Newbie battery challenge only 12.4 V after charge

R

RobinTR6

New member
Ive bought a P300 F type. Done about 1000 miles so far without issue. I added Ctek battery Comfort indicator to the battery (bus bar and earth) and noted that overnioght it flashed amber and red. So charged with a Ctek 3.8 on the AGM mode overnight and in the am it had fully charged and the green monitor led on (along with all the other leds).

I measured voltage at 12.4V which I believe is ok but marginal. If I leave the car overnight iy drops to 12.1V. (yes double locked and Hazzard ligh off as it should after double lock).

Ive never had a Low Battery warning having repeated this process a couple of times just to check.

I did wonder if the Ctek 3.8v vs 5v was an issue but Ctek claims that my 3.8V should be fine for AGM up to 80AH.

Should I buy a new battery or leave well alone till I get 'Battery low warning' (which Ive never seen.

Thanks
Robin
 
Doesn't sound good - how old is the battery (you haven't given us any clue as to the age of the car, assuming it's on its original battery)? You could try a recondition cycle and see if that improves things.
 
Most use a CTEK 5.0, the 3.8 will get there just take a little longer. My indicator is wired in through the busbar and body only flashes green when connected to CTEK, always orange when disconnected. Maybe on its way out, wouldn’t rush to buy a battery but check the age and go and get a free battery check. See link.
https://www.national.co.uk/blog/how-to-find-your-car-battery-age
 
its a 2022 car first reg 27/5/22, I bought it a few months ago with 1,093 miles on clock so obviously not much use before me, so maybe battery suffered from lack of use before even tho its not old.

My convenience CTEK is the flashing green when CTEK charger says fully charged and on maintenance. However once I disconnect the CTEK the convenience flasher soon goes to amber flashing and volts now read 12,2V
 
It should be okay as less than 3 yrs old, it may not have been managed well with its low mileage. As SCM advised put it onto a recondition cycle. Wouldn’t pay to much attention to the amber on the comfort indicator, mine only shows green when connected to the CTEK unit.
 
MikeM said:
Wouldn’t pay to much attention to the amber on the comfort indicator, mine only shows green when connected to the CTEK unit.
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Ah, it's not just mine that does that then! :D
 
I gave my seven year old original battery a check this morning measured 12.83 volts at the terminals. I have it connected to the CTEK when not in use and give it an annual regen.
 
I'd give the battery one more 24 hour charge on the CTEK with it disconnected from the car. This clarifies if the issue is the battery failing or a current drain within the car.
However, an AGM should have a charge of 12.7v to 12.8v rested after a charge, so with it only reaching 12.4v after a long charge (80%) and 12.1v after standing overnight (55%), I'd just buy a new battery.
Ignore any voltage readings in the hours immediately after disconnecting the charger..
 
Looking at the information on a CTEK 3.8 they are only recommended for batteries up to 80ah, normally the F-Type has a 95ah battery also there is no regen function.
 
scm said:
MikeM said:
Wouldn’t pay to much attention to the amber on the comfort indicator, mine only shows green when connected to the CTEK unit.
Click to expand...

Ah, it's not just mine that does that then! :D
Click to expand...

Yeah, same with mine. My battery did need replacing when the F-Type was new to me within a couple of months, because I was constantly getting the low battery warning. Never had the warning since the new battery was fitted and I keep it on a CTEK 5.0 via a comfort indicator socket wired in whenever it’s in my garage at home (wired in as it correctly should, between the positive bus-bar and an earth-stud in the boot). The comfort indicator socket flashes green when on the charger and after a decent distance drive, but otherwise it flashes orange. I’ve never had it flashing red.
 
Hmm, I hook mine up to my CTEK5.0 every now and then. This thread reminded me that it perhaps would be good to run a full recondition charging but I read that you're not supposed to use that feature with AGM batteries. Clearly some of you do use the recond mode, so what's your view on that?

CTEK themselves apparently say "Reconding an AGM battery does not harm the battery, but does not help either, so we cannot recommend recond program on AGM batteries either.", as mentioned here:
https://www.jaguarforums.com/forum/xk-xkr-x150-33/ctek-mxs-5-agm-batteries-recondition-mode-282233/
 
Prior to last weekend I had not driven mine for quite a while although had been on the CTEK all the time, prior to starting I did have a battery low warning although started with no problems. I drove the car for more than an hour although ambient temperature was no more than 3 Deg.C still had a battery low warning when I switched the car off and then on again.When connecting the CTEK I put it into AGM regeneration mode and after completing the cycle no more battery low warning so it does work on AGM batteries and can find nothing to the contrary in the CTEK instructions. As per my previous post the battery at rest measures a healthy 12.83 volts, I know this does not give a definitive condition of the battery, but still looks good for a while.
 
Odd that you got the low battery warnings although the car had been hooked up to the charger all the time. Do you double lock the car when not using it? A couple of years ago mine started to throw low battery warnings although it seemed to be well charged. Seems like it was because I was always just single locking the car and since I started double locking it I've never seen the error message.

After some more googling it feels like the jury's still out on whether it's wise to use the CTEK recond feature with our AGM batteries so I think I'll stay clear of that option.
 
MajorTom said:
After some more googling it feels like the jury's still out on whether it's wise to use the CTEK recond feature with our AGM batteries so I think I'll stay clear of that option.
Click to expand...

Looking at the handbook that came with my MXS 5.0 it clearly shows the charging values for "CAR AGM RECON", so they seem to think it's okay to use.
 
Many people from different car forums asked CTEK and got similar answers as the one above. And as mentioned in that US forum thread, the manual states a 15.8V charging voltage for the recon function while the interwebz seem to suggest that AGM batteries can handle max 15V. That's all a bit too unclear for me to be happy with reconding my F-Type battery.
 
MajorTom said:
Odd that you got the low battery warnings although the car had been hooked up to the charger all the time. Do you double lock the car when not using it?
Click to expand...

I was quite surprised as well about the warning the car had been at step eight on the CTEK for the past month or so, normally the car goes out every week so does not go onto that step.I don’t think it was double locked, keyless entry so just push the door handle in. The links you posted made interesting reading although CTEK do say recon on a AGM battery will not have any effect it will not do any harm either. My own view on this is if you get five years out of a battery that’s ok and after that if you give it a regen every year to get rid of the battery low warning there is nothing to loose. With regard to the 15.8 volts, step one on the CTEK is to that value for up to eight hours although in practice this passes very quickly, the regen is a maximum of 15.8 volts although how high it actually goes who knows without actually measuring it.
 
NCE 61 said:
MajorTom said:
Odd that you got the low battery warnings although the car had been hooked up to the charger all the time. Do you double lock the car when not using it?
Click to expand...

I was quite surprised as well about the warning the car had been at step eight on the CTEK for the past month or so, normally the car goes out every week so normally does not go onto that step.I don’t think it was double locked, keyless entry so just push the door handle in. The links you posted made interesting reading although CTEK do say recon on a AGM battery will not have any effect it will not do any harm either. My own view on this is if you get five years out of a battery that’s ok and after that if you give it a regen every year to get rid of the battery low warning there is nothing to loose. With regard to the 15.8 volts, step one on the CTEK is to that value for up to eight hours although in practice this passes very quickly, the regen is a maximum of 15.8 volts although how high it actually goes who knows without actually measuring it.
Click to expand...

I would try double locking then. Apparently there are some gubbins which might not go entirely to sleep if you only single lock and may draw power. My car seems to be about the same age as yours, is still on its original battery, also often only gets out once a week or even more seldom when the weather is rubbish, is rarely hooked up to the CTEK and (touch wood) never throws the low battery warning since I started double locking it. You just need to press the door handle (not the button on the handle) a second time once it's retracted.
 
RobinTR6 said:
Now Im confused , my battery is 80AH not 95, might this be an (the issue) ?
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You should always try to have a battery of the specified Ah else it may not have enough power to meet the cars needs from cold cranking to the requirements to run the car and all its ancilliaries. It will likely have a lower CCA, although not directly linked to Ah.

Of course it's more likely to throw low voltage warnings and I'd certainly replace with the correct version.
 
Think battery is original, has a Jaguar label on it and its 80AH, is that why even with the CTEK comfort (Ctek 3amp) on for a couple of days and says 'Fully Charged'' battery still only reads 12.4V (car double locked) .

Still no warnings for low battery.

No mention orf replacement battery in service records either so seemingly original fitment.

Should I replace with a 95AH and a Ctek 5 or wait......(Battery and Ctek probs about £300)
 
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