> 
> I'm working on a conceptual project as summer student(at http://fusionforenergy.europa.eu/) and my task is to estimate how the required battery for a 100 tone electrical transporter(for nuclear components within ITER fusion reactor: (http://www.sciencedirect.com/science/article/pii/S0920379610005624)
> 
> ...


Hi Jordanie

First - you need to sort out your units
energy is not measured in Kg!

Second 
You are talking about moving a heavy object slowly - friction forces are likely to dominate -


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## Jordanie (Aug 28, 2012)

Hello Duncan,

apologies what I ment is that my Battery power requirement prediction is: (look at the current sheet applied for the current velocity profile) 

*9626.22*
9626 Wh(Watthours) for 100Tone, 130meter and 0.182m/s meen velocity and high acceleration deceleration profile.

Using an eqation derived (in a similar manner to Breguet range equations used for aircraft range - fuel requirements). For this RMS power required and this velocity profile, distance I get 16.34 kg (of LI-Acid battery required). After oversizing for DoD and Peukert --> I get about 37 kg of expected battery weight for this velocity profile.

 The (RMS) Power [Wh] required for the trajectory I calculate by using the RMS formula and summing all the power requirements for each small axelleration or deceleration along the trajectory path.


Please can you tell me if that is a right way of representing the power requirement and finaly the expected battery weight(size) for a particular trajectory and velocity profile?!

 Thank you allot!


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## Jordanie (Aug 28, 2012)

here is the spreadsheet!


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## Jordanie (Aug 28, 2012)

here is the spreadsheet!


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## PStechPaul (May 1, 2012)

(Copied from other thread on another EV calculator)

I used my online EVcalculator with your figures (100,000 kg for 100 tons?), and I got 9803 N force and energy of 1625 W. For acceleration I used 0.0000286 m/s/s assuming the nominal speed will be reached at 1/2 the total transport time. It's written in JavaScript so you can make changes or add to it if you wish. If you do, please post the changes and I might add them to my version.


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## Jordanie (Aug 28, 2012)

Hello, PStechPaul

The results your calculator has seem relatevly close to the one I have. Problem is that I dont calculate single axeleration or deceleration. I assume a sequence of 1500 x,y cordinates and a wave shaped velovity profile created by a series of various axellerations and decellerations. What I calculate is the P(rms). Did you manage to open my exell spreadsheet?

Do you have any comments on the way I estimate the battery weight?

Regards,

Jordanie


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## Woodsmith (Jun 5, 2008)

First thing that would strike me would be 'Why batteries?'.

There are mining shovels that weigh in at 100s of tons, move short distances and move slowly. They tend to be plugged into a three phase AC power supply with a massive armoured cable, both to supply the excavator shovel in use and also to power the drive motors.
A pantograph to pick up overhead power would be another option.

You would seem to be only looking at 1.6kw to motivate it but possibly many many more times that to overcome friction in the moving parts and drivetrain.

At 100 tons vehicle weight, battery weight could be relatively insignificant.


How many times would the transport be required to travel the 130m route between battery charges?


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## PStechPaul (May 1, 2012)

Jordanie said:


> Hello, PStechPaul
> 
> The results your calculator has seem relatevly close to the one I have. Problem is that I dont calculate single axeleration or deceleration. I assume a sequence of 1500 x,y cordinates and a wave shaped velovity profile created by a series of various axellerations and decellerations. What I calculate is the P(rms). Did you manage to open my exell spreadsheet?
> 
> ...


Just looking quickly at the spreadsheet, it just seems too complex for a very simple math exercise. Assuming there is no net change of elevation, the energy of the system is the same at start and finish. So all of the energy will be used to overcome losses due to friction and motor inefficiency, and from acceleration of the mass to its peak velocity. I'm also assuming no regeneration, so that energy is also lost in braking.

Just a quick estimate of about 1600 watts average over the 1160 seconds transit time comes to 515 watt-hours which is easily met by a 70 Ah 12V battery (840 wH), and its weight (about 60 lb) is inconsequential in relation to the mass of the vehicle and load. Note that my Wh estimate is about 1/10 of your 9626 figure, so that must be resolved.


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## Jordanie (Aug 28, 2012)

Thanx for the reply PStechPaul,

What rolling friction coeficient, friction coeficient, system efficiency and braking force and velocity profile did you use for the test? Were those the same as mine? 

Here I have applied another test with a selected velocity profile, for the 116M I get about 88kg of Li-Acid battery and 4000Wh for 1400seconds. Please can you have a look? I'm not considering as well the change in rolling coeficient at start and stop of movement.

What I get is that for a 400m (with this velocity profile) I would need get 352kg. The manufacturers of similar vechicle state that for a such 100 tone mover they supply 24x2V 300Ah (20kgx24 - 480kg worth of battery capable of delivering about 400+meters autonomos).

What I get from that is my estimation is relatevly close but a bit optimistic than what the manufacturer says. What do you think? You can have a look at my spread sheet:


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## PStechPaul (May 1, 2012)

I couldn't really understand your previouis spreadsheet, and I don't see a new one, but I think it's perhaps the wrong way to approach this problem. I used the coefficient of rolling resistance you supplied but the formula in my calculator is designed more for ordinary EVs and not a specialized machine like this. 

Much depends on the profile of the acceleration and deceleration over the travel of the vehicle, and I am assuming a perfectly flat surface with no change of elevation and a constant amount of rolling friction. All of the energy should be expended during the first half of the transport, as the remainder would be spent in braking. An ideal profile might factor in the rolling resistance alone at the end of the path to bring it to a stop, but I think this vehicle would be a prime candidate for regenerative braking. In that case, only the rolling resistance would need to be considered (except for efficiency), and the maximum overall efficiency may be determined by the relationship of rolling resistance to velocity and the resulting energy required per meter of movement.

I think a fully optimized system will require a lot more information, and the actual battery requirements will be determined by other details of the design, such as the actual motor parameters and reduction drive efficiency. Also, the battery chosen will involve other factors such as initial and overall cost and charging requirements.


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