[dogtag114]

Thanks, this is my next upgrade. I'm just not sure which model.
I assume this key bob needs to be outside the car or you can't get into the cabin or trunk.

 

[Midenginer]

Great info, thanks!

 

[Marrk]

Sorry, what did you say the price was?

 

[skiloads]

You can get the price of the T6 at the Antigravity Batteries website:

T6/L2 Lithium Car Battery

Antigravity T6/L2 Hi-Power lightweight Lithium Automotive Battery with RESTART Technology. Replace lead/acid battery in Hi-Performance Cars

antigravitybatteries.com

 

[Marrk]

When it comes to sports cars, I don't consider myself a price-sensitive shopper, but $829.99 is an attention-getter.

 

[dogtag114]

When it comes to sports cars, I don't consider myself a price-sensitive shopper, but $829.99 is an attention-getter.

Another user just installed this one. Lighter, $320, but 680 cranking amps.

ATX20 Lithium Motorsports Battery

Hi-Power lightweight ATX20-RS lithium motorcycle/powersports battery with RE-START Technology (built-in jump-starting). Replace YTX-20, more. 680 CA.

antigravitybatteries.com

 

[skiloads]

The ATX20 re-start lithium battery is intended for a motorcycle and should work fine in the Evora with a full charge; 680 CA. The weight savings is tremendous over a lead acid battery, the ATX20 being about 4lbs, which is why it'd be great in a track focused car. But, if this battery were drained to the point where it shuts off, I'd be concerned if it has enough power when you turn it back on to jump start the Evora's V6 motor; considering it was designed for a motorcycle.

 

[wonk]

I have a Shorai LiPo in my Elise. I take it out when I'm not driving it and stick it on the charger in the house. Keeps the battery well maintained and adds a security feature

 

[Julian73]

I apologize for the lengthy post. I’m hoping it’s a good read though, if you’re interested in a lithium battery for your Evora.

I bought my 2017 Evora 400 last summer. The OEM battery is a getting a bit long in the tooth for a lead acid battery, depending on its care. As folks on the forum know, the Evora has a good amount of parasitic draw which can discharge the battery to low voltage levels in a few weeks’ time. If the battery is allowed to discharge to a certain point, it can end up with sulfation, shortening the lifespan of the battery. Sulfation occurs when sulfur in the solution leaches from the electrolyte and begins to stick to the lead plates becoming lead sulfate crystals. The crystal build up on the lead plates keeps the plates from working as intended and eliminates the needed sulfur in the electrolyte solution. I’m the second owner of my Evora and I don’t know how the battery was cared for. The car didn’t come with the OEM Battery Tender. The original owner must have kept or lost it, so I’ve been using a battery maintainer I already have. I haven’t had any trouble with the battery so far. With COVID going on, all I’ve done are day drives and I immediately put the battery maintainer on when I get back. Now that corona virus vaccines are rolling out, I’m hoping to take a road trip late this summer to visit friends a couple of states away. I would hate then to find out the battery needs replacing in some small town which probably won’t have any group 91/T6 batteries available.

I’ve been checking out the newer LiFePO4 lithium batteries they now make for cars, which are much more expensive. On the bright side though they’re much lighter (lighter makes you go faster everywhere) and have an expected lifespan of 8–10 years. Skip ahead if you’ve read this before, LiFePO4 is a Lithium Iron Phosphate battery (also called lithium ferrophosphate). They’re the safest type of lithium battery as they will not overheat, and even if punctured they will not catch on fire. Due to the oxygen being bonded tightly to the molecule, there is no danger of the battery erupting into flames like there is with LiCoO2 and Lithium Polymer batteries. There’s always tradeoffs though. LiFePO4 doesn’t have the energy density that LiCoO2 does, but LiCoO2 and Lithium polymer batteries lifespan are only about 3 years or so; as many cell phones can attest to.

A lead acid starter battery Ah rating is not as it would appear. A LiFePO4 battery can use 95% of its storage capability (measured as Amp-Hour, Ah), while a lead-acid battery, for starting applications, typically only uses 30%; per Peukert’s Law (it’s a EE thing, if you’re curious). Additionally, LiFePO4 batteries have a flat discharge curve, so their cranking power does not drop-off. What all this means is a LiFePO4 battery that is 1/3 the Ah rating of a lead acid battery, is actually equivalent.

Some Lotus owners on the forum have been using 15Ah and 20 Ah LiFePO4 batteries intended for motorcycles with success; weighing in near 5 lbs (like the ATX-20-HD, ATX20-HD Lithium Motorsports Battery – Antigravity Batteries). It required modification/removal of the battery tray and different battery cable connectors, although there are car terminal adaptors available (Car Terminal Adapters (SAE) – Antigravity Batteries). This is great for a track focused car, but not the path I was wanting to take. I found Antigravity Batteries makes a LiFePO4 battery in the Evora’s T6 size. Their T6 comes in 40Ah 1500 CA and 60Ah 1800 CA configurations; same sized battery box. I purchased their 60 Ah 1800 CA T6 battery. It’s not close to 5 lbs, but it is 20 lbs lighter than the lead acid OEM battery it replaced.

View attachment 1281735

View attachment 1281736

LifePO4 batteries have battery management system circuitry (or BMS) in the battery box. The BMS prevents over discharging, over charging and short circuit protections. It has cell balancing as well as thermal protections. This is supposed to extend the lifespan of the battery. The intriguing thing that Antigravity has done with their BMS in this T6 battery is to keep the battery from fully discharging. When the power level reaches a certain point, the BMS switches the battery off. There’s no voltage at the terminals. There’s a button on the battery that when pushed will turn the battery on again. That’s problematic for the Evora, because we can’t easily open the rear hatch to access the battery without power. Fortunately the Antigravity battery comes with two wireless remote control key fobs. When pressed the fob will also turn the battery on. Once the battery is turned on again, there’s enough power left in it to allow you to start the car. They called this feature Re-Start Technology or built-in jump starting. I really like the idea of not being stranded with a dead battery because I left the lights on. LiFePO4 batteries do require a battery charger/maintainer specifically designed for LiFePO4 batteries. I got the CTEK Lithium US Smart Charger 4.3A (P/N 56-926), CTEK Lithium US Smart Charger – Antigravity Batteries.

When my Antigravity Battery arrived I found they threw in one of their Battery Trackers, which is a great piece of tech.
I wrote about their Battery Tracker a while ago in this post: Battery Tracker

View attachment 1281737

I don’t use my Evora as a daily driver, because I’m worried about getting door dings, scratches, and nicks that my G35 accrues as my daily driver. People in parking lots, don’t get me started on that subject. Because a LiFePO4 battery is able to dig deeper into its power reserves than a lead acid battery, I’m thinking I shouldn’t need to use a battery maintainer on my Evora until the long winter hibernation. No more cords to connect and trip over. Just jump in and go for a drive. Come winter I’ll just tape the cord to the floor to avoid tripping. As this year progresses, I’ll be watching the battery’s state with my Battery Tracker’s phone app to confirm whether this expectation holds true.

Great deal, Ive been using LFP batteries for awhile now, even the 5# versions in my Miata and RX-7, as to the Evora I too when with the larger yet still lighter units like you are planning. One word of warning, the parasitic drain in the Lotus will pull the charge down to the point that starter protective cut-off point will be reached after a week or so. My older Evora S did not have the reset feature in its aftermarket battery so I never trusted taking the car to the airport. My current 410 came with factory LFP does have that feature and while not wireless does have a remote reset button than can be mounted externally. It's needed.

As to Chargers, I've had great luck with the OptiMate 5 amp LFP 4s

 

[norphaedrus]

Great write up.

So not having owned an Evora long I have a question here related to battery in general, and this upgrade specifically.

I recall seeing a video on this some time back (

). He seemed to be pretty giddy about not having to use his tender since there was some residual charge kept. However, clearly the electronics will lose power at some point.

What is the effect on the Evora electronics when this happens? I ask as I have seen threads related to making sure things power down appropriately. Assume this will be fine with parasitic drain over time.

Seems that you are still using the CTEK smart charger, so clearly you are still following the same scheme as you did before.

 

[rustyb]

FYI, Antigravity Battery Co. generally has a spring sale mid March, usually 10-20% off. Still expensive, but not sure there is a cheaper way to shed 30 lbs. I am not affiliated with this Co., just thought it might help if someone is on the fence.

 

[agentdr8]

What is the effect on the Evora electronics when this happens? I ask as I have seen threads related to making sure things power down appropriately. Assume this will be fine with parasitic drain over time.

The ECU needs like ~20-30 minutes after key out to properly shut down according to the service notes. Parasitic drain will definitely take longer than this amount of time before it's under 12V, so it should be fine. Of course you'd likely lose your radio presets, dash clock setting, and window indexes, all of which would have to be reset every time you take it out to drive. The window indexes being the most important.

 

[skiloads]

Great write up.

So not having owned an Evora long I have a question here related to battery in general, and this upgrade specifically.

I recall seeing a video on this some time back (

). He seemed to be pretty giddy about not having to use his tender since there was some residual charge kept. However, clearly the electronics will lose power at some point.

What is the effect on the Evora electronics when this happens? I ask as I have seen threads related to making sure things power down appropriately. Assume this will be fine with parasitic drain over time.

Seems that you are still using the CTEK smart charger, so clearly you are still following the same scheme as you did before.

We're currently getting some nicer (i.e. drier) days, so I'm taking advantage of that to get my Evora some well deserved exercise. Right now I'm not connecting up the battery maintainer when I return. But I am watching the Battery Tracker app on my phone to monitor the battery's voltage as the days between driving pass by. I'm curious to see how much voltage loss there will be between opportunities to go for a romp. If the voltage drop is quicker than I anticipate, I'll connect the CTEK smart charger. This is a bit of an experiment for me and I enjoy a good experiment.

 

[DaffyDuck1983]

If you install an external battery tender port, putting the car on a tender after you park it is really simple to do. Yes, not having to do that is nice I fully agree, however, just saying that it's OK for a car battery to need to be tendered especially in a non-daily driven car and there are some ways to make that painless.

MattJK's 3D Printed Magnetic Battery Charger -...

Quick review/how-to... Got my mitts on MattJK's 3D printed magnetic disconnect charger as it was the coolest looking solution I'd run across - and got the install done today on my Evora 17/400. Importantly, I didn't want to change ANYTHING on my existing wiring harness - wanted the new solution...

www.lotustalk.com

 

[dogtag114]

Of course you'd likely lose your radio presets, dash clock setting, and window indexes, all of which would have to be reset every time you take it out to drive. The window indexes being the most important.

I was wondering about this. Does all this need to be redone even if you disconnect and switch to any battery? Is there other navigation/radio stuff lost that is important? Is there a way to keep voltage on while you switch or does that get dicey?

 

[skiloads]

This is what I did... I had another unused car battery that was charged. I used a couple of 5 ft long wires, which I put eyelet connectors on and connected them to the Evora's battery connectors. The other wire ends I connected to the spare battery on the floor. That way I could remove and replace the battery in the Evora without losing power to the car electronics during the swap. It worked, I didn't have to reset anything. I imagine one could use four wires and just the new and old batteries to accomplish the same thing without loosing power to the car too. It's kind of a battery shell game.

 

[dogtag114]

But If you did run your battery down to the restart feature, let’s say for a week for arguments sake, wouldn’t the electronics still be without power that week and them all need resetting anyway? Could you still open the front door without any issues of the windows not dropping?

 

[skiloads]

Yes if the lead acid battery dies or in the case of a modern LFP battery, it turns off the battery, the car's electronics will be without power. The doors won't unlock via the key press any longer. You'd have to unlock the car using the key manually, per the owners instruction manual. Then to access the battery you'd have to open the rear hatch by pulling the release cable found under the passenger rear seat in the 2+2.
In the case of the Antigravity Re-Start battery, that's turned off due running too low on power, pressing the included battery key fob button would turn on the Antigravity battery. The doors would open as usual and you could start the car to charge the battery or open the rear hatch as usual and connect a lithium battery charger to recharge the battery. In either case, all those things that would need resetting due to power loss, would need resetting.
If you're using the Battery Tracker and are within Bluetooth range with your phone, you'll get a notification that the battery is getting low and needs charging before the battery voltage drops to the point where the BMS turns the battery off.
If you know you're going to be gone for a week, why not connect the battery maintainer while you're gone?

 

[Carlotus]

I just spoke to someone at Antigravity and they are offering 15% off March 19th through March 22