CTEK widely acknowledged as the battery charger/maintainer of choice. Chosen by all the top marques and supplied as OE. The F-Type like all modern electronically loaded cars, requires a healthy battery to prevent rogue errors/faults. CTEK top up provides peace of mind if the car is not used daily, or left standing for long periods.

 

I'm impressed you can feel a 1.2% weight reduction in a street car - that's the equivalent of an extra 6hp in a 500hp car. Scoring a used battery from a track car is definitely a good win though, at least it reduces the impact of your wallet's weight on your butt dyno readings

The thing is you're not saving 45lbs by going lithium because you've significantly reduced the capacity of the battery as well. A 40Ah AGM battery is about 25lbs and US$100-150 whereas a 90Ah about 50lbs, so really you've saved 25lbs by reducing the capacity and then an additional 10lbs by going to lithium. The 10lbs saved by going to lithium costs around US$800 if you're paying retail ($950 for the 40Ah H5 AG vs ~$150 for a 40Ah AGM) and is 0.27% of the car's weight, which is the equivalent of 1.3hp increase in a 500hp car. The fact you scored this battery cheap makes this upgrade fairly reasonable (maybe "not unreasonable" is a better way to put it), but when you do the numbers with retail prices the "dollars per horsepower gained" with AG batteries is utterly ridiculous and, unless you've maxxed out weight savings EVERYWHERE else, pretty much pointless.

@ftype_rick if you're sold you're sold, but before you go throwing cash around try to think about it this way - would you pay VAP $800 for a tune that gave you 1.3hp? If the answer is no, install a 40Ah AGM and spend the $800 you saved on something worthwhile.

 

I don’t think I’d go 40ah so depends on 60ah AGM vs 95ah AGM…if that isn’t too far off of 60ah AG then a valid point. I’ll take a look, thanks. But 60ah AG vs 95ah AGM is 40lbs savings and that I can feel, albeit modestly. The idea is progress through compounded changes…VAP rotors, lightweight wheels and exhaust, plus AG battery saves close to 200lbs. That you feel! The web says the 17 R is ~3800 but the forum speaks to ~3950. If I drop 200lbs to 3750, I’m only 100 more than a 911 Turbo, but with more horsepower = similar power-to-weight ratio. My options to increase power at this point are limited so weight savings is the most cost efficient route to keep going, even if the marginal benefit is small. A bigger blower, pistons, and block sleeve to reach the 800 crank hp level means $10k+

 

Don't compare 95Ah AGM to 60Ah Antigravity... compare a 60Ah AGM to a 60Ah Antigravity. That comparison will give you a true indication of the savings by going to lithium, rather than thinking you're saving 40lbs when most of the saving comes from the capacity reduction. A 60Ah AGM is about 30lbs and the 60Ah Antigravity is 18lbs, so going lithium will save you about 12lbs. Anyone who can feel 12lbs in a ~3750lb street car (0.32%) is either lying, or suffering from confirmation bias.

I 100% support the approach of small improvements adding up to a big improvement (it's referred to as "Aggregate/aggregation of marginal gains" in racing circles) but I'm sure you can make a 0.32% improvement somewhere else for much much less than an AG battery.

If you have plenty of cash to throw at minimal gains, send me a PM and I'll make you carbon fibre panels. A bonnet is only $5500

 

I keep getting bounced around with your concerted efforts to dissuade someone from going from a stock 62 pound battery to a 18 pound 80Ah AG battery. That's a pretty fair amount of weight (44 lbs) on the drivers side to be rid of. I am no track guy but even I can feel the difference so it becomes an option to consider if you are replacing a stock battery, you like the emergency function and knowing that it comes with a five year warranty. If the cost is not a factor then it should be considered, at least as an option. If it doesn't work for someone that is certainly understandable.

 

how much weight does the bonnet save? Lol

 

Agree. The AG is $700 more than the AGM replacement but it gets you more than just 12lbs weight savings (compared to an AGM 60ah). The AG lifespan is 2x so back one AGM battery off the price. Now we’re at $400 extra. A portable jumpstart for the car (or avoiding asking a stranger for a jump) is worth $100 easy in my opinion. Now we’re at $300. So $300 for 12lbs. My VAP rotors were $2400 for 50lbs (rotating so maybe 100lbs worth in sprung). That’s $24/lb savings, vs $25/lb on the battery. OK, fine…I’m just trying to rationalize this purchase.

 

I might have to go dig up my calculator but my off the cuff math tells me that 62 pounds minus 18 pounds equal 44 pounds. That's 44 pounds less weight ..... you will need to recompute.....

 

You're right the AG lifespan was not factored in, I don't know if that's true or not so I'll leave that to your judgement. I also haven't factored in the cost of a new 95Ah AGM battery as it depends whether yours is dead or you're replacing a working one. My thoughts on AG batteries are great in a race car where you've already stripped half a ton out and every kilo counts, I just don't think they're good value in a street car and the main problem I see is that people don't factor in the weight they save just by reducing the capacity of the battery but staying with AGM.... when you do, the AG batteries start looking like poor value. The purpose of my post was to get you to have a proper think about the numbers and whether it's valuable to you... we aren't talking about my money so if you land on "yes" then go for it

I was joking about the CF bonnet, I do a bit of CF but am not set up for bonnets yet. Do you know the weight of the stock F-Type bonnet? CMST advertise their full CF as 45lbs and ~$2300usd, I'd be curious what the saving is and the cost per lb. Of course you've also got to weigh up the fully-sik-m8 factor of a CF bonnet, something you won't get from a battery 😂😂

 

You are falling into the trap AG's marketing has set for you - you are comparing a 95Ah wet battery to a 60Ah lithium battery, instead of comparing the lithium battery to a wet battery of the same capacity.

The weights I found in a very quick google were:
95Ah AGM battery = 58lbs
60Ah AGM = 30lbs
60Ah Antigravity = 18lbs

That means you can go from 58 to 30 for $170, or from 58 to 18 for $1050. Another way to think about this is that the first 28lbs cost you $170, while the next 12 cost you $880.

 

Possibly for many owners a good way to save 15lb of weight in the car would be to lose 15lbs themselves, and it would have attendant benefits. I might have a crack at it myself and see if the car seems faster.

 

BUT, that is the MOST DIFFICULT method of weight reduction.
XX:

Perhaps, a tummy-tuck?

 

Another performance option - Ozempic.

 

Dysentry makes it easy!

 

Sure would. Had it twice. Once in Bolivia and once in India. Didn't know which end to aim at the toilet.

 

Funny you say that, in bike racing it's not uncommon to have a coffee an hour or two before a race with the express intent of prompting a trip to the dunny! The running joke when someone is talking about spending $1000 to save 50 grams is that you can save more with a $5 coffee 🤣

This is analogous to the AG batteries - guys will spend $1000 to save 50g on their bike when they're 10kg overweight and could have saved much more at no cost just by tweaking their diet.... spending money is funnnnnn so it's easy to get blinded by the numbers and the marketing babble from parts companies, and often we don't stop to think about the value of what we're doing. If your diet and training are so dialled that you're at perfect race weight and you've maxxed out everything else then yes, 50g might be worth $1k.. but 99.9% of amateurs have a ton of large improvements they can make before there's any sense spending that kind of money for such a small gain. I think AG batteries are great if you've maxxed out everything else and you don't mind spending an average Joe's weekly pay cheque to shave an extra 10lbs, but worthless if you're still driving around with electric seats and a glass sunroof and all that stuff.. unfortunately AG's marketing works very hard to convince people like George to compare apples with oranges and spend $1k to shave 10lbs off a car that's several hundred kilos overweight.

 

I'm about 10kg overweight, I wonder what the "$ per lb" is on liposuction 🤣

 

But I have been taking Ozempic for three years now and I don't feel any performance improvement (in either the car or me)!
Disclaimer - I take Ozempic for the right reason - Type 2 diabetes - not to lose weight.

 

I use a CTEK lithium charger on an AG battery in my Jag. However, on my other vehicles, all of which use AGM batteries, I prefer to use an Optima charger which provides a lot more details of whaI the charger is doing. I am sure that either one will be just fine. I just thought I would offer you another alternative to complicate your decision.....

 

Sounds like the built in BMS went into thermal protection mode. if its like the lithium batteries i use in my camper they shut down around 26 degrees, they will still power accessories but not take a charge at low temps as it can damage them. Also will only drain until the voltage gets down too low to the low shutoff point set by the BMS then the BMS will cut it off completely, when this happens it usually requires using a charger to get it to once again take a charge. Till then it will just play dead. Im guessing your battery is still good.