# unconventional project



## Aeronaut (Feb 10, 2016)

Hello community,

I need your help for a challange.
The goal would be to power a 150 kW electric engine for the duration of 30 s to 1 min. Afterwards the batteries could be broken (so only one use).
I found some performance data for engines, e.g.

Mass 43 kg Power 150 kW Operating Speed 10000 RPM Torque 460 Nm Nominal voltage 650 V 
and calculated a current of 243 Amps for 95 % efficiency.

The goal would be to find a battery that is very light weight and able to be drained within this short time.

The best I came up with so far would be the 
*SLS APL MAGNUM 4400mAh 14S1P 51,8V 45C/90C*

which could provide the necessary voltage with 13 packs in series.

However I think there is still potential for a better solution.
The batteries could also be primary batteries (non rechargeable) as it only has to work once. 

I don't want to give any cost restrictions for a solution so it can also be high prized, important is only the weight and fast discharge.

I would really be happy if you could help me on this,
Best regards 
Aeronaut


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## mizlplix (May 1, 2011)

You might try big liquid cooled capacitors instead of cells in such an application. You would then need a way to fast charge them at the track or whatever.

Although I think if the lithium cells are water cooled also, they might not necessarily be destroyed.

Could you give some more info on your project?

Miz


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## major (Apr 4, 2008)

Aeronaut said:


> Hello community,
> 
> I need your help for a challange.
> The goal would be to power a 150 kW electric engine for the duration of 30 s to 1 min. Afterwards the batteries could be broken (so only one use).
> ...


This sounds too much like a bomb delivery system. I don't think we should help.


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## AmpEater (Mar 10, 2008)

major said:


> This sounds too much like a bomb delivery system. I don't think we should help.


What sort of a bomb delivery system needs 150kw for under 60 seconds? Torpedo?


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## major (Apr 4, 2008)

AmpEater said:


> What sort of a bomb delivery system needs 150kw for under 60 seconds? Torpedo?


Or a drone. Or surface vehicle.


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## Duncan (Dec 8, 2008)

I thought it sounded like one of the old free flight competition model aircraft,

Do you remember them?
They had a very short power burst - 10 seconds? - and then they had to glide for about four minutes

Took off straight up like a rocket and then glided until the "de-thermaliser" activated
(a short piece of slow fuse that burnt through the elastic band holding the tail into position)


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## Aeronaut (Feb 10, 2016)

Don't worry, its only for a fuel pump 

The capacitor solution sounds nice but I don't think this would be an option as the amount of energy I can store in such a capacitor is usually small in comparison to a LiPo.


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## WolfTronix (Feb 8, 2016)

Aeronaut said:


> Don't worry, its only for a fuel pump
> 
> The capacitor solution sounds nice but I don't think this would be an option as the amount of energy I can store in such a capacitor is usually small in comparison to a LiPo.


Flywheel.

Use external power to spool up a flywheel, then when ready engage a clutch to the pump. 

This is also how they open the multi-ton external doors in the minute man missle silo in seconds before a launch.


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## Duncan (Dec 8, 2008)

Primary lithium batteries - non rechargeable run up to about 400watthours/Kg - or about three times the best rechargeable s

The standard "lithium" batteries that you can find in stores go up to about 300whrs/kg and they are pretty good at high discharge rates


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## Aeronaut (Feb 10, 2016)

Duncan said:


> Primary lithium batteries - non rechargeable run up to about 400watthours/Kg - or about three times the best rechargeable s
> 
> The standard "lithium" batteries that you can find in stores go up to about 300whrs/kg and they are pretty good at high discharge rates


Do you know where I can find a supplier with specifications?
I had a hard time finding some high voltage cells/packs


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## Duncan (Dec 8, 2008)

I had assumed that you would be building your pack from individual cells, so not high voltage until assembled in your pack,

Depending on the cells about 3.7v - so for 650v about 176 in series,
I'm pretty sure that we don't have a cell manufacturing plant here (NZ) so I would probably be looking on Alibaba - I find them a pain to use but you can get directly in touch with the manufacturers


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## dougingraham (Jul 26, 2011)

Aeronaut said:


> The goal would be to power a 150 kW electric engine for the duration of 30 s to 1 min. Afterwards the batteries could be broken (so only one use).
> I found some performance data for engines, e.g.
> 
> Mass 43 kg Power 150 kW Operating Speed 10000 RPM Torque 460 Nm Nominal voltage 650 V
> ...


You need 120 C in order to discharge a battery in 30 seconds. You need 60 C for 1 minute. Sanity check calculations: 150000 watts at 243 amps requires a voltage of 617. Adjusting for 95% efficiency would need 650 volts. Your numbers match probably because I worked backwards what you worked forwards. So you need 243 amps for one minute. This would require a minimum of 4.05 amp hours. Using the sag voltage of 3.00 volts per cell you would need ~216 cells in series to get 650 volts. Using the nominal 3.7 would require ~175 cells in series. Using the full charge voltage of 4.2 volts per cell you would need ~155 cells in series. You need to figure out the cell count based on what the controller will allow and just how much the cells you choose sag at 243 amps.

To do 243 amps you need a minimum of 10 gauge wire. 10 gauge wire has a fusing current of ~333 amps in about 10 seconds. Lots of things affect this but your 243 amps should be ok for 1 minute although this is really at the limit. Most of the high performance RC packs that claim 60 C continuous that are larger than 3 AH come equipped with 10 gauge wire. The John Metric Amphaulic packs built for drag racing are 4.5 AH and come equipped with 8 gauge wire. You can order them with 6 gauge wire. They are 6S bricks for $120 each. To reach your voltage limit you would need at least 26 and at most 36 in series. Each brick weighs 1.7 lbs so a 26 brick pack would weigh a little over 44 lbs and a 36 brick pack would weigh a little over 62 lbs. You will need some way to attach and restrain the bricks so add in maybe 20 lbs on top of that. This would be $3120 and at the high end $4320. The good news is that they would not be damaged by your use and you could expect several hundred uses at the very least. If you want to do a lot more work you could assemble your own packs from lower performance RC hobby cells and lower the cost of the cells by about half but it would require a lot of man hours of additional effort and most likely weigh more.

That is what I would do. I doubt you will find a solution that weighs much less at any price. The problem is the current you need. To use the cells that have a higher energy density you cannot pull the current so you end up paralleling so many you end up carrying around lots more capacity than you need.

Good luck with your project!


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## dcb (Dec 5, 2009)

umm, I'm still w/major on this one. 150kw for 30 seconds lightweight disposable fuel pump still doesn't sound good.

and, this has nothing to do with ev conversions or builds anyway.


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## mizlplix (May 1, 2011)

"Don't worry, its only for a fuel pump "

30 seconds at full (emergency) power

Fuel pump

One shot system.....

OK, my guess is a liquid fuel missile system.

Seriously, your hiding of more information defeats your very request.


Miz


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## poprock (Apr 29, 2010)

How close would u need to be to the US Embassy?


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## Aeronaut (Feb 10, 2016)

@dougingraham

thanks for the information. That sounds quite helpful.
Regarding your concerns: There is a company in New Zealand which claims to have developed an electric turbo pump replacement and I have my doubts if this is possible in such a power range (even for a single use system).
However, by now I think they use a longer time of discharge of about 3-5 minutes so the requirements would not be as harsh regarding the C rating but higher regarding the capacity.


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