Yeah, so just like the title says. Am I better off with the relocation to the rear/trunk for weight distribution , or mini battery for the removal of weight for HPDEs? My thought was to the trunk. Thanx to those who are helpful in their reply.

 

If it's just for DE's; not sure you need to think about weight removal at this point.

However, a lighter car is easier and cheaper to run! I'd say go with the mini-bat personally as it's just a lot easier.

 

I'm planning on relocating the full size battery to the trunk myself but I'm driving my car daily in all weather so I wouldn't trust one of those small batteries to start my car reliably through the winter in NY. If its not your dd or you're not worried about the car not starting then just get the little guy, you could even do both and put the little battery in the trunk to clear the space under the hood and move a little weight to the back of the car.

 

My vote is relocate. It will cost you half the $ of a mini battery kit. 2 terminals, a tray, and ~25' of 4awg wire. Took me about an hour. The mini's are prone to dying in cold weather.

 

Relocating adds more weight and is a whole lot more work. Most of the autocrossers simply use a lighter battery. The gains aren't there if you want to relocate.

 

In ur climate mini battery might be better for u unless ur gonna add any extra lights or electronics. Im currently in Houston but live in chicago so ima do mini battery for now and then relocating an optima to the trunk for when i get back to chicago cuz the climate is not kind to the mini battery. Although AMS says the mini battery will withstand chicago climate I may be adding additional fog lamps. If u relocate the battery just make sure u bolt that thing really wellu dont want 30lbs flyin into the car plus if u autocross or race in anyway find out wat the rules are pertaining to trunk mounted batteries

 

I don't auto cross just RR. Well, and kart. If I choose to relocate to the trunk, mostly because I have an Optima already, will the shift in weight, for balance, be enough to offset just the removal of weight. Basically, I would shift 45 from the front to the back of the car, or just removing about 25 from the front. What's more important the balance or the weight I think is what I'm trying to say.

 

Yoooo swoln, long time no see. I previously relocated the batt to the trunk and installed and optima blue. However I soon realized this actually added more weight and problems. Granted, the optima batt's are ....badass....they'll start no matter what but they weigh a metric fu*k ton. I also didn't consider two things, the added weight of running 1 aug wire from the front to the back (even 4aug, metal is metal and the less the better), and the added distance the electricity had to travel to get charged AND start. The basics of electricity dictate that the shorter the wire, the better, the same is true for weight purposes. So my cranking on cold starts actually took a tad bit longer (I know most people won't notice, but it's technically true). I didn't realize this till I met up with Robi again a few months later, and he explained the differences. So now, I have an alum box behind the pass. seat and a carbon 3121 braille batt inside it. This works for me because the fire bottle is behind the driver, and it's a full race car.

In your situation, i'd advise to use a small batt in the engine compartment, pref a braille because their technical specs and proven performance out-weigh the other small batt kits. This is just my exp of course, i'm sure there are other solutions out there but I'd like to save you the trouble

 

I have used the Deka etx 14 which is the same dimensions and weight as the braille for 2 years now and it hasn't failed me yet, add has start the car fine on 30deg days. The deka is even made at the same factory as the braille. I bought the battery, made and the tray and had it powdercoated($25) all for under $130. The total weight of battery and tray was 12.6lbs. But the bottomline is:

1. moving the stock battery to the back dropping 35lbs of the front adding 35 to the back plus 5-10lbs of cable (about a 2% increase in rear weight bias with a total weight change of +5 to 10lbs)

2. go the mini up front route and drop 22 lbs of the front (about a 0.6% increase in in rear weight bias with a total weight change of -22lbs)

3. mini in back: removing 35 up front adding adding 13 in the back plus 5-10lbs of cable (about a 1.3 increase in rear weight bias with a total weight change of -12 to 17lbs)

 

just out of curiosity, from a polar-moment of inertia perspective, any difference if a trunk battery is mounted:
a) close up to the rear seat-back
versus
b) further back, near the rear wiper spray bottle?

 

i used to run the mini battery but they would die all the time.... now i use a regular size battery in the trunk with a kill switch & never have any battery problems... car handles decently too

 

yeah, any increase in distance from the CG will increase the polar moment of inertia. Longitudinally the CG is approxiamately the tip of the e-brake. If you know your weight distribuiton from you can figure it out by measureing the wheel base and mutliplying by the rear weight bias to get the distance from the front axle to the CG (ie, 100 inch wheelbase X 40% rear weight bias= CG 40inches aft of front axle)

 

Well a few ways to look at it:

(1) Going the route of the mini is not going to shed 100+ lbs, so you'll likely not see a time difference on a road race course...If you are so good that 20lbs makes a diference in your times, then we are likely seeing you on TV
(2) Moving the full sized batter to the rear adds a bunch of additional weight (wire)
(3) Adding a mini somewhere to better balance the car could be interesting, but will it prove to be beneficial is highly unlikely....

 

true true

and i also still have a mini battery but as soon as it is found to be not working i will relocate to the trunk. i have had numerous numerous issues with it not wanting to start in cold weather. and sometimes it doesnt even have to be ***** cold. just around the 45-50 degree mark. so, i can say for certain that when it comes time to replace i will just relocate an optima to the trunk

 

go with the mini battery.

Ive had a PC 680 in my DD for 4 years (3 winters) and it hasn't NOT started the car yet. I'm in the NE and in the winter it usually gets to freezing or below. I even took the car up to NH where it was -13 and the car started right up after sitting all night.

Moving the battery in the trunk will require running heavy gauge wire and installing a cut-off switch, thats more work, more weight and more money then just getting a mini battery and leaving it in the stock location.