Batteries

[BMH]

Hello everyone,

I am currently looking at batteries for our next car. We are using a R6 engine with a PE ECU. The battery on our last car was around 11 lbs which is excessive in my opinion. So I am looking for something around 4-6 lbs. I am not really sure about how to determine what requirements we need in a battery. Could someone offer some tips on determining what your requirements are for a battery?

I would like to go with the YUASA YTZ7S battery due to its 4.6 lb weight (Specs: Capacity 6AH, CCA 130), however, I want to make sure that it is suitable for our car.

Thanks in advance for your (helpful) comments.

[mrrc]

i would strongly recommend getting a battery of the same amp-hour rating that the r6 motorcycle had. i say this because the rectifier and starter motor will be somewhat matched to that size of battery. (by size i mean Ah rating)

If you go smaller, try to have your team watch the voltage level closely, as the battery voltage level will affect how the car starts. we used the PE ECU and you can compensate for the battery voltage, but that takes extra time to dial in. if the battery is low on juice, the spark plugs won't work normally and you might end up getting a residue on the spark plugs, they can be cleaned to a questionable extent, but we don't like using plugs after they have been exposed to that.

If you are responsible for the electrical functionality of the race car you will probably hate yourself if you run out of juice due to excessive starting/stalling while testing, as this may prompt you to take the plugs out and change/clean them, as well as recharge the battery using a 1-2A motorcycle charger.

6AH is pretty low, if you have the money and testing time it might be worth the weight savings but your main challenge will be keeping that battery charged.

[Mumpitz]

Do a little energy calculation, now put your hand on the toasty rectifier/regulator after a hard run, and think about depending on the charging system to do MORE work.
That being said I think there are lighter batteries out there.
hint (mower batteries)

[TMichaels]

A lot of teams at FSG last year and this year have switched to 4,6Ah LiFePo-Batteries weighing around 600g, delivering more current (~200A) during cranking.
See a comparison between lead acid and LiFePo motorcycle batteries here:
http: / /shop. strato.de /WebRoot/Store13 /Shops/61333079/ MediaGallery/Lastdiagramm-A123vsPB_700.gif

4,6Ah is usually enough as the cyclic efficiency of LiFePos is much better than lead acid. Some teams run with 2,3Ah at comp, weighing 300g.
The price is around 150,00 Euros => 210,00$
LiFePos do not require any changes on your rectifier/voltage regulator setup.

Regards,

Tobias

[Hub]

We use the stock battery for our engine (Hornet 2008) and it's a YTZ7S. During the first tests and event our engine never work fine at idle so after a lot of re-start our battery run low but it's natural. After a better map tuning we never had problem to start the engine. We always start on the internal battery and never charge it during comp, we only control the voltage.

But for cbr engine the battery is bigger. Probably due to a higher compression Ratio. Check if it's the same for r6.

[Demon Of Speed]

If you have the money I recommend looking at Braille's selection of Lithium batteries.

[EHog]

Braille B106 is what we have run for years. Works great, and very affordable for a 6lb battery.

[TMichaels]

The price of the Braille Lithium batteries is ridiculous.
I'm still waiting for my post to be approved. You can get LiFePos with 4.6Ah for around 150 Euros / 210 USD. You don't have to change anything on your rectifier / voltage regulator setup and they weigh about 600gr.
A lot of the teams at FSG2009 and 2010 were using them already.
There is a webshop selling them in Germany especially for motorcycle racing teams, Formula Student and people who just want to get rid of the lead acid battery weight. But I don't know if they ship outside Germany.

EDIT: My post finally showed up above. Just remove the spaces in the link address to see the diagramm.

Regards,

Tobias

[RANeff]

Where are you finding LiFePo's for $200?

I looked at some last year that were a (crazy) 800 USD. We went with a lithium battery that is 5 lbs for ~$240. Starts the engine great, and will crank it for quite a while if you have engine starting troubles.

[TMichaels]

Hi,
it is a german shop, but Google's translation does the job at least well enough to get the basic information:
http://translate.google.de/tra...s/4s2p_A123_Block_V2

They work pretty well.

Regards,

Tobias