Lexus999

i really wanna stay away from anything electrical... i just got a custom aftermarket sub and I was sweating bullets the whole time the car was in there.... everything went okay but still it got me nervous

ToothDoc

That's my reaction! So exhaust and coilovers = 30 more pounds! So I guess I really do have another mod to work on this winter/spring for next fall's drag racing season.

Joe Z

iTrader: (10)

I know.. I couldn't believe it at first either.

So I tripple checked everything, while I was weighing the suspension..

OEM Front Shock & Spring assemble came in at approx. 14 lbs each
OEM Rear Shock & Spring assemble came in at approx. 16 lbs each
Total combined = 60 lbs

D2 Racing Front Coilover assemble came in at approx. 10 lbs each
D2 Racing Rear Coilover assemble came in at approx. 9 lbs each
Total combined = 38 lbs

OEM Exhaust System (2 sections)
Front-Mid section = 33 lbs
Rear Axle section = 37 lbs
Total = 70 lbs

PTS - 304 Stainless Steel Dual Exhaust (4 sections)
Front X-pipe = 16 lbs
Mid section = 19 lbs
Rear axle sections = 29 lbs
Total = 64 lbs


So basically, right now I am right around 28 lbs for weight reduction.....

I also checked to see if my wheel & tire combo weighed more than stock setup.. Too my happy surprise, the total combined number did not...

Brand New setup with Bridgestones (50 miles)
OEM Front Rim & Tire = approx. 49.5 lbs each
OEM Rear Rim & Tire = approx. 53.5 lbs each
Total = 206 lbs

Used setup with Yokohamas (16,000 miles)
Five Axis Front Rim & Tire = approx. 50.5 lbs each
Five Axis Rear Rim & Tire = approx. 52 lbs each
Total = 205 lbs


I am going to add the battery swap to my "things to do list"...

To be honest, I hadn't really put much thought into the whole weight reduction thing..
Just happy to know its getting LIGHTER....


Regards,

Joe Z

bnizzle87

has anyone considered taking out the seats, especially the rears, for added weight reduction? i was thinking about switching my OEM front seats for some lighter sparco's, but i've grown fond of the technology and the leather from them haha

verals05

iTrader: (3)

How much do you think the D2's will run?

ToothDoc

Update! Yikes, after 1 full week the batteries have completely discharged and I couldn't even get the doors to open. It appears that the slightly higher voltage fooled the car's charging system into thinking that the batteries are fully charged or something. Unfortunately, one of the characteristics of GOOD batteries are that they maintain a voltage and suddenly "dump" which is not like Lead Acids. So, it was sitting at 13.05 volts for a few days and suddenly dumped to 2.6 volts. This was just overnight.

So, now I have a little dilemma. Do I build/buy a circuit that has a low voltage cutoff and some sort of charge monitor? Or do I just buy the $1300 battery (they say it's for racing only) or do I just plug it into a charger every week? Or should I just use it for the 1 or 2 times I go drag racing and 1 or 2 times I go tracking? Darn... too good to be true. The electronics on the IS-F are pretty sophisticated. I thought it would just be a dumb connection between alternator - voltage regulator - battery. But apparently, there is some circuitry that charges when batteries reach a certain voltage and it probably only charges during deceleration. Some modern cars have that feature to save gas/improve efficiency.

ToothDoc

BTW, I'm suspecting the HID lights sucked up the juice faster. It was the first time I drove around at night. I suspect as I took that night cruise last night, the HID sucked up the juice but still maintained a high enough voltage for the car to not initiate charge. When I went to bed last night, it was at 12.9 volts (which is still higher than a max charged lead acid - 12.8) but just that 20 hour period of sitting around probably killed the remaining 5% battery left.

ToothDoc

I am/was considering it - but it would kind of make our IS-F look like a boy racer car. Just not my taste... However, if they had a black leather with black CF rear backing so it didn't look too out of place, it might work. But that's gotta be expensive!

I don't think the rear seats weigh all that much - they're just usually some leather and some foam - probably the whole back seats weigh less than 20 pounds! Not to mention, that would look UGLY.

CircuitMS

iTrader: (51)

$1300 for a battery is a bit excessive, how much does the voltage cutoff cost?

Also, Almost any aftermarket exhaust and coilvoer setup will drop considerable weight, stock stuff weighs a ton

ToothDoc

Update: I've been using my car everyday for a month now. I would use it for 2 days, charge it up. Use it for 3 days charge it up. Use it for 1 week and charge it up. Everytime I charge it up, only .5 amp hours goes into the batteries. It appears that the car is charging the battery now. I don't know what happened - perhaps when the battery died, maybe I left the lights on? The voltage of the battery typically sits around 13.2 volts.

Today it was in the low 30's and the car started up instantly w/o any problems. Later this week it's supposed to get into the teens. We'll see how it starts then.

stick

Very cool!! And like I said, build these, sell them, and we will come!

caymandive

iTrader: (2)

Tooth,

I have a few questions for ya about the setup. I know that lithium-ion batteries are extremely sensitive to high temperatures (being in the engine bay puts it in this category), which causes battery packs to degrade much faster than they normally would. They only last two to three years to begin with, even if they are sitting on a shelf unused. Do you have plans to modify the setup to include some kind of heat barrier?

My other question is, do you have some kind of on-board computer to manage the battery? I think it usually monitors temp, voltage, current, energy capacity and has a charge state monitor. From what I have read lithium-ion batteries require this, which is one of the reasons they are typically so expensive. Though a small chance, but if a lithium-ion battery pack fails, it could burst into flames.

ToothDoc

Lithium polymer batteries can burst into flames - they release H2 and spark upon puncture, overcharge, etc. LiFePO4 have vents and do not release H2 gas. Also, LiFePO4 are much more robust and can handle 2000 cycles of complete charge/discharge and even after that life cycle, still maintain 80% capacity when brand new. In addition, our voltage regulators never go above 14 volts so overcharging is impossible. These batteries can be charged at 5C rate which is in my case over 50 amps - but the difference in voltage between battery and voltage regulator would automatically make it charge slower and slower as it reaches higher charge.

Right now, I've been manually monitoring voltage, manually checking cell capacity and at least when daily driven, it seems everything is fine. The batteries typically sit at 90% full capacity whether I drive it once or for a whole week. Next time, I'll drive for 2 weeks and measure capacity. If it can pass this winter's extreme low temperatures, I think I can safely recommend these then.

Also, I'm not too concerned with heat. RC models routinely run them until they're too hot to touch and under the hood, they're barely warm. If anything, being slightly warm makes them work even better.

ToothDoc

No intention of selling them - but I'd be happy to show you how I did it and or what parts were needed to make them. They're already being made and sold by voltphreaks for $1300 or so. You can make your own for less than 200 bucks.

stick

Cool. A DIY and/or parts list would be helpful, thanks!