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2011 Evora NA 6MT
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102 Posts
Discussion Starter #1 (Edited)
I like the idea of weight removal through the practice of changing battery size, but prefer not to spend 2-3x the cost of an OEM battery to achieve the weight savings at the expense of longevity or durability.

In the past, I've always tried a lead acid battery in a smaller size and cranking output of OEM, but one that still starts the car and keeps a reserve charge long enough for the battery to go a week without needing a charger assist.

To this end, I started looking into the battery on my recently purchased Evora. It seems that the original battery dimension is 11" x 6 7/8" x 6 7/8" (BCI Group# 91)
As a replacement, I found a BCI group #99 battery has a measurement of 8 1/8" x 6 7/8" x 6 7/8". This should have the same top and depth clearance of the stock battery, so the original hold down bracket and battery terminals should reach as well as clear the body.

Weight wise, I think the stock battery is 38 lbs and this group 99 battery is 26 lbs, so it's an easy 12 lb weight reduction for the same price (or less!) of a stock battery.

My only concern is whether or not the advertised 450 CCA is going to be enough to crank over the starter well enough. I live in a warm climate that does not see temps lower than 40 degrees F, but does see the other extreme (up to 120 degrees F), so cold cranking performance is less of an issue as is reserve capacity. I do wire up a battery tender so I will be prepared for those times that the car does sit for over 7 days without a start.

So...
Think a Group 99 battery will achieve this intended purpose? Has anyone tried this or something similar?
 

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Premium Member
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6,778 Posts
If going through the effort, do it right. Shorais in your climate are fabulous. Oddyset's work well also. Lead acid batteries are dinosaurs. Why save 12 lbs when you can save 36-38 when tray etc no longer needed. I can tell you no one has done this that I know of. Its a half a .. solution.
 

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2011 Evora NA 6MT
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102 Posts
Discussion Starter #3
IMO, they work for racing but not for a street car. 've gone the lipo and the Odyssey gel battery route with the 5-10 lb batteries. My experience is they come up short on one week without charging support. Plus their overall life is short and initial cost is high.
 

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6,778 Posts
They last as long as a lead battery as I have had 3 Lotus with them. 1 wk is the tipping point regardless of source and running a low voltage battery is the root of many evils in our cars. I have an extra Shorai for cheap if you want to try it. Make me an offer.
 

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2011 Evora NA 6MT
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102 Posts
Discussion Starter #5
They last as long as a lead battery as I have had 3 Lotus with them. 1 wk is the tipping point regardless of source and running a low voltage battery is the root of many evils in our cars. I have an extra Shorai for cheap if you want to try it. Make me an offer.
Thanks for the offer, I thought I might need a replacement battery because it seemed only to charge to about 50 percent. I did the trick of taking an old school non-regulated 3 amp battery charger and overcharging it for the night. It now seems to be holding 90% of charge so I've thwarted the need for a new battery - for now. On to other Evora fish to fry :)
 
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