Battery or Tender?

You could try using a different battery tender for a couple days and see if that makes a difference. Cheap to mail order one from Amazon and it'll come in handy for other vehicles

 

And another

 

Agreed

Buy a Ctek mxs 5.0 which is the same as what you have .. try it directly on battery ..if it charges fine you can swap the magnetic head from your charger to the Ctek by sacrificing the battery loop leads that come with tender or you can buy an adapter (very over priced)

If you don't want to buy anything first ..you will have to pierce the wires and run the leads to another good battery and see if this charger works

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No lights on tender normally means there is no connection to battery

 

The simplest thing is to put a direct pigtail with a SAE terminal on the battery terminals and leave it outside of the battery box. No BS intermittent connections etc. There are better chargers than the CTEK. I don't know why everybody is all wrapped up with CTEK. But if you are willing to do that your charging problems will be over. Also Get a bluetooth battery monitor and attach that while connecting the pigtail. I find after much experimentation and trial that the yellow Granite Battery Saver charger works the best of any. It comes with all the necessary pigtails. This thing does everything and with a monitor you can follow the charging status . desulfation mode, voltage, starting voltage drop etc.

https://www.amazon.com/Battery-Saver-2365-lcd-Charger-Maintainer/dp/B075NWPZ2B

https://www.amazon.com/QUICKLYNKS-Battery-Monitor-Bluetooth-Device/dp/B01MT4583U/ref=sr_1_5?keywords=bluetooth%2Bbattery%2Bmonitor&qid=1705417061&sr=8-5&th=1

 

I have a few of both .. the one you mentioned and the ctek 5.0 i mentioned above .. never had any issues .
The reason I like the ctek 5.0 is becuase it is basically the factor charger without "ferrari" on it ..especially in the case of a 458
I am sure either would be fine
The CTek got a bad rep with the older models including the ones ferrari used on the early 430s etc

 

Do you have an electrical voltmeter? If so take the reading directly from the positive and negative terminal. It look like the unit is not sensing any voltage. Is the cable seated completely in its adapter? Is there metal to metal contact of alligator clips to terminals? The plastic shields may be preventing contact. If you have a vom see what resting voltage is. If zero it may not try to charge battery as it senses no voltage of polarity. Strange.

 

If zero voltage then battery is shot. What does the manual say about completely discharged batteries? It may be the type that won’t charge a completely flat battery. I don’t have a manual handy just yet.

 

Do you have an old fashioned charger like a Schauer ?sp or harbor freight transformer charger? They will charge or at least apply a charging current to the flat battery. If the battery is as flat as it appears it is probably damaged beyond any trustworthy recovery. What voltage do you get with a stand alone vom?

 

7.2 bolts is too low
. Seems like your battery is toast
If you want continue to charge until you see 13 plus volts and see if battery hold charge

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7.2 volts is a dead battery. It probably has a shorted cell in it that caused a self discharge and killed the battery. Car won’t recognize or respond to that voltage snd you shouldn’t be even trying anything with the key starting etc on the car as the low voltage can seriously screw up the electronics, instrument cluster etc. this battery is toast as Dom also states. Quit wasting your time and get new one ASAP group H6 charge it up fully with the new charger then put it in car. Leave doors ajar so windows don’t bind and open frunk if you need to get in. I hope you electronics aren’t harmed. I lost a cluster on 430 when mechanic tried to start car with a partially charged battery.

 

The charger probably thinks it has charged a 6V battery to 7.2 and shows 100 percent charge. Dead cell internally shorted cell. What is the history of this battery you have? It probably has been deeply discharged before then sat in that state for a long time thus shorting and sulphating it beyond recovery. Start with a new one and keep it on tender at all time when not using and you will know the history. Also install a Bluetooth battery monitor as I have previously suggested. Let us know how it goes. When you get a new battery ,I would avoid an Optima spiral wound type as there have been a lot of quality issues with them. I you can get an Oddesy battery I think they are top
Notch. Other AGM H6 are fine also. JMHO.

 

i am having good experience with Duracell AGM 34r lately

 

Any lead acid battery (flooded, AGM, GEL, etc.) that has been taken down to zero volts, as this one has, is junk. There’s no fixing that battery, no matter what you try. Replace it. Then confirm that your battery tender is working correctly as it should have prevented the battery from getting down to zero volts.

 

Yes that would be a great battery. Also check out their extreme series. Where are you located? Napa stores may carry this line also. If you are ordering from Amazon throw in a Bluetooth battery monitor with the order and you’ll be good to go. Charge it up fully with the battery saver you have and attach the minder to it while charging and w at h what is happening during the charging cycles. You will have to download a program for your phone to use the Bluetooth monitor. I posted the link in the earlier posts in this thread. Also look for my posts in another thread that show the graphical interface with all charging parameters.

 

Buy a new battery.

 

Ive had really good luck with Interstate Batteries in my past Porsche's, My 488 and now my F8. I also drive my car every week or 2 and keep it on the stock Ferrari tender. My 488 got a new Interstate battery in spring 2021 and when I sold it May 2024 the battery was still in spec no issues.