I've managed to kill the almost new (less then 2 year) varta battery by letting her run very low for very long, and then came the frost, and now it won't hold the full charge for more than a week, I do a few short trips a week and few long a month so the battery have no time to fully recharge. I don't want have the car hanged on the charger like some blasphemous tesla owner so i thought to stick there AGM battery, at least in theory they recharge faster and take short trips and cold temperatures better then lead acids
Does anyone run that type on their car, how is your experience with them, are jag charge voltage adequate for the AGM?

 

Don't know anything about an AGM brand battery, but if you don't invest in a trickle charger of some type, you'll be breaking your back (and your wallet) changing out batteries. These cars have a natural draw on them, from the clock to the ECU to the security system. $45 for a Battery Tender for life or $190+ each time its dead. Plus, each time you let it bleed down, you kill the molecular structure of the cells and it deteriorates to the point of not accepting a charge anymore.

Also, letting the charge bleed off causes electrolytes to deplete and when recharged suddenly they swell and the case leaks. You let it bleed down again, it leaks and corrosion starts. Repeating this process, creates more corrosion. Then your replacing your battery cables or before that, your trying to figure out those electrical ghosts that seem unexplainable, but is the cause of letting the battery deplete. Don't say no one warned you.

I've had my Die Hard in mine for 10+ yrs now and I religiously use a Battery Tender. I use one on the Vette (another battery eating vehicle) ...and when I had it, used one on the Expedition. I have had zero corrosion on any of those vehicles with a tender.

 

I think xjack is referring to an Absorbed Glass Mat (AGM) battery rather than a brand name. AGM batteries have the electrolyte absorbed in a fiberglass matting rather than liquid sulfuric acid mix like a "regular" battery.

AGMs do not need to be checked for electrolyte levels and in my experience they do seem to have a longer service life, but they have different charging needs/characteristics. My battery charger has a specific AGM charge mode.

I have not used one on any of my cars/trucks but use AGMs on my motorcycle and they last over twice as long as regular "wet" batteries.

 

Thanks CK,..interesting... but still having the electrolytes, they aren't they still susceptible to power depletion and thus needing maintained or suffer the same consequences?

 

Yes i meant absorbed glass mat stuff, it is said they charge faster and don't deplete as fast as flooded type if left unused, also electrolyte evaporates at fraction of rate of normal battery so they last much longer, some people swear they are superior to old flooded lead acid type. If i'm not mistaken agm shouldn't be charger with more then 14.8v, not sure what is jag alternator output is and if it is really that important

 

Well, I did a quick review and there are Tenders for AGM's...because it states AGM's are highly sensitive to overcharging (the electrolytes I'm sure) and need to not fall below a certain charge level or be recharged with a big input charge.

 

Maximum voltage of car alternators, including Jag's, is 14.2 to 14.4 volt so no problem using an AGM battery. AGM batteries draw somewhat higher Amps during recharge (thus charging faster) but the Jag alternator should have no problem handling that. It is correct that AGM batteries hold their charge better when not in use but this is only when they are disconnected (they have lower rate of self-discharge). However, an AGM battery will discharge in the same way (and last the same number of days) as a standard battery in a parked Jaguar due to battery drain by the car's electronic systems. It will also suffer sulfation and loss of capacity if left at lower state of charge (this is when the battery voltage is down to 12 to 12.2 volts) for prolonged periods of time.

Basically, any lead-acid battery needs to be kept at close to 100% charge (at about 12.6 volts when off the charge) to get maximum life out of it. So, in the case of our Jaguars, there are three solutions: use the car every day or, if the car is going to be parked for more than 2-3 days, disconnect the battery or connect a trickle charger to it.

 

Indeed, 3 days was the magic # for mine to die, my NOCO Genius G1100 battery maintainer has been a godsend.

 

Do all of you guys keep jags on the trickle chargers?
I don't mind charging battery every now and then, but having it constantly on the charger don't appeal to my sense of garage aesthetics, my theory is that if varta lasted 1 year without going low (if i would not miss topping it up before winter it would probably still be fine), and given AMG recharges faster, then my usual short trips could suffice to keep it topped up.
If there is no issue with the fitting one to jag voltage-wise, then i will probably try and see how it does in real life, various forums folks seems to be extremely happy with them, the only drawback was high price but it is not the case anymore, i have seen them at slight extra compared to flooded type.

 

Mine's on the charger whenever not in use, there's no "aesthetic" issue for me as I use the eyelet connectors & just connect my extension cord when parked. To each their own, but I thoroughly enjoy my NOCO.

 

I travel extensively and anything over 2 weeks she gets put on the tender which keeps the battery fresh at a constant voltage. So the aspect of garage aesthetics, as KC says, is moot to having a car which starts when your out on the town.


The lead with the eyelets is a permanent connection to the battery lugs which all you have to do then is plug the line together and run it out the trunk and close it. I've never used the battery clip accessory.

 

My cheapo charger is not as impressive as yours but still up to the task of charging and trickle charging, it is just me too being too lazy to lift the boot panels every so often while feeling it should somehow be maintenance free thing, Permanent fit in the boot is not a bad idea at all but induction/wireless charger would be the absolute winner in case of jags
I will closely observe the voltages on AGM, hopefully it will do fine without my help and trickle charging.

 

Yeah, you'd think an original $80k car would be able to be hands off. But then again, Mercedes said the 722.6 trans was maintenance free...lol

 

Not that 5hp24 is an bullet proof fine tech, my previous jag gearbox didn't look like gonna-give-up-soon at twice that mileage.

 

AGM batteries are supposed to be more resilient to deep cycling, so losing a lot of charge and then recharging a lot... which normal SLA batteries get worn down by pretty quickly in comparison.

The comments on AGM specific chargers are correct, but most "smart" chargers should have an option for AGM batteries. Trickle chargers may be slightly different but should still have the option.

On using an AGM in these cars, I bought the auto parts store brand AGM because it was on sale and didnt cost much more than the "nice" SLA batteries, as well as a 1yr longer warranty. Had it for 4(?) years now, first year the car didn't get driven very much at all, mostly just started every few weeks and warmed up... since then it's been driven at least every few days, typically 5-6 days a week. No issues noticed with it yet.

 

4 years is a good score, mine seldom last more then 3 but again i don't give them any attention and just let them live till the end which usually happens at the third winter and then no amount of charging can fix it anymore.
All done now, got one online so it should arrive next week, i expect it to last much longer and require less attention this time