# Choosing a battery Formula Student Car Electric



## SURTEES (Nov 22, 2011)

Hi guys,

Im currently doing a project on converting the formula student race car from an ICE to a FEV. Still in the early stages of my design and very new to this whole electric thing.

So far:

- Chosen a Warp13 Motor 35.5HP, 72Volts, has 130ft.pounds torque, maximum of 5,500rpm. 

Requirements:

- Need to complete an endurance race of 22km, quickest lap wins.
- fastest time to complete a 75metre sprint.
- batteries need to be as light as possible as there is a 230kg limit incl. driver (80kg)
- NO limits on cost or efficiency

Any suggestions please?

SURTEES


----------



## Yabert (Feb 7, 2010)

SURTEES said:


> - Chosen a Warp13 Motor 35.5HP


Stange choice..... to don't said bad choice!

I think you will need to learn a lot before buy some bad components
Welcome on the forum... you are at a good place to have good answer!


----------



## Theredone51 (Oct 15, 2011)

That Warp engine is heavy! Bettery look into an Agni/Emrax/Yasa engine for these kind of applications.


----------



## SURTEES (Nov 22, 2011)

Theredone51 said:


> That Warp engine is heavy! Bettery look into an Agni/Emrax/Yasa engine for these kind of applications.


any suggestions on a light weight high torque output motor?

Ideally the battery choice is important right now... methods on choosing correct battery? I have read one of the threads regarding choosing a battery


----------



## dtbaker (Jan 5, 2008)

SURTEES said:


> any suggestions on a light weight high torque output motor?


a Warp9 might be a better power/weight match for you. especially if you can bump up the voltage and stay within rules on weight for batteries. There are probably limits on kWhr of nominal energy in pack depending on your classification.... right? makes a difference in selecting between large format, cylindrical, or pouch for instance. also major class change between lead gel mat and lithium.....

check in to rules for class you want to compete in, and expected range of event, target speeds, and event conditions like flat, hills, corners (braking)... then people can help you with deciding what might be best.


----------



## SURTEES (Nov 22, 2011)

My 'target' for this project is to gain _maximum points and maximum power_

'Whenever a circuit carries more than a nominal operation voltage of 40V DC or 25V AC RMS it is defined as part of the High Voltage system. 600V DC or AC RMS is the maximum permitted nominal operation voltage that may occur between any two electrical connections.
Low voltage is defined as any voltage below 40V DC or 25V AC RMS.'

'Only electrical motors are allowed.
Any type of electrical motors is allowed. The number of motors is not limited'

more rules:

http://www.formulastudentelectric.de/uploads/media/FSE_Rules_2012_Draft_-Technical_Rules.pdf


----------



## ishiwgao (May 5, 2011)

SURTEES said:


> My 'target' for this project is to gain _maximum points and maximum power_
> 
> more rules:
> 
> http://www.formulastudentelectric.de/uploads/media/FSE_Rules_2012_Draft_-Technical_Rules.pdf


well... you can't possibly be asking us to read the document and do your work for you right? I might be a little mean saying this, but I find it quite irresponsible of you to throw the work to us and expect us to solve your problems for you. If I'm wrong, then i take my words back. But for this whole FSE to be meaningful to you and your team, do a bit more reading up and you'll know how to solve all the major "problems" you're facing now, and that includes choosing your component and battery size etc.

my .02 cents, take a look through the rules once again. a few things i've spotted that clearly rules out the warp.



> 4.3.1 Brake System Master cylinder actuation
> ...
> The first 50% of the brake pedal travel may be used to regenerate brake energy.
> 
> ...


You don't want to be using a warp13 at 72V just to be giving out 85kW of power. In terms of ICE, that's using a V12 engine with 1000bhp in a small car and limiting it to only 100bhp (just theoretically speaking)

what Theredone51 said is right. Look at Agni, mars etc

I would put more focus into part 7.9 onwards till the end of the rules


> 7.9 Rain test
> Teams have to pass a rain test during Scrutineering to be allowed to move the car
> under its own power on the event


These cover the safety aspect of the vehicle, which is imo more important than the motor itself. If your vehicle burns out during the race, doesn't matter if you had the strongest motor or the best battery.

Speaking of battery, look at what Dan (dtbaker) said. Many different batteries to choose. depending on power, weight, energy, chemistry requirement, you can do so many different combinations with this. Look up a few more common ones like TS, CALB, Headway and A123. You can start to make comparisons from there.


----------



## Theredone51 (Oct 15, 2011)

SURTEES, may I ask which Formula Student Team you're part of?

As I said, the Warp engines are way too heavy. Just look at the other FSE teams and see what engines they are using. IF there really is no limit in costs (as stated in your OP) then I'd look into the YASA750: http://www.yasamotors.com/technology/products/yasa-750 That thing is awe-some! But pretty expensive too, somewhere around 13.000 GBP.

For the cells, look here: http://liionbms.com/php/cells.php
There's a bunch of information about all kinds of cells you can use.


----------



## Yabert (Feb 7, 2010)

An incredibly advantage of the yesa motor is the possibility to go direct drive with small diameter tire.

His peak power is at only 1200 rpm and it stay to 2400 rpm. (from the graph)
One motor will be enough for a 230 kg formula, but without diferrencial, that can be challenging.


----------

