Anyone with experience of Lightweight Lithium 12V (starter) batteries in (ICE) Cars?

lynchy73

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As per the subject. Has anyone got any experience with using a lightweight lithium battery in your existing/previous cars?

How much weight did you save? Any problems? Roughly what is the typical cost? Brands used? Thoughts on whether it’s worth the trouble/expense?

It’s been popular on sports bikes for years but not so much on Cars. It was offered on some Evora models I believe. Would have thought it could offer a worthwhile weight saving.
 
I've not had one but yes they were fitted on some models of Evora. I get the impression they need more care than a standard battery - using a specialist Lithium battery conditioner if the car isn't driven regularly, not letting them run flat, don't attempt to jump start them.

On the Evora the OEM lithium battery will drain in about 2 weeks if not being used. It has some ancillary systems to protect the battery, which is good to save the battery but can catch people out. One is a regulator that cuts off the battery before it gets too discharged and then needs a manual reset. The problem on the Evora is the rear hatch won't open without power, so you have to get into the cabin and pull a manual release cable (assuming it still works). That's true with any battery in the Evora. If the battery cuts off, that will trigger a "battery disconnect" alert on your tracker and potentially alert your monitoring company.

People have seen savings of around 13-15kg but I think they cost £300-1100 depending on spec, compared to £50 for a standard battery.

The Evora GT410 (GT in the US) and GT430 have them fitted, and several Evora owners with standard batteries have converted across, so you'll find a lot of info on the TLF and Lotus Talk Evora sub-forums. Here's one of many examples:

 
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Great info TomE. I’ll have a look into it. We are in the business of battery manufacturing, but not this application. I’m familiar with the cell type and what the battery management has to do in this application. It’s interesting to hear the shortfalls with existing products.

We manufacture Ebike batteries and the batteries for a leading E-Foil Brand.
 
Great info TomE. I’ll have a look into it. We are in the business of battery manufacturing, but not this application. I’m familiar with the cell type and what the battery management has to do in this application. It’s interesting to hear the shortfalls with existing products.

We manufacture Ebike batteries and the batteries for a leading E-Foil Brand.
I had a lithium battery in my 2021 Evora it died after 2 days 😂 I did not close the door completely. It cannot be charged once completely dead. Changed to a regular battery. Straight swop my dealership did it at no charge. Have not had an issue since. That one died on me as well 😂 don’t ask my fault again.
Jumped it no problem. Then trickle charge
Never had an issue again. But that is due to the fact that I have not left any door or trunk/ boot open.
As for weight yes it’s heavier. Has it made that big a difference, not that I have noticed
 
My Evora 410 Sport (sold last year for Emira funds) had the lithium ion battery and I had some problems and at the time I posted a thread at the other place. Hope it is OK to post the thread address here, but trust that @TomE will remove if inappropriate.
I did quite a bit of research at the time and gained more knowledge of lithium batteries than I really wanted to have!
One of the issues with lithium is leaving the car standing. In my case, when I purchased the car at just over 2 years old, my due diligence research showed that it spent over 12 months for sale and subsequently had been stood for a long time. I had to have new brake discs on one set of wheels as it had been stood for so long. Also, the air conditioning failed (just out of warranty) and according to the Lotus service centre this was most likely due to the car being unused for so long. They were abe to get a reconditioned unit which last for 4 months, but I had already agreed to sell the car to the dealer at this point.
I would have switched back to a lead acid battery if the lithium had failed completely. I didn't do any track days and I am what you may call a steady driver, so the weight saving wasn't an issue.
 
Put a light weight AGM battery in my Camaro. The factory battery weighed 45 lbs, and I replaced it with a 21 lb. Braille battery (braillebattery.com). They offer the advantage of light weight but without the issues of lithium (which are also more expensive). They also have lithium batteries which are double to triple the price if you still want those. For the lightweight AGM batteries the 21 lb battery is about $250 which may seem high just for a battery, but that's actually a pretty cheap way to remove (in my case) 24 lbs of weight from the car.

Their green lithium batteries are just over twice as much (about $600) but are 1/3 the weight of their AGM batteries, so the green battery weighs just over 6 lbs and can replace their 21 lb AGM battery. If I had gotten that one, I would have saved about 39 lbs compared to the OEM battery. Their lithium race batteries start at $1,000 and up, but that isn't really necessary for the street.

I don't know how much the Lotus AGM battery is going to weigh, but I'm guessing somewhere between 30-40 lbs. for a standard OEM battery. What we need to know is how many cranking amps the Emira needs.
 
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The Lithium battery if suitably sized will have the same or greater capacity than the standard lead battery. The only reason for it to run flat in a shorter time is if the capacity was lower versus the lead acid battery and that’s just a choice that was made to undersize the capacity (versus standard battery) to reduce weight or cost.

Also, so long as it has a suitable battery management system it wouldn’t be damaged if left for too long that it ran flat. The battery management would disconnect the battery from the car when it gets to say 80 or 90% discharged. It could then be woke by a switch or even a remote device (Bluetooth app from your phone even) and still start the car with the reserve power. If anything the Lithium Battery should be much better in this respect (left to run flat) compared to a Standard Battery, as there is nothing to stop the standard battery from being run flat (which will damage it fairly quickly), whereas the lithium battery will have a BMS (battery management system) that will protect it from over charge/discharge (amongst other functions).

Actually the battery cells to make such a battery and linking them together to make a battery pack are not such a massive challenge. The battery management is a bit challenging though, as it needs to deliver several hundred amps from a fairly small device (but at a low voltage, and not for a long time, so perfectly possible).

At the end of the day, a lithium starter battery is a fairly simple way to make a useful weight reduction. There is no reason it can’t be better than the equivalent lead acid battery in every way, except the cost. It’s gonna be significantly more expensive (but should have a longer service life) than a regular lead acid battery.
 
I had a lithium shorai in my S2000 — and my M4 comes with a lithium 12V battery as OEM.

Prices are anywhere from $500-$1500 for the battery depending on size and mfg.

Weight savings were drastic on the s2000 and saved about half the weight compared to the equivalent AGM on the m4.

No issues.
 
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I had a lithium shorai in my S2000 — and my M4 comes with a lithium 12V battery as OEM.

Prices are anywhere from $500-$1500 for the battery depending on size and mfg.

Weight savings weee drastic on the s2000 and saved about half the weight compared to the equivalent AGM on the m4.

No issues.
I didn’t know the M4 had a lithium battery. But it makes sense. It’s actually a cheap way to cut weight and where it needs to be cut on a front engined car.

Many new cars now have a 48v system for a mild hybrid or electric turbocharger or other such features that require significant power levels that are impractical to get with just 12. A 48V system will always be Lithium type I’d expect. I’m not sure what they do about the 12V stuff in the car, maybe they use a step down voltage converter.

My 95 R33 Skyline GTR has a tiny Micra (small/compact 1.0l Nissan that we used to get in Europe) battery in the back (from factory), above the rear axle. Good for weight distribution, not so good when it runs flat after a few days parked up.

An I4 Emira with Lithium battery could get into the sub 1400kg category and improve the weight distribution to boot.
 
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My Evora 410 Sport (sold last year for Emira funds) had the lithium ion battery and I had some problems and at the time I posted a thread at the other place. Hope it is OK to post the thread address here, but trust that @TomE will remove if inappropriate.
Links to other forums are fine. I know some forums are sensitive about it, but not on here 👍
 
I don't know how much the Lotus AGM battery is going to weigh, but I'm guessing somewhere between 30-40 lbs. for a standard OEM battery. What we need to know is how many cranking amps the Emira needs.
I'd expect the Emira battery, at least for the V6, to be similar spec to the Evora given the starter motor and engine-related electrical systems are identical. The extra infotainment and electric seats compared to an Evora are probably a small factor in sizing the battery.

This is the OEM Evora battery and it weighs 17kg:
 
I'd expect the Emira battery, at least for the V6, to be similar spec to the Evora given the starter motor and engine-related electrical systems are identical. The extra infotainment and electric seats compared to an Evora are probably a small factor in sizing the battery.

This is the OEM Evora battery and it weighs 17kg:
Okay, 37 lbs.; in the range I was expecting. If you get this green lithium battery from Braille, that would save 30 lbs out of the car and be an easy change.


The Varta battery you linked to shows a CCA (cold cranking amps) of 750 A, and the Braille has 947 A of starting power which would be enough to handle the CCA requirements of 750 A. CCA is how much starting power a battery can provide for 30 seconds at 0 degrees Celsius (32 degrees F). The Braille battery weighs 6.4 lbs.

The Varta battery is 175 mm wide, the Braille is 132 mm. The Varta is 278 mm long, the Braille is 174 mm. The Varta is 175 mm tall, the Braile is 177 mm. There should be enough play in the hold-down bracket to accommodate the extra 2 mm of height for the Braille, so there shouldn't be any problem fitting the Braille battery in the battery compartment.
 
Emira battery, from the now-vanished handbook:


Type. Platinum AGM096E
Voltage (V). 12
CCA (EN). 760
Ah Capacity (C20). 70
Size, L×B×H. 278 x 175 x 190 mm

£95 aftermarket.

 
Emira battery, from the now-vanished handbook:


Type. Platinum AGM096E
Voltage (V). 12
CCA (EN). 760
Ah Capacity (C20). 70
Size, L×B×H. 278 x 175 x 190 mm

£95 aftermarket.

That's a 44 lb (20 kg) battery. If that's the one that comes with the Emira, the Braille lightweight AGM battery only weighs 15 lbs. for about $250; an easy way to remove 29 lbs in the back of the car. For $650 (with charger) their Greenlite battery only weighs 6.4 lbs. so you can remove 37.6 lbs with that one.
 
I didn’t know the M4 had a lithium battery. But it makes sense. It’s actually a cheap way to cut weight and where it needs to be cut on a front engined car.

Many new cars now have a 48v system for a mild hybrid or electric turbocharger or other such features that require significant power levels that are impractical to get with just 12. A 48V system will always be Lithium type I’d expect. I’m not sure what they do about the 12V stuff in the car, maybe they use a step down voltage converter.

My 95 R33 Skyline GTR has a tiny Micra (small/compact 1.0l Nissan that we used to get in Europe) battery in the back (from factory), above the rear axle. Good for weight distribution, not so good when it runs flat after a few days parked up.

An I4 Emira with Lithium battery could get into the sub 1400kg category and improve the weight distribution to boot.
The m4 battery is actually in the trunk, there’s so much going on up front for cooling etc there’s simply no space.
 
To get better weight balance Lotus could have moved the fuel tank to the front as well as the battery. The heavy battery would then provide some advantage.
 
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The standard battery is 70Ah (C20). This means a 3.5A drain/discharge for 20 hours. People rightly claim that the peukert effect (my spelling might be wrong) means a lead acid battery will only deliver a fraction of the rated (Ah) capacity when they are discharged at high current (maybe 1/4 or 1/3rd for example), such as when starting a car at 700A (700A is 10C on a 70Ah battery).

However, parasitic losses when parked up, are discharged at very low current rates (much lower than 20C, meaning peukerts effect is not applicable) and so it’s not really true/accurate to be stating a 20Ah Lithium battery is going to be equivalent to a 70Ah AGM, when you are talking about how long it can remain parked up, without draining the battery.

Peukerts effect means for example a fully charged 20Ah lithium battery might start an engine an equal number of time (or more), as a 70Ah AGM, before it no longer has the power to do so. It doesn’t mean the 20Ah Lithium can maintain a charge for as long when parked up as the 70Ah AGM. By rights the AGM should be able to maintain sufficient charge for 2 times, 3 times longer.

A suitable lithium battery can deliver the necessary cranking current without the need to have so high a capacity (Ah) as an AGM battery, because it has a higher C rate. So you can get away with a smaller battery, yet it’s still got the necessary punch. So you can undersize it.

I get the sense the suppliers/manufacturers of these Lithium ICE starter batteries, are skimming over some aspects of their performance, and twisting the truth somewhat regards the peukerts effect. A much smaller capacity Lithium battery can be totally adequate, it just will not retain Charge anywhere near as long when parked up as a higher capacity AGM battery.
 
If you daily drive the car, or drive it at least once or twice a week or two, there's no problem with having a Lithium battery. If you're storing it for a month or longer, put it on a maintenance charger. If it's parked up for the winter for example, then putting it on a maintenance charger will keep it in shape, same as an AGM battery stored over the winter.
 

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