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 Post subject: battery and ultracapacitor system
 Post Posted: Tue Apr 17, 2012 1:20 pm 
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Joined: Thu Mar 22, 2012 2:08 pm
Posts: 2
Hello all !
I have a doubt regarding the feasibility of implementing battery and ultracapacitor system.
We are planning for our maiden participation in the 2013 formula hybrid event and are not sure that should we go for battery only or both(considering the complexities in that dual system). I have seen many teams going for battery only , but how do they really manage for the regenerative braking voltage and current spikes ! ..
Any advice in this regard would be sincerely appreciated.

Thank you.
-pratik


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 Post subject: Re: battery and ultracapacitor system
 Post Posted: Tue Apr 17, 2012 10:45 pm 
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Joined: Wed Jun 03, 2009 1:29 am
Posts: 117
Location: Texas A&M
I think a very thorough analysis of regen braking should be done before picking, sizing, and spec'ing an acumulator system. How much energy is actually available during the braking phase, how much can be synced by the power electronics, and actually stored in the accumulator. These cars are going so slowly and the course is so tight, there are no prolonged braking areas.

My analysis showed something like 3-4% of the energy shed during braking actually made it into the accumulator, which suggested it wasn't worth the added complexity.

Also, only 1 car passed tech in time last year to compete in all the dynamic events, which says to me that many cars are overly complicated.

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- Texas A&M 2009 FH Crew Chief
- 1st place FH '09: 981 pts


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 Post subject: Re: battery and ultracapacitor system
 Post Posted: Wed Apr 18, 2012 11:31 am 
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Joined: Thu Mar 22, 2012 2:08 pm
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Thank you for the reply.The only other problem is that if we use only battery then the life of battery will reduce owing to high current demands during acceleration etc so how do the teams manage with battery life reducing given the the fact that batteries are very costly.


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 Post subject: Re: battery and ultracapacitor system
 Post Posted: Thu Apr 19, 2012 8:08 pm 
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Joined: Wed Jun 03, 2009 1:29 am
Posts: 117
Location: Texas A&M
pratik wrote:
Thank you for the reply.The only other problem is that if we use only battery then the life of battery will reduce owing to high current demands during acceleration etc so how do the teams manage with battery life reducing given the the fact that batteries are very costly.


That is a tricky question. Obviously you should size, setup, and program your components to keep the current within reasonable limits. Your motor controller shouldn't draw too much current, and the BMS should shut down during an over-current situation. Depending on your test schedule, you may not have the car running long enough to really damage the batteries. Or for testing, you might run a slightly lower current limit most of the time to reduce wear and tear, with only a few full current tests.

Texas A&M just keep an eye on the batteries and didn't push them too much before competition (especially since April in Texas is HOT), but our cars have had a very minimalist approach to the HV electrical system.

_________________
- Texas A&M 2009 FH Crew Chief
- 1st place FH '09: 981 pts


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